Photoelectric conversion devices, substrates and equipment

Abstract

To reduce the influence due to a change in internal temperature of a photoelectric conversion device.SOLUTION: A photoelectric conversion device comprises: a light receiving circuit that converts light into an electric signal; a first holding circuit that holds a data signal representing the electric signal converted from the light; a second holding circuit that holds a noise signal read out from the light receiving circuit in a reset state; a first resistance element that is applied with a voltage according to the difference between the data signal held in the first holding circuit and the noise signal held in the second holding circuit; an AD converter that converts an analog current flowing in the first resistance element into digital data; a second resistance element; and a temperature detection circuit that generates an analog output according to the internal temperature of the photoelectric conversion device based on a current flowing in the second resistance element.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion device, a substrate, and an apparatus. [Background technology]

[0002] A photoelectric conversion device is known that removes noise from a data signal by performing correlated double sampling. In Patent Document 1, a resistive element is connected between the output terminal of a sample-and-hold circuit for a data signal and the output terminal of a sample-and-hold circuit for a reset signal. A current proportional to the potential difference between the data signal and the reset signal flows through this resistive element. The value of this current is converted into digital data by an AD converter and output to an external device as a pixel value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 069614 Summary of the Invention [Problem to be solved by the invention]

[0004] The resistance value of a resistor element connected between the output terminal of a data signal sample-and-hold circuit and the output terminal of a reset signal sample-and-hold circuit varies depending on the internal temperature of the photoelectric conversion device. Therefore, even if the same voltage is applied to the resistor element, the value of the current flowing through the resistor element varies depending on the internal temperature. As a result, the obtained pixel value also varies. One aspect of the present invention aims to reduce the effects of changes in the internal temperature of the photoelectric conversion device. [Means for solving the problem]

[0005] In view of the above problem, there is provided a photoelectric conversion device comprising: a light receiving circuit that converts light into an electric signal; a first holding circuit that holds a data signal representing the electric signal converted from the light; a second holding circuit that holds a noise signal read from the light receiving circuit in a reset state; a first resistor element to which a voltage corresponding to a difference between the data signal held in the first holding circuit and the noise signal held in the second holding circuit is applied; an AD converter that converts an analog current flowing through the first resistor element into digital data; a second resistor element; and a temperature detection circuit that generates an analog output corresponding to an internal temperature of the photoelectric conversion device based on the current flowing through the second resistor element, wherein the light receiving circuit is disposed on a first substrate, and the first resistor element, the second resistor element, and the AD converter are disposed on a second substrate. , the analog output is input to the AD converter A photoelectric conversion device characterized by the above features is provided. [Effects of the Invention]

[0006] By the above means, the influence of changes in the internal temperature of the photoelectric conversion device is reduced. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the arrangement of a photoelectric conversion device according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the circuit configuration of a pixel circuit according to the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of the circuit configuration of a pixel circuit according to the first embodiment. [Figure 4] FIG. 2 is a diagram for explaining an example of the circuit configuration of a readout circuit according to the first embodiment. [Figure 5] FIG. 2 is a diagram illustrating an example of the circuit configuration of a ΔΣ modulator according to the first embodiment. [Figure 6] FIG. 2 is a diagram illustrating an example of the circuit configuration of a current generating circuit and a temperature detecting circuit according to the first embodiment. [Figure 7] FIG. 4 is a diagram illustrating another example of the circuit configuration of the current generating circuit and the temperature detecting circuit according to the first embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of the arrangement of a photoelectric conversion device according to a second embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of the circuit configuration of a temperature detection circuit according to a second embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of the arrangement of a photoelectric conversion device according to a third embodiment. [Figure 11] FIG. 10 is a diagram illustrating an example of the configuration of a photoelectric conversion device according to a modified example. [Figure 12] FIG. 10 is a diagram illustrating an example of the arrangement of a device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0009] The following mainly describes an embodiment in which the photoelectric conversion device 100 is used for imaging. In this case, the photoelectric conversion device 100 can be used as an imaging element (image sensor) for generating an image. Other examples of the photoelectric conversion device 100 include a rangefinder (a sensor used for distance measurement using focus detection or TOF (Time Of Flight)), a photometry element (a sensor used for measuring the amount of incident light), and a LiDAR (Light Detection and Ranging) sensor. The embodiments described below can be applied to photoelectric conversion devices in general.

[0010] First Embodiment An example configuration of a photoelectric conversion device 100 according to the first embodiment will be described with reference to the block diagram of Fig. 1. In the example shown in Fig. 1, the photoelectric conversion device 100 includes a pixel unit 110, a readout unit 120, an AD conversion unit 130, a horizontal scanning circuit 140, a signal processing circuit 150, an output circuit 160, a vertical scanning circuit 170, and a timing control circuit 180.

[0011] The pixel section 110 includes a plurality of pixel circuits 111 arranged in a two-dimensional array, a plurality of drive lines 112 provided for each pixel row, and a plurality of signal lines 113 provided for each pixel column. The pixel rows refer to the plurality of pixel circuits 111 lined up in the horizontal direction in Fig. 1. The pixel columns refer to the plurality of pixel circuits 111 lined up in the vertical direction in Fig. 1.

[0012] The pixel circuits 111 convert incident light into an electric signal. Therefore, the pixel circuits 111 may also be called light receiving circuits. A control signal is supplied to each of the plurality of pixel circuits 111 from the vertical scanning circuit 170 via a drive line 112. An electric signal is read out from the pixel circuit 111 to which an active level control signal has been supplied by the readout unit 120 via a signal line 113.

