WO2002056460A2 - Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components - Google Patents

Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components Download PDF

Info

Publication number
WO2002056460A2
WO2002056460A2 PCT/US2001/050953 US0150953W WO02056460A2 WO 2002056460 A2 WO2002056460 A2 WO 2002056460A2 US 0150953 W US0150953 W US 0150953W WO 02056460 A2 WO02056460 A2 WO 02056460A2
Authority
WO
WIPO (PCT)
Prior art keywords
detector
power amplifier
output signal
signal
power
Prior art date
Application number
PCT/US2001/050953
Other languages
French (fr)
Other versions
WO2002056460A3 (en
Inventor
David R. Pehlke
Ronald Meadows
Original Assignee
Telefonaktiebolaget L.M. Ericsson (Publ)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget L.M. Ericsson (Publ) filed Critical Telefonaktiebolaget L.M. Ericsson (Publ)
Priority to AT01990271T priority Critical patent/ATE511237T1/en
Priority to AU2002229135A priority patent/AU2002229135A1/en
Priority to EP01990271A priority patent/EP1356585B1/en
Publication of WO2002056460A2 publication Critical patent/WO2002056460A2/en
Publication of WO2002056460A3 publication Critical patent/WO2002056460A3/en

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0261—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the polarisation voltage or current, e.g. gliding Class A
    • H03F1/0272—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the polarisation voltage or current, e.g. gliding Class A by using a signal derived from the output signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion
    • H03F1/3241—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits
    • H03F1/3247—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits using feedback acting on predistortion circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H03F1/345—Negative-feedback-circuit arrangements with or without positive feedback using hybrid or directional couplers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B1/0475—Circuits with means for limiting noise, interference or distortion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B2001/0408—Circuits with power amplifiers
    • H04B2001/0433—Circuits with power amplifiers with linearisation using feedback

