WO2008016049A1 - Convertisseur a/n et circuit de lecture - Google Patents
Convertisseur a/n et circuit de lecture Download PDFInfo
- Publication number
- WO2008016049A1 WO2008016049A1 PCT/JP2007/064986 JP2007064986W WO2008016049A1 WO 2008016049 A1 WO2008016049 A1 WO 2008016049A1 JP 2007064986 W JP2007064986 W JP 2007064986W WO 2008016049 A1 WO2008016049 A1 WO 2008016049A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- capacitor
- circuit
- switch
- output
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
- H03M1/124—Sampling or signal conditioning arrangements specially adapted for A/D converters
- H03M1/1245—Details of sampling arrangements or methods
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
- H03M1/18—Automatic control for modifying the range of signals the converter can handle, e.g. gain ranging
- H03M1/181—Automatic control for modifying the range of signals the converter can handle, e.g. gain ranging in feedback mode, i.e. by determining the range to be selected from one or more previous digital output values
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
- H04N25/616—Noise processing, e.g. detecting, correcting, reducing or removing noise involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/71—Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
- H04N25/75—Circuitry for providing, modifying or processing image signals from the pixel array
Definitions
- the present invention relates to an A / D converter and a readout circuit for a CMOS image sensor.
- Non-Patent Document 1 the influence of noise on the signal is reduced by amplifying the signal from the column using a high gain amplifier connected to the column.
- the amplifier has a 1x amplification factor and an 8x amplification factor in order to achieve both noise reduction and a wide dynamic range.
- the circuit of Non-Patent Document 3 provides low-noise signal reading.
- the peripheral circuit of the image sensor includes a two-stage noise cancellation circuit using a high gain amplifier.
- Patent Document 1 describes an A / D conversion array and an image sensor! In the A / D conversion array and image sensor, the difference between the signal level and the reset level is generated using three capacitors, and this difference is amplified n times.
- Patent Document 2 describes an image sensor having a digital noise canceling function. In this image sensor, the digital value is generated by performing A / D conversion of the signal level and reset level of the image array without using the noise cancellation circuit in the analog domain in the column, and then the difference is calculated. Seeking.
- Non-Patent Document 1 Krymski, N. haliullin, H rymski, N. haliullin, H. Rhodes, n 2e noise 1. ⁇ Megapixel CMOS sensor, "Proc. IEEE workshop CCD an d Advanced Image Sensors, Elmau, Germany.
- Non-Patent Document 2 M. Sakakibara, S. awahito, D. Handoko, N. Nakamura, H. S at oh, M. Higashi,. Mabuchi, H. Sumi, "A high-sensitivity CMOS image sen sor with gain- adaptive column amplifiers, IEEE J. Solid—State Circuits, vol.
- Non-Patent Document 3 N. awai, S. Kawahito, "Noise analysis of high-gain low-noise column readout circuits for CMOS image sensors ", IEEE Trans. Electron Devices, vol.51, no.2, pp.185—194 (2004).
- Patent Document 1 Japanese Patent Laid-Open No. 2005-136540
- Patent Document 2 Japanese Patent Laid-Open No. 2006-25189
- CMOS image sensor includes a peripheral circuit connected to a column, and the peripheral circuit reduces noise by using a readout circuit having an amplification function. Therefore, a very low noise image sensor can be realized using this peripheral circuit.
- the above document describes that noise is reduced using amplification by a column processing circuit!
- Non-Patent Document 1 loses the dynamic range of the signal, and as a result, it is possible to obtain both high sensitivity / low noise and a large dynamic range. Can not.
- the circuit of Non-Patent Document 2 since the amplifier power has only one type of gain! /, There is a limit in obtaining a desired gradation necessary for A / D conversion.
- Non-Patent Document 3 describes the possibility of very low noise by increasing the gain of the amplifier, but this method is also simple amplification, and high sensitivity and low noise are compatible with a large dynamic range. Have difficulty.
- the present invention has been made in view of such circumstances, and provides an A / D converter and a readout circuit capable of performing noise cancellation on a signal from a pixel of a CMOS image sensor. There is to do.
- One aspect of the present invention is an A / D converter for an image sensor.
- the A / D converter (a) has an input and an output for receiving a signal from the image sensor, and performs sampling of the first signal including a component related to noise and integration of the sample value. Integrating the first signal with multiple sampling of the second signal including the light-induced signal component from the pixel of the image sensor and the noise component and integration of the sample value during the first period A gain stage for performing the second period so as to have a polarity opposite to that of (b), An A / D conversion circuit that provides a digital signal that can take the first and second values according to the signal from the in-stage output, and (c) a signal corresponding to the number of occurrences of the first value.
- the gain stage is configured to integrate a first capacitor for sampling, a second capacitor for integration, and a signal sampled in the first capacitor into the second capacitor. And an operational amplifier circuit.
- Another aspect of the present invention is an A / D converter for an image sensor. This A /
- the D converter has an input and an output for receiving a signal from the image sensor, and performs sampling of the first signal including a component related to noise and integration of the sample value in the first period. And the sampling of the second signal including the light-induced signal from the pixel of the image sensor and the component related to noise and the integration of the sample value are opposite in polarity to the integration with respect to the first signal.
- a / D conversion that provides a digital signal that can take the first and second values according to the signal from the output of the gain stage.
- a circuit (c) a circuit that provides a signal corresponding to the number of occurrences of the first value; (d) a logic circuit that generates a control signal in response to the digital signal; and (e) the first signal.
- a D / A conversion circuit for providing a voltage signal to the gain stage according to the control signal in the second period, the gain stage comprising: (al) an operational amplifier circuit; and the D / A conversion A first capacitor having one end connected to the circuit and the other end connected to the inverting input of the operational amplifier circuit; and (a2) connected between the input and the one end of the first capacitor.
- a first switch for sampling a signal from the image sensor and (a3) a second capacitor and a second switch connected in series, and the non-inverting output of the operational amplifier circuit and the second switch A first capacitance circuit connected between the inverting input and (a4) a first feedback switch connected between the inverting input and the non-inverting output.
- sampling and integration of the first signal including the component related to noise are performed a plurality of times, and the second signal including the component related to the light-induced signal from the pixel and the noise
- Multiple samplings of the signal and integration with the opposite polarity of the first signal are performed during the first and second periods, respectively, so that the charge accumulated in the first capacitor circuit is the same as the first signal. It represents the integral value associated with the difference from the second signal.
- This difference corresponds to the light-induced signal component of the pixel and is multiplied by N (N: number of integrations) by multiple integrations, but the random noise component caused by the circuit is sqr t (N) times (" sqrt "indicates the square root).
- the A / D conversion circuit provides a signal corresponding to the number of appearances of the first value among the first and second values of the digital signal corresponding to the signal from the output of the gain stage.
- the number of appearances corresponds to the upper A / D conversion value output by the A / D converter circuit in response to the input.
- the gain stage provides a voltage signal provided from the D / A conversion circuit corresponding to a digital signal corresponding to a signal from the output of the gain stage. It is preferable that cyclic A / D conversion be performed in a third period after the first and second periods.
- the A / D converter circuit may include a comparator that compares a signal from the output of the gain stage with first and second reference signals. wear.
- the comparator receives the first reference signal during the second period, and the comparator receives the second reference signal during the third period.
- the value of the second reference signal is preferably smaller than the value of the first reference signal.
- the first capacitor is provided to receive the first and second signals for the sampling
- the gain stage includes: In response to one of signal supply from the D / A conversion circuit and sampling to the first capacitor, the first signal is integrated into the second capacitor using the operational amplifier circuit. Then, the gain stage uses the operational amplifier circuit to output the second signal in response to either the signal supply from the D / A conversion circuit or the sampling to the first capacitor. Integrate into the second capacitor.
- the gain stage may further include a third capacitor for sampling and a fourth capacitor for integration.
- One of the first and third capacitors receives the first signal for the sampling.