[0013] The readout unit 120 includes a plurality of readout circuits 121 provided for each signal line 113, and a control circuit 122 that controls the operation of these readout circuits 121. The readout circuits 121 read out analog signals corresponding to the electrical signals generated by the pixel circuits 111, and supply the analog signals to the AD conversion unit 130.

[0014] The AD conversion unit 130 includes a plurality of AD converters 131 provided for each signal line 113, a control circuit 132 that controls the operation of these AD converters 131, and a temperature detection circuit 133. The AD converters 131 convert analog signals supplied from the readout circuit 121 into digital signals. In the following description, the AD converters 131 may be ΔΣ AD converters, slope-type AD converters, or successive approximation AD converters. The temperature detection circuit 133 detects the internal temperature of the photoelectric conversion device 100 and supplies an analog output corresponding to this internal temperature to each AD converter 131.

[0015] The horizontal scanning circuit 140 sequentially reads out the digital signals from the plurality of AD converters 131 and supplies them to the signal processing circuit 150. The photoelectric conversion device 100 may have a memory circuit for storing the digital signals between the AD conversion unit 130 and the horizontal scanning circuit 140. The signal processing circuit 150 processes digital signals corresponding to the electrical signals generated by each pixel circuit 111. The signal processing circuit 150 may perform correction processing, interpolation processing, etc. on the digital signals, for example.

[0016] The digital signal processed by the signal processing circuit 150 is output from the output circuit 160 to an external device 190 located outside the photoelectric conversion device 100. The external device 190 may be, for example, a control device for a device incorporating the photoelectric conversion device 100. The timing control circuit 180 controls the overall operation of the photoelectric conversion device 100 by supplying control signals to each circuit of the photoelectric conversion device 100.

[0017] A specific example of the circuit configuration of the pixel circuit 111 will be described with reference to the circuit diagram in Fig. 2. The pixel circuit 111 can have any configuration that converts incident light into an electrical signal. Fig. 2 describes one example, but the pixel circuit 111 may have other configurations.

[0018] 2, the pixel circuit 111 includes a photoelectric conversion element 201, a transfer transistor 202, a reset transistor 203, an amplification transistor 204, and a selection transistor 205. In the example of Fig. 2, the pixel unit 110 includes three drive lines 112 for each pixel row, which supply control signals PRES, PTX, and PSEL to the pixel circuit 111, respectively.

[0019] The photoelectric conversion element 201 converts incident light into electric charges and accumulates the electric charges. The photoelectric conversion element 201 may be, for example, a photodiode or a phototransistor. The photoelectric conversion element 201 may be a CMOS (Complementary Metal Oxide Semiconductor) sensor. Alternatively, the photoelectric conversion element 201 may be a SPAD (Single Photon Avalanche Diode) sensor.

[0020] The photoelectric conversion element 201 is connected to a floating diffusion 206 via a transfer transistor 202. A control signal PTX is supplied to the gate of the transfer transistor 202 from the vertical scanning circuit 170. When the control signal PTX becomes active level, the transfer transistor 202 becomes conductive. In response to this, the signal charge accumulated in the photoelectric conversion element 201 is transferred to the floating diffusion 206.

[0021] The floating diffusion 206 is also connected to the gate of the amplification transistor 204. One main electrode of the amplification transistor 204 is connected to the signal line 113 via the selection transistor 205. The other main electrode of the amplification transistor 204 is connected to the power supply potential VDD. A control signal PSEL is supplied to the gate of the selection transistor 205 from the vertical scanning circuit 170. In response to the control signal PSEL becoming active level, the selection transistor 205 becomes conductive. In response to this, one main electrode of the amplification transistor 204 is connected to the current source of the readout circuit 121. As a result, the amplification transistor 204 operates as a source follower, and a signal corresponding to the potential of the floating diffusion 206 is read out to the signal line 113.

[0022] The reset transistor 203 is connected between the floating diffusion 206 and the power supply potential VDD. A control signal PRES is supplied to the gate of the reset transistor 203 from the vertical scanning circuit 170. In response to the control signal PRES becoming active level, the reset transistor 203 becomes conductive. In response to this, the potential of the floating diffusion 206 is reset to the power supply potential VDD.

[0023] A specific example of the circuit configuration of the readout circuit 121 will be described with reference to the circuit diagram of Fig. 3. The readout circuit 121 can have any configuration that reads out the electrical signal generated in the pixel circuit 111. Fig. 3 describes one example, but the readout circuit 121 may have other configurations.

[0024] In the example illustrated in FIG. 3, the readout circuit 121 includes current sources 301 , 308 , and 309 , sample-and-hold circuits 302 and 303 , amplifiers 304 and 306 , transistors 305 and 307 , and a resistive element 312 .

[0025] The current source 301 supplies a bias current to the pixel circuit 111 (specifically, its amplification transistor 204). The sample and hold circuits 302 and 303 each hold an output voltage from the pixel circuit 111. The sample and hold circuits may also be called holding circuits. The timing control circuit 180 controls the pixel circuit 111 to output an electrical signal when the photoelectric conversion element 201 is in a reset state (hereinafter referred to as a noise signal) and an electrical signal corresponding to incident light (hereinafter referred to as a data signal). The control circuit 122, in accordance with instructions from the timing control circuit 180, reads out the noise signal and controls the readout circuit 121 to hold it in the sample and hold circuit 302. The control circuit 122 also, in accordance with instructions from the timing control circuit 180, controls the readout circuit 121 to read out the data signal from the pixel circuit 111 and hold it in the sample and hold circuit 303.