Definitions

  • the present invention relates to communications apparatus and methods, and more particularly, to power amplifier monitoring and control apparatus and methods.
  • Communications apparatus often include a power amplifier that is used to amplify a signal to appropriate levels for transmission, for example, in free space or on a transmission line.
  • wireless terminals e.g., cellular telephones and other wireless-capable devices
  • RF radio frequency
  • Power amplifiers often encounter non-ideal reflection arising from impedance mismatches between the power amplifier and transmission medium.
  • impedance mismatches may be caused by a variety of factors, including changes in surroundings caused by motion of the terminal and/or objects in the terminal's environment. Such changes may occur, for example, when the terminal is moved near a user's body or near reflective or shielding structures.
  • Impedance mismatches can significantly affect performance of a power amplifier.
  • impedance mismatch may cause the voltage standing wave ratio (NSWR) presented to the power amplifier to be high enough to cause damaging voltages and/or currents at the power amplifier's output
  • NSWR voltage standing wave ratio
  • large reflected power and high NSWR may lead to performance-degrading phenomena, such as ⁇ AM/AM and AM/PM distortion.
  • mismatch can be reduced by using an isolator or a balanced antenna circuit.
  • Other conventional approaches attempt to detect when undesirable or dangerous NSWR or reflected power conditions are present (or are about to be present), and take corrective and/or protective actions that can prevent damage or reduce performance degradation.
  • an apparatus for monitoring a power amplifier coupled to a transmission medium includes a detector circuit, coupled to the transmission medium, that generates first and second detector signals corresponding to respective fundamental and harmonic components of a power amplifier output signal produced by the power amplifier.
  • a comparing circuit is coupled to the detector circuit and compares the first and second detector signals. The comparing circuit, responsive to a comparison of the first and second detector signals, may generate a signal that indicates linearity of the power amplifier.
  • the detector circuit may generate the second detector signal without requiring phase information for the harmonic component.
  • the detector circuit may include a directional coupler and a first power detector that generate the first detector signal.
  • the second detector signal may be generated by a combination of a filter, in particular, a bandpass or high pass filter coupled to the transmission medium by a high impedance shunt circuit, and a second power detector.
  • a filter in particular, a bandpass or high pass filter coupled to the transmission medium by a high impedance shunt circuit
  • a second power detector may take advantage of a low pass filter coupled to the power amplifier's output, which reflects the harmonic component such that detection of the harmonic based on amplitude is substantially independent of impedance matching between the power amplifier and a load, such as an antenna.
  • the detector circuit includes a first directional coupler that couples a power amplifier to the antenna and that generates a first output signal responsive to the power amplifier output signal.
  • a first power detector is coupled to the first directional coupler and generates a first detector signal corresponding to a fundamental component of a power amplifier output signal from the first output signal.
  • the detector circuit further includes a second directional coupler that couples the power amplifier to the antenna and that generates a second output signal.
  • a second power detector, coupled to the second directional coupler generates a second detector signal corresponding to a harmonic component of the power amplifier output signal from the second output signal.
  • the first output signal may correspond to a forward fundamental component
  • the second output signal may correspond to a reflected harmonic component.
  • the second directional coupler may be a dual-band coupler that may also detect a reflected fundamental component.
  • an apparatus includes an antenna and a power amplifier that generates a power amplifier output signal in a transmission medium coupling the power amplifier to the antenna.
  • a detector circuit coupled to the transmission medium, generates first and second detector signals corresponding to respective fundamental and harmonic components of the power amplifier output signal.
  • a control circuit coupled to the detector circuit and operatively associated with the power amplifier, controls the power amplifier responsive to a comparison of the first and second detector signals.
  • the control circuit may control linearity of the power amplifier responsive to a comparison of the first and second detector signals, for example, by controlling the level of an input signal applied to the power amplifier and/or DC bias of the power amplifier.
  • the detector circuit may include various combinations of directional couplers and filter circuits as described above.
  • first and second detector signals corresponding to respective fundamental and harmonic components of a power amplifier output signal are generated.
  • the first and second detector signals are compared to determine linearity of the power amplifier.
  • the power amplifier linearity may be controlled responsive to the comparison of the first and second detector signals, for example, by controlling input signal level and/or DC bias.
  • FIGs. 1-4 are schematic block diagrams illustrating power amplifier monitoring apparatus and operations according to embodiments of the invention.
  • FIGs. 5-8 are schematic block diagrams illustrating power amplifier control apparatus and operations according to embodiments of the invention.
  • FIG. 9 is a schematic diagram illustrating a power detection, circuit according to embodiments of the invention.
  • FIG. 10 is a schematic diagram illustrating a power comparison circuit according to embodiments of the invention.
  • non-linear operation e.g., saturation or clipping
  • fundamental and harmonic components can be detected in ways that take advantage of components, such as directional couplers and output filters, typically used in wireless or other transmitters for purposes other than power amplifier linearity detection, as will be described for various embodiments of the invention herein.
  • FIG. 1 illustrates a power amplifier monitoring apparatus 100 according to embodiments of the invention.
  • a power amplifier 10 generates an output signal 11 (e.g., a radio frequency (RF) signal) on a transmission line 20.
  • the monitoring apparatus 100 includes a detector circuit 110, here shown as including first and second detectors 112, 114.
  • the first detector 112 generates a first detector signal 113 corresponding to a fundamental component of the power amplifier output signal 11.
  • the second detector 114 generates a second detector signal 115 that corresponds to a harmonic component of the power amplifier output signal 11.
  • the monitoring apparatus 100 further includes a comparing circuit 120 that compares the first and second detector signals 113,.115, and generates a power amplifier linearity indicating signal 125 based on the comparison.
  • the linearity indicating signal 125 is generated based on a comparison of the first and second detector signals 113, 115.
  • the first and second detector signals 113, 115 may be analog signal power sense signals that are generated using diode-type power detection circuits, such as the detection circuit 930 discussed below with reference to FIG. 9. Such signals may be compared using, for example, an analog comparison circuit, such as the comparison circuit 1000 discussed below with reference to FIG. 10.
  • the detector circuit 110 and the comparing circuit 120 of the monitoring apparatus 100 may be implemented in a number of different forms.
  • the detector circuit 100 may utilize analog and/or digital circuitry to implement the functions of the detectors 112, 114, such as frequency selective couplers and analog filters that detect selected components of the power amplifier output signal 11, and analog power detectors that determine respective power levels of the passed components.
  • analogous digital circuitry such as by code executing on a data processor such as a microprocessor, microcontroller or digital signal processor (DSP).
  • the comparing circuit 120 may be implemented in analog circuitry, digital circuitry, or combinations thereof.
  • the detector signals 113, 115 produced by the detector circuit 110 include respective analog voltages representing respective power levels of respective fundamental and harmonic components of the power amplifier output signal 11, the comparing circuit 120 may include, for example, an analog comparator circuit or a similar circuit that compares the respective voltage levels and generates and output signal representative of the comparison. It will be appreciated, however, that other comparison techniques may also be used.
  • FIG. 2 illustrates an exemplary implementation of a power amplifier monitoring apparatus 200 according to embodiments of the invention. As in FIG. 1, a
  • power amplifier 10 generates an output signal 11 on a transmission line 20, here shown as connected to a low pass filter 30 and an antenna 40.
  • the power amplifier monitoring apparatus 200 includes a detector circuit 210 coupled to the transmission line 20.
  • the detector circuit 210 includes a directional coupler 211 coupled to a first power detector 214a.
  • the directional coupler 211 and the first power 0 detector 214a generate a first detector signal 215a representing power of a forward fundamental component of the power amplifier output signal 11.
  • the detector circuit 210 further includes first, second, and third bandpass filters 213a, 213b, 213b, that are capacitively coupled to the transmission line 20 by a high-impedance capacitive shunt circuit 212.
  • the bandpass filters 213a, 213b, 213c 5 may be designed to respective harmonics of the fundamental frequency of the power amplifier output signal 11.
  • the respective bandpass filters 213a, 213b, 213c generate respective second, third, and fourth detector signals 215b, 215c, 215d representing respective power levels of respective harmonic components of the power 0 amplifier output signal 11.
  • the detector signal 215a for the forward fundamental component is compared with the detector signals 215b, 215c, 215d for the harmonic components in a comparing circuit 220, which generates a linearity indicating signal 225 based on the comparison.
  • the detector circuit 210 and comparing circuit 220 of 5 the monitoring apparatus 200 may be implemented using a variety of different components.
  • the power detectors 214a, 214b, 214c may include discrete RF diode detector circuits and/or integrated circuit devices that provide similar functionality.
  • such detector circuits may produce an analog and/or a digital output signal representative of the power detected by the detector circuit 210.
  • the comparing circuit 220 may include analog and/or digital circuitry appropriate for processing such signals.
  • the monitoring apparatus 200 can take advantage of elements that are typically found in a wireless terminal or other device, but are conventionally used for other purposes.
  • a directional coupler and associated power detector such as the directional coupler 211 and the first power detector 214a, may be used in a wireless te ⁇ ninal to perform conventional power control functions, such as output power and VSWR control. Accordingly, generation of the first detector signal 215a may not require additional hardware.
  • the shunt circuit 212 and filters 213a, 213b, 213c can take advantage of the presence of the output filter 30 to simplify detection of harmonics.
  • a potential problem in determining power levels for a harmonic is accounting for changes in relative amplitudes of forward and reflected harmonic waves arising from changes in impedance on the transmission line 20.
  • the low pass filter 30, which is typically designed to preferentially pass the fundamental component of the power amplifier output signal 11, may reflect the harmonic such that detection of the harmonic power based on amplitude information is substantially independent of antenna matching.
  • This allows the use of shunt elements, such as the shunt circuit 312 and filters 313a, 313b, 313c, which can provide potentially less loss than might be experienced if additional series elements are used.
  • FIG. 3 illustrates an alternative configuration for a power amplifier monitoring apparatus 300 according to other embodiments of the invention.