- the other of the first and third capacitors is provided to receive the second signal for the sampling, and the operational amplifier circuit includes the D / A
- the values sampled in the first and third capacitors are integrated into the second and fourth capacitors.
- the pixel is a pixel of a CMOS image sensor.
- the first signal is provided by the signal from the pixel.
- the floating diffusion layer of the pixel is in a photo-induced charge accumulation state after reset, the second signal is provided by a signal from the pixel.
- the sampling of the first signal from the pixel is performed within the first period using the first capacitor.
- the sampled signal is applied to the second capacitor of the first capacitor circuit in response to a predetermined reference voltage signal from the D / A converter circuit. Transferred with. Sampling and integration are performed alternately in the first period, and the charge stored in the second capacitor indicates the integrated value of the first signal multiple times.
- the sampling of the second signal from the pixel is performed in the sampling period within the second period using the first capacitor,
- the simultaneously sampled signal is transferred to the second capacitor of the first capacitor circuit.
- the first capacitor is sampled in the reference voltage sampling period in the second period in response to the voltage signal from the D / A conversion circuit.
- pixel sampling and signal transfer to the second capacitor are performed at the same time, and integration is performed with the opposite polarity to that of the first period, resulting in accumulation in the first capacitor circuit.
- the charge represents the integral value associated with the difference between the first signal and the second signal.
- the A / D conversion circuit provides a signal corresponding to the number of appearances of the first value among the first and second values of the digital signal corresponding to the signal from the output of the gain stage.
- the number of appearances corresponds to the upper A / D conversion value output by the A / D converter circuit in response to the input.
- the gain stage performs an operation for cyclic A / D conversion in a third period after the first and second periods.
- a ternary digital signal corresponding to the signal from the output of the stage is provided in the third period.
- the gain stage includes another feedback switch connected between one end of the first capacitor and the non-inverting output, and a transfer switch connected between the other end of the first capacitor and the inverting input. That power S.
- cyclic A / D conversion is performed on the charge accumulated in the first capacitor circuit when the second period has elapsed.
- the charge is sampled in the first capacitor via another feedback switch during the sampling period of the third period.
- the charge is rearranged by applying a voltage signal from the D / A converter circuit to the first capacitor during the transfer period of the third period.
- a new voltage value is generated at the output of the gain stage.
- the A / D conversion circuit generates a digital signal in the cyclic cycle.
- the A / D converter according to the present invention may have a fully differential configuration.
- the fully differential A / D converter according to the present invention can perform cyclic A / D conversion in the third period after the first and second periods.
- the first capacitance circuit in the first capacitance circuit, one end of the second capacitor is connected to the inverting input, and the second switch is connected to the other end of the second capacitor.
- the first capacitance circuit includes a fifth capacitor connected to the first node between the other end of the second capacitor and the second switch. It is preferable. According to this A / D converter, it is possible to reduce the voltage dependency of noise caused by switching of the second switch (for example, charge injection noise in the MOS analog switch used as the second switch). Can do.
- one end of the fourth capacitor is connected to the inverting input in the second capacitor circuit, and the fourth switch is connected to the fourth capacitor.
- the second capacitance circuit is connected to the second node between the other end of the fourth capacitor and the fourth switch.
- a sixth capacitor connected to can be included. According to this A / D converter, the voltage dependency of noise caused by switching of the fourth switch (for example, the charge injection noise in the MOS analog switch used as the fourth switch) is reduced. be able to.
- the A / D converter includes an input between a pixel of a CMOS image sensor and a gain stage. And a preamplifier connected between the power and providing the first and second signals.
- the preamplifier includes an operational amplifier circuit, a first capacitor connected to an input of the operational amplifier circuit, a second capacitor connected between an output and an input of the operational amplifier circuit, an output and an input
- the signal from the pixel is amplified according to the capacitance ratio of the first and second capacitors.
- the first signal includes a component related to the noise of the preamplifier
- the second signal includes the component related to the noise of the preamplifier, the signal from the pixel when the pixel is placed in the reset state, and the pixel is a light-induced signal. Contains a component indicating the difference from the signal from the pixel when placed in the output state.
- the readout circuit for an image sensor.
- the pixel of the image sensor generates a first signal when in the pixel force S reset state and generates a second signal when the pixel is in the light induced signal output state.
- the readout circuit includes (a) an operational amplifier circuit, a first capacitor connected to the input of the operational amplifier circuit, and a second capacitor connected between the output and input of the operational amplifier circuit.
- a preamplifier for amplifying the first signal and the second signal according to the capacitance ratio of the first and second capacitors and (b) a sampling switch connected to the output of the preamplifier A plurality of integrations of the first signal are performed using the sampling switch and a plurality of integrations of the amplified second signal are performed so that the polarity is opposite to that of the integration of the first signal. And an integrator that amplifies the difference between the first signal and the second signal by using the switch.
- integration of the amplified first signal is performed a plurality of times, and integration of the amplified second signal is performed a plurality of times so that the output of the preamplifier has a reverse polarity. Since the integrator does, the amplified signal indicating the difference between the first signal and the second signal provides the difference.
- the A / D converter according to the present invention further includes a readout circuit, and the readout circuit is connected between the pixel of the CMOS image sensor and the input of the gain stage.
- an A / D converter and a readout circuit capable of performing noise cancellation on a signal from a pixel of a CMOS image sensor are provided.
- FIG. 1 is a circuit diagram of an A / D converter according to the present embodiment.
- FIG. 2 is a block diagram of a CMOS image sensor.
- FIG. 3 is a drawing showing a timing chart for the operation of the A / D converter.
- FIG. 4 is a drawing showing a timing chart for the operation of the A / D converter.
- FIG. 5 is a diagram showing input / output characteristics of a gain stage by simulation.
- FIG. 6 is a circuit diagram of an A / D converter according to the present embodiment.
- FIG. 7 is a drawing showing a timing chart for the operation of the A / D converter.
- FIG. 8 is a drawing showing a timing chart for the operation of the A / D converter.
- FIG. 9 is a drawing showing the operation of integral A / D conversion.
- FIG. 10 is a drawing showing the operation of cyclic A / D conversion.
- FIG. 11 is a drawing showing a readout circuit of an image sensor.
- FIG. 12 is a drawing showing a timing chart for this readout circuit.
- FIG. 13 is a drawing showing a CMOS image sensor.
- FIG. 14 is a drawing showing the operation of a multiple integration readout circuit.
- FIG. 15 is a drawing showing the operation of a multiple integration readout circuit.
- FIG. 16 is a graph showing the relationship between preamplifier gain and input conversion noise.
- FIG. 1 is a circuit diagram of the A / D converter according to the present embodiment.
- the A / D converter 11 is used for a CMOS image sensor.
- FIG. 2 is a block diagram of a CMOS image sensor.
- the A / D converter 11 is used in the CMOS image sensor 1.
- the cell array 2 has CMOS image sensor pixels 2a arranged in the row direction and the column direction.
- FIG. 2 shows an example of the CMOS image sensor pixel 2a.
- the pixel 2a generates the first signal S1 in the reset state and the second signal S2 in the photoinduced signal output.
- An input 13 of the A / D converter 11 is connected to the pixel 2a.
- the input 15a of the gain stage 15 receives the signal from the pixel 2a.
- the A / D converter 11 performs sampling of the first signal S 1 and integration of the sample values in the first period T1 and integration of the second signal S2 in the second period T2. Perform sampling and integration of sample values.
- the A / D conversion circuit 17 provides a digital signal corresponding to the signal from the output 15b of the gain stage 15 during the second period T2, and this digital signal is supplied with the first and second values (for example, , “1” and “0”).
- the A / D conversion circuit 17 includes comparators 17b and 17c for 1.5-bit A / D conversion.
- the circuit 18 is connected to the output of the A / D conversion circuit 17 (for example, the output of the comparator 17b), and provides a signal S corresponding to the number of appearances of the first value (for example, “1”).