[0026] The amplifier 304 and the transistor 305 function as a source follower. The current source 308 supplies a bias current to the source follower. The potential of a node 310 between the current source 308 and the transistor 305 has a value corresponding to the voltage (noise signal) held in the sample-and-hold circuit 302.

[0027] The amplifier 306 and the transistor 307 function as a source follower. The current source 309 supplies a bias current to the source follower. The potential of a node 311 between the current source 309 and the transistor 307 has a value corresponding to the voltage (data signal) held in the sample-and-hold circuit 303.

[0028] The resistive element 312 is connected between the node 310 and the node 311. Therefore, the voltage applied to the resistive element 312 is the potential difference between the node 310 and the node 311. In other words, a voltage corresponding to the difference between the noise signal held in the sample and hold circuit 302 and the data signal held in the sample and hold circuit 303 is applied to the resistive element 312. Therefore, an analog current signal corresponding to the difference between the data signal and the noise signal is supplied from the readout circuit 121 to the AD converter 131. In this way, the readout circuit 121 has a function of performing correlated double sampling (CDS).

[0029] A specific circuit configuration example of the AD converter 131 will be described with reference to the block diagram of FIG. 4. The AD converter 131 is a ΔΣ AD converter. The AD converter 131 converts an input analog signal into a digital signal. The AD converter 131 in FIG. 4(a) includes a first-order ΔΣ modulator 404 and a decimation filter 405. The AD converter 131 in FIG. 4(b) includes a second-order ΔΣ modulator 407 and a decimation filter 405. Alternatively, the AD converter 131 may include a third-order or higher-order ΔΣ modulator. Using a higher-order ΔΣ modulator improves the noise shaping effect. The ΔΣ modulators 404 and 407 convert the input analog signal into a 1-bit digital signal string. The decimation filter 405 performs decimation (thinning) on ​​this 1-bit digital signal string. For example, the decimation filter 405 generates a digital signal corresponding to the proportion of the time during which the 1-bit digital signal string is 1 within a predetermined time period. The delta-sigma modulator 404 may convert the input analog signal into a digital signal sequence of 2 or more bits.

[0030] 4(a), the first-order ΔΣ modulator 404 has a subtractor 401, an integrator 402, a quantizer 403, and a DA converter (DAC) 406. The subtractor 401 is supplied with an input to the AD converter 131 (i.e., the analog signal from the readout circuit 121). The subtractor 401 is also supplied with an analog signal from the DA converter 406. The subtractor 401 supplies the difference between the analog signal from the readout circuit 121 and the analog signal from the DA converter 406 to the integrator 402.

[0031] The integrator 402 integrates the output from the subtractor 401. The quantizer 403 quantizes the integration result from the integrator 402. For example, the quantizer 403 generates a 1-bit digital signal sequence based on the integration result and supplies it to the decimation filter 405. The output from the quantizer 403 becomes the output from the ΔΣ modulator 404.

[0032] The output from the quantizer 403 is also supplied to the DA converter 406. The DA converter 406 generates a signal according to the output from the quantizer 403 and supplies this to the subtractor 401. The signal supplied from the DA converter 406 to the subtractor 401 is subtracted from the analog signal supplied from the readout circuit 121, as described above.

[0033] 4(b), the second-order ΔΣ modulator 404 has subtractors 401 and 408, integrators 402 and 409, a quantizer 403, and DA converters (DACs) 406 and 410. The configurations of the subtractor 401, the integrator 402, the quantizer 403, and the DA converter (DAC) 406 are the same as those of the first-order ΔΣ modulator 404.

[0034] The output from the integrator 402 is supplied to the subtractor 408. In addition, the analog signal from the DA converter 410 is also supplied to the subtractor 408. The subtractor 408 supplies the difference between the analog signal from the integrator 402 and the analog signal from the DA converter 410 to the integrator 409. The integrator 409 integrates the output from the subtractor 408. The quantizer 403 quantizes the integration result from the integrator 409.

[0035] The output from the quantizer 403 is also supplied to a DA converter 410. The DA converter 410 generates a signal according to the output from the quantizer 403 and supplies this to a subtractor 408. The signal supplied from the DA converter 410 to the subtractor 408 is subtracted from the analog signal supplied from the integrator 402, as described above.

[0036] 5, an example of the circuit configuration of the ΔΣ modulators 404 and 407 when the input to the AD converter 131 is an analog current signal will be described. Fig. 5(a) shows an example of the circuit configuration of the first-order ΔΣ modulator 404, and Fig. 5(b) shows an example of the circuit configuration of the second-order ΔΣ modulator 407.

[0037] First, we will explain an example of the circuit configuration of the first-order ΔΣ modulator 404. The subtractor 401 is composed of a node 501 connected to the readout circuit 121, the DA converter 406, and the integrator 402. The analog current from the DA converter 406 is subtracted from the analog current signal from the readout circuit 121 supplied to the node 501, and the resulting current is supplied to the integrator 402.

[0038] The integrator 402 is composed of a capacitor 502. The capacitor 502 is charged by the output from the subtractor 401 so as to integrate the output. The voltage of the capacitor 502 is supplied to the quantizer 403. The quantizer 403 is composed of a comparator 503. The comparator 503 outputs a high-level or low-level voltage depending on the value of the voltage supplied from the integrator 402.

