SINGLE CHIP TUNER FOR MULTI RECEIVER APPLICATIONS
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is related to co-pending and commonly assigned United States patent application serial number 09/572,393 entitled "Broadband Integrated Tuner," filed May 15, 2000, which is a continuation of United States patent application serial number 08/904,908, now patent number 6,177,964, entitled "Broadband Integrated Television Tuner," filed August 1, 1997, and United States patent application serial number 09/407,734 entitled "System and Method for a Single Conversion Tuner," filed September 28, 1999, the disclosures of which are hereby incorporated herein by reference.
SINGLE CHIP TUNER FOR MULTI RECEIVER APPLICATIONS
TECHNICAL FIELD OF THE INVENTION
[0002] The invention relates to tuner circuits and more particularly to tuner circuit configurations adapted for use in multiple tuner applications.
BACKGROUND OF THE INVENTION
[0003] Presently more and more applications using multiple tuners are developing. For example, state-of-the-art consumer electronic devices are beginning to utilize multiple TV tuners, such as for providing picture-in-picture functionality or for recording multiple programs using emerging digital television recording systems. In addition to the above mentioned more traditional television tuner type applications, many less traditional tuner applications which may benefit from the use of multiple tuners are developing, such as the use of television tuners installed in personal computer (PC) systems, thereby allowing the PC to function as a television set or receive data from a broadband broadcast such as in a cable modem system.
[0004] However, there is difficulty in providing a configuration of multiple tuners coupled to a common received signal, such as a cable television signal. Many of the multiple tuner applications demand high quality signal output, such as a low bit error rate in the aforementioned cable modem applications or a sharp and relatively high definition image in the aforementioned television picture applications. Moreover, many such applications provide relatively little space for accommodating multiple tuners and associated circuitry. For example, consumer electronic devices, such as television recording systems, and computer components, such as PC expansion boards, are becoming smaller and smaller, thus requiring small footprint components, such as the aforementioned multiple tuner circuits.
[0005] One current solution for providing multiple tuners for such applications is to provide splitters, which are devices provided one input and two outputs, in a signal path to provide a received signal to multiple tuners. For example, a first splitter may be provided to couple a received signal to a first tuner and the received signal to a second splitter which, in turn, couples the received signal to a second and third tuner. However, such a solution utilizes an appreciable amount of space to accommodate the splitter network. Moreover, such splitters generally degrade the signal being split and, therefore, are may not be acceptable for providing a desired tuner output signal quality without the addition of discrete amplifier circuits. However, the use of such amplifier components, further aggravates the aforementioned space issues.
[0006] Another solution for providing multiple tuners is to utilize devices referred to as "micro-splitters," which are amplifying devices with one input and several outputs, in a signal path to provide a received signal to multiple tuners. For example, a first, second, and third tuner might be connected to a single micro-splitter. Although typically adequately addressing the above mentioned issues with respect to the signal quality of the split signal, micro-splitters still utilize an appreciable amount of space for deployment. Additionally, a variety of micro-splitters must be provided for use with particular numbers of tuners, such as a micro-splitter having two outputs for use with two tuners and a micro- splitter having three outputs for use with three tuners. Accordingly, micro-splitters generally do not provide as low cost of a solution as is desirable.
[0007] A need therefore exists in the art for systems and methods which provide for multiple tuner circuits using a minimum of space while maintaining a desired output signal quality. A further need exists in the art for systems and methods allowing for a single circuit configuration to be utilized in providing any number of tuners in a multiple tuner application.
BRIEF SUMMARY OF THE INVENTION
[0008] These and other objects, features and technical advantages are achieved by a single tuner circuit adapted according to the present invention to accept a received signal input and provide both a desired tuner output and the received signal as an output, such as may be cascaded to another such tuner circuit. Accordingly, a preferred embodiment of the present invention provides a multiple tuner solution within an integrated circuit tuner. Any number of such integrated circuit tuners may be cascaded together for a multiple tuner application.
[0009] Tuners of the present invention are preferably adapted to be deployed in the aforementioned cascade fashion or not, as desired. Because the preferred embodiment tuners support both connection of a subsequent tuner in a "daisy chain" or no subsequent tuner connected thereto, a single tuner component design may be utilized throughout a multiple tuner application. Accordingly, a single tuner component may be manufactured, stocked, and installed for use in such multiple tuner applications, as well as for use in single tuner applications, thus reducing costs associated therewith.
[0010] h addition to the aforementioned advantages associated with a single tuner configuration of the present invention being operable in a variety of applications, the preferred embodiment tuner configuration does not require external splitting or amplification devices. Accordingly, the preferred embodiment provides a solution which minimizes the deployment footprint required.