- the D / A converter circuit 21 responds to the control signal V with the first
- a predetermined voltage signal is provided to the gain stage 15 in the period T1, and a voltage signal is provided to the gain stage 15 in the second period T2 in response to the control signal V.
- gain Stage 15 includes an operational amplifier circuit 23.
- One end 25 a of the first capacitor 25 is connected to the output 21 a of the D / A conversion circuit 21, and the other end 25 b of the first capacitor 25 is connected to the inverting input 23 a of the operational amplifier circuit 23.
- the first switch 24 is connected between the input 13 and the capacitor end 25a. The first switch 24 operates in response to the clock ⁇ 3 and is used to sample the signal from the pixel 2a.
- a first capacitor circuit 27 is connected between the inverting input 23a and the non-inverting output 23b.
- a second switch 29 and a second capacitor 31 connected in series are connected between the inverting input 23a and the non-inverting output 23b.
- the second switch 29 operates in response to the clock ⁇ 3 and is used for integration into the second capacitor 31.
- the first capacitor circuit 27b can be used instead of the first capacitor circuit 27.
- a first feedback switch 33 is connected between the inverting input and the non-inverting output.
- CMOS image sensor 1 vertical shift register 3 is connected to a row of cell array 2, and A / D converter array 4 is connected to a column of cell array 2.
- the A / D converter array 4 includes a plurality of A / D converters arranged in an array.
- a / D converter 11 can be used as each A / D converter.
- a data register 5 is connected to the A / D converter array 4, and an A / D conversion value corresponding to a signal from the pixel 2 a is stored in the data register 5.
- the data register 5 provides the digital signal to the redundant representation non-redundant representation conversion circuit 7 in response to the signal from the horizontal shift register 6. Redundant representation Non-redundant representation conversion circuit 7 generates an N-bit digital code corresponding to the signal from pixel 2a.
- Pixel 2a receives one pixel of light associated with the photodiode D force image.
- the gate of the select transistor M is connected to a row select line S extending in the row direction. reset
- the transistor M is connected to the reset potential line Reset via the transistor M.
- One current terminal (eg, drain) of transistor M is
- Transistor is floating diffusion layer FD
- the potential is supplied to the column line via the selection transistor M in accordance with the amount of charges.
- the noise canceling operation is performed as follows. First, the reset control signal R is provided to the reset transistor M to reset the floating diffusion layer FD.
- This reset level is read out through the amplification transistor M. Then charge transfer control
- the signal T is supplied to the transfer transistor M, and the photo-induced signal charge is floated from the photodiode D.
- the difference between the reset level and the signal level is obtained by using an integration / cyclic cascade A / D converter as shown in FIG. As a result, fixed pattern noise due to transistor characteristic variations of pixel 2a and reset noise generated when the floating diffusion layer is reset.
- 3 and 4 are timing charts for the operation of the A / D converter.
- an A / D converter that uses a single-ended operational amplifier circuit for the gain stage is described.
- the input of the A / D converter receives a signal from one pixel in the image sensor array.
- This circuit performs signal integration and coarse A / D conversion (hereinafter referred to as “integration A / D conversion”) while performing image noise cancellation.
- Integral A / D conversion is performed during the first and second periods Tl and ⁇ 2.
- cyclic A / D conversion is applied to the integral output.
- the first signal S 1 (for example, a signal indicating a reset level) is sampled into four periods Tl l, T12, T13, and T14.
- the second signal S2 (for example, a signal indicating the photoinduced signal level) is sampled in four periods T21, ⁇ 22, ⁇ 23, and ⁇ 24. These samplings provide, for example, 2-bit A / D conversion values during the period for integral A / D conversion. The number of samplings is an example, and the number is changed as necessary.
- the A / D converter 11 performs an integration operation by sampling a number of times for the noise reduction processing, and reduces random noise generated in the amplification transistor and the noise cancellation circuit in the pixel. In addition, A / D conversion is performed to generate higher bits, ensuring a dynamic range. [0037]
- the input 13 of the A / D converter 11 receives the first signal S1 (reset level signal value Vr) of the pixel in the initial part of the period Tl1 of the first period T1. At the sampling period T11
- switches 24 and 33 are turned on, and this signal is sampled in capacitor 25.
- Switch 29 is conducting according to clock ⁇ 3. During the integration period T11, the clock ⁇ s
- the signal is transferred to the second capacitor 31 via the switch 29.
- V (Vr-V)
- V N X (Vr-V)
- the D / A converter circuit 21 turns on the switch 21d in response to ⁇ of the control signal V, and
- the reference voltage V is sampled in the capacitor 25 by turning on the switch 33 as well. Pull
- the second signal S2 (signal level signal value V s) of the pixel is received at the input 13 of the A / D converter 11.
- This signal S2 is switched in response to the clock ⁇ s in the sampling period T21.
- the switch 29 is turned on in response to the clock ⁇ 3, so that the charge force switch proportional to the difference between the reference voltage V sampled on the capacitor 25 and the received Vs.
- the D / A converter circuit 21 related to the operation of the A / D converter circuit 17 generates the voltage V.
- the polarity is reversed depending on the order in which the voltage signals are received.
- forward polarity an input signal is received at one end of the first capacitor 25 for sampling.
- the charge is transferred to the second capacitor 31 by switching to provide a reference voltage to one end of the first capacitor 25 (capacitance).
- the charge CI X ((input signal) (reference voltage)) is transferred to the second capacitor 31.
- a reference voltage is first received at one end of the first capacitor 25.
- the charge is transferred to the second capacitor 31 by switching to provide an input signal to one end of the first capacitor 25.
- the charge C1 X ((reference voltage) (input signal)) is transferred to the second capacitor 31. Comparing these equations, the order of C1 X (reference voltage) and C1 X (input signal) is reversed. As will be explained later, forward polarity connection and reverse polarity connection can also be realized depending on whether the terminal to which the input is connected is applied to the inverting input or whether it is applied to the non-inverting input.
- the output of the gain stage 15 is provided to a comparator (in this embodiment, the compensator 17b in the AZD conversion circuit 17 is used).
- This comparator is given a reference voltage V for integral A / D conversion.
- the comparison result V of the comparator is supplied to the logic circuit 19, and refl COMP is output from the logic circuit 19.
- the D / A conversion circuit 21 operates according to the control signal V of the signal. However, the first signal sampler
- the D / A conversion circuit 21 provides the voltage V regardless of the control signal V.
- the comparator works as follows:
- V N X (Vr-V) + ⁇ 1 ⁇ (V -Vs) + N2 X (V Vs)
- the value N2 indicates the number of times that “1” appears in the output of the comparator, that is, the A / D converter circuit determines the first and second digital signals according to the signal from the output of the gain stage. A signal corresponding to the number of occurrences of the first value among the values is provided. The value of this signal can be counted using, for example, the circuit 18 connected to the A / D conversion circuit 17. Provided as signal S from A / D converter circuit 17. This value is above the A / D conversion value.
- FIG. 1 shows an example of the circuit 18.
- Circuit 18 includes first and second inputs 20a, 20b and an adder 20 having an output 20c, and a register (M bit) 22 having an input 22a and an output 22b.
- a first input 20 a of the adder 20 receives a signal from one comparator 17 b of the A / D conversion circuit 17.
- the second input 20b of the adder 20 receives a signal from the output 22b of the register 22.
- the adder 20 provides the addition result (digital signal) of the received signal to the M-bit register 22.
- the register 22 holds the addition result obtained by adding the values “1” and “0” of the signal V from the comparator 17b during the integral A / D conversion. register
- the sampling of the first signal S1 is performed using the first capacitor 25 in the sampling period (for example, T11) within the first period T1.
- the signal is transferred to the second capacitor 31 in response to a predetermined voltage signal from the D / A conversion circuit during an integration period (eg, period T11) within the first period. Sampling in the first period
- the integration is performed alternately, and the electric charge accumulated in the second capacitor 31 indicates the integration value of the first signal S1 a plurality of times.