[0039] The DA converter 406 is composed of a switch element 504 and a current generating circuit 505. The current generating circuit 505 generates an analog current to be supplied to the subtractor 401. The switch element 504 is located on a signal path between the subtractor 401 and the current generating circuit 505. The on / off state of the switch element 504 is switched depending on the output from the quantizer 403. When the output from the quantizer 403 is high, the switch element 504 is turned on, and as a result, a current is supplied from the current generating circuit 505 to the subtractor 401. On the other hand, when the output from the quantizer 403 is low, the switch element 504 is turned off, and as a result, no current is supplied from the current generating circuit 505 to the subtractor 401. In this way, the value of the analog current supplied from the DA converter 406 to the subtractor 401 changes depending on the output from the quantizer 403.

[0040] Next, an example circuit configuration of the second-order ΔΣ modulator 407 will be described. The ΔΣ modulator 407 has subtractors 401 and 408, integrators 402 and 409, a Gm amplifier 506, a quantizer 403, and DA converters 406 and 410. The circuit configurations of the subtractor 401, the integrator 402, the quantizer 403, and the DA converter 406 are the same as those of the first-order ΔΣ modulator 404. The Gm amplifier 506 is an amplifier that converts the analog voltage signal supplied from the integrator 402 into an analog current signal and supplies this to the subtractor 408. The analog voltage signal is supplied from the integrator 402 to the inverting input terminal of the Gm amplifier 506, and a reference voltage Vref is supplied from the control circuit 132 to the non-inverting input terminal of the Gm amplifier 506.

[0041] The subtractor 408 is configured with a node 507 connected to the Gm amplifier 506, the DA converter 410, and the integrator 409. The analog current from the DA converter 410 is subtracted from the analog current signal from the Gm amplifier 506 supplied to the node 507, and the resulting current is supplied to the integrator 409. The integrator 409 is configured with a capacitor 508. The capacitor 508 is charged by the output from the Gm amplifier 506 so as to integrate the output. The voltage of the capacitor 508 is supplied to the quantizer 403.

[0042] The DA converter 410 is composed of a switch element 509 and a current generating circuit 510. The current generating circuit 510 generates an analog current to be supplied to the subtractor 408. The switch element 509 is located on a signal path between the subtractor 408 and the current generating circuit 510. The on / off state of the switch element 509 is switched depending on the output from the quantizer 403. When the output from the quantizer 403 is at a high level, the switch element 509 is turned on, and as a result, a current is supplied from the current generating circuit 510 to the subtractor 408. On the other hand, when the output from the quantizer 403 is at a low level, the switch element 509 is turned off, and as a result, no current is supplied from the current generating circuit 510 to the subtractor 408. In this way, the value of the analog current supplied from the DA converter 416 to the subtractor 408 changes depending on the output from the quantizer 403.

[0043] 6, a specific example of the circuit configuration of the current generating circuit 505 and the temperature detecting circuit 133 will be described. The temperature detecting circuit 133 may have any configuration that generates an analog output corresponding to the internal temperature of the photoelectric conversion device 100. The current generating circuit 505 may have any configuration that generates a current corresponding to the analog output supplied from the temperature detecting circuit 133.

[0044] The temperature detection circuit 133 may have the circuit elements shown in FIG. 6 . A bandgap circuit 600 supplies a constant voltage to a non-inverting input terminal of an operational amplifier 601. The inverting input terminal of the operational amplifier 601 is connected to ground via a resistor 605. The output terminal of the operational amplifier 601 is supplied to the gate of an N-type transistor 604. The source of the N-type transistor 604 is connected to ground via the resistor 605. The drain of the N-type transistor 604 is connected to one end of a current mirror circuit formed by P-type transistors 602 and 603. The other end of the current mirror circuit formed by the P-type transistors 602 and 603 is connected to ground via an N-type transistor 606. The gate and drain of the N-type transistor 606 are short-circuited to each other. The gate voltage of the N-type transistor 606 is supplied to the current generating circuit 505 as an output from the temperature detection circuit 133. In this way, the temperature detection circuit 133 generates an analog voltage output corresponding to the internal temperature of the photoelectric conversion device 100 based on the current flowing through the resistor 605.

[0045] The current generating circuit 505 has cascade-connected N-type transistors 610 and 611. An analog voltage is supplied as a bias voltage from the temperature detecting circuit 133 to the gate of the N-type transistor 610. Another bias voltage is supplied to the gate of the N-type transistor 611 (for example, from the control circuit 132 of the AD conversion unit 130). Therefore, the current generating circuit 505 generates a current according to the analog voltage supplied from the temperature detecting circuit 133, and supplies the current to the switch element 504.

[0046] The bandgap circuit 600 is only minimally affected by changes in the internal temperature of the photoelectric conversion device 100. Therefore, the bandgap circuit 600 can be considered to supply a constant voltage to the operational amplifier 601 regardless of the internal temperature of the photoelectric conversion device 100. Below, an example will be described in which the bandgap circuit 600 outputs a voltage of 1.2 V. Since the voltage between the two input terminals of the operational amplifier 601 can be considered to be zero, the voltage applied to the resistive element 605 is 1.2 V. Therefore, if the resistance of the resistive element 605 is R [Ω], a current of 1.2 / R [A] flows through the resistive element 605. The gate voltage of the N-type transistor 606 depends on the value of the current flowing through the N-type transistor 606. Therefore, when the resistance of the resistive element 605 changes, the value of the analog output voltage from the temperature detection circuit 133 also changes. As a result, the value of the current generated by the current generating circuit 505 also changes.