[0011] The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other stractures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be
characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 shows a multiple tuner configuration using multi-tuners of a preferred embodiment of the present invention;
[0013] FIG. 2 shows a preferred embodiment of a multi-tuner of the present invention; and
[0014] FIG. 3 shows an alternative multiple tuner configuration using multiple tuner adapters of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Directing attention to FIGURE 1, multiple tuner circuit 100, including multi-tuners 101, 102, and 103 adapted according to a preferred embodiment of the present invention, is shown. Specifically, multiple tuner circuit 100 of the illustrated embodiment is configured to accept a radio frequency (RF) signal input, such as may be a broadband cable television signal, at an input interface of multi-tuner 101, RFini. The RF input signal is preferably processed by multi-tuner 101 to provide a desired output signal, such as may be a particular channel of the RF input signal down converted to a baseband signal, at an output interface of multi-tuner 101, tuner outputi. Moreover, the RF input signal is also preferably provided as an RF output signal at an output interface of multi-tuner 101, RFouti. Accordingly, the RF signal is available for input to additional tuners.
[0016] A multiple tuner configuration is provided according to the illustrated embodiment by "daisy chaining" multiple ones of the multi-tuners together. Accordingly, any number of tuners may be daisy chained according to the present invention. As shown in the illustrated embodiment the RF input signal as output by tuner outputi of multi-tuner 101 is provided to an input interface of multi-tuner 102, RFin2, for processing by multi-tuner 102 to provide a desired output signal at an output interface of multi-tuner 102, tuner output2. As with multi-tuner 101, the RF input signal is also provided as an RF output signal at an output interface of multi-tuner 102, RFout , according to the illustrated embodiment. The RF input signal as output by tuner output2 of multi-tuner 102 is provided to an input interface of multi- tuner 103, RFin3, for processing by multi-tuner 103 to provide a desired output signal at an output interface of multi-tuner 103, tuner output3. It should be appreciated that, although the illustrated embodiment shows a multiple tuner configuration including 3 multi-tuners, multi- tuners of the present invention may be utilized in configurations of 1 and 2 multi-tuners, in addition to configurations with 3 or more multi-tuners as represented in FIGURE 1.
[0017] As with multi-tuners 101 and 102, multi-tuner 103 preferably includes an RF signal output interface, RFout3. A preferred embodiment of multi-tuners 101, 102, and 103 provides for selective output of a signal at the RF output interface thereof. For example, a multi-tuner of the present invention may include a control input to allow selective termination of the RF output interface. Additionally or alternatively, multi-tuners of the
present invention may provide for controlled attenuation, interruption, or the like of a signal of the RF output interface. Accordingly, output of the RF signal from the last multi-tuner in a chain (or in single tuner implementations) may be prevented, such as for impedance matching or avoiding undesired noise energy. However, in situations where deactivation of the RF output port is unnecessary or where the components of the tuner providing output of the RF signal provide sufficient isolation or impedance matching without preventing output of the RF signal, multi-tuners of the present invention may not be provided with the aforementioned means by which RF signal output is controllably prevented.
[0018] It should be appreciated that it may be desirable not to terminate the RF signal output of multi-tuner 103, even when multi-tuner 103 is the last multi-tuner of a multiple tuner configuration. For example, the RF signal may be output from multi-tuner 103 for uses other than additional tuner input, such as to be provided to an output of the application device in order to supply the RF signal to another device for other purposes.
[0019] According to alternative embodiments of the present invention, multi- tuner 103 may not include an RF output interface (RFout3), if desired. Accordingly, multi- tuner 103 may be provided by a tuner circuit which is different than that of multi-tuner 101 and 102 for use in terminating the multiple tuner daisy chain.
[0020] Directing attention now to FIGURE 2, a preferred embodiment implementation of multi-tuners, such as multi-tuners 101, 102, and 103 of FIGURE 1, is shown. Specifically, a preferred embodiment tuner for multiple tuner applications is shown as multi-tuner 201. Preferably multi-tuner 201 is provided on a single substrate, such as using large scale integration technology on a substrate such as silicon. Accordingly, each of input buffer amplifier 211, receiver buffer amplifier 212, output buffer amplifier 213, output control circuitry 221, and tuner 250 are preferably implemented as a single integrated circuit component, e.g. "chip." For example, input buffer amplifier 211, receiver buffer amplifier 212, and output buffer amplifier 213 may be embodied as monolithic operational amplifiers as are well known in the art. Output control circuitry 221 may be provided by a monolithic diode and transistor circuit operable to provide biasing of the diode for switching functionality in response to a control signal as is well known in the art. Tuner 250 may be
provided by a monolithic tuner structure as shown and described in the above referenced patent application entitled "Broadband Integrated Tuner."
[0021] h operation according to the preferred embodiment, input buffer amplifier 211 provides low noise amplification of an RF signal provided to the input interface RFin to control the signal level thereof. Thereafter, the RF signal is distributed, such as by a coupler disposed in the signal path after input buffer amplifier 211, for providing to tuner 250 and for output at output interface RFout. According to the preferred embodiment, buffer amplifier 212 provides low noise amplification of the RF signal as distributed to tuner 250 to thereby provide a signal level suitable for receiver operation by tuner 250. Similarly, buffer amplifier 213 preferably provides low noise amplification of the RF signal as distributed for output at output interface RFout to thereby provide an output signal level suitable for downstream operation, such as coupling to subsequent tuners of the present invention or to be provided to an output of the application device in order to supply the RF signal to another device for other purposes.