  • the power amplifier 10, transmission line 20, low pass filter 30 and antenna 40 are as described above with reference to FIG. 2.
  • the monitoring apparatus 300 includes a detector circuit 310 coupled to the transmission line 20 and operatively associated with a comparing circuit 320.
  • the detector circuit 310 includes a forward directional coupler 311 coupled to a first power detector 314a, which produces a first detector signal 315a representing power of a forward fundamental component of a power amplifier output signal 11.
  • a second, dual-band directional coupler 312 has a first output coupled to a second power detector 314b, which generates a second detector signal 315b that
  • ⁇ 1 represents power of a reflected fundamental component of the power amplifier output signal 11.
  • the second directional coupler 312 also has a second output coupled to a bank of bandpass filters 313a, 313b, 313c. Respective ones of the bandpass filters 313a, 313b, 313c pass respective selected harmonics of the fundamental of the power amplifier output signal 11. Respective ones of the band pass filters 313a, 313b, 313c are coupled to respective ones of third, fourth and fifth power detectors 314c, 314d, 314e, which generate respective third, fourth and fifth detector signals 315c, 315d, 315e representing respective power levels of the selected harmonics.
  • FIG. 4 illustrates yet another alternative configuration for a power amplifier monitoring apparatus 400 according to other embodiments of the invention.
  • the power amplifier 10, transmission line 20, low pass filter 30 and antenna 40 are as described above with reference to FIG. 2.
  • the monitoring apparatus 400 includes a detector circuit 410 coupled to the transmission line 20 and operatively associated with a comparing circuit 420.
  • the detector circuit 410 includes a forward directional coupler 411 coupled to a first power detector 414a, which produces a first detector signal 415a representing power of a forward fundamental component of a power amplifier output signal 11.
  • a second, dual-band directional coupler 412 has a first output coupled to a second power detector 414b, which generates a second detector signal 415b that represents power of a reflected fundamental component of the power amplifier output signal 11.
  • the second directional coupler 412 also has a second output coupled to a high pass filter 413.
  • the high-pass filter 413 passes one or more selected harmonics of the fundamental.
  • the high pass filter 413 is coupled to a broadband power detector 414c, which generates a third detector signal 415c representing an aggregate power level of the selected harmonic(s).
  • the third detector signal 415c and the first detector signal 415a are compared by the comparing circuit 420 to generate a linearity indicating signal 425.
  • the first and second detector signals 415a, 415b may also be passed on to a circuit 50 that detects VSWR and/or reflected power.
  • FIG. 5 illustrates other embodiments of the present invention.
  • a signal processing circuit 510 including a power amplifier 512, generates an output signal 11 on a transmission line 20.
  • the signal processing circuit 510 is responsive to a control input 535 to adjust the linearity of the power amplifier 512, for example, to change the DC bias if the power amplifier 512 and/or the input signal level presented to the power amplifier 512.
  • a detector circuit 520 is coupled to the transmission line 20, and includes first and second detectors 522, 524 that generate respective first and second detector signals 523, 525 corresponding to respective fundamental and harmonic components of the power amplifier output signal 11.
  • a control circuit 530 is responsive to the first and second detector signals 523, 525 and generates the control input 535 based on a comparison of the first and second detector signals 523, 525.
  • a power amplifier 610 receives an input signal 631 from a variable gain circuit 636 of a control circuit 630 and, responsively thereto, generates an output signal 11 on a transmission line 20 coupled to a low pass filter 30 and antenna 40.
  • the power amplifier 610 operates with a DC bias controlled by a bias control signal 633 applied by a processor 634 in the control circuit 630.
  • a detector circuit 620 is coupled to the transmission line 20, and includes a first and second directional couplers 62.1a, 621b coupled to respective first and second power detectors 624a, 624b.
  • the first and second power detectors 624a, 624b generate respective first and second detector signals 625a, 625b representing respective forward and reflected fundamental power levels of the power amplifier output signal 11.
  • the detector circuit 620 further includes first, second and third bandpass filters 623a, 623b, 623c coupled to the transmission line 20 by a shunt circuit 622. Responsive to the bandpass filters 623a, 623b, 623c, third, fourth, and fifth power detectors 624c, 624d, 624e generate third, fourth and fifth detector signals 625c, 625d, 625e that represent respective power levels of respective harmonic components of the power amplifier output signal 11.
  • the control circuit 630 further includes first, second, third, fourth, and fifth analog to digital (A/D) converters 632a, 632b, 632c, 632d, 632e that receive respective ones of the detector signals 625a, 625b, 625c, 625d, 6235e, and generate digital values therefrom representing respective measured power levels for the fundamental and harmonic components. These digital values are passed on to the processor 634, which generates a level control signal 635 for the variable gain circuit 636 and the bias control signal 633 based on a comparison of the digital values.
  • A/D analog to digital
  • the detector circuit 620 and the control circuit 630 of FIG. 6 may be implemented in a number of different ways.
  • the processor 634 may include a microcontroller, microcomputer, digital signal processor or similar computing device, which may implement other computing or signal processing operations in addition to the comparing and control operations described above.
  • the variable gain circuit 636 may, for example, be a variable gain amplifier or similar device in an RF signal path, or may be integrated into other signal processing apparatus, such as a modulator, that can vary the level of the input signal 631 applied to the power amplifier 610.
  • An implementation as might be used in a wireless terminal according to embodiments of the invention is illustrated in FIG. 7.
  • a power amplifier 710 receives an input signal 731 (e.g., an RF carrier modulated signal) from a modulator 736 in a control circuit 730.
  • the modulator 736 generates the input signal 731 responsive to a data signal- 739 generated by a baseband processor 734 of the control circuit 730, with a level that is controlled responsive to a level control signal 735.
  • the power amplifier 710 Responsive to the input signal 731, the power amplifier 710 generates an output signal 11 on a transmission line 20 coupled to a low pass filter 30 and antenna 40.
  • the power amplifier 710 operates with a DC bias controlled by a bias control signal 733 applied by the baseband processor 734.
  • a detector circuit 720 is coupled to the transmission line 20, and includes a first and second directional couplers 721a, 721b coupled to respective first and second power detectors 724a, 724b.
  • the first and second power detectors 724a, 724b generate respective first and second detector signals 725a, 725b representing respective forward and reflected fundamental power levels of the power amplifier output signal 11.
  • the detector circuit 720 further includes first, second and third bandpass filters 723a, 723b, 723c coupled to the transmission line 20 by a shunt circuit 722.
  • third, fourth, and fifth power detectors 724c, 724d, 724e Responsive to the bandpass filters 723a, 723b, 723c, third, fourth, and fifth power detectors 724c, 724d, 724e generate third, fourth and fifth detector signals 725c, 725d, 725e that represent respective power levels of respective harmonic components of the power amplifier output signal 11.
  • the control circuit 730 also includes first, second, third, fourth, and fifth analog to digital (A/D) converters 732a, 732b, 732c, 732d, 732e that receive respective ones of the detector signals 725a, 725b, 725c, 725d, 725e, and generate digital values therefrom representing respective measured power levels for the fundamental and harmonic components. These digital values are passed on to the baseband processor 734, which generates the level control signal 735 and the bias control signal 733 based on a comparison of the fundamental and harmonic power levels represented by the digital values. Other embodiments of the invention are illustrated in FIG. 8.
  • a power amplifier 810 receives an input signal 831 from a variable gain amplifier 832 of a control circuit 830.
  • the variable gain amplifier 832 generates the input signal 831 responsive to a carrier-modulated signal 839 generated by, for example, a modulator (not shown), at a gain that is controlled responsive to a level control signal 835. Responsive to the input signal 831, the power amplifier 810 generates an output signal 11 on a transmission line 20 coupled to a low pass filter 30 and antenna 40. The power amplifier 810 operates with a DC bias controlled by a bias control signal 833 applied by the bias control circuit 834 included in the control circuit 830.
  • a detector circuit 820 is coupled to the transmission line 20, and includes a first and second directional couplers 821a, 821b coupled to respective first and second power detectors 824a, 824b.
  • the first and second power detectors 824a, 824b generate respective first and second detector signals 825a, 825b representing respective forward and reflected fundamental power levels of the power amplifier output signal 11.
  • the detector circuit 820 further includes first, second and third bandpass filters 823a, 823b, 823c coupled to the transmission line 20 by a shunt circuit 822.
  • third, fourth, and fifth power detectors 824c, 824d, 824e Responsive to the outputs of the bandpass filters 823a, 823b, 823c, third, fourth, and fifth power detectors 824c, 824d, 824e generate third, fourth and fifth detector signals 825c, 825d, 825e that represent respective power levels of respective harmonic components of the power amplifier output signal 11.
  • the control circuit 830 receives the detector signals 825a, 825b, 825c, 825d, 825e, and controls the variable gain amplifier 832 and the bias control circuit 834 responsive to a comparison of the detector signals 825a, 825b, 825c, 825d, 825e.
  • FIG. 9 illustrates a power detection circuit 930, in particular, an envelope-type power detection circuit, that may be used with the present invention.
  • the power detection circuit 930 is coupled, along with a termination circuit 920, to a directional coupler 910.
  • the directional coupler 910 is also coupled to a transmission line 901, e.g., a transmission line connecting a power amplifier to an antenna, and generates a signal that is applied to the power detection circuit 930 responsive to a signal present on the transmission line 901.
  • the power detection circuit 930 includes a diode pair 932 that produces a power second signal 935 that is biased and filtered by first and second circuits 934, 936.
  • the second circuit 936 may be configured such that the power sense signal 935 represents a selected component, e.g., fundamental or harmonic, of a signal present on the transmission line 901.
  • FIG. 10 illustrates an exemplary comparison circuit 1000 that compares respective power sense signals 1001a, 1001b for respective fundamental and harmonic components of a signal.
  • the power sense signals 1001a, 1001b are threshold detected by respective threshold detector circuits 1010a, 1010b and amplified by respective variable gain amplifiers 1020a, 1020b.
  • the variable gain amplifiers 1020a, 1020b generate respective signals that have desired levels for comparison of the fundamental and harmonic components that are applied to a comparator circuit 1030, e.g., an operational amplifier circuit configured to generate a signal 1005 indicative of the relative power levels of the fundamental and harmonic components represented by the power sense signals 1001a, 1001b.
  • the signal 1005 may serve, for example, as an indication of linearity of a power amplifier that produces the fundamental and harmonic components, as described above with reference to FIG. 1.
  • the power detection circuit 930 of FIG. 9 and the comparison circuit 1000 of FIG. 10 are provided for exemplary purposes, and that a variety of other types of detector and comparison circuits may be used with the invention. It will be understood that, in general, such circuits may include analog and/or digital circuitry.