[0047] Assume that the resistance value of the resistive element 312 increases as the internal temperature of the photoelectric conversion device 100 changes. In this case, even if the amount of light incident on the pixel circuit 111 remains the same, the value of the signal (i.e., the pixel signal after correlated double sampling) supplied to the AD conversion unit 130 decreases. In this embodiment, the resistance value of the resistive element 605 also increases as the internal temperature of the photoelectric conversion device 100 changes. Accordingly, the value of the current generated by the current generating circuit 505 decreases, and the gain of the AD converter 131 increases. As a result, the decrease in pixel signal due to the change in internal temperature of the photoelectric conversion device 100 is reduced. Similarly, if the resistance value of the resistive element 312 decreases as the internal temperature of the photoelectric conversion device 100 changes, the increase in pixel signal due to this temperature change is reduced. In this way, the analog output generated by the temperature detection circuit 133 changes the gain of the AD converter 131 so as to reduce the fluctuation in pixel signal due to the change in internal temperature of the photoelectric conversion device 100.

[0048] The resistive element 312 and the resistive element 605 may be formed to have similar temperature characteristics. For example, the resistive element 312 and the resistive element 605 may be formed of the same material. The resistive element 312 and the resistive element 605 may be polysilicon resistors, diffused resistors, metal resistors, or the like. The resistive element 312 and the resistive element 605 may also be formed on the same substrate. For example, when the photoelectric conversion device 100 is formed by bonding multiple substrates, the resistive element 312 and the resistive element 605 may be formed on the same one of the multiple substrates. Forming them on the same substrate reduces process variations between these resistive elements.

[0049] Another example of the circuit configuration of the current generating circuit 505 will be described with reference to the circuit diagram of FIG. 7. The temperature detecting circuit 133 may have the circuit elements shown in FIG. 7. P-type transistors 701 to 703 form a current mirror circuit. N-type transistors 704 and 705 form a current mirror circuit. The source of the N-type transistor 705 is connected to ground via a resistive element 605. The drain of the P-type transistor 703 is connected to ground via an N-type transistor 706. The gate and drain of the N-type transistor 706 are short-circuited to each other. The gate voltage of the N-type transistor 706 is supplied to the current generating circuit 505 as an output from the temperature detecting circuit 133. Even with this circuit configuration, if the resistance value of the resistive element 605 changes, the value of the analog output voltage from the temperature detecting circuit 133 also changes.

[0050] In the above example, the analog output voltage from the temperature detection circuit 133 is supplied to the current generation circuit 505, and the value of the current generated by the current generation circuit 505 is changed. Alternatively or in addition to this, the analog output voltage from the temperature detection circuit 133 may be supplied to the current generation circuit 510, and the value of the current generated by the current generation circuit 510 may be changed. Even in this modification, the analog output generated by the temperature detection circuit 133 changes the gain of the AD converter 131 so as to reduce fluctuations in pixel signals due to changes in the internal temperature of the photoelectric conversion device 100.

[0051] Second Embodiment An example configuration of a photoelectric conversion device 800 according to the second embodiment will be described with reference to the block diagram of Fig. 8. Components of the photoelectric conversion device 800 according to the second embodiment that may be similar to those of the photoelectric conversion device 100 according to the first embodiment will be assigned the same reference numerals, and duplicated descriptions will be omitted. The photoelectric conversion device 800 differs from the photoelectric conversion device 100 in that it has a temperature detection circuit 801 and an AD converter 802 instead of the temperature detection circuit 133.

[0052] The temperature detection circuit 801 detects the internal temperature of the photoelectric conversion device 100 and supplies an analog output corresponding to the internal temperature to the AD converter 802. The AD converter 802 converts the analog output supplied from the temperature detection circuit 801 into digital data and supplies the digital data to the signal processing circuit 150. The AD converter 802 may be any configuration, such as a ΔΣ AD converter, a slope-type AD converter, or a successive approximation AD converter. The AD converter 802 may be the same type as the AD converter 131 or a different type. The signal processing circuit 150 estimates the internal temperature of the photoelectric conversion device 100 based on the digital data supplied from the AD converter 802. The signal processing circuit 150 corrects the pixel signal (i.e., the output from the AD conversion unit 130) based on the estimated internal temperature so as to suppress fluctuations in the pixel signal caused by changes in the resistance value of the resistor element 312.

[0053] 9, a specific example of the circuit configuration of the temperature detection circuit 801 will be described. The temperature detection circuit 801 may have any configuration that generates an analog output according to the internal temperature of the photoelectric conversion device 100. The temperature detection circuit 801 may have the circuit elements shown in FIG.

[0054] P-type transistors 901 to 903 form a current mirror circuit. N-type transistors 904 and 905 form a current mirror circuit. The source of N-type transistor 904 is connected to ground via bipolar transistor 908. The source of N-type transistor 905 is connected to ground via resistor element 906 and bipolar transistor 909. The drain of P-type transistor 903 is connected to ground via resistor element 907. The voltage value of the node between P-type transistor 903 and resistor element 907 is supplied to AD converter 802 as an analog output.

[0055] Assume that the emitter size of bipolar transistor 909 is n times larger than the emitter size of bipolar transistor 908. In this case, the collector potential of bipolar transistor 908 is higher than the collector potential of bipolar transistor 909 by Vt×log(n). Here, Vt is a value proportional to the internal temperature of photoelectric conversion device 100 and is approximately 26 mV at room temperature. If the resistance value of resistor element 906 is R1 [Ω], the current flowing through resistor element 906 is Vt×log(n) / R1 [A]. If the resistance value of resistor element 907 is R2 [Ω], the output voltage from temperature detection circuit 801 is Vt×log(n)×(R2 / R1) [A]. In this way, temperature detection circuit 133 generates an analog voltage output corresponding to the internal temperature of photoelectric conversion device 800 based on the current flowing through resistor elements 906 and 907.