[0022] According to a preferred embodiment, output control circuitry 221 is coupled to output buffer amplifier 213 in order to provide for controlled operation thereof. Specifically, a control signal may be provided to output control circuitry 221 to selectively cause output buffer amplifier 213 to pass the RF signal through to output interface RFout. For example, where multi-tuner 201 is utilized in a single tuner application or is provided as a last tuner in a multiple tuner daisy chain, an appropriate control signal may be provided to output control circuitry 221, such as through the control interface labeled "control," to thereby cause output buffer amplifier 213 to terminate the RF signal. It should be appreciated that control of output control circuitry 221 may be provided without utilization of a discrete control interface. For example, control of output control circuitry 221 maybe provided through an existing digital control network associated with tuner 250 (not shown).
[0023] It should be appreciated that alternative embodiments of the invention may be configured differently than shown in FIGURE 2. For example, one or more of buffer amplifiers 211, 212, and 213 maybe omitted, if desired, such as where signal levels and/or signal quality are such that buffering is not necessary at one or more points in the signal path. Similarly, output control circuitry 221 may be omitted, if desired, such as where output buffer
amplifier 213 provides a desired level of isolation or impedance matching without preventing output of the RF signal.
[0024] Moreover, circuitry in addition to that illustrated may additionally or alternatively be utilized according to the present invention. For example, gain control circuitry may be coupled to one or more of buffer amplifiers 211, 212, and 213 to provide controllable operation thereof. Additionally, signal path selection circuitry, such as a controllable switch, may be provided for directing signals within multi-tuner 201. For example, where single conversion tuner technology, such as shown and described in the above reference patent application entitled "System and Method for a Single Conversion Tuner," is used, it may be desirable to provide switching of the RF signal between various frequency filters provided as a front end to the single conversion tuner circuit. Such a single conversion tuner circuit and associated front end is shown with respect to an alternative embodiment in FIGURE 3 discussed below.
[0025] An alternative embodiment of circuitry for providing a multiple tuner implementation is shown in FIGURE 3. In the embodiment of FIGURE 3, circuitry adapted for daisy chaining any number of tuners, similar to that shown in FIGURE 2, is shown as multiple tuner adapters 301 and 302. It should be appreciated that the multiple tuner adapters of the present invention may be utilized with any number of tuners to provide a multiple tuner configuration as discussed with respect FIGURE 1 above. Accordingly, like multi-tuner 201 of FIGURE 2, multiple tuner adapters 301 and 302 of the illustrated embodiment include input buffer amplifier 311, receiver buffer amplifier 312, output buffer amplifier 313, and output control circuitry 321 to provide operation as described above with respect to FIGURE 2. Of course, alternative embodiments of the multiple tuner adapters may omit one or more of these components and/or include additional components as described above with respect to FIGURE 2, if desired.
[0026] Preferably multiple tuner adapters of the present invention, such as multiple tuner adapter 301, are provided on a single substrate, such as using large scale integration technology on a substrate such as silicon. Accordingly, each of multiple tuner adapter 301 and multiple tuner adapter 302 are preferably implemented as an integrated
circuit component, e.g., a "chip." Of course, an integrated circuit (chip) may be provided with several multiple tuner adapters of the present invention, if desired.
[0027] It should be appreciated that the multiple tuner adapters of FIGURE 3 include gain control circuitry coupled to buffer amplifiers 312. According to a preferred embodiment this gain control circuitry is operable to provide a desired signal level input to a coupled tuner, e.g., single conversion tuners 351 and 352. Alternative embodiments of the invention may omit such gain control circuitry, such as where the coupled devices are less sensitive to input signal levels.
[0028] Additionally, it should be appreciated that the multiple tuner adapters of FIGURE 3 include signal path selection circuitry, shown as controllable switching circuitry, provided for directing signals of multiple tuner adapters 301 and 302. Specifically, single conversion tuners 351 and 352 include three frequency filters coupled thereto for use depending upon the channel or portion of a received RF signal to be converted by the tuner. Accordingly, the illustrated embodiments of multiple tuner adapters 301 and 302 provide switching of the RF signal between the various frequency filters as a function of the channel or portion of the RF signal to be utilized by the corresponding tuners. Of course, alternative embodiments of the invention may omit such signal path selection circuitry, such as where single input double conversion tuners are used, if desired.
[0029] Although preferred embodiments of the present invention have been described with reference to RF signals, it should be appreciated that there is no limitation that the present invention operate with respect to RF signal processing. For example, multi-tuners and multiple tuner adapters of the present invention may operate with intermediate frequency (IF) input. Moreover, there is no limitation that the present invention operate with respect to tuner circuitry. For example, the multi-tuners of FIGURE 2 may be adapted to include a digital signal processor in place of the tuner of the illustrated embodiment. Similarly, the multiple tuner adapters of FIGURE 3 may be coupled to any number of devices, such as modems, radios, and the like, for which a particular input signal is to be provided to a multiple device application.
[0030] Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or late to be developed that perform substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.