Abstract

An apparatus for monitoring a power amplifier coupled to a transmission medium includes a detector circuit, coupled to the transmission medium, that generates first and second detector signals corresponding to respective fundamental and harmonic components of a power amplifier output signal produced by the power amplifier. A comparing circuit is coupled to the detector circuit and compares the first and second detector signals. The comparing circuit, responsive to a comparison of the first and second detector signals, may generate a signal that indicates linearity of the power amplifier. In some embodiments, the detector circuit may generate the second detector signal without requiring phase information for the harmonic component. In other embodiments, a control circuit controls linearity of the power amplifier responsive to comparison of the first and second detector signals, for example, by controlling power amplifier bias and/or input signal level based on the comparison. Related methods are also discussed.

Description

APPARATUS AND METHODS FOR MONITORING AND CONTROLLING POWER AMPLIFIER LINEARITY USING DETECTED FUNDAMENTAL AND
HARMONIC COMPONENTS
BACKGROUND OF THE INVENTION The present invention relates to communications apparatus and methods, and more particularly, to power amplifier monitoring and control apparatus and methods. Communications apparatus often include a power amplifier that is used to amplify a signal to appropriate levels for transmission, for example, in free space or on a transmission line. For example, wireless terminals (e.g., cellular telephones and other wireless-capable devices) typically include a power amplifier that is used to amplify a radio frequency (RF) signal for transmission by an antenna. Power amplifiers often encounter non-ideal reflection arising from impedance mismatches between the power amplifier and transmission medium. In the case of a wireless teπninal power amplifier, for example, impedance mismatches may be caused by a variety of factors, including changes in surroundings caused by motion of the terminal and/or objects in the terminal's environment. Such changes may occur, for example, when the terminal is moved near a user's body or near reflective or shielding structures.
Impedance mismatches can significantly affect performance of a power amplifier. For example, impedance mismatch may cause the voltage standing wave ratio (NSWR) presented to the power amplifier to be high enough to cause damaging voltages and/or currents at the power amplifier's output In addition, large reflected power and high NSWR may lead to performance-degrading phenomena, such as ■ AM/AM and AM/PM distortion.
Conventional solutions for avoiding or reducing such problems include reducing mismatch and/or reducing its damaging or degrading effects. In a wireless terminal, for example, mismatch can be reduced by using an isolator or a balanced antenna circuit. Other conventional approaches attempt to detect when undesirable or dangerous NSWR or reflected power conditions are present (or are about to be present), and take corrective and/or protective actions that can prevent damage or reduce performance degradation.
SUMMARY OF THE INVENTION
In embodiments of the invention, an apparatus for monitoring a power amplifier coupled to a transmission medium includes a detector circuit, coupled to the transmission medium, that generates first and second detector signals corresponding to respective fundamental and harmonic components of a power amplifier output signal produced by the power amplifier. A comparing circuit is coupled to the detector circuit and compares the first and second detector signals. The comparing circuit, responsive to a comparison of the first and second detector signals, may generate a signal that indicates linearity of the power amplifier.
In some embodiments of the invention, the detector circuit may generate the second detector signal without requiring phase information for the harmonic component. For example, the detector circuit may include a directional coupler and a first power detector that generate the first detector signal. The second detector signal may be generated by a combination of a filter, in particular, a bandpass or high pass filter coupled to the transmission medium by a high impedance shunt circuit, and a second power detector. Such a configuration may take advantage of a low pass filter coupled to the power amplifier's output, which reflects the harmonic component such that detection of the harmonic based on amplitude is substantially independent of impedance matching between the power amplifier and a load, such as an antenna. In other embodiments of the invention, the detector circuit includes a first directional coupler that couples a power amplifier to the antenna and that generates a first output signal responsive to the power amplifier output signal. A first power detector is coupled to the first directional coupler and generates a first detector signal corresponding to a fundamental component of a power amplifier output signal from the first output signal. The detector circuit further includes a second directional coupler that couples the power amplifier to the antenna and that generates a second output signal. A second power detector, coupled to the second directional coupler, generates a second detector signal corresponding to a harmonic component of the power amplifier output signal from the second output signal. The first output signal may correspond to a forward fundamental component, and the second output signal may correspond to a reflected harmonic component. The second directional coupler may be a dual-band coupler that may also detect a reflected fundamental component.
According to other embodiments of the invention, an apparatus includes an antenna and a power amplifier that generates a power amplifier output signal in a transmission medium coupling the power amplifier to the antenna. A detector circuit, coupled to the transmission medium, generates first and second detector signals corresponding to respective fundamental and harmonic components of the power amplifier output signal. A control circuit, coupled to the detector circuit and operatively associated with the power amplifier, controls the power amplifier responsive to a comparison of the first and second detector signals. In particular, the control circuit may control linearity of the power amplifier responsive to a comparison of the first and second detector signals, for example, by controlling the level of an input signal applied to the power amplifier and/or DC bias of the power amplifier. The detector circuit may include various combinations of directional couplers and filter circuits as described above. According to method embodiments of the invention, first and second detector signals corresponding to respective fundamental and harmonic components of a power amplifier output signal are generated. The first and second detector signals are compared to determine linearity of the power amplifier. The power amplifier linearity may be controlled responsive to the comparison of the first and second detector signals, for example, by controlling input signal level and/or DC bias.
BRIEF DESCRIPTION OF THE DRAWINGS FIGs. 1-4 are schematic block diagrams illustrating power amplifier monitoring apparatus and operations according to embodiments of the invention. FIGs. 5-8 are schematic block diagrams illustrating power amplifier control apparatus and operations according to embodiments of the invention.
FIG. 9 is a schematic diagram illustrating a power detection, circuit according to embodiments of the invention. FIG. 10 is a schematic diagram illustrating a power comparison circuit according to embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As will be appreciated by those of skill in the art, the present invention may be embodied as methods or apparatus.
For power amplifier applications in which an input signal having a desired, fundamental frequency is applied to a power amplifier, non-linear operation (e.g., saturation or clipping) of the amplifier can be detected by comparison of fundamental and harmonic components of the output signal produced by the amplifier. These fundamental and harmonic components can be detected in ways that take advantage of components, such as directional couplers and output filters, typically used in wireless or other transmitters for purposes other than power amplifier linearity detection, as will be described for various embodiments of the invention herein.
FIG. 1 illustrates a power amplifier monitoring apparatus 100 according to embodiments of the invention. A power amplifier 10 generates an output signal 11 (e.g., a radio frequency (RF) signal) on a transmission line 20. The monitoring apparatus 100 includes a detector circuit 110, here shown as including first and second detectors 112, 114. The first detector 112 generates a first detector signal 113 corresponding to a fundamental component of the power amplifier output signal 11. The second detector 114 generates a second detector signal 115 that corresponds to a harmonic component of the power amplifier output signal 11. The monitoring apparatus 100 further includes a comparing circuit 120 that compares the first and second detector signals 113,.115, and generates a power amplifier linearity indicating signal 125 based on the comparison.
The linearity indicating signal 125 is generated based on a comparison of the first and second detector signals 113, 115. For example, the first and second detector signals 113, 115 may be analog signal power sense signals that are generated using diode-type power detection circuits, such as the detection circuit 930 discussed below with reference to FIG. 9. Such signals may be compared using, for example, an analog comparison circuit, such as the comparison circuit 1000 discussed below with reference to FIG. 10.
It will also be appreciated that, generally, the detector circuit 110 and the comparing circuit 120 of the monitoring apparatus 100 may be implemented in a number of different forms. For example, the detector circuit 100 may utilize analog and/or digital circuitry to implement the functions of the detectors 112, 114, such as frequency selective couplers and analog filters that detect selected components of the power amplifier output signal 11, and analog power detectors that determine respective power levels of the passed components. Some of these functions may alternatively be performed by analogous digital circuitry, such as by code executing on a data processor such as a microprocessor, microcontroller or digital signal processor (DSP).
Similarly, the comparing circuit 120 may be implemented in analog circuitry, digital circuitry, or combinations thereof. For example, if the detector signals 113, 115 produced by the detector circuit 110 include respective analog voltages representing respective power levels of respective fundamental and harmonic components of the power amplifier output signal 11, the comparing circuit 120 may include, for example, an analog comparator circuit or a similar circuit that compares the respective voltage levels and generates and output signal representative of the comparison. It will be appreciated, however, that other comparison techniques may also be used.
FIG. 2 illustrates an exemplary implementation of a power amplifier monitoring apparatus 200 according to embodiments of the invention. As in FIG. 1, a
5. power amplifier 10 generates an output signal 11 on a transmission line 20, here shown as connected to a low pass filter 30 and an antenna 40. The power amplifier monitoring apparatus 200 includes a detector circuit 210 coupled to the transmission line 20. The detector circuit 210 includes a directional coupler 211 coupled to a first power detector 214a. In combination, the directional coupler 211 and the first power 0 detector 214a generate a first detector signal 215a representing power of a forward fundamental component of the power amplifier output signal 11.
The detector circuit 210 further includes first, second, and third bandpass filters 213a, 213b, 213b, that are capacitively coupled to the transmission line 20 by a high-impedance capacitive shunt circuit 212. The bandpass filters 213a, 213b, 213c 5 may be designed to respective harmonics of the fundamental frequency of the power amplifier output signal 11. In combination with respective second, third and fourth power detectors 214b, 214c, 214d, the respective bandpass filters 213a, 213b, 213c generate respective second, third, and fourth detector signals 215b, 215c, 215d representing respective power levels of respective harmonic components of the power 0 amplifier output signal 11. The detector signal 215a for the forward fundamental component is compared with the detector signals 215b, 215c, 215d for the harmonic components in a comparing circuit 220, which generates a linearity indicating signal 225 based on the comparison.
It will be understood that the detector circuit 210 and comparing circuit 220 of 5 the monitoring apparatus 200 may be implemented using a variety of different components. For example, the power detectors 214a, 214b, 214c may include discrete RF diode detector circuits and/or integrated circuit devices that provide similar functionality. As will be appreciated by those skilled in the art, such detector circuits may produce an analog and/or a digital output signal representative of the power detected by the detector circuit 210. Accordingly, the comparing circuit 220 may include analog and/or digital circuitry appropriate for processing such signals.
The monitoring apparatus 200 can take advantage of elements that are typically found in a wireless terminal or other device, but are conventionally used for other purposes. In particular, a directional coupler and associated power detector, such as the directional coupler 211 and the first power detector 214a, may be used in a wireless teπninal to perform conventional power control functions, such as output power and VSWR control. Accordingly, generation of the first detector signal 215a may not require additional hardware. The shunt circuit 212 and filters 213a, 213b, 213c can take advantage of the presence of the output filter 30 to simplify detection of harmonics. In particular, a potential problem in determining power levels for a harmonic is accounting for changes in relative amplitudes of forward and reflected harmonic waves arising from changes in impedance on the transmission line 20. The low pass filter 30, which is typically designed to preferentially pass the fundamental component of the power amplifier output signal 11, may reflect the harmonic such that detection of the harmonic power based on amplitude information is substantially independent of antenna matching. This allows the use of shunt elements, such as the shunt circuit 312 and filters 313a, 313b, 313c, which can provide potentially less loss than might be experienced if additional series elements are used.