- Sampling of the voltage signal from the D / A conversion circuit 21 is performed in the sampling period (for example, period T21) within the second period T2 using the first capacitor 25.
- the sampled signal has an integration period (e.g. period T21) within the second period T2.
- the A / D converter 11 will be further described with reference to FIG. 1 again.
- the A / D converter circuit 17 outputs the output of the gain stage 15 so that the gain stage 15 performs the operation for cyclic A / D conversion in the first and second periods Tl and the third period ⁇ 3 after ⁇ 2.
- a ternary digital signal V V consists of (dO, dl)) corresponding to the signal from 15b is provided in the third period.
- the feedback switch 35 is connected between the capacitor end 25a and the non-inverted output 15b, and operates in response to the clock ⁇ Id.
- the other end 25 b of the first capacitor 25 is connected to the inverting input 15 a and the first capacitance circuit 27 via the transfer switch 37.
- the transfer switch 37 operates in response to the clock ⁇ 2.
- Capacitor etc. A switch 39 is connected to the end 25b. Switch 39 operates in response to clock ⁇ 1 and is connected to provide a reference potential in a single-ended gain stage.
- a cyclic A / D is applied to the gain stage output 15b generated by the charge accumulated in the first capacitor circuit when the second period has elapsed. Perform D conversion.
- the charge is transferred from the first capacitor 25 to the second capacitor 31 via the transfer switch 37, and the charge is rearranged. As a result, a new voltage value is generated at the output 15b of the gain stage 15.
- the signal from the gain stage 15 is converted into two reference voltages V in the A / D conversion circuit 21.
- V V is, for example, V / 4 V / 4, respectively.
- the output of the A / D conversion circuit 17 provides a redundant digital code.
- the control circuit 19 In response to the redundant digital code, the control circuit 19 generates a control signal V for controlling the D / A conversion circuit 21.
- the A / D conversion circuit 17 is connected to the digital signal in the cyclic cycle.
- V (i) 2 XV (i- l) -V (i)
- Voltage V is a positive value and is V V.
- the D / A converter circuit 21 includes a voltage source 21a that provides the voltage V V and a control signal.
- the digital signal D (i) is a digital signal
- the voltage range is determined using the comparators 17 b and 17 c of the A / D conversion circuit 17. In order to obtain an A / D conversion value with 12-bit resolution in cyclic A / D conversion operation, it is necessary to perform one cyclic operation.
- FIG. 5 is a diagram showing input / output characteristics when operating as an integral A / D converter of a gain stage obtained by simulation.
- Figure 5 shows the results of simulation using two types of values as the reference voltage Vrefl for integration A / D conversion (number of integrations: 16).
- Vrefl the reference voltage for integration A / D conversion
- the full range of output voltage is 1 volt. (Power supply voltage) is exceeded.
- the reference voltage for integral A / D conversion is preferably lower than the reference voltage for cyclic A / D conversion!
- a reference voltage V is used, and this value is 0 volts, for example.
- the A / D converter according to the present embodiment can have a full differential configuration instead of a single-ended configuration.
- FIG. 1 again, an A / D converter with a fully differential configuration will be described.
- one end 41 a of the third capacitor 41 is connected to the output 21 b of the D / A conversion circuit 21 and the other end 41 b is not connected via the switch 55.
- the third switch 43 is connected between one end 25 a of the first capacitor 25 and one end 41 a of the third capacitor 41.
- the second capacitor circuit 45 is connected between the non-inverting input 23c and the inverting output 23d, and has the same configuration as the first capacitor circuit 27.
- the second capacitance circuit 45 includes the fourth switch 4 connected in series. 7 and a fourth capacitor 49 are provided.
- the third feedback switch 51 is connected between the non-inverting input 23c and the inverting output 23d. The switch 51 operates in response to the clock ⁇ s, and the fourth switch 47 operates in response to the clock ⁇ 3.
- the gain stage 15 of the A / D converter 11a has a complementary output 15c in addition to the output 15b.
- the integral A / D conversion is performed in the first and second periods Tl and ⁇ 2.
- the A / D converter 11a operates in the same manner as the single-ended A / D converter.
- an integration operation is performed by sampling a number of times for the noise cancellation process, and random noise generated in the amplification transistor and the noise cancellation circuit in the pixel is reduced.
- a / D conversion is performed to generate higher bits, so dynamic range is ensured.
- the A / D converter 11a includes the following circuit elements in order to perform cyclic A / D conversion in the third period T3.
- the sixth switch 39 is connected between the other end 25 b of the first capacitor 25 and the other end 41 b of the third capacitor 41.
- a fourth feedback switch 53 is connected between one end 41a of the third capacitor 41 and the inverted output 23d.
- An eighth switch 55 is connected between the other end 41b of the third capacitor 41 and the non-inverting input 23c. The fourth feedback switch 53 operates in response to the clock ⁇ Id, and the eighth switch 55 operates in response to ⁇ 2.
- FIG. 6 is a circuit diagram of the A / D converter according to the present embodiment.
- the A / D converter l ib is used for the CMOS image sensor, like the A / D converters 11 and 11a.
- the A / D converter l ib includes a switch 57 that operates in response to a clock instead of the switch 24.
- the A / D converter l ib also includes a switch 59 connected between the input 13 and one end 41a of the third capacitor 41, which is used to sample the signal from the CMOS image sensor. Used for. This switch 59 operates in response to a clock (i> sd).
- 7 and 8 are timing charts for the operation of the A / D converter.
- the A / D converter l ib operates according to the timing charts shown in FIG. 7 and FIG.
- the clock for this is provided by the clock generator 61.
- a clock generator similar to clock generator 61 has an A / D conversion function. Used for converters 11 and 11a.
- the integration A / D conversion of the A / D converter l ib will be described with reference to FIGS.
- the reset level signal Vr from the pixel of the CMOS image sensor is sampled a plurality of times to integrate the reset level signal Vr using the gain stage 15.
- step (a) shown in FIG. 9 the reset level signal Vr is supplied to the input 15a, the predetermined voltage signal VRP from the D / A conversion circuit 21 is supplied to the input 15e, and the feedback switch is further supplied.
- the inputs and outputs of the operational amplifier circuit 23 are connected by making 33 and 51 conductive. As a result, the electric charges of the capacitors 31 and 49 are reset, and the voltages Vr and V are sampled in the capacitors 25 and 41, respectively.
- step (b) shown in FIG. 9 the switch 43 is turned on to connect one end of the capacitors 25 and 41, and the voltage sampled in the capacitors 25 and 41 is transferred to the capacitors 31 and 49.
- V + and V— are generated at the outputs 15b and 15c of the gain stage 15, respectively.
- V V + — V "
- step (c) shown in FIG. 9 the reset level signal Vr and the voltage signal V are supplied to the inputs 15a and 15e. Do not reset the charge on capacitors 31 and 49
- step (d) shown in FIG. 9 one end of the capacitors 25 and 41 is connected by conducting the switches 29 and 47 and the switch 43, and the voltage sampled in the capacitors 25 and 41 is connected. Is transferred to capacitors 31 and 49. V + and V — are generated at the outputs 15b and 15c of the gain stage 15,
- V V + — V "
- Steps (c) and (d) are repeated.
- Gain stage 15 output in N iterations V + and V — are generated in 15b and 15c,
- step (e) shown in Fig. 9 the voltage signal V and the signal level signal Vs are supplied to the inputs 15a and 15e.
- step (f) shown in FIG. 9 the switches 29 and 47 and the switch 43 are turned on to connect one end of the capacitors 25 and 41, and the voltage sampled in the capacitors 25 and 41 is applied to the capacitor 31. , Forward to 49.
- Gain stage 15 outputs 15b and 15c have V o respectively
- the signal from the output of the gain stage 15 is compared with the reference voltage (for example, Vcom) in the A / D conversion circuit 17, and the comparison result is In the next step, the voltage signal supplied by the D / A conversion circuit 21 is determined.