[0056] The signal processing circuit 150 estimates the internal temperature of the photoelectric conversion device 100 based on the digital data supplied from the AD converter 802. The signal processing circuit 150 corrects the pixel signal based on the estimated internal temperature. For example, the signal processing circuit 150 may store in advance a correspondence table between the internal temperature of the photoelectric conversion device 100 and a correction value. The signal processing circuit 150 may determine the correction value for the pixel signal by comparing the estimated internal temperature with this correspondence table. In this way, the signal processing circuit 150 corrects the pixel signal to reduce fluctuations in the pixel signal due to changes in the internal temperature of the photoelectric conversion device 100.

[0057] In the above example, the signal processing circuit 150 estimates the internal temperature of the photoelectric conversion device 100 and corrects the digital data representing the pixel signal. Alternatively, the control circuit 132 of the AD conversion unit 130 may estimate the internal temperature of the photoelectric conversion device 100 based on the digital data supplied from the AD converter 802, and change the gain of the AD conversion unit 131 based on the estimated internal temperature. The control circuit 132 changes the gain of the AD conversion unit 131 so as to reduce fluctuations in the pixel signal due to changes in the internal temperature of the photoelectric conversion device 100.

[0058] Specifically, changing the gain of the AD converter 131 may include changing the value of the analog current supplied from the DA converter 406 to the subtractor 401 for the same output from the quantizer 403. Also, changing the setting of the AD converter 131 may include changing the value of the analog current supplied from the DA converter 410 to the subtractor 408 for the same output from the quantizer 403.

[0059] Changing the gain of the AD converter 131 may include changing the value of the reference voltage Vref supplied to the Gm amplifier 506. By changing the value of the reference voltage Vref, the output from the Gm amplifier 506 changes for the same output from the integrator 402. This causes the gain of the AD converter 131 to change.

[0060] Changing the gain of the AD converter 131 may include changing the settings of the decimation filter 405. The settings to be changed may be, for example, the constant of the decimation filter 405 or the frequency of the clock signal of the decimation filter 405.

[0061] In the above example, the signal processing circuit 150 estimated the internal temperature of the photoelectric conversion device 100 and corrected the digital data representing the pixel signals. Alternatively, the signal processing circuit 150 may output the estimated internal temperature to the external device 190 via the output circuit 160. This allows the external device 190 to correct the digital data representing the pixel signals with this estimated internal temperature.

[0062] <Third embodiment> An example configuration of a photoelectric conversion device 1000 according to the third embodiment will be described with reference to the block diagram of Fig. 10. Of the photoelectric conversion device 1000 according to the third embodiment, components that may be similar to those of the photoelectric conversion device 800 according to the second embodiment will be assigned the same reference numerals, and duplicated descriptions will be omitted. The photoelectric conversion device 1000 differs from the photoelectric conversion device 800 in that it does not have a temperature detection circuit 133 but has an optical black pixel circuit 1001.

[0063] The optical black pixel circuit 1001 differs from the pixel circuit 111 in that the photoelectric conversion element 201 is covered with a light-shielding layer, but other points may be the same. The optical black pixel circuit 1001, together with the pixel circuit 111, constitutes the pixel unit 110. Even when light is irradiated onto the pixel unit 110, the light does not substantially reach the photoelectric conversion element 201 of the optical black pixel circuit 1001.

[0064] In the third embodiment, the signal processing circuit 150 estimates the internal temperature of the photoelectric conversion device 100 based on a signal read from the optical black pixel circuit 1001. The signal read from the optical black pixel circuit 1001 depends on the value of the dark current, which in turn depends on the temperature of the photoelectric conversion device 100. Therefore, the internal temperature of the photoelectric conversion device 100 can be estimated based on the signal read from the optical black pixel circuit 1001. The signal processing circuit 150 corrects the pixel signal based on the estimated internal temperature. For example, the signal processing circuit 150 may store in advance a correspondence table between the internal temperature of the photoelectric conversion device 100 and a correction value. The signal processing circuit 150 may determine the correction value for the pixel signal by comparing the estimated internal temperature with this correspondence table. In this way, the signal processing circuit 150 corrects the pixel signal to reduce fluctuations in the pixel signal due to changes in the internal temperature of the photoelectric conversion device 100.

[0065] In the third embodiment, as in the second embodiment, the control circuit 132 of the AD conversion unit 130 may estimate the internal temperature of the photoelectric conversion device 100 based on a signal read from the optical black pixel circuit 1001. Then, the control circuit 132 may change the gain of the AD conversion unit 131 based on the estimated internal temperature. Furthermore, the signal processing circuit 150 may output the estimated internal temperature to the external device 190 via the output circuit 160.

[0066] <Modification> In the above-described embodiment, the photoelectric conversion device 100 has one AD converter 131 for each pixel column. Alternatively, the photoelectric conversion device 100 may have a common AD converter 131 for multiple pixel columns. The capacitance of the floating diffusion 206 may be switchable. The floating diffusion 206 may be shared by multiple photoelectric conversion elements. Multiple photoelectric conversion elements may be formed under a single microlens and be capable of detecting a phase difference. Multiple signal lines 113 may be arranged for one pixel column, and in this case, multiple selection transistors may be arranged. The comparator 503 may be configured to include a capacitance or switch for auto-zero operation. The photoelectric conversion device 100 may be formed using a single substrate, two substrates stacked and bonded together, or three or more substrates stacked and bonded together.

[0067] Referring to FIG. 11 , a configuration example of a photoelectric conversion device 100 formed by two substrates 1101 and 1102 stacked and bonded to each other will be described. The pixel section 110 and the vertical scanning circuit 170 are disposed on the substrate 1101. The readout section 120, the AD conversion section 130, the horizontal scanning circuit 140, the signal processing circuit 150, the output circuit 160, and the timing control circuit 180 are disposed on the substrate 1102. Alternatively, some of the components may be disposed on a different substrate. For example, the vertical scanning circuit 170 may be disposed on the substrate 1102 instead of the substrate 1101. The temperature detection circuit 133 described above may be disposed on the substrate 1102. Alternatively, only the resistive element 605 of the temperature detection circuit 133 may be disposed on the substrate 1101, and the remaining components may be disposed on the substrate 1102. Furthermore, the entire temperature detection circuit 133 may be disposed on the substrate 1101.

[0068] 11 has been described based on the photoelectric conversion device 100 of the first embodiment, but similar modifications may also be made to the photoelectric conversion devices 800 and 1000 of the other embodiments. In this case, the entire temperature detection circuit 801 may be disposed on the substrate 1101, or the entire temperature detection circuit 801 may be disposed on the substrate 1102. Furthermore, the components of the temperature detection circuit 801 may be disposed separately on the substrate 1101 and the substrate 1102.

[0069] <Other embodiments> With reference to FIG. 12(a), an embodiment of a device 1200 including a semiconductor device 1203 will be described in detail. The semiconductor device 1203 may be the photoelectric conversion device of any of the above-described embodiments. The semiconductor device 1203 may include a semiconductor device 1201 and a package 1202 that houses the semiconductor device 1201. The package 1202 may include a base to which the semiconductor device 1201 is fixed, and a lid such as glass that faces the semiconductor device 1201. The package 1202 may further include a bonding member such as a bonding wire or bump that connects a terminal provided on the base to a terminal (bonding pad) provided on the semiconductor device 1201.

[0070] The device 1200 may include at least one of an optical device 1204, a control device 1205, a processing device 1206, a display device 1207, a memory device 1208, and a mechanical device 1209. The optical device 1204 is, for example, a lens, a shutter, or a mirror. The optical device 1204 corresponds to a photoelectric conversion device. The control device 1205 controls the semiconductor device 1203. The control device 1205 is, for example, a semiconductor device such as an FPGA (an abbreviation for Field Programmable Gate Array) or an ASIC (an abbreviation for Application Specific Integrated Circuit).

[0071] The processing device 1206 processes the signal output from the semiconductor device 1203. The processing device 1206 is a semiconductor device such as a CPU (abbreviation for Central Processing Unit) or ASIC for configuring an AFE (analog front end) or a DFE (digital front end). The display device 1207 is an EL (abbreviation for Electro-Luminescence) display device or a liquid crystal display device that displays information (images) obtained by the semiconductor device 1203. The storage device 1208 is a magnetic device or a semiconductor device that stores the information (images) obtained by the semiconductor device 1203. The storage device 1208 is a volatile memory such as an SRAM (abbreviation for Static Random Access Memory) or a DRAM (abbreviation for Dynamic Random Access Memory), or a non-volatile memory such as a flash memory or a hard disk drive.

[0072] The mechanical device 1209 has a moving part or a propulsion part such as a motor or an engine. In the device 1200, the signal output from the semiconductor device 1203 is displayed on the display device 1207, or transmitted to the outside by a communication device (not shown) included in the device 1200. For this purpose, the device 1200 may further include a memory device 1208 and a processing device 1206 in addition to the memory circuit and arithmetic circuit included in the semiconductor device 1203. The mechanical device 1209 may be controlled based on the signal output from the semiconductor device 1203.

[0073] The device 1200 is also suitable for electronic devices such as information terminals with a photographing function (e.g., smartphones and wearable devices) and cameras (e.g., interchangeable lens cameras, compact cameras, video cameras, and surveillance cameras). The mechanical device 1209 in the camera may drive components of the optical device 1204 for zooming, focusing, and shutter operation. Alternatively, the mechanical device 1209 in the camera may move the semiconductor device 1203 for vibration isolation.

[0074] Furthermore, the device 1200 may be transportation equipment such as a vehicle, a ship, or an aircraft. The mechanical device 1209 in the transportation equipment may be used as a moving device. The device 1200 as transportation equipment may transport the semiconductor device 1203 or may assist and / or automate driving (piloting) using an imaging function. The processing device 1206 for assisting and / or automating driving (piloting) may perform processing for operating the mechanical device 1209 as a moving device based on information obtained by the semiconductor device 1203. Alternatively, the device 1200 may be a medical device such as an endoscope, a measuring device such as an analytical distance sensor, an analytical device such as an electron microscope, or office equipment such as a copier.

[0075] An embodiment relating to an imaging system and a moving object will be described using FIGS. 12(b) and 12(c). FIG. 12(b) shows an example of an imaging system 1210 relating to an in-vehicle camera. The imaging system 1210 includes a photoelectric conversion device 1211. The photoelectric conversion device 1211 may be any of the photoelectric conversion devices of the above-described embodiments. The imaging system 1210 includes an image processing unit 1212, which is a processing device that performs image processing on multiple pieces of image data acquired by the photoelectric conversion device 1211. The imaging system 1210 also includes a parallax acquisition unit 1213, which is a processing device that calculates parallax (phase difference between parallax images) from the multiple pieces of image data acquired by the photoelectric conversion device 1211. The imaging system 1210 also includes a distance acquisition unit 1214, which is a processing device that calculates a distance to an object based on the calculated parallax, and a collision determination unit 1215, which is a processing device that determines whether or not there is a possibility of a collision based on the calculated distance. Here, the parallax acquisition unit 1213 and the distance acquisition unit 1214 are examples of information acquisition means for acquiring information such as distance information to an object. That is, distance information is information related to parallax, defocus amount, distance to an object, etc. The collision determination unit 1215 may determine the possibility of a collision using any of this distance information. The various processing devices described above may be realized by dedicated hardware or general-purpose hardware that performs calculations based on software modules. Furthermore, the processing devices may be realized by FPGAs, ASICs, etc., or a combination thereof.

[0076] The imaging system 1210 is connected to a vehicle information acquisition device 1216 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The imaging system 1210 is also connected to a control ECU 1217, which is a control device that outputs a control signal to generate a braking force on the vehicle based on the determination result of the collision determination unit 1215. In other words, the control ECU 1217 is an example of a mobile object control means that controls a mobile object based on distance information. The imaging system 1210 is also connected to an alarm device 1218 that issues an alarm to the driver based on the determination result of the collision determination unit 1215. For example, if the determination result of the collision determination unit 1215 indicates a high possibility of a collision, the control ECU 1217 performs vehicle control to avoid the collision and mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 1218 warns the user by sounding an alarm, displaying alarm information on a screen of a car navigation system, etc., or vibrating a seat belt or steering wheel.

[0077] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the imaging system 1210. Fig. 12(c) shows the imaging system 1210 when imaging the area in front of the vehicle (imaging range 1219). The vehicle information acquisition device 1216 sends an instruction to operate the imaging system 1210 to perform imaging.

[0078] In the above explanation, an example of control to prevent collision with other vehicles has been described, but the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from a lane, etc. Furthermore, the imaging system is not limited to vehicles such as automobiles, but can be applied to moving bodies (transportation equipment) such as ships, aircraft, and industrial robots. The moving devices in moving bodies (transportation equipment) are various means of movement such as engines, motors, wheels, and propellers. In addition, the present invention can be applied not only to moving bodies, but also to a wide range of equipment that uses object recognition, such as intelligent transport systems (ITS).

[0079] The above-described embodiments can be modified as appropriate without departing from the spirit and scope of the present invention. The disclosure of this specification includes not only what is described herein but also all matters that can be understood from the specification and the accompanying drawings. The disclosure of this specification also includes the complement of the concepts described herein. In other words, if the specification contains a statement that "A is greater than B," it can be said that the specification discloses "A is not greater than B" even if the statement that "A is not greater than B" is omitted. This is because a statement that "A is greater than B" presupposes that the case where "A is not greater than B" is taken into consideration. Claims are attached to publicly define the scope of the invention. [Explanation of symbols]

[0080] 100 photoelectric conversion device, 111 pixel circuit, 121 readout circuit, 131 AD converter

Claims

1. A photoelectric conversion device, a light receiving circuit that converts light into an electrical signal; a first holding circuit that holds a data signal representing the electrical signal converted from the light; a second holding circuit that holds a noise signal read from the light receiving circuit in a reset state; a first resistor element to which a voltage corresponding to a difference between the data signal held in the first holding circuit and the noise signal held in the second holding circuit is applied; an AD converter that converts the analog current flowing through the first resistor element into digital data; A second resistor element; a temperature detection circuit that generates an analog output corresponding to an internal temperature of the photoelectric conversion device based on a current flowing through the second resistance element, the light receiving circuit is disposed on a first substrate; the first resistor element, the second resistor element, and the AD converter are disposed on a second substrate; The photoelectric conversion device is characterized in that the analog output is input to the AD converter.

2. the AD converter is a ΔΣ AD converter, The analog output generated by the temperature detection circuit changes the gain of the ΔΣ AD converter.

2. The photoelectric conversion device according to claim 1.

3. the analog current flowing through the first resistive element is a first analog current; The ΔΣ AD converter is a subtractor supplied with the first analog current; an integrator that integrates the output from the subtractor; a quantizer for quantizing the integration result by the integrator; a decimation filter that performs decimation processing on the output from the quantizer; a DA converter that supplies a second analog current corresponding to the output from the quantizer to the subtractor so that the second analog current is subtracted from the first analog current; the DA converter includes a current generating circuit that generates the second analog current; The value of the second analog current generated by the current generating circuit for the same output from the quantizer varies based on the analog output generated by the temperature sensing circuit.

3. The photoelectric conversion device according to claim 2.

4. The first resistance element and the second resistance element are formed of the same material.

4. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device comprises: a first electrode;

5. The photoelectric conversion device according to any one of claims 1 to 4, an optical device corresponding to the photoelectric conversion device; a control device that controls the photoelectric conversion device; a processing device that processes a signal output from the photoelectric conversion device; a display device that displays information obtained by the photoelectric conversion device; a storage device that stores information obtained by the photoelectric conversion device; and and a mechanical device that operates based on information obtained by the photoelectric conversion device.

6. A substrate to be laminated on a substrate provided with a light receiving circuit that converts light into an electrical signal, a first holding circuit that holds a data signal representing the electrical signal converted from the light; a second holding circuit that holds a noise signal read from the light receiving circuit in a reset state; a first resistor element to which a voltage corresponding to a difference between the data signal held in the first holding circuit and the noise signal held in the second holding circuit is applied; an AD converter that converts the analog current flowing through the first resistor element into digital data; A second resistor element; a temperature detection circuit that generates an analog output corresponding to an internal temperature of the photoelectric conversion device based on a current flowing through the second resistor element, the light receiving circuit is disposed on a first substrate; the first resistor element, the second resistor element, and the AD converter are disposed on a second substrate; The board is characterized in that the analog output is input to the AD converter.

Images