' FIG. 3 illustrates an alternative configuration for a power amplifier monitoring apparatus 300 according to other embodiments of the invention. The power amplifier 10, transmission line 20, low pass filter 30 and antenna 40 are as described above with reference to FIG. 2. The monitoring apparatus 300 includes a detector circuit 310 coupled to the transmission line 20 and operatively associated with a comparing circuit 320. The detector circuit 310 includes a forward directional coupler 311 coupled to a first power detector 314a, which produces a first detector signal 315a representing power of a forward fundamental component of a power amplifier output signal 11. A second, dual-band directional coupler 312 has a first output coupled to a second power detector 314b, which generates a second detector signal 315b that
■ 1 represents power of a reflected fundamental component of the power amplifier output signal 11.
The second directional coupler 312 also has a second output coupled to a bank of bandpass filters 313a, 313b, 313c. Respective ones of the bandpass filters 313a, 313b, 313c pass respective selected harmonics of the fundamental of the power amplifier output signal 11. Respective ones of the band pass filters 313a, 313b, 313c are coupled to respective ones of third, fourth and fifth power detectors 314c, 314d, 314e, which generate respective third, fourth and fifth detector signals 315c, 315d, 315e representing respective power levels of the selected harmonics. The third, fourth and fifth detector signals 315c, 315d, 315e, representing the harmonic power levels, and the first detector signal 315a, representing the forward fundamental power, are compared by the comparing circuit 320 to generate a linearity indicating signal 325. As shown, the first and second detector signals 315a, 315b may also be passed on to a circuit 50 that detects VSWR and/or reflected power. FIG. 4 illustrates yet another alternative configuration for a power amplifier monitoring apparatus 400 according to other embodiments of the invention. The power amplifier 10, transmission line 20, low pass filter 30 and antenna 40 are as described above with reference to FIG. 2. The monitoring apparatus 400 includes a detector circuit 410 coupled to the transmission line 20 and operatively associated with a comparing circuit 420. The detector circuit 410 includes a forward directional coupler 411 coupled to a first power detector 414a, which produces a first detector signal 415a representing power of a forward fundamental component of a power amplifier output signal 11. A second, dual-band directional coupler 412 has a first output coupled to a second power detector 414b, which generates a second detector signal 415b that represents power of a reflected fundamental component of the power amplifier output signal 11.
The second directional coupler 412 also has a second output coupled to a high pass filter 413. The high-pass filter 413 passes one or more selected harmonics of the fundamental. The high pass filter 413 is coupled to a broadband power detector 414c, which generates a third detector signal 415c representing an aggregate power level of the selected harmonic(s). The third detector signal 415c and the first detector signal 415a are compared by the comparing circuit 420 to generate a linearity indicating signal 425. As shown, the first and second detector signals 415a, 415b may also be passed on to a circuit 50 that detects VSWR and/or reflected power. FIG. 5 illustrates other embodiments of the present invention. A signal processing circuit 510, including a power amplifier 512, generates an output signal 11 on a transmission line 20. The signal processing circuit 510 is responsive to a control input 535 to adjust the linearity of the power amplifier 512, for example, to change the DC bias if the power amplifier 512 and/or the input signal level presented to the power amplifier 512. A detector circuit 520 is coupled to the transmission line 20, and includes first and second detectors 522, 524 that generate respective first and second detector signals 523, 525 corresponding to respective fundamental and harmonic components of the power amplifier output signal 11. A control circuit 530 is responsive to the first and second detector signals 523, 525 and generates the control input 535 based on a comparison of the first and second detector signals 523, 525.
According to other embodiments of the invention illustrated in FIG. 6, a power amplifier 610 receives an input signal 631 from a variable gain circuit 636 of a control circuit 630 and, responsively thereto, generates an output signal 11 on a transmission line 20 coupled to a low pass filter 30 and antenna 40. The power amplifier 610 operates with a DC bias controlled by a bias control signal 633 applied by a processor 634 in the control circuit 630. A detector circuit 620 is coupled to the transmission line 20, and includes a first and second directional couplers 62.1a, 621b coupled to respective first and second power detectors 624a, 624b. The first and second power detectors 624a, 624b generate respective first and second detector signals 625a, 625b representing respective forward and reflected fundamental power levels of the power amplifier output signal 11.
The detector circuit 620 further includes first, second and third bandpass filters 623a, 623b, 623c coupled to the transmission line 20 by a shunt circuit 622. Responsive to the bandpass filters 623a, 623b, 623c, third, fourth, and fifth power detectors 624c, 624d, 624e generate third, fourth and fifth detector signals 625c, 625d, 625e that represent respective power levels of respective harmonic components of the power amplifier output signal 11.
The control circuit 630 further includes first, second, third, fourth, and fifth analog to digital (A/D) converters 632a, 632b, 632c, 632d, 632e that receive respective ones of the detector signals 625a, 625b, 625c, 625d, 6235e, and generate digital values therefrom representing respective measured power levels for the fundamental and harmonic components. These digital values are passed on to the processor 634, which generates a level control signal 635 for the variable gain circuit 636 and the bias control signal 633 based on a comparison of the digital values.
It will be appreciated that the detector circuit 620 and the control circuit 630 of FIG. 6 may be implemented in a number of different ways. For example, the processor 634 may include a microcontroller, microcomputer, digital signal processor or similar computing device, which may implement other computing or signal processing operations in addition to the comparing and control operations described above. The variable gain circuit 636 may, for example, be a variable gain amplifier or similar device in an RF signal path, or may be integrated into other signal processing apparatus, such as a modulator, that can vary the level of the input signal 631 applied to the power amplifier 610. An implementation as might be used in a wireless terminal according to embodiments of the invention is illustrated in FIG. 7. A power amplifier 710 receives an input signal 731 (e.g., an RF carrier modulated signal) from a modulator 736 in a control circuit 730. The modulator 736 generates the input signal 731 responsive to a data signal- 739 generated by a baseband processor 734 of the control circuit 730, with a level that is controlled responsive to a level control signal 735. Responsive to the input signal 731, the power amplifier 710 generates an output signal 11 on a transmission line 20 coupled to a low pass filter 30 and antenna 40. The power amplifier 710 operates with a DC bias controlled by a bias control signal 733 applied by the baseband processor 734. A detector circuit 720 is coupled to the transmission line 20, and includes a first and second directional couplers 721a, 721b coupled to respective first and second power detectors 724a, 724b. The first and second power detectors 724a, 724b generate respective first and second detector signals 725a, 725b representing respective forward and reflected fundamental power levels of the power amplifier output signal 11. The detector circuit 720 further includes first, second and third bandpass filters 723a, 723b, 723c coupled to the transmission line 20 by a shunt circuit 722. Responsive to the bandpass filters 723a, 723b, 723c, third, fourth, and fifth power detectors 724c, 724d, 724e generate third, fourth and fifth detector signals 725c, 725d, 725e that represent respective power levels of respective harmonic components of the power amplifier output signal 11.
The control circuit 730 also includes first, second, third, fourth, and fifth analog to digital (A/D) converters 732a, 732b, 732c, 732d, 732e that receive respective ones of the detector signals 725a, 725b, 725c, 725d, 725e, and generate digital values therefrom representing respective measured power levels for the fundamental and harmonic components. These digital values are passed on to the baseband processor 734, which generates the level control signal 735 and the bias control signal 733 based on a comparison of the fundamental and harmonic power levels represented by the digital values. Other embodiments of the invention are illustrated in FIG. 8. A power amplifier 810 receives an input signal 831 from a variable gain amplifier 832 of a control circuit 830. The variable gain amplifier 832 generates the input signal 831 responsive to a carrier-modulated signal 839 generated by, for example, a modulator (not shown), at a gain that is controlled responsive to a level control signal 835. Responsive to the input signal 831, the power amplifier 810 generates an output signal 11 on a transmission line 20 coupled to a low pass filter 30 and antenna 40. The power amplifier 810 operates with a DC bias controlled by a bias control signal 833 applied by the bias control circuit 834 included in the control circuit 830.
A detector circuit 820 is coupled to the transmission line 20, and includes a first and second directional couplers 821a, 821b coupled to respective first and second power detectors 824a, 824b. The first and second power detectors 824a, 824b generate respective first and second detector signals 825a, 825b representing respective forward and reflected fundamental power levels of the power amplifier output signal 11. The detector circuit 820 further includes first, second and third bandpass filters 823a, 823b, 823c coupled to the transmission line 20 by a shunt circuit 822. Responsive to the outputs of the bandpass filters 823a, 823b, 823c, third, fourth, and fifth power detectors 824c, 824d, 824e generate third, fourth and fifth detector signals 825c, 825d, 825e that represent respective power levels of respective harmonic components of the power amplifier output signal 11. The control circuit 830 receives the detector signals 825a, 825b, 825c, 825d, 825e, and controls the variable gain amplifier 832 and the bias control circuit 834 responsive to a comparison of the detector signals 825a, 825b, 825c, 825d, 825e.
It will be appreciated that the embodiments described with reference to FIGs. 7 and 8 are provided for illustrative purposes, and that a variety of other circuit configurations fall within the scope of the invention. For example, instead of determining power for discrete, multiple harmonics as illustrated in FIGs. 7 and 8, power of a single harmonic or an aggregate of harmonics may be determined. In addition, instead of shunt-type harmonic detection, dual-band directional couplers (as described, for example, with reference to FIGs. 3 and 4) or other devices may be used to detect harmonics. Techniques for controlling power amplifier linearity other than input signal level and bias may also be used.
FIG. 9 illustrates a power detection circuit 930, in particular, an envelope-type power detection circuit, that may be used with the present invention. As shown, the power detection circuit 930 is coupled, along with a termination circuit 920, to a directional coupler 910. The directional coupler 910 is also coupled to a transmission line 901, e.g., a transmission line connecting a power amplifier to an antenna, and generates a signal that is applied to the power detection circuit 930 responsive to a signal present on the transmission line 901. The power detection circuit 930 includes a diode pair 932 that produces a power second signal 935 that is biased and filtered by first and second circuits 934, 936. In particular, the second circuit 936 may be configured such that the power sense signal 935 represents a selected component, e.g., fundamental or harmonic, of a signal present on the transmission line 901.
FIG. 10 illustrates an exemplary comparison circuit 1000 that compares respective power sense signals 1001a, 1001b for respective fundamental and harmonic components of a signal. The power sense signals 1001a, 1001b are threshold detected by respective threshold detector circuits 1010a, 1010b and amplified by respective variable gain amplifiers 1020a, 1020b. In conjunction with the threshold detector circuits 1010a, 1010b, the variable gain amplifiers 1020a, 1020b generate respective signals that have desired levels for comparison of the fundamental and harmonic components that are applied to a comparator circuit 1030, e.g., an operational amplifier circuit configured to generate a signal 1005 indicative of the relative power levels of the fundamental and harmonic components represented by the power sense signals 1001a, 1001b. The signal 1005 may serve, for example, as an indication of linearity of a power amplifier that produces the fundamental and harmonic components, as described above with reference to FIG. 1.
It will be appreciated that the power detection circuit 930 of FIG. 9 and the comparison circuit 1000 of FIG. 10 are provided for exemplary purposes, and that a variety of other types of detector and comparison circuits may be used with the invention. It will be understood that, in general, such circuits may include analog and/or digital circuitry.
In the drawings and specification, there have been disclosed typical illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.