- Vcom reference voltage
- step (g) shown in FIG. 9 the switches 29 and 47 are made non-conductive and the feedback switch computations 33 and 51 are made conductive so that the charges of the capacitors 31 and 49 are not reset.
- the voltages V and V are sampled in capacitors 25 and 41, respectively.
- step (h) shown in FIG. 9 switches 29, 47 and switch 43 are connected to connect one end of capacitors 25, 41, and capacitors 25, 41 to capacitors 31, 4 9 are connected. Transfer the sampled charge.
- step (h) shown in FIG. 9 switches 29, 47 and switch 43 are connected to connect one end of capacitors 25, 41, and capacitors 25, 41 to capacitors 31, 4 9 are connected. Transfer the sampled charge.
- Vcom reference voltage
- step (e) to (f) and steps (g) to (!) Is selected according to the result, and the selected series of steps is repeated.
- V + and V- are generated at the outputs 15b and 15c of the gain stage 15, respectively.
- V v -V
- N N1 + N2 is satisfied, and the D / A converter circuit supplies the voltage V in Nl integrations and supplies the voltage V in N2 integrations.
- V v -V
- V v -v
- the amplified signal can be kept within the desired voltage range even if the signal from the pixel is amplified N times.
- the signal amplitude is amplified N times by integration and the random noise amplitude is sqrt (N) times by integration of N times, so the signal-to-noise ratio (S / N ratio) is improved by the integration operation.
- Noise reduction effect can be obtained. For example, 16 times of integration can improve the S / N ratio by about 4 times. That is relative Noise becomes 1/4.
- the value N2 is a high-order digital code. If the cyclic A / D conversion described later is applied to the residual signal of the gain stage 15, a low-order digital code having high resolution can be obtained.
- FIG. 10 is a drawing showing the operation of cyclic A / D conversion. As shown in step (a) of FIG. 10, the feedback switches 35 and 53 are turned on, and the residual signal of the gain stage 15 is sampled in the capacitors 25 and 41. Next, as shown in step (a) of FIG.
- the D / A conversion circuit 21 applies a voltage corresponding to the capacitor 25, 41 to the capacitor 25,
- a / D conversion circuit 17 is used to generate a digital signal from the output signal of gain stage 15. Repeat steps (a) and (b) to perform cyclic A / D conversion for the desired number of bits.
- the capacitor circuit 27b for the capacitor circuits 27 and 45 is used. be able to.
- the capacitance circuit 27b preferably includes a capacitor 30 (capacitance value Cst) connected to the first node nodel between the other end 31b of the second capacitor 31 and the second switch 29.
- Capacitor 30 reduces noise caused by switching of second switch 29 (for example, MOS analog switch used as second switch 29! / Or voltage dependence of charge injection noise) it can.
- the capacitor circuit 27b When the capacitor circuit 27b is used instead of the capacitor circuit 45, one end 31a of the second capacitor 31 is connected to the non-inverting input 23c.
- the second switch 29 is connected between the other end 31b of the second capacitor 31 and the inverted output 23d.
- the capacitor circuit 27b uses the capacitor 30, the voltage dependence of charge injection noise can be reduced.
- the A / D converters 11, 11a, and ib according to the first and second embodiments may include a preamplifier 63.
- the preamplifier 63 is connected between the pixel 2a of the CMOS image sensor and the input 15a of the gain stage 15.
- the preamplifier 63 is connected between the operational amplifier circuit 65, the first capacitor 67 connected to the inverting input 65a of the operational amplifier circuit 65, and the output 65b and the input 65a of the operational amplifier circuit 65.
- Second capacitor 69 and switch 71 and amplifies the first and second signals S 1 and S 2 according to the capacitance ratio (C / C) of the first and second capacitors 67 and 69 .
- the preamplifier 63 is effective to arrange the preamplifier 63 in parallel in an array on the column of the image sensor array 2 as shown in FIG.
- the clock ⁇ sp is activated to make the switch 71 conductive.
- the input of the preamplifier 63 receives the reset level signal Vr from the pixel 2a. This signal is sampled on capacitor 67 (C). After that, switch 71 is turned off.
- the preamplifier 63 generates the output voltage V. Next, turn on preamplifier 63.
- the force receives the signal level signal Vs from the pixel 2a. At this time, the preamplifier 63 generates the output voltage V.
- the voltage V is displayed by the switch 71 in response to the clock ⁇ sp at the input / output of the preamplifier 63.
- V V + Vnf + Vnl (1)
- the noise component includes noise (freeze noise) Vnf sampled by the capacitance of the preamplifier 63 and expressed as a fixed value, and noise Vnl that varies with time.
- the voltage V includes the following components.
- V (Vr— Vs) X C / C + V + Vnf + Vn2 (2)
- the first term is the transfer charge from the capacitor C force to the capacitor C, and the noise level from the pixel.
- the capacitor C When the signal level signal from the pixel is received after that, the capacitor C has Q
- the third term corresponds to freeze noise Vnf and time-varying noise Vn2.
- the noise component common to the two levels Vs and Vr is canceled and amplified by the ratio of the difference (Vr ⁇ Vs) forces S and C. Amplified (Vr— Vs) X C / Noise component, etc.
- Equation (2) shows that the pixel force, the force S for performing noise cancellation (determining the difference between Vr and Vs) for these signals, and the freeze noise component remain.
- Equation (3) there is no correlation between the time-varying components Vnl and Vn2, so the noise due to that component increases.
- the ratio C / is greater than 8.
- the preamplifier may have a fully differential configuration, or a single-ended input or single-ended output amplifier may be used instead of the internal operational amplifier.
- an A / D converter is provided.
- This A / D converter is particularly suitable for integration in the column of image sensors, and with a simple circuit configuration, it is possible to read out image sensor signals with low noise, and a wide dynamic range; Output high-resolution digital values.
- the noise from the image sensor pixels is reduced by sampling the signal many times and amplifying by integration.
- the intermediate result (integral value) of the above integration is sequentially compared with a reference value by a comparator. When the comparison result indicates that the integrated value is larger than the reference value, subtracting a predetermined value from the integrated value suppresses saturation of the output of the A / D converter during the integration operation, and this subtraction.
- cyclic A / D conversion is performed using the circuit used for noise cancellation and integration, and A / D conversion of the lower bits is performed.
- a high-resolution digital code is obtained by combining the upper bits from the integral A / D conversion and the lower bits from the cyclic A / D conversion.
- a preamplifier is provided prior to the integration A / D conversion, and the freeze noise generated by the preamplifier is removed to read out a signal with even lower noise.
- FIG. 11 is a drawing schematically showing a readout circuit for a CMOS image sensor.
- FIG. 12 shows a timing chart for this readout circuit.
- the pixel of the CMOS image sensor generates the first signal in the reset state and the second signal in the light receiving state.
- FIG. 13 shows an image sensor.
- the read circuit 81 includes a print amplifier 83 and an integrator 85.
- the preamplifier 83 is connected between the operational amplifier circuit 87, the first capacitor 89 connected to the inverting input 87a of the operational amplifier circuit 87, and the non-inverting output 87b and the inverting input 87a of the operational amplifier circuit 87.
- Second capacitor 91 is included.
- Preamplifier 83 amplifies first signal S1 and second signal S2 received at input 93 according to the capacitance ratio of first and second capacitors 89 and 91.
- the printer 83 includes a switch 95 connected between the non-inverting output 87b and the inverting input 87a of the operational amplifier circuit 87, and the switch 95 is responsive to the clock.
- the non-inverted input 87c of the operational amplifier circuit 87 is connected to, for example, a ground line and! /, And a reference potential line! /.
- the integrator 85 includes a sampling switch 97 connected to the output 83a of the preamplifier 83, and performs a plurality of integrations of the amplified first signal using the sampling switch 97.
- the sampling signal 97 is used to integrate the amplified second signal a plurality of times, thereby amplifying the difference between the first signal and the second signal.
- the increase Performs multiple integrations of the first amplified signal and multiple integrations of the amplified second signal so that the output 85a of the preamplifier 83 has the opposite polarity of the input 85a of the integrator 85.
- the integrator 85 provides an amplified signal indicating the difference between the first signal S 1 and the second signal S 2.
- a first capacitor 98 is connected between the inverting input 99a of the operational amplifier circuit 99 and the switch 97.
- Switch 97 responds to clock ⁇ 1.
- a capacitor circuit 101 is connected between the non-inverting output 99b and the inverting input 99a of the operational amplifier circuit 99.
- Capacitance circuit 101 includes a second capacitor 103 and a switch 105 connected in series.
- Integrator 85 includes a switch 107 connected between non-inverting output 99b and inverting input 99a of operational amplifier circuit 99, and switch 107 is responsive to clock ⁇ 2.
- Capacitance circuit 101 also includes a reset switch 111 connected to a common node node3 of second capacitor 103 and switch 105.
- the capacitor circuit 101 includes a capacitor 109 having one end connected to the common node node3, and the other end of the capacitor 109 is connected to a reference potential line such as a ground line. Capacitor 109 serves to reduce the voltage dependence of the switching noise of reset switch 1 1 1. A common node node4 between the first capacitor 98 and the switch 97 is connected to the switch 112 for supplying the reference voltage V. Si
- the tube 112 operates in response to the clock ⁇ 3.
- a sample / hold (S / H) circuit 1 13 is connected to the output 85b of the integrator 85.
- the S / H circuit 1 13 includes a holding capacitor 1 1 5 and a holding capacitor 1 1 5
- a sampling switch 1 1 7 connected between one end 1 1 5a and the output 85b of the integrator 85.
- the held signal is connected to the horizontal scanning line 121 via the synchronization switch 1 19.
- a non-inverting input of the operational amplifier circuits 87 and 99 is supplied with a reference potential such as a ground potential.
- the readout circuit 81 shown in FIG. 11 has a single-ended configuration, an operational amplifier circuit with a fully differential configuration can be used for the preamplifier and the integrator. Also, for example, cyclic A / D conversion can be performed by connecting an A / D converter to the output of the integrator 85.
- FIG. 13 shows a block diagram of the image sensor la.
- This array of readout circuits 81 is The image cell array 2 can be provided in a column. Thus, the readout circuit 81 can read out the image sensor signal with low noise by a simple circuit configuration.
- the timing chart shows the reset level integration period T and the signal level integration period TS.
- the reset level integration period T is divided into four periods ⁇ to T.
- R Rl R4 is integrated, and the signal level integration period ⁇ is integrated in each of the four periods ⁇ to ⁇
- the preamplifier 83 is reset using the switch 95. After period T
- the clock ⁇ is performed in parallel with the period ⁇ of the signal level integration period ⁇ .
- the clock ⁇ is performed in parallel with the period ⁇ of the signal level integration period ⁇ .
- switch 97 In response to 1, switch 97 is conducting for almost the entire period ⁇ , T. Signal
- the second signal S2 is provided to the preamplifier 83 in response to the clock TXi.
- the preamplifier 83 samples the amplified second signal S2 in the capacitor 98 via the switch 97 in response to the clock ⁇ 1.
- the clock ⁇ 1 is active in the first half of each period.
- the clock ⁇ 1 is active in the second half of each period. Therefore
- Integration in the integrator 85 during the reset level integration period T is performed during the reset level integration period T.
- the first signal (reset level) S1 of the pixel 2a is sampled by the preamplifier 83 with respect to the output.
- the reset switch 95 is turned on to reset the capacitor 91.
- noise associated with the reset operation is generated at the output 83a of the preamplifier 83.
- the integrator 85 performs sampling a number of times in order to integrate this first signal S 1.
- the second signal (signal level) S 2 of the pixel 2 a is applied to the preamplifier 83.
- This signal is amplified by the capacitance ratio of the capacitors 89 and 91 in the preamplifier 83.
- the integrator 85 generates a signal indicating the difference between the first signal S1 and the second signal S2.
- the integrator 85 samples the signal many times so that the signal from the output 83a of the preamplifier 83 has a reverse polarity.
- the output of the integrator provides a signal amplified by integration while taking the difference between the first signal S1 and the second signal S2 from the output 83a of the preamplifier 83.
- the integration result is sampled and stored by the S / H circuit 113, and is read out by the horizontal scanning line 121.
- FIG. 14 and 15 are diagrams showing the operation of the multiple integration readout circuit.
- FIG. 12 in the example operation below the force at which sampling is performed four times, integration is performed twice for each of the reset level and signal level from pixel 2a.
- V and V are used as the first and second signals S 1 and S 2.
- step (a) the reset level signal V of the pixel 2a is applied to the input 83b of the preamplifier 83.
- the signal VR is sampled on the capacitor 89 by connecting the inverting input 87a of the operational amplifier circuit 87 to the non-inverting output 87b through the switch 95.
- the switch 107 is turned on to connect the inverting input 99a and the non-inverting input 99b of the operational amplifier circuit 99, and the switch 111 is turned on in response to the clock.
- the electric charge of the capacitor 103 is reset.
- the switch 97 is turned on.
- the electric charge of the capacitor 98 is reset.
- step (b) the switch 95 is turned off in response to the clock ⁇ ⁇ and the clock 95
- the switch 107 non-conductive in response to the phi gamma 2.
- the capacitor 91 samples the noise component generated by the switch or amplifier and appears at the output 83a.
- the integrator 85 samples the signal from the preamplifier 83 into the capacitor 98 through the switch 97.
- step (c) switch 111 of integrator 85 is turned off and switch 105 is turned on to integrate the charge of capacitor 98 into capacitor 103. At this time, the voltage of the following formula appears at the output of the integrator 85.
- V (1) C / C X Vndl (l) + C / C X C / C X Vnpd (l)
- Vndl (l) and Vnpd (l) are noise components (noise that varies with time) of the source follower of the preamplifier 83 and the pixel 2a, respectively.
- the numbers in parentheses correspond to the order of the steps.
- the first term is noise caused by the preamplifier 83
- the second term is noise caused by the pixel 2a
- this noise is amplified by the preamplifier 83.
- step (d) the switch 97 is turned off in response to the clock ⁇ 1 and the switch 112 is turned on in response to the clock ⁇ 3.
- Supply voltage VREF to capacitor 98 of integrator 85 The electric charge corresponding to this voltage moves from the capacitor 98 to the capacitor 103. At this time, the voltage of the following formula appears at the output of the integrator 85.
- V (1) C / C X (Vnfl (l) + Vndl (l) -VREF) + C / C XC / C XVnpd
- Vnfl (l) is freeze noise of the preamplifier 83. Freeze noise exists as a fixed charge sampled in a capacitor and does not vary with time.
- step (e) switch 105 is turned off in response to clock ⁇ 2. Since one end of the capacitor 103 (capacitor terminal connected to the output of the integrator) is open, the integration result is held in the capacitor 103. In response to the clock ⁇ ⁇ 2, the switch 107 is conducted to connect the inverting input 99a of the operational amplifier circuit 99 to the non-inverting output 99b.
- step (2) the second signal S2 is supplied to the input 93 of the readout circuit 81.
- the preamplifier 83 amplifies the signal S2.
- the capacitor 98 of the integrator 85 receives the amplified signal. At this time, the following voltage appears at the output of the integrator 85.
- V (1) C / C X (Vnfl (l) + Vndl (l) -V -Vndl (3)) + C / C XC / C
- step (g) switch 97 is turned off in response to clock ⁇ 1 and switch 112 is turned on in response to clock ⁇ 3.
- Supply voltage VREF to capacitor 98 of integrator 85 The electric charge corresponding to this voltage moves from the capacitor 98 to the capacitor 103. At this time, the voltage of the following formula appears at the output of the integrator 85.