Claims

WHAT IS CLAIMED IS:
1. An apparatus for monitoring a power amplifier coupled to a transmission medium, the apparatus comprising: a detector circuit, coupled to the transmission medium, that generates first and second detector signals corresponding to fundamental and harmonic components, respectively, of a power amplifier output signal produced by the power amplifier; and a comparing circuit, coupled to the detector circuit, that compares the first and second detector signals.
2. An apparatus according to Claim 1, wherein the comparing circuit is operative to generate a signal that indicates linearity of the power amplifier responsive to a comparison of the first and second detector signals.
3. An apparatus according to Claim 1, wherein the detector circuit is operative to generate the second detector signal without requiring phase information for the harmonic component.
4. An apparatus according to Claim 1, wherein the detector circuit comprises: a directional coupler that couples the power amplifier to the antenna and that generates an output signal responsive to the power amplifier output signal; and a power detector, coupled to the directional coupler, that generates the first detector signal from the output signal generated by the directional coupler.
5. An apparatus according to Claim 4, wherein the detector circuit further comprises: . . a filter, coupled to the transmission medium, that filters the power amplifier output signal to produce a filtered output signal; and a power detector, coupled to the filter, that generates the second detector signal from the filtered output signal.
6. An apparatus according to Claim 5, wherein the filter is capacitively coupled to the transmission medium.
7. An apparatus according to Claim 4:
..wherein the directional coupler comprises a first directional coupler that couples the power amplifier to the antenna and that generates a first output signal responsive to the power amplifier output signal; wherein the power detector comprises a first power detector, coupled to the first directional coupler, that generates the first detector signal from the first output signal; and wherein the detector circuit further comprises: a second directional coupler that couples the power amplifier to the antenna and that generates a second output signal; and a second power detector, coupled to the second directional coupler, that generates the second detector signal from the second output signal.
8. An apparatus according to Claim 7, wherein the first output signal corresponds to a forward fundamental component, wherein the second output signal corresponds to a reflected harmonic component, and wherein the second directional coupler generates a third output signal corresponding to a reflected fundamental component.
9. An apparatus according to Claim 8, further comprising a third power detector, coupled to the second directional coupler, that processes the third output signal to determine power reflected to the power amplifier.
10. An apparatus according to Claim 1 , wherein the detector circuit comprises: a filter, coupled to the transmission medium, that filters the power amplifier output signal to produce a filtered output signal; and a power detector, coupled to the filter, that generates the second detector signal from the filtered output signal.
11. An apparatus according to Claim 10, wherein the filter is capacitively coupled to the transmission medium.
12. An apparatus according to Claim 1, wherein the detector circuit comprises: a directional coupler that couples the power amplifier to the antenna and that generates an output signal; and a power detector, coupled to the directional coupler, that generates the second detector signal from the directional coupler output signal.
13. An apparatus according to Claim 1, wherein the first and second detector signals represent first and second powers for the fundamental and harmonic components, respectively.
14. An apparatus according to Claim 13, wherein the first detector signal represents a forward power for the fundamental component.
15. An apparatus according to Claim 14, wherein the second detector signal represents a reflected power for the harmonic component.
16. An apparatus according to Claim 1, wherein the second detector signal comprises a plurality of second detector signals, respective ones of which correspond to respective harmonic components of the power amplifier output signal.
17. An apparatus, comprising: an antenna; a power amplifier that generates a power amplifier output signal in a transmission medium coupling the power amplifier to the antenna; a detector circuit, coupled to the transmission medium, that generates first and second detector signals corresponding to fundamental and harmonic components, respectively, of the power amplifier output signal; and a control circuit, coupled to the detector circuit and operatively associated with the power amplifier, that controls the power amplifier responsive to a comparison of the first and second detector signals.
18. An apparatus according to Claim 17, wherein the control circuit controls linearity of the power amplifier responsive to a comparison of the first and second detector signals.
19. An apparatus according to Claim 18, wherein the control circuit, responsive to a comparison of the first and second detector signals, controls at least one of a level of an input signal applied to the power amplifier and a DC bias of the power amplifier.
20. An apparatus according to Claim 19, wherein the control circuit comprises: a baseband processor that generates a data signal; and a modulator, coupled to the baseband processor, that receives the data signal and modulates the received data signal to generate the input signal such that the level of the input signal varies responsive to a level control signal applied to the modulator, wherein the power amplifier receives the input signal and generates the power amplifier output signal therefrom, and wherein the baseband processor is responsive to the detector circuit to generate the level control signal applied to the modulator responsive to a comparison of the first and second detector signals.
21. An apparatus according to Claim 20, wherein the baseband processor is further operative to apply a bias control signal to the power amplifier responsive to a comparison of the first and second detector signals.
22. An apparatus according to Claim 19, wherein the control circuit comprises a variable gain circuit, responsive to the detector circuit, that generates the input signal with a gain that is dependent upon a comparison of the first and second detector signals.
23. An apparatus according to Claim 19, wherein the control circuit comprises a bias control circuit, responsive to the detector circuit, that applies a bias control signal to the power amplifier responsive to a comparison of the first and second detector signals.
24. An apparatus according to Claim 17, wherein the detector circuit is operative to generate the second detector signal without requiring phase information for the harmonic component.
25. An apparatus according to Claim 17, wherein the detector circuit comprises: a directional coupler that couples the power amplifier to the antenna and that generates an output signal responsive to the power amplifier output signal; and a power detector, coupled to the directional coupler, that generates the first detector signal from the output signal generated by the directional coupler.
26. An apparatus according to Claim 25 : wherein the directional coupler comprises a first directional coupler that couples the power amplifier to the antenna and that generates a first output signal responsive to the power amplifier output signal; wherein the power detector comprises a first power detector, coupled to the first directional coupler, that generates the first detector signal from the first output signal; and wherein the detector circuit further comprises: a second directional coupler that couples the power amplifier to the antenna and that generates a second output signal; and a second power detector, coupled to the second directional coupler, that generates the second detector signal from the second output signal.
27. An apparatus according to Claim 26, wherein the first output signal corresponds to a forward fundamental component, wherein the second output signal corresponds to a reflected harmonic component, and wherein the second directional coupler generates a third output signal corresponding to a reflected fundamental component.
28. An apparatus according to Claim 27, further comprising a third power detector circuit, coupled to the second directional coupler, that processes the third output signal to determine power reflected to the power amplifier.
29. An apparatus according to Claim 17, wherein the first detector signal represents a forward power for the fundamental component.
■ 30. An apparatus according to Claim 29, wherein the second detector signal represents a reflected power for the harmonic component.
31. An apparatus according to Claim 17, wherein the first and second detector signals represent respective powers for the fundamental and harmonic components.
32. An apparatus according to Claim 17, wherein the detector circuit comprises: a filter, coupled to the transmission medium, that filters the power amplifier output signal to produce a filtered output signal; and a power detector, coupled to the filter, that generates the second detector signal from the filtered output signal.
33. An apparatus according to Claim 32, wherein the filter is capacitively coupled to the transmission medium.
34. An apparatus according to Claim 17, wherein the detector circuit comprises: a directional coupler that couples the power amplifier to the antenna and that generates an output signal; and a power detector, coupled to the directional coupler, that generates the second detector signal from the directional coupler output signal.
35. An apparatus according to Claim 17, wherein the second detector signal comprises a plurality of second detector signals, respective ones of which correspond to respective harmonic components of the power amplifier output signal.
36. A method, comprising: generating first and second detector signals corresponding to respective fundamental and harmonic components of a power amplifier output signal produced in a transmission medium by a power amplifier; and comparing the first and second detector signals to determine linearity of the power amplifier.
37. A method according to Claim 36, wherein the step of comparing comprises generating a signal that indicates linearity of the power amplifier.
38. A method according to Claim 36, wherein the step of generating first and second detector signals comprises the step of generating the second detector signal without using phase information for the harmonic component.
39. A method according to Claim 36, wherein the first and second detector signals represent respective powers for the fttndamental and harmonic components.
40. A method according to Claim 36, wherein the first detector signal represents a forward power for the fundamental component.
41. A method according to Claim 36, wherein the second detector signal represents a reflected power for the harmonic component.
42. A method according to Claim 36, wherein the second detector signal comprises a plurality of second detector signals, respective ones of which correspond to respective harmonic components of the power amplifier output signal.
43. A method according to Claim 36, further comprising controlling linearity of the power amplifier responsive to a comparison of the first and second detector signals.
44. A method according to Claim 43, wherein the step of controlling comprises controlling, responsive to a comparison of the first and second detector signals, at least one of a level of an input signal applied to the power amplifier and a DC bias of the power amplifier.
PCT/US2001/050953 2001-01-12 2001-12-19 Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components WO2002056460A2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AT01990271T ATE511237T1 (en) 2001-01-12 2001-12-19 DEVICE AND METHOD FOR MONITORING AND CONTROLLING THE LINEARITY OF A POWER AMPLIFIER BY DETECTING FUNDAMENTAL AND HARMONICS
AU2002229135A AU2002229135A1 (en) 2001-01-12 2001-12-19 Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components
EP01990271A EP1356585B1 (en) 2001-01-12 2001-12-19 Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/759,739 2001-01-12
US09/759,739 US6960956B2 (en) 2001-01-12 2001-01-12 Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components

Publications (2)

Publication Number Publication Date
WO2002056460A2 true WO2002056460A2 (en) 2002-07-18
WO2002056460A3 WO2002056460A3 (en) 2003-09-04

Family

ID=25056777

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2001/050953 WO2002056460A2 (en) 2001-01-12 2001-12-19 Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components

Country Status (5)

Country Link
US (1) US6960956B2 (en)
EP (1) EP1356585B1 (en)
AT (1) ATE511237T1 (en)
AU (1) AU2002229135A1 (en)
WO (1) WO2002056460A2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108199742A (en) * 2017-11-13 2018-06-22 深圳市万普拉斯科技有限公司 Self-tuning method, self-tuning system and mobile terminal

Families Citing this family (48)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7071776B2 (en) * 2001-10-22 2006-07-04 Kyocera Wireless Corp. Systems and methods for controlling output power in a communication device
US20040072554A1 (en) * 2002-10-15 2004-04-15 Triquint Semiconductor, Inc. Automatic-bias amplifier circuit
US20040070454A1 (en) * 2002-10-15 2004-04-15 Triquint Semiconductor, Inc. Continuous bias circuit and method for an amplifier
US7010284B2 (en) * 2002-11-06 2006-03-07 Triquint Semiconductor, Inc. Wireless communications device including power detector circuit coupled to sample signal at interior node of amplifier
US6924698B2 (en) * 2003-07-31 2005-08-02 Agilent Technologies, Inc. Power detector for mismatched load
US7023292B2 (en) * 2003-12-17 2006-04-04 Telefonaktiebolaget L.M. Dericsson Polar modulation using amplitude modulated quadrature signals
US20050208907A1 (en) * 2004-03-18 2005-09-22 Ryo Yamazaki Detecting and maintaining linearity in a power amplifier system through envelope power comparisons
US20050227646A1 (en) * 2004-03-18 2005-10-13 Ryo Yamazaki Detecting and maintaining linearity in a power amplifier system through comparing peak and RMS power levels
US7327803B2 (en) 2004-10-22 2008-02-05 Parkervision, Inc. Systems and methods for vector power amplification
US7355470B2 (en) 2006-04-24 2008-04-08 Parkervision, Inc. Systems and methods of RF power transmission, modulation, and amplification, including embodiments for amplifier class transitioning
US7440731B2 (en) * 2005-07-27 2008-10-21 Freescale Semiconductor, Inc. Power amplifier with VSWR detection and correction feature
US8334722B2 (en) 2007-06-28 2012-12-18 Parkervision, Inc. Systems and methods of RF power transmission, modulation and amplification
US7911272B2 (en) 2007-06-19 2011-03-22 Parkervision, Inc. Systems and methods of RF power transmission, modulation, and amplification, including blended control embodiments
US8031804B2 (en) 2006-04-24 2011-10-04 Parkervision, Inc. Systems and methods of RF tower transmission, modulation, and amplification, including embodiments for compensating for waveform distortion
US7937106B2 (en) 2006-04-24 2011-05-03 ParkerVision, Inc, Systems and methods of RF power transmission, modulation, and amplification, including architectural embodiments of same
US8170604B2 (en) * 2006-06-27 2012-05-01 Motorola Mobility, Inc. Method and system for managing communications for a multi-mode communications device
US8315336B2 (en) 2007-05-18 2012-11-20 Parkervision, Inc. Systems and methods of RF power transmission, modulation, and amplification, including a switching stage embodiment
US20080102874A1 (en) * 2006-10-28 2008-05-01 Motorola, Inc. Control of transmit power of a second transmitter based on antenna loading parameters measured on a first transmitter
US8665778B2 (en) 2006-11-30 2014-03-04 Motorola Mobility Llc Monitoring and control of transmit power in a multi-modem wireless communication device
US8059702B2 (en) * 2006-11-30 2011-11-15 Motorola Mobility, Inc. Monitoring multiple modem transmission in a communication device
US8744519B2 (en) * 2006-12-14 2014-06-03 Motorola Mobility Llc Multimodal phone data session management enhancement that alleviates dual transmission problems
US20080160990A1 (en) * 2006-12-29 2008-07-03 Yair Karmi System, method and apparatus for identification of power control using reverse rate indication
US8311496B2 (en) * 2007-02-26 2012-11-13 Broadcom Corporation Transmitter with digital up conversion and multimode power amplifier
US7804922B2 (en) * 2007-03-02 2010-09-28 Skyworks Solutions, Inc. System and method for adjacent channel power detection and dynamic bandwidth filter control
US20080297171A1 (en) * 2007-05-30 2008-12-04 Ruppel Christopher D Transceiver system that estimates a voltage standing wave ratio
WO2008156800A1 (en) 2007-06-19 2008-12-24 Parkervision, Inc. Combiner-less multiple input single output (miso) amplification with blended control
DE102007028695A1 (en) 2007-06-21 2009-01-02 Kathrein-Austria Ges.M.B.H. Method and device for generating an amplitude-modulated signal
US8606200B2 (en) * 2007-06-26 2013-12-10 Intel Corporation Error vector magnitude control within a linear transmitter
US8195250B2 (en) * 2008-04-30 2012-06-05 Motorola Mobility, Inc. Method and apparatus for controlling power among modems in a multi-mode mobile communication device
WO2009145887A1 (en) 2008-05-27 2009-12-03 Parkervision, Inc. Systems and methods of rf power transmission, modulation, and amplification
US7768353B2 (en) 2008-06-13 2010-08-03 Samsung Electro-Mechanics Company, Ltd. Systems and methods for switching mode power amplifier control
TW201236365A (en) * 2011-02-25 2012-09-01 Novatek Microelectronics Corp Method and device of automatic gain control
WO2012139126A1 (en) 2011-04-08 2012-10-11 Parkervision, Inc. Systems and methods of rf power transmission, modulation, and amplification
WO2012167111A2 (en) 2011-06-02 2012-12-06 Parkervision, Inc. Antenna control
DE102011106234A1 (en) * 2011-06-27 2012-12-27 Tesat-Spacecom Gmbh & Co.Kg Method and apparatus for protecting a high frequency power amplifier against mismatch
US9313596B2 (en) * 2011-08-19 2016-04-12 D'amore Engineering Llc Audio signal distortion detection device
US20130324057A1 (en) * 2012-05-31 2013-12-05 Qualcomm Incorporated Determining a delivered power estimate and a load impedance estimate using a directional coupler
US9281852B2 (en) * 2013-01-04 2016-03-08 Marvell World Trade Ltd. Method and apparatus for calibrating time alignment
JP5897529B2 (en) * 2013-03-07 2016-03-30 株式会社東芝 Power amplifier and transmitter
US9418950B2 (en) * 2013-04-24 2016-08-16 Skyworks Solutions, Inc. Multiple band multiple mode transceiver front end flip-chip architecture and circuitry with integrated power amplifiers
KR20160058855A (en) 2013-09-17 2016-05-25 파커비전, 인크. Method, apparatus and system for rendering an information bearing function of time
CN105637770B (en) * 2013-10-16 2018-07-10 株式会社村田制作所 R-T unit
CN103532587B (en) * 2013-10-24 2015-07-08 天津光电通信技术有限公司 L-band RF system output port protection equipment
JP2016058773A (en) 2014-09-05 2016-04-21 ルネサスエレクトロニクス株式会社 Semiconductor device and radio communication equipment
US9866335B2 (en) * 2015-03-31 2018-01-09 Skyworks Solutions, Inc. Testing circuit with directional coupler
US20200044612A1 (en) * 2018-07-31 2020-02-06 Advanced Micro Devices, Inc. Transmitter dynamic rf power control via vswr detection for wireless radios
US11082011B1 (en) 2019-02-07 2021-08-03 Harmonic, Inc. RF power amplifier performance by clipping prevention of large PAPR signals
DE102019119177A1 (en) * 2019-07-16 2021-01-21 Tu Dresden Arrangement for impedance matching