- V (1) C / C X (Vnfl (l) + Vndl (l) -V — Vndl (3) — Vndl (4) — Vnfl (
- the freeze noise component Vnfl of the preamplifier 83 is first canceled. Also, by sampling N times, the input signal (V -V W times is amplified.
- the time-varying noise components (Vnpd, Vndl) are also integrated, the time-varying noise components are uncorrelated and random. Therefore, as a result of N integrations, the signal component (V -V) is amplified by sqrt (2 XN— 1) times in amplitude while the signals V and V are N
- the gain of the preamplifier 83 (determined by the capacitor ratio C /) can be increased.
- the time-varying noise component is reduced by the band limiting effect of the preamplifier 83.
- the ratio C / C is 8 or more.
- FIG. 16 is a graph showing estimation by noise analysis. “INT” in the figure indicates the number of integrations.
- the preamplifier gain is 1 and the integration is not performed multiple times, the total input equivalent noise including thermal noise and i / f noise is 232 H Vrms, but the preamplifier gain is 32. When doubled, it is reduced to 56.4 Vrms. When the preamplifier gain is 32 times and 16 integrations are performed, the gain is reduced to 18.4 Vrms. It is assumed that the conversion gain is 60 V / e—, and this value is equivalent to 0.3 or less in terms of equivalent noise electrons. If the noise is 0.3 or less in terms of the number of equivalent electrons, the discrete level generated according to the number of signal electrons can be roughly identified.
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/375,879 US8553112B2 (en) | 2006-07-31 | 2007-07-31 | A/D converter and readout circuit |
EP07791671.6A EP2048785B1 (en) | 2006-07-31 | 2007-07-31 | A/d converter and reading circuit |
JP2008527759A JP4793602B2 (ja) | 2006-07-31 | 2007-07-31 | A/d変換器および読み出し回路 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2006-208664 | 2006-07-31 | ||
JP2006208664 | 2006-07-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2008016049A1 true WO2008016049A1 (fr) | 2008-02-07 |
Family
ID=38997223
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2007/064986 WO2008016049A1 (fr) | 2006-07-31 | 2007-07-31 | Convertisseur a/n et circuit de lecture |
Country Status (4)
Country | Link |
---|---|
US (1) | US8553112B2 (ja) |
EP (1) | EP2048785B1 (ja) |
JP (1) | JP4793602B2 (ja) |
WO (1) | WO2008016049A1 (ja) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009296423A (ja) * | 2008-06-06 | 2009-12-17 | Sony Corp | 固体撮像装置、撮像装置、電子機器、ad変換装置、ad変換方法 |
JP2011097658A (ja) * | 2008-03-19 | 2011-05-12 | Commissariat A L'energie Atomique & Aux Energies Alternatives | 電荷を電圧に変換するシステムおよびこのシステムを制御する方法 |
WO2012111821A1 (ja) | 2011-02-18 | 2012-08-23 | 国立大学法人静岡大学 | A/d変換器、イメージセンサデバイス及びアナログ信号からディジタル信号を生成する方法 |
JP2013153380A (ja) * | 2012-01-26 | 2013-08-08 | Hitachi Kokusai Electric Inc | 撮像装置および撮像方法 |
JP2013153381A (ja) * | 2012-01-26 | 2013-08-08 | Hitachi Kokusai Electric Inc | 撮像装置および撮像方法 |
US9917119B2 (en) | 2014-12-26 | 2018-03-13 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including unit pixel cell which includes capacitor circuit and feedback circuit |
CN108306647A (zh) * | 2012-09-26 | 2018-07-20 | 瑞萨电子株式会社 | 半导体装置 |
US10141364B2 (en) | 2014-12-26 | 2018-11-27 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including unit pixel cell |
Families Citing this family (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012009413A2 (en) * | 2010-07-13 | 2012-01-19 | University Of Washington Through Its Center For Comm... | Methods and systems for compressed sensing analog to digital conversion |
JP5822547B2 (ja) * | 2011-06-10 | 2015-11-24 | キヤノン株式会社 | 撮像装置および撮像システム |
KR102023938B1 (ko) * | 2012-12-26 | 2019-09-23 | 엘지디스플레이 주식회사 | 터치 센싱 장치 및 방법 |
JP5767660B2 (ja) * | 2013-02-20 | 2015-08-19 | 株式会社東芝 | Dc−dcコンバータ |
US8610443B1 (en) * | 2013-03-12 | 2013-12-17 | Cypress Semiconductor Corp. | Attenuator circuit of a capacitance-sensing circuit |
US9264644B2 (en) * | 2013-04-25 | 2016-02-16 | Forza Silicon Corporation | Analog-to-digital conversion for image sensor with non-destructive read pixel |
JP6205885B2 (ja) * | 2013-06-18 | 2017-10-04 | 株式会社リコー | 光電変換素子、画像読取装置、画像形成装置及び画像読取方法 |
US9270895B2 (en) * | 2013-07-31 | 2016-02-23 | Massachusetts Institute Of Technology | Methods and apparatus for true high dynamic range imaging |
JP2015146560A (ja) * | 2014-02-04 | 2015-08-13 | ソニー株式会社 | 撮像装置、電流/電圧変換回路及び撮像方法 |
US9380208B1 (en) * | 2015-04-13 | 2016-06-28 | Omnivision Technologies, Inc. | Image sensor power supply rejection ratio noise reduction through ramp generator |
JP6727771B2 (ja) | 2015-08-13 | 2020-07-22 | キヤノン株式会社 | 撮像装置 |
FR3048317B1 (fr) * | 2016-02-26 | 2019-06-28 | Stmicroelectronics Sa | Adc en pipeline a demande de charge constante |
JP6830672B2 (ja) * | 2016-11-11 | 2021-02-17 | 国立大学法人静岡大学 | A/d変換器 |
CN109787563B (zh) * | 2019-01-16 | 2021-08-24 | 电子科技大学 | 一种基于运放失调补偿的相关双采样电路 |
JP7166240B2 (ja) * | 2019-12-17 | 2022-11-07 | 株式会社東芝 | 電子回路 |
WO2023186527A1 (en) * | 2022-03-31 | 2023-10-05 | Sony Semiconductor Solutions Corporation | Image sensor assembly with converter circuit for temporal noise reduction |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH03225284A (ja) * | 1990-01-30 | 1991-10-04 | Nec Corp | 固体撮像装置の出力信号計測方法 |
JP2005136540A (ja) | 2003-10-29 | 2005-05-26 | National Univ Corp Shizuoka Univ | A/d変換アレイ及びイメージセンサ |
JP2005269471A (ja) * | 2004-03-22 | 2005-09-29 | Sony Corp | 固体撮像装置および固体撮像装置の駆動方法 |
JP2006025189A (ja) | 2004-07-08 | 2006-01-26 | Shoji Kawahito | ディジタルノイズキャンセル機能をもつイメージセンサ |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5651166A (en) | 1979-10-03 | 1981-05-08 | Hitachi Ltd | Solid image pickup device |
DE3719967A1 (de) | 1986-06-16 | 1987-12-17 | Hitachi Ltd | Festkoerper-bildwandler |
JP3225284B2 (ja) | 1995-03-31 | 2001-11-05 | 大阪ダイヤモンド工業株式会社 | サーキュラソーで片面切削する方法ならびに同方法に用いるサーキュラソー |
US6529237B1 (en) * | 1997-12-02 | 2003-03-04 | Texas Instruments Incorporated | Complete CDS/PGA sample and hold amplifier |
US6885396B1 (en) * | 1998-03-09 | 2005-04-26 | Micron Technology, Inc. | Readout circuit with gain and analog-to-digital a conversion for image sensor |
US6166367A (en) * | 1998-03-26 | 2000-12-26 | Photobit Corporation | Programmable analog arithmetic circuit for imaging sensor |
US7821555B2 (en) * | 2003-04-21 | 2010-10-26 | Micron Technology, Inc. | Multi path power for CMOS imagers |
JP2005269741A (ja) * | 2004-03-17 | 2005-09-29 | Hitachi Cable Ltd | 保護管把持具 |
-
2007
- 2007-07-31 EP EP07791671.6A patent/EP2048785B1/en active Active
- 2007-07-31 US US12/375,879 patent/US8553112B2/en active Active
- 2007-07-31 WO PCT/JP2007/064986 patent/WO2008016049A1/ja active Search and Examination
- 2007-07-31 JP JP2008527759A patent/JP4793602B2/ja active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH03225284A (ja) * | 1990-01-30 | 1991-10-04 | Nec Corp | 固体撮像装置の出力信号計測方法 |
JP2005136540A (ja) | 2003-10-29 | 2005-05-26 | National Univ Corp Shizuoka Univ | A/d変換アレイ及びイメージセンサ |
JP2005269471A (ja) * | 2004-03-22 | 2005-09-29 | Sony Corp | 固体撮像装置および固体撮像装置の駆動方法 |
JP2006025189A (ja) | 2004-07-08 | 2006-01-26 | Shoji Kawahito | ディジタルノイズキャンセル機能をもつイメージセンサ |
Non-Patent Citations (4)
Title |
---|
A. KRYMSKI ET AL.: "A 2e noise 1.3 Megapixel CMOS sensor", PROC. IEEE WORKSHOP CCD AND ADVANCED IMAGE SENSORS |
M. SAKAKIBARA ET AL.: "A high- sensitivity CMOS image sensor with gain-adaptive column amplifiers", IEEE J. SOLID-STATE CIRCUITS, vol. 40, no. 5, 2005, pages 1147 - 1156, XP011131312, DOI: doi:10.1109/JSSC.2005.845969 |
N. KAWAI; S. KAWAHITO: "Noise analysis of high-gain low-noise column readout circuits for CMOS image sensors", IEEETRANS. ELECTRON DEVICES, vol. 51, no. 2, 2004, pages 185 - 194, XP002594208, DOI: doi:10.1109/TED.2003.822224 |
See also references of EP2048785A4 |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2011097658A (ja) * | 2008-03-19 | 2011-05-12 | Commissariat A L'energie Atomique & Aux Energies Alternatives | 電荷を電圧に変換するシステムおよびこのシステムを制御する方法 |
US8502899B2 (en) | 2008-06-06 | 2013-08-06 | Sony Corporation | Solid-state imaging device, imaging device, electronic equipment, A/D converter and A/D conversion method |
JP2009296423A (ja) * | 2008-06-06 | 2009-12-17 | Sony Corp | 固体撮像装置、撮像装置、電子機器、ad変換装置、ad変換方法 |
WO2012111821A1 (ja) | 2011-02-18 | 2012-08-23 | 国立大学法人静岡大学 | A/d変換器、イメージセンサデバイス及びアナログ信号からディジタル信号を生成する方法 |
US9236879B2 (en) | 2011-02-18 | 2016-01-12 | National University Corporation Shizuoka University | A/D converter, image sensor device, and method of generating digital signal from analog signal |
KR101743800B1 (ko) | 2011-02-18 | 2017-06-05 | 고쿠리츠 다이가꾸 호우진 시즈오까 다이가꾸 | A/d 변환기, 이미지 센서 디바이스 및 아날로그 신호로부터 디지털 신호를 생성하는 방법 |
JP2013153380A (ja) * | 2012-01-26 | 2013-08-08 | Hitachi Kokusai Electric Inc | 撮像装置および撮像方法 |
JP2013153381A (ja) * | 2012-01-26 | 2013-08-08 | Hitachi Kokusai Electric Inc | 撮像装置および撮像方法 |
CN108306647A (zh) * | 2012-09-26 | 2018-07-20 | 瑞萨电子株式会社 | 半导体装置 |
US9917119B2 (en) | 2014-12-26 | 2018-03-13 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including unit pixel cell which includes capacitor circuit and feedback circuit |
US10141364B2 (en) | 2014-12-26 | 2018-11-27 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including unit pixel cell |
US10325945B2 (en) | 2014-12-26 | 2019-06-18 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including unit pixel cell which includes interconnection between photoelectric converter and signal detection circuit |
US10672827B2 (en) | 2014-12-26 | 2020-06-02 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including unit pixel cell |
US10770491B2 (en) | 2014-12-26 | 2020-09-08 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including photoelectric converter and capacitor with a capacitor and a switching element connected in series between a first electrode of a photoelectric converter and a voltage source or a ground |
US11329079B2 (en) | 2014-12-26 | 2022-05-10 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including photoelectric converter and circuitry including a first capacitance element, a second capacitance element and a transistor |
US11482558B2 (en) | 2014-12-26 | 2022-10-25 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including unit pixel cell |
US11670652B2 (en) | 2014-12-26 | 2023-06-06 | Panasonic Intellectual Property Management Co., Ltd. | Imaging device including a photoelectric converter and a capacitive element having a dielectric film sandwiched between electrodes and a mode switching transistor |
Also Published As
Publication number | Publication date |
---|---|
EP2048785A1 (en) | 2009-04-15 |
US8553112B2 (en) | 2013-10-08 |
JPWO2008016049A1 (ja) | 2009-12-24 |
EP2048785A4 (en) | 2011-08-31 |
US20090303358A1 (en) | 2009-12-10 |
JP4793602B2 (ja) | 2011-10-12 |
EP2048785B1 (en) | 2013-09-04 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2008016049A1 (fr) | Convertisseur a/n et circuit de lecture | |
EP2571169B1 (en) | A/d converter | |
JP5378945B2 (ja) | X線画素検出器の読出し回路及び集積回路 | |
JP5893573B2 (ja) | 固体撮像装置 | |
JP4022862B2 (ja) | 固体撮像装置及びその制御方法 | |
JP5818170B2 (ja) | A/d変換器、イメージセンサデバイス及びアナログ信号からディジタル信号を生成する方法 | |
JP4474982B2 (ja) | 固体撮像装置および固体撮像装置の信号処理方法 | |
WO2005041419A1 (ja) | A/d変換アレイ及びイメージセンサ | |
JP2004304413A (ja) | イメージセンサ用2段階a/d変換器 | |
KR101157749B1 (ko) | 순회형 아날로그·디지털 변환기 | |
US7598896B2 (en) | A/D converter with noise cancel function | |
US8189079B2 (en) | Imaging apparatus and method | |
US10715757B2 (en) | A/D converter | |
JP4684028B2 (ja) | パイプラインa/d変換器 | |
JP2015105869A (ja) | 電圧検出装置 | |
JP5187782B2 (ja) | 巡回型a/d変換器、イメージセンサデバイス、及びアナログ信号からディジタル信号を生成する方法 | |
JP4478798B2 (ja) | オフセット低減機能をもつ巡回型a/d変換器、およびオフセット電圧を低減する方法 | |
JP4328863B2 (ja) | 巡回型a/d変換器およびイメージセンサ | |
JP4469988B2 (ja) | ノイズキャンセル機能付きa/d変換器 | |
JP2812169B2 (ja) | A/d変換装置 | |
JP6771758B2 (ja) | A/d変換器 | |
JP2004023750A (ja) | 電荷検出回路の駆動方法、および、電荷検出回路 | |
JP2008141396A (ja) | アナログディジタル変換器およびイメージセンシング半導体デバイス | |
JP5011538B2 (ja) | 巡回型アナログ・ディジタル変換器およびイメージセンサデバイス |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
DPE2 | Request for preliminary examination filed before expiration of 19th month from priority date (pct application filed from 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 07791671 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2008527759 Country of ref document: JP |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2007791671 Country of ref document: EP |
|
NENP | Non-entry into the national phase |
Ref country code: RU |
|
WWE | Wipo information: entry into national phase |
Ref document number: 12375879 Country of ref document: US |
|
DPE2 | Request for preliminary examination filed before expiration of 19th month from priority date (pct application filed from 20040101) |