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4882547A (en) * 1988-11-15 1989-11-21 General Electric Company Linearizer control system
US5164678A (en) * 1990-07-12 1992-11-17 Asea Brown Boveri Ltd Process for compensating nonlinearities in an amplifier circuit

Family Cites Families (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3641451A (en) * 1970-02-24 1972-02-08 Motorola Inc Amplifier protection circuit
US3852669A (en) * 1973-06-26 1974-12-03 Us Army Circuit to protect rf output amplifier against mismatch damage
US4011512A (en) * 1975-05-21 1977-03-08 Motorola, Inc. Electrical component failure detection apparatus
US4019150A (en) 1975-11-17 1977-04-19 Motorola, Inc. PA protection circuit for a single sideband radio
JPS6110327Y2 (en) 1980-01-10 1986-04-03
US4885551A (en) * 1988-10-31 1989-12-05 American Telephone And Telegraph Company At&T Bell Laboratories Feed forward linear amplifier
GB2233515B (en) * 1989-06-20 1993-12-15 Technophone Ltd Levelling control circuit
US5036527A (en) * 1990-02-05 1991-07-30 Hayes Microcomputer Products, Inc. Iterative automatic gain control for an analog front end of a modem
US5278994A (en) * 1991-06-03 1994-01-11 Motorola, Inc. Power amplifier saturation detection and correction method and apparatus
JP2876837B2 (en) * 1991-08-20 1999-03-31 日本電気株式会社 Detection circuit
US5196808A (en) * 1991-12-02 1993-03-23 Motorola, Inc. RF amplifier protector and method
US5423081A (en) * 1993-08-16 1995-06-06 Hughes Aircraft Company Cellular power amplifier power level control circuitry
US5722056A (en) 1993-08-20 1998-02-24 Motorola, Inc. Radio transmitter with power amplifier linearizer
US5524285A (en) 1993-11-02 1996-06-04 Wray; Anthony J. Radio transmitter with power amplifier and linearization
JPH07154169A (en) 1993-11-30 1995-06-16 Matsushita Electric Ind Co Ltd High frequency power amplifier
US5530923A (en) 1994-03-30 1996-06-25 Nokia Mobile Phones Ltd. Dual mode transmission system with switched linear amplifier
JP3192323B2 (en) 1994-07-29 2001-07-23 沖電気工業株式会社 Power control circuit
JPH08307182A (en) 1995-04-27 1996-11-22 Sony Corp Power control circuit
US5973568A (en) 1998-06-01 1999-10-26 Motorola Inc. Power amplifier output module for dual-mode digital systems
JP2001016116A (en) * 1999-07-02 2001-01-19 Nec Corp Portable radio equipment
KR100674586B1 (en) * 1999-12-30 2007-01-25 엘지전자 주식회사 Predistortion linearizer for HPA

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4882547A (en) * 1988-11-15 1989-11-21 General Electric Company Linearizer control system
US5164678A (en) * 1990-07-12 1992-11-17 Asea Brown Boveri Ltd Process for compensating nonlinearities in an amplifier circuit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108199742A (en) * 2017-11-13 2018-06-22 深圳市万普拉斯科技有限公司 Self-tuning method, self-tuning system and mobile terminal
US11265036B2 (en) 2017-11-13 2022-03-01 Oneplus Technology (Shenzhen) Co., Ltd. Self-tuning method, self-tuning system and mobile terminal

Also Published As

Publication number Publication date
EP1356585B1 (en) 2011-05-25
ATE511237T1 (en) 2011-06-15
AU2002229135A1 (en) 2002-07-24
WO2002056460A3 (en) 2003-09-04
US20020094791A1 (en) 2002-07-18
US6960956B2 (en) 2005-11-01
EP1356585A2 (en) 2003-10-29

Similar Documents

Publication Publication Date Title
EP1356585B1 (en) Apparatus and methods for monitoring and controlling power amplifier linearity using detected fundamental and harmonic components
US6233438B1 (en) Wide-range power control systems and methods for radio frequency transmitters and mobile radiotelephones
US8606200B2 (en) Error vector magnitude control within a linear transmitter
KR101216562B1 (en) Detector circuit and semiconductor device using the same
US20110190028A1 (en) Power Amplifier Linearization Feedback Methods and Systems
EP1093222A1 (en) Transmitter and receiver
WO1996031954A1 (en) Output power controller
US7920836B2 (en) System and method for saturation detection, correction and recovery in a polar transmitter
WO2009052283A2 (en) Adaptively tuned rf power amplifier
JP2005051775A (en) Transmitting apparatus and method of mobile communication terminal equipment
US8442459B2 (en) Transmitter and communication apparatus using the same
CN112753175B (en) Electronic device for controlling communication circuit based on signal received from antenna
US10992268B2 (en) Radio frequency amplification device capable of detecting the frequency band
KR102582479B1 (en) Electronic device for tuning module for processing radio frequency signals
EP1719250A1 (en) Load insensitive power amplifier
US20030119462A1 (en) Apparatus for linear transmitter with improved loop gain stabilization
JPH04352528A (en) High frequency power amplifier
KR102090466B1 (en) Interference suppression for switched mode power supply with error correction
KR20130013702A (en) Antenna and impedance matching device comprising the same
JP2003087129A (en) Radio transmitter circuit
US6791406B2 (en) Power servo-loop, an RF signal amplifier circuit, and an RF signal transmitter fitted with such a circuit
US20210344307A1 (en) Load detection circuit and amplifier circuit
JP2003017957A (en) High frequency amplifier and receiver employing the same
KR100377794B1 (en) Apparatus for compensating mixer signal loss of BTS in a communication system
KR100377023B1 (en) Variable attenuator

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2001990271

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2001990271

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP