Light receiving device and distance measuring device

Abstract

A light reception device according to this disclosure comprises a light reception element for generating a signal corresponding to the reception of photons, a reading circuit for reading the signal generated by the light reception element, and a protection circuit that is provided between the light reception element and reading circuit and protects the circuit elements of the reading circuit from overvoltage. Further, a distance measurement device according to this disclosure comprises the light reception device.

Description

[Technical field]

[0001] The present disclosure relates to a light receiving device and a distance measuring device. [Background technology]

[0002] There is a light receiving device (light detection device) that uses an element that generates a signal in response to receiving a photon as a light receiving element (light detection element). In this type of light receiving device, as a measurement method for measuring the distance to an object (subject) to be measured, for example, a ToF (Time of Flight) method is adopted, in which the time it takes for light irradiated from a light source toward the object to be measured and reflected by the object to return is measured.

[0003] As a light receiving element that generates a signal in response to receiving a photon, for example, a single photon avalanche diode (SPAD) element is known. In a light receiving device using a SPAD element as a light receiving element, the light receiving device is configured to use the SPAD element by applying a voltage equal to or higher than the breakdown voltage to the anode electrode (or cathode electrode) of the SPAD element (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-125717 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a SPAD element is irradiated with a large amount of laser light (greater than a predetermined amount of light), such as when the SPAD element is directly irradiated with laser light, the effect of photoelectric conversion due to the large amount of light becomes stronger, and the internal impedance of the SPAD element drops significantly. As a result, an excessive voltage is applied to the readout circuit that reads out the signal generated by the SPAD element, and there is a possibility that the circuit elements that make up the readout circuit will be destroyed.

[0006] The above problems are not limited to SPAD elements, but apply to all light-receiving elements that generate a signal in response to receiving photons.

[0007] Therefore, an object of the present disclosure is to provide a light receiving device that can protect circuit elements constituting a downstream readout circuit from overvoltage even when a large amount of light greater than a predetermined amount of light is irradiated onto the light receiving element, and a distance measuring device having the light receiving device. [Means for solving the problem]

[0008] In order to achieve the above object, the light receiving device of the present disclosure comprises: a light receiving element that generates a signal in response to receiving a photon; a readout circuit for reading out a signal generated by the light receiving element; and Provided between the light receiving element and the readout circuit to protect the circuit elements of the readout circuit from overvoltage protection circuit, Equipped with. The protection circuitry consists of a clamp circuit that clamps the overvoltage to a fixed voltage. The clamp circuit is a resistive element having one end connected to the light receiving element; a first clamp element connected between the other end of the resistive element and a reference potential node; and a second clamp element provided between the first clamp element and the input of the readout circuit; has.

[0009] In order to achieve the above object, the distance measuring device of the present disclosure comprises: A light source unit that irradiates light onto an object to be measured; and a light receiving device that receives reflected light from an object to be measured based on light emitted from a light source unit; Equipped with: And the light receiving device is a light receiving element that generates a signal in response to receiving a photon; a readout circuit for reading out a signal generated by the light receiving element; and Provided between the light receiving element and the readout circuit to protect the circuit elements of the readout circuit from overvoltage protection circuit, Equipped with. The protection circuitry consists of a clamp circuit that clamps the overvoltage to a fixed voltage. The clamp circuit is a resistive element having one end connected to the light receiving element; a first clamp element connected between the other end of the resistive element and a reference potential node; and a second clamp element provided between the first clamp element and the input of the readout circuit; has. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic configuration diagram showing an example of a distance measuring device to which the technology according to the present disclosure is applied. [Diagram 2] 2A and 2B are block diagrams showing an example of a specific configuration of a distance measuring device according to this application example. [Diagram 3] FIG. 3 is a circuit diagram showing an example of a basic pixel circuit configuration using a SPAD element. [Figure 4] FIG. 4A is a characteristics diagram showing the current-voltage characteristics of a PN junction of a SPAD element, and FIG. 4B is a waveform diagram illustrating the circuit operation of a pixel circuit. [Diagram 5] FIG. 5 is an exploded perspective view of a stacked chip structure of a sensor chip and a circuit chip of a light receiving device. [Figure 6] Figure 6A is an equivalent circuit diagram showing a breakdown model and a photoelectric conversion model of a SPAD element, Figure 6B is a diagram showing the change in internal impedance of a SPAD element relative to the amount of incident light, and Figure 6C is a waveform diagram showing the cathode potential VCA under normal and large light conditions. [Figure 7] FIG. 7 is a circuit diagram illustrating a configuration example of a light receiving device according to an embodiment of the present disclosure. [Figure 8]FIG. 8 is a circuit diagram illustrating a configuration example of the light receiving device according to the first embodiment. [Figure 9] FIG. 9 is a waveform diagram illustrating a clamping operation when an overvoltage occurs in the light receiving device according to the first embodiment. [Figure 10] FIG. 10 is a circuit diagram showing an element arrangement example 1 of a SPAD element, a resistor element, a first clamp element, and a second clamp element in a stacked chip structure. [Figure 11] FIG. 11 is a circuit diagram showing an element arrangement example 2 of a SPAD element, a resistive element, a first clamp element, and a second clamp element in a stacked chip structure. [Figure 12] FIG. 12 is a circuit diagram showing an element arrangement example 3 of a SPAD element, a resistive element, a first clamp element, and a second clamp element in a stacked chip structure. [Figure 13] FIG. 13 is a circuit diagram illustrating a configuration example of a light receiving device according to the second embodiment. [Figure 14] FIG. 14 is a circuit diagram illustrating a configuration example of a light receiving device according to the third embodiment. [Figure 15] FIG. 15 is a circuit diagram illustrating a configuration example of a light receiving device according to a fourth embodiment. [Figure 16] FIG. 16 is a circuit diagram illustrating a configuration example of a light receiving device according to a fifth embodiment. [Figure 17] FIG. 17 is a circuit diagram illustrating a configuration example of a light receiving device according to a sixth embodiment. [Figure 18] FIG. 18 is a circuit diagram illustrating a configuration example of a light receiving device according to a seventh embodiment. [Figure 19] FIG. 19 is a circuit diagram illustrating a configuration example of a light receiving device according to an eighth embodiment. [Figure 20] FIG. 20 is a circuit diagram illustrating a configuration example of a light receiving device according to a ninth embodiment. [Figure 21] FIG. 21 is a block diagram showing an example of a schematic configuration of a vehicle control system, which is an example of a moving object control system to which the technology according to the present disclosure can be applied. [Figure 22] FIG. 22 is a diagram showing an example of the installation positions of the imaging unit and the outside-of-vehicle information detection unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a form for carrying out the technology of the present disclosure (hereinafter, referred to as "embodiment") will be described in detail with reference to the drawings. The technology of the present disclosure is not limited to the embodiment. In the following description, the same elements or elements having the same functions will be designated by the same reference numerals, and duplicated description will be omitted. The description will be given in the following order. 1. General Description of the Light Receiving Device and Distance Measuring Device of the Present Disclosure 2. Distance measuring device to which the technology disclosed herein is applied 2-1. Specific configuration example of distance measuring device 2-2.Basic pixel circuit example using SPAD element 2-3. Example of circuit operation of pixel circuit using SPAD element 2-4. Overvoltage applied to the readout circuit of the SPAD element 3. Light receiving device according to an embodiment of the present disclosure 3-1. Example 1 (Example of negative bias configuration: Example in which the protection circuit is composed of a clamp circuit) 3-2. Example 2 (Modification of Example 1: Example in which the second clamp element is omitted) 3-3. Example 3 (Example of negative bias configuration: Example in which the protection circuit is made of a resistive element) 3-4. Example 4 (Modification of Example 1: Example in which the first clamp element is configured with an N-type MOS transistor in a diode-connected configuration) 3-5. Example 5 (Modification of Example 1: Example in which the first clamp element is configured with a P-type MOS transistor in a diode-connected configuration) 3-6. Example 6 (Modification of Example 5: Example in which a resistive element is provided between the gate and drain of a P-type MOS transistor) 3-7. Example 7 (Example of positive bias configuration: Example in which the protection circuit is composed of a clamp circuit) 3-8. Example 8 (Modification of Example 7: Example in which the second clamp element is omitted) 3-9. Example 9 (Example of positive bias configuration: Example in which the protection circuit is made of a resistive element) 4. Variations 5. Application Examples of the Technology Disclosed Herein (Examples of Mobile Objects) 6. Configurations that the present disclosure can take

[0012] <General Description of the Light Receiving Device and Distance Measuring Device of the Present Disclosure> In the light receiving device and distance measuring device of the present disclosure, the protection circuit may be configured to include a clamp circuit that clamps an overvoltage to a constant voltage. The clamp circuit may include a resistive element having one end connected to the light receiving element, and a first clamp element connected between the other end of the resistive element and a reference potential node, and the first clamp element may be configured to include a clamp diode having a cathode electrode connected to the other end of the resistive element and an anode electrode connected to the reference potential node.

[0013] In the light receiving device and distance measuring device of the present disclosure including the preferred configuration described above, the clamp circuit can be configured to have a second clamp element provided between the first clamp element and the input terminal of the readout circuit, and the second clamp element can be configured to be connected between the first clamp element and the input terminal of the readout circuit and to consist of a MOS transistor having a gate electrode connected to a reference potential node.

[0014] Furthermore, the light receiving device and distance measuring device of the present disclosure including the above-mentioned preferred configuration may have a stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked together. The light receiving element may be disposed on the first semiconductor substrate, and the resistive element, the first clamp element, and the second clamp element may be disposed on the second semiconductor substrate, or the light receiving element and the resistive element may be disposed on the first semiconductor substrate, and the first clamp element and the second clamp element may be disposed on the second semiconductor substrate, or the light receiving element, the resistive element, and the first clamp element may be disposed on the first semiconductor substrate, and the second clamp element may be disposed on the second semiconductor substrate.

[0015] In the light receiving device and distance measuring device of the present disclosure including the above-mentioned preferred configuration, the protection circuit may be configured to include a resistor element connected between the light receiving element and the input terminal of the readout circuit. When an N-type MOS transistor is connected between the input terminal of the readout circuit and a reference potential node, the resistor element constituting the protection circuit may be configured to form a clamp circuit together with a body diode present in the N-type MOS transistor.

[0016] In the light receiving device and distance measuring device of the present disclosure including the above-mentioned preferred configuration, the first clamp element may be configured to be a MOS transistor in a diode connection configuration, or the first clamp element may be configured to be a second resistive element connected in series with the resistive element, and a P-type MOS transistor connected between the output end of the second resistive element and a reference potential node, with the gate electrode of the P-type MOS transistor connected to a common connection node between the resistive element and the second resistive element.

[0017] In the light receiving device and distance measuring device of the present disclosure including the above-mentioned preferred configuration, the readout circuit may be configured using a CMOS inverter circuit.

[0018] In the light receiving device and distance measuring device of the present disclosure including the above-mentioned preferred configuration, the light receiving element may be configured to be an element that is used by applying a voltage equal to or higher than the breakdown voltage, and the light receiving element may be configured to be an avalanche photodiode that operates in Geiger mode.

[0019] In the light receiving device and distance measuring device of the present disclosure including the above-mentioned preferred configuration, the light receiving element is preferably configured to be a single-photon avalanche diode, and the single-photon avalanche diode may be configured to be used with a negative bias voltage applied to its anode electrode or a positive bias voltage applied to its cathode electrode.

[0020] <Range measuring device to which the technology disclosed herein is applied> FIG. 1 is a schematic configuration diagram showing an example of a distance measuring device to which the technology according to the present disclosure is applied (that is, the distance measuring device of the present disclosure).

[0021] The distance measuring device 1 according to this application example employs a ToF method for measuring the distance to a subject 10, which is an object to be measured, in which light (e.g., laser light having a peak wavelength in the infrared wavelength range) irradiated toward the subject 10 measures the time of flight until it is reflected by the subject 10 and returns. To achieve distance measurement using the ToF method, the distance measuring device 1 according to this application example includes a light source unit 20 and a light receiving device 30. The light receiving device 30 can be a light receiving device according to an embodiment of the present disclosure, which will be described later.

[0022] [Specific example of distance measuring device configuration] 2A and 2B show an example of a specific configuration of the distance measuring device 1 according to this application example. The light source unit 20 has, for example, a laser driving unit 21, a laser light source 22, and a diffusing lens 23, and irradiates the subject 10 with laser light. The laser driving unit 21 drives the laser light source 22 under the control of the control unit 40. The laser light source 22 is made of, for example, a semiconductor laser, and emits laser light by being driven by the laser driving unit 21. The diffusing lens 23 diffuses the laser light emitted from the laser light source 22 and irradiates the subject 10 with the diffused laser light.

[0023] The light receiving device 30 has a light receiving lens 31, an optical sensor 32 which is a light receiving section, and a signal processing section 33, and receives reflected laser light which is emitted from the light source section 20 and reflected by the subject 10 and returns. The light receiving lens 31 focuses the reflected laser light from the subject 10 on the light receiving surface of the optical sensor 32. The optical sensor 32 receives the reflected laser light from the subject 10 which has passed through the light receiving lens 31 on a pixel-by-pixel basis, and performs photoelectric conversion. The optical sensor 32 can be a two-dimensional array sensor in which pixels including light receiving elements are arranged two-dimensionally in a matrix (array).

[0024] The output signal of the optical sensor 32 is supplied to the control unit 40 via the signal processing unit 33. The control unit 40 is configured with, for example, a CPU (Central Processing Unit) and controls the light source unit 20 and the light receiving device 30, and measures the time it takes for the laser light irradiated from the light source unit 20 towards the subject 10 to be reflected by the subject 10 and return. Based on this measured time, the distance to the subject 10 can be calculated.

[0025] As a method of measuring time, a timer is started when pulsed light is emitted from the light source unit 20, and the timer is stopped when the light receiving device 30 receives the pulsed light, thereby measuring the time. As another method of measuring time, pulsed light may be emitted from the light source unit 20 at a predetermined cycle, the cycle when the light receiving device 30 receives the pulsed light may be detected, and the time may be measured from the phase difference between the cycle of light emission and the cycle of light reception. Time measurement is performed multiple times, and the time is measured by detecting the position of the peak of a ToF histogram obtained by accumulating the times measured multiple times.

[0026] In the distance measuring device 1 according to this application example, the light sensor 32 uses a sensor in which the light receiving element of the pixel is an element that generates a signal in response to receiving a photon, for example, a SPAD (Single Photon Avalanche Diode) element. That is, the light receiving device 30 in the distance measuring device 1 according to this application example is configured to use a SPAD element as the light receiving element of the pixel. The SPAD element operates in a Geiger mode in which the element is operated with a reverse voltage exceeding the breakdown voltage.

[0027] In this example, the light receiving element (light detection element) of the pixel is exemplified as a SPAD element, but is not limited to a SPAD element. In other words, as the light receiving element of the pixel, various elements that operate in Geiger mode, such as an APD (avalanche photodiode) or a SiPM (silicon photomultiplier), can be used in addition to the SPAD element.

[0028] [Basic pixel circuit example using SPAD element] An example of the basic configuration of a pixel circuit in a light receiving device 30 using a SPAD element is shown in Fig. 3. Here, the basic configuration of one pixel is shown.

[0029] The basic pixel circuit of a pixel 50 using a SPAD element is as follows: the cathode electrode of the SPAD element 51 is connected to a power supply voltage V through a first control transistor 52 and a current source 53. DD The power supply voltage V DD For example, a voltage of about 3 V is applied to the anode electrode of the SPAD element 51. ano The anode voltage V ano As the negative voltage, a large negative voltage at which avalanche multiplication occurs, that is, a voltage equal to or higher than the breakdown voltage (for example, about −20 V) is applied (see FIG. 4B).

[0030] The first control transistor 52 is, for example, a P-type MOS transistor, and is turned on when an enable signal EN applied to the gate electrode becomes low level, causing a current from the current source 53 to flow through the SPAD element 51. A second control transistor 55 is connected between the cathode electrode of the SPAD element 51 and a reference potential node (for example, ground). The second control transistor 55 is, for example, an N-type MOS transistor, and is turned on when a signal xEN in phase with the enable signal EN is applied to the gate electrode, causing the voltage applied to the SPAD element 51 to be equal to or lower than the breakdown voltage, thereby causing the SPAD element 51 to be inactivated.

[0031] The signal generated by the SPAD element 51 in response to the reception of a photon is the cathode potential V CA The read circuit 56 is, for example, a P-type MOS transistor Q p and N-type MOS transistor Q nIt is composed of a CMOS inverter circuit consisting of these, and detects the reaction edge of the SPAD element 51. The output of the readout circuit 56 is supplied as a SPAD output (pixel output) to a time measurement unit (Time-to-Digital Converter: TDC) 57. Based on the SPAD output, the time measurement unit 57 measures the time it takes for light irradiated towards the measurement object to be reflected by the measurement object and return.

[0032] As described above, the SPAD element 51 has a breakdown voltage V BD A voltage of about -20V or more is applied. BD The excess voltage above is the excess bias voltage V EX It is called the breakdown voltage V BD How large is the excess bias voltage V? EX The characteristics of the SPAD element 51 change depending on whether a voltage is applied.

[0033] FIG. 4A shows the I (current)-V (voltage) characteristics of the PN junction of the SPAD element 51 operating in the Geiger mode. BD , excess bias voltage V EX , and the relationship between the operating point of the SPAD element 51.

[0034] [Example of circuit operation of pixel circuit using SPAD element] Next, an example of the circuit operation of the pixel circuit having the above configuration will be described with reference to the waveform diagram of FIG. 4B.

[0035] When no current flows through the SPAD element 51, the SPAD element 51 has a DD -V ano ) is applied. This voltage value (V DD -V ano ) is (V BD +V EX). In the PN junction of the SPAD element 51, the dark electron generation rate DCR (Dark Count Rate) and electrons generated by light irradiation cause avalanche multiplication, generating an avalanche current. This phenomenon occurs stochastically even in a light-shielded state (i.e., a state in which no light is incident). This is the dark electron generation rate, or dark count rate DCR.

[0036] Cathode potential V CA drops, and the voltage across the terminals of the SPAD element 51 drops to the breakdown voltage V BD When the avalanche current is at 1, the avalanche current stops. Then, the electrons generated and accumulated in the avalanche multiplication are transferred to the load 54 (for example, the P-type MOS transistor Q L ) and discharged to a cathode potential V CA rises. And the cathode potential V CA is the power supply voltage V DD and then returns to the initial state.

[0037] When light is incident on the SPAD element 51 and even one electron-hole pair is generated, this acts as a seed to generate an avalanche current, so that even the incidence of a single photon can be detected with a certain detection efficiency PDE (Photon Detection Efficiency).

[0038] The above operations are repeated. In this series of operations, the cathode potential V CA The signal is waveform-shaped by a readout circuit 56 consisting of a CMOS inverter circuit, and a pulse signal with a pulse width T, starting from the arrival time of one photon, becomes the SPAD output (pixel output).

[0039] [Stacked chip structure of photodetector] The chip structure of the light receiving device 30 may be a so-called stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked. As shown in Fig. 5, the pixels 50 including the SPAD elements 51 are arranged in a two-dimensional array of M rows and N columns on the first semiconductor substrate to form a pixel array section. The first semiconductor substrate on which the pixels 50 are arranged constitutes a sensor chip 101. This sensor chip 101 corresponds to the optical sensor 32 in Fig. 2A.

[0040] A circuit unit 58 is provided for each pixel 50. The pixel 50 includes at least a SPAD element 51. The circuit unit 58 includes, for example, a first control transistor 52, a current source 53, a second control transistor 55, a readout circuit 56, and a time measurement unit 57, all of which are shown in FIG. 3. The circuit units 58 are arranged in a two-dimensional array of M rows and N columns on the second semiconductor substrate in correspondence with each of the pixels 50.

[0041] The second semiconductor substrate on which the circuit section 58 is arranged constitutes the circuit chip 102. The circuit chip 102 is stacked on the sensor chip 101. As a result, in the stacked chip structure of the sensor chip 101 and the circuit chip 102, a circuit section 58 is provided for each pixel 50.

[0042] [Overvoltage applied to the readout circuit of a SPAD element] In the above example, the readout circuit 56 that detects the reaction edge of the SPAD element 51 is directly connected to the cathode electrode of the SPAD element 51, and is configured so that when detecting reflected light, it can detect a change in the amplitude of the voltage (for example, about 3 V) that is set as the Geiger mode.

[0043] Here, with reference to Figures 6A, 6B, and 6C, we will explain the case where the SPAD element 51 is irradiated with a large amount of laser light, greater than a predetermined amount (more than expected), such as when the laser light is directly irradiated onto the SPAD element 51.

[0044] FIG. 6A is an equivalent circuit diagram showing a breakdown model and a photoelectric conversion model of the SPAD element 51, FIG. 6B is a diagram showing the change in internal impedance of the SPAD element 51 with respect to the amount of incident light, and FIG. 6C is a diagram showing the cathode potential V CA FIG.

[0045] In the equivalent circuit diagram shown in FIG. 6A, a model of a series circuit of a switch SW, a resistor R, and a voltage source E is a SPAD breakdown model. Here, as an example, a model in which the resistor R of the SPAD element 51 is 20 kΩ and the voltage source E is 20 V is shown. In the SPAD breakdown model, the light amount dependency is small, and in the normal light amount below a certain light amount, the cathode potential V CA is decided.

[0046] The photoelectric conversion model is a photocurrent I SPAD In this photoelectric conversion model, as shown in Fig. 6B, the internal impedance Z is high during normal irradiation with a laser beam of a predetermined light amount or less, but when the SPAD element 51 is irradiated with a laser beam of a large light amount exceeding the predetermined light amount, the internal impedance Z of the SPAD element 51 decreases.

[0047] According to the evaluation by the inventors of the present application, for example, 500 kW / cm 2 At a high light intensity of about 100Ω, the internal impedance Z of the SPAD element 51 drops to about 100Ω. At this time, the cathode potential V CA However, it has been confirmed that there is a possibility of the potential reaching a high level of -10V or more.

[0048] In this way, when a large amount of laser light is irradiated onto the SPAD element 51, the effect of photoelectric conversion due to the large amount of light becomes stronger, and the internal impedance Z of the SPAD element 51 drops significantly. As a result, as shown in FIG. 6C, an excessive voltage (for example, about several tens of volts) is applied to the read circuit 56, which may lead to destruction of the circuit elements constituting the read circuit 56. Specifically, the application of an excessive voltage causes the P-type MOS transistor Q p and N-type MOS transistor Q n Alternatively, the first control transistor 52 or the second control transistor 55 may be destroyed.

[0049] <Light receiving device according to an embodiment of the present disclosure> Fig. 7 is a block diagram showing a configuration example of a light receiving device according to an embodiment of the present disclosure. As shown in Fig. 7, in this embodiment, in a light receiving device including a SPAD element 51 that generates a signal in response to reception of a photon and a readout circuit 56 that reads out the signal generated by the SPAD element 51, a protection circuit 60 is provided between the SPAD element 51 and the input terminal of the readout circuit 56.

[0050] The protection circuit 60 protects the P-type MOS transistor Q composing the read circuit 56 from an overvoltage that occurs when a large amount of laser light is irradiated onto the SPAD element 51. p and N-type MOS transistor Q n , as well as an overvoltage protection circuit that serves to protect the first control transistor 52 and the second control transistor 55.

[0051] In this way, by providing the protection circuit 60 between the SPAD element 51 and the input terminal of the readout circuit 56, even if the SPAD element 51 is irradiated with a large amount of laser light exceeding a predetermined amount (more than expected), the protection circuit 60 prevents the P-type MOS transistor Q p and N-type MOS transistor Q n , as well as the first control transistor 52 and the second control transistor 55 can be protected from overvoltage.

[0052] A specific embodiment of the protection circuit 60 for protecting the circuit elements constituting the read circuit 56 from an overvoltage will be described below.

[0053] [Example 1] The first embodiment is an example of a negative bias configuration, in which the protection circuit 60 is composed of a clamp circuit. A circuit diagram of a configuration example of a light receiving device 30 according to the first embodiment is shown in FIG.

[0054] The light receiving device 30 according to the first embodiment has a negative bias configuration in which a negative bias voltage (for example, about -20 V) is applied to the anode electrode of the SPAD element 51, and uses a clamp circuit 70 that clamps an overvoltage to a constant voltage as the protection circuit 60. That is, in the light receiving device 30 according to the first embodiment, the protection circuit 60 is composed of the clamp circuit 70 that clamps an overvoltage to a constant voltage.

[0055] 8, the clamp circuit 70 includes a resistive element 71, a first clamp element 72, and a second clamp element 73. One end of the resistive element 71 is connected to the cathode electrode of the SPAD element 51. The first clamp element 72 is, for example, a clamp diode, and has a cathode electrode connected to the other end (output end) of the resistive element 71 and an anode electrode connected to a reference potential node (for example, ground).

[0056] The resistor element 71 is provided to limit the current value flowing through the clamp diode, which is the first clamp element 72, so as not to exceed the rated forward current of the clamp diode when an overvoltage occurs in the SPAD element 51. When an overvoltage that exceeds the clamp voltage occurs in the SPAD element 51, the clamp diode, which is the first clamp element 72, limits the overvoltage to a constant voltage (forward voltage V F ) to clamp.

[0057] The first clamp element 72 is not limited to a clamp diode. For example, the first clamp element 72 may be a Schottky barrier diode or the like in addition to a clamp diode.

[0058] The second clamp element 73 is, for example, a P-type MOS transistor, and is connected between the first clamp element 72 (specifically, the anode electrode of a clamp diode) and a node N to which the input terminal of the read circuit 56 is connected. The P-type MOS transistor that is the second clamp element 73 has a gate electrode connected to a reference potential node (for example, ground) and a back gate connected to a source electrode.

[0059] Here, as an example, a clamp operation when an overvoltage of several tens of volts occurs in the SPAD element 51 will be described with reference to the waveform diagram of FIG. 9. The clamp diode, which is the first clamp element 72, clamps the overvoltage generated in the SPAD element 51 at a constant voltage (forward voltage V F By this clamping operation, the overvoltage generated in the SPAD element 51 is clamped to a negative voltage of, for example, about −1V to −3V.

[0060] Here, a negative voltage is generated by the clamping action of the first clamp element 72, and this negative voltage may exceed the withstand voltage of the subsequent MOS transistor. In order to deal with this problem of negative voltage, the second clamp element 73 is provided. That is, the second clamp element 73 clamps the voltage of the node N to which the input terminal of the read circuit 56 is connected to the gate-source voltage V of the P-type MOS transistor. gs (For example, about 0.5 V). This makes it possible to solve the problem of negative voltage by the clamping operation of the first clamp element 72.

[0061] As described above, in the light receiving device 30 according to the first embodiment, the clamp circuit 70 provided as the protection circuit 60 can clamp the overvoltage generated when the SPAD element 51 is irradiated with a large amount of light equal to or greater than a predetermined amount of light to a constant voltage. As a result, the P-type MOS transistor Q p and N-type MOS transistor Q n , as well as the first control transistor 52 and the second control transistor 55 can be protected from overvoltage.

[0062] Next, in the light receiving device 30 of Example 1 having the above configuration, variations in the element arrangement of the SPAD element 51, the resistance element 71, the first clamp element 72, and the second clamp element 73 will be described in the case where the chip structure is a stacked chip structure (see FIG. 5) in which the sensor chip 101 and the circuit chip 102 are stacked as an upper chip and a lower chip.

[0063] (Element layout example 1) FIG. 10 is a circuit diagram showing an element arrangement example 1 of a SPAD element 51, a resistor element 71, a first clamp element 72, and a second clamp element 73 in a stacked chip structure.

[0064] The stacked chip structure of element arrangement example 1 is configured such that only a SPAD element 51 is arranged on the upper chip, the sensor chip 101, and a resistive element 71, a first clamp element 72, and a second clamp element 73 are arranged on the lower chip, the circuit chip 102, as well as a first control transistor 52, a current source 53, a second control transistor 55, and a readout circuit 56.

[0065] (Element layout example 2) FIG. 11 is a circuit diagram showing an element arrangement example 2 of a SPAD element 51, a resistor element 71, a first clamp element 72, and a second clamp element 73 in a stacked chip structure.

[0066] The stacked chip structure of element arrangement example 2 is configured such that a SPAD element 51 and a resistive element 71 are arranged on the upper chip, the sensor chip 101, and a first clamp element 72 and a second clamp element 73 are arranged on the lower chip, the circuit chip 102, as well as a first control transistor 52, a current source 53, a second control transistor 55, and a readout circuit 56.

[0067] (Element layout example 3) FIG. 12 is a circuit diagram showing an element arrangement example 3 of a SPAD element 51, a resistor element 71, a first clamp element 72, and a second clamp element 73 in a stacked chip structure.

[0068] The stacked chip structure of element arrangement example 3 is configured such that a SPAD element 51, a resistive element 71, and a first clamp element 72 are arranged on the upper chip, the sensor chip 101, and a second clamp element 73 is arranged on the lower chip, the circuit chip 102, as well as a first control transistor 52, a current source 53, a second control transistor 55, and a readout circuit 56.

[0069] [Example 2] Example 2 is a modification of Example 1, in which the second clamp element is omitted. A circuit diagram of a configuration example of a light receiving device 30 according to Example 2 is shown in FIG.

[0070] In the light receiving device 30 according to the second embodiment, the clamp circuit 70 includes a resistance element 71 and a first clamp element 72. That is, the light receiving device 30 according to the second embodiment does not include the second clamp element 73 that is used as one of the components of the clamp circuit 70 in the first embodiment.

[0071] In the case of the light receiving device 30 according to the second embodiment having the above configuration, the action and effect of the second clamp element 73 of the first embodiment cannot be obtained, and although the voltage of the node N becomes a negative voltage, it is extremely lower than the overvoltage (minus several tens of volts). Therefore, even if a large amount of light exceeding a predetermined amount is irradiated onto the SPAD element 51 and an overvoltage occurs, the P-type MOS transistor Q p and N-type MOS transistor Q n , as well as the first control transistor 52 and the second control transistor 55 can be protected from overvoltage.

[0072] [Example 3] The third embodiment is an example of a negative bias configuration, in which the protection circuit 60 is made of a resistive element. A circuit diagram of a configuration example of a light receiving device 30 according to the third embodiment is shown in FIG.

[0073] In the photodetector 30 according to the third embodiment, the protection circuit 60 is configured to include a resistive element 71 connected between the SPAD element 51 and the input terminal of the readout circuit 56, i.e., the node N. That is, the photodetector 30 according to the third embodiment is configured without the first clamp element 72 and the second clamp element 73 used as components of the clamp circuit 70 in the first embodiment.

[0074] In the light receiving device 30 according to the third embodiment, the resistive element 71 configures a clamp circuit between a node N to which the input terminal of the readout circuit 56 is connected and a reference potential node (for example, ground), together with a body diode present in an N-type MOS transistor connected as the second control transistor 55. Here, the "body diode" refers to a built-in diode formed by a PN junction between the source and drain in the structure of a MOSFET.

[0075] According to the light receiving device 30 of the third embodiment having the above configuration, when a large amount of light, equal to or greater than a predetermined amount, is irradiated onto the SPAD element 51 and an overvoltage occurs, a voltage that is extremely lower than the overvoltage (minus several tens of volts) is applied to the node N due to the voltage drop caused by the resistor element 71 and the clamping action of the body diode of the N-type MOS transistor. Therefore, even if a large amount of light, equal to or greater than a predetermined amount, is irradiated onto the SPAD element 51 and an overvoltage occurs, the P-type MOS transistor Q p and N-type MOS transistor Q n , as well as the first control transistor 52 and the second control transistor 55 can be protected from overvoltage.

[0076] [Example 4] Example 4 is a modification of Example 1, and is an example in which the first clamp element 73 is configured using an N-type MOS transistor in a diode-connected configuration. A circuit diagram of an example of the configuration of a light receiving device 30 according to Example 4 is shown in FIG.

[0077] In the light receiving device 30 according to the fourth embodiment, the first clamp element 72 is configured to be composed of an N-type MOS transistor in a clamp circuit 70 composed of a resistive element 71, a first clamp element 72, and a second clamp element 73. The N-type MOS transistor is connected between the other end (output end) of the resistive element 71 and a reference potential node (for example, ground), and is configured to be diode-connected with its gate electrode and drain electrode commonly connected.

[0078] As described above, the light receiving device 30 according to the fourth embodiment is configured to use an N-type MOS transistor in a diode-connected configuration as the first clamp element 72 constituting the clamp circuit 70, instead of the clamp diode of the first embodiment. In this way, even with the configuration using an N-type MOS transistor in a diode-connected configuration as the first clamp element 72, it is possible to obtain the same action and effect as in the first embodiment, that is, to protect circuit elements such as the readout circuit 56 in the subsequent stage from an overvoltage when a large amount of light equal to or greater than a predetermined amount of light is irradiated onto the SPAD element 51 and an overvoltage occurs.

[0079] [Example 5] The fifth embodiment is a modification of the first embodiment, and is an example in which the first clamp element 73 is configured using a P-type MOS transistor in a diode-connected configuration. A circuit diagram of a configuration example of a light receiving device 30 according to the fifth embodiment is shown in FIG.

[0080] In the light receiving device 30 according to the fifth embodiment, the first clamp element 72 in the clamp circuit 70 including the resistive element 71, the first clamp element 72, and the second clamp element 73 is configured to include a P-type MOS transistor. The P-type MOS transistor is connected between the other end (output end) of the resistive element 71 and a reference potential node (for example, ground), and is configured to be diode-connected with its gate electrode and source electrode commonly connected.

[0081] As described above, the light receiving device 30 according to the fifth embodiment is configured to use a P-type MOS transistor in a diode-connected configuration as the first clamp element 72 constituting the clamp circuit 70, instead of the clamp diode of the first embodiment. In this way, even with the configuration using a P-type MOS transistor in a diode-connected configuration as the first clamp element 72, it is possible to obtain the same action and effect as in the first embodiment, that is, to protect circuit elements such as the readout circuit 56 in the subsequent stage from an overvoltage when a large amount of light equal to or greater than a predetermined amount of light is irradiated onto the SPAD element 51 and an overvoltage occurs.

[0082] [Example 6] Example 6 is a modification of Example 5, and is an example in which a P-type MOS transistor is used as the first clamp element 73, and a resistive element is provided between the gate and drain of the P-type MOS transistor. A circuit diagram of a configuration example of a light receiving device 30 according to Example 6 is shown in FIG.

[0083] In the light receiving device 30 according to the sixth embodiment, in a clamp circuit 70 including a resistive element 71, a first clamp element 72, and a second clamp element 73, the first clamp element 72 includes a second resistive element 74 connected in series to the resistive element 71, and a P-type MOS transistor connected between the output terminal of the second resistive element 74 and a reference potential node (for example, ground). The gate electrode of the P-type MOS transistor is connected to a common connection node of the resistive element 71 and the second resistive element 74.

[0084] As described above, the light receiving device 30 according to the sixth embodiment has a configuration in which the second resistor element 74 is connected in series to the resistor element 71, and the gate electrode of the P-type MOS transistor is connected to the common connection node between the resistor element 71 and the second resistor element 74. With this configuration, the P-type MOS transistor can be brought into a completely conductive state (on state), so that the voltage of the common connection node between the source electrode of the P-type MOS transistor and the output terminal of the second resistor element 74 does not become a negative voltage. Therefore, in the sixth embodiment, the second clamp element 73 can be omitted.

[0085] [Example 7] The seventh embodiment is an example of a positive bias configuration, in which the protection circuit 60 is composed of a clamp circuit. A circuit diagram of a configuration example of a light receiving device 30 according to the seventh embodiment is shown in FIG.

[0086] The photodetector 30 according to the seventh embodiment has a positive bias configuration in which a positive bias voltage (for example, about 20 V) is applied to the cathode electrode of the SPAD element 51, and uses a clamp circuit 70 that clamps an overvoltage to a constant voltage as the protection circuit 60. That is, the photodetector 30 according to the seventh embodiment having a positive bias configuration has a circuit configuration corresponding to the photodetector 30 according to the first embodiment having a negative bias configuration.

[0087] 18, the clamp circuit 70 includes a resistive element 71, a first clamp element 72, and a second clamp element 73. One end of the resistive element 71 is connected to the anode electrode of the SPAD element 51. The first clamp element 72 is, for example, a clamp diode, and has an anode electrode connected to the other end (output end) of the resistive element 71 and a cathode electrode connected to the power supply voltage V DD The second clamp element 73 is, for example, an N-type MOS transistor, and is connected between the first clamp element 72 and the node N. The gate electrode of the second clamp element 73 is connected to the power supply voltage V DD are connected to the nodes.

[0088] According to the light receiving device 30 of the seventh embodiment having the above-mentioned configuration, even if a large amount of light exceeding a predetermined amount is irradiated on the SPAD element 51 and an overvoltage occurs, the readout circuit 56 at the downstream side can be protected from the overvoltage by the action of the clamp circuit 70 provided as the protection circuit 60. More specifically, the P-type MOS transistor Q p and N-type MOS transistor Q n , as well as the first control transistor 52 and the second control transistor 55 can be protected from overvoltage.

[0089] [Example 8] Example 8 is a modification of Example 7, in which the second clamp element is omitted. A circuit diagram of a configuration example of a light receiving device 30 according to Example 8 is shown in FIG.

[0090] In the light receiving device 30 according to the eighth embodiment, the clamp circuit 70 includes a resistor element 71 and a first clamp element 72. That is, the light receiving device 30 according to the eighth embodiment is configured without the second clamp element 73 used as one of the components of the clamp circuit 70 in the seventh embodiment, and has a circuit configuration corresponding to the light receiving device 30 according to the second embodiment, which has a negative bias configuration. Therefore, according to the light receiving device 30 according to the eighth embodiment, it is possible to obtain the same actions and effects as those of the light receiving device 30 according to the second embodiment.

[0091] [Example 9] The ninth embodiment is an example of a positive bias configuration, in which the protection circuit 60 is made of a resistive element. A circuit diagram of a configuration example of a light receiving device 30 according to the ninth embodiment is shown in FIG.

[0092] In the photoreceiving device 30 according to the ninth embodiment, the protection circuit 60 is configured to include a resistive element 71 connected between the SPAD element 51 and the input terminal of the readout circuit 56, i.e., the node N. That is, the photoreceiving device 30 according to the third embodiment is configured without the first clamp element 72 and the second clamp element 73 used as components of the clamp circuit 70 in the first embodiment, and has a circuit configuration corresponding to the photoreceiving device 30 according to the third embodiment, which has a negative bias configuration. Therefore, according to the photoreceiving device 30 according to the ninth embodiment, it is possible to obtain the same actions and effects as those of the photoreceiving device 30 according to the third embodiment.

[0093] <Modification> Although the technology according to the present disclosure has been described above based on a preferred embodiment, the technology according to the present disclosure is not limited to the embodiment. The configurations and structures of the light receiving device and the distance measuring device described in the above embodiment are merely examples and can be modified as appropriate.

[0094] For example, in the photodetector 30 according to the seventh embodiment having a positive bias configuration, the first clamp element 72 may be configured similarly to the photodetector 30 according to the fourth to sixth embodiments having a negative bias configuration. That is, the first clamp element 72 may be configured using a MOS transistor having a diode connection configuration, or may be configured by a combination of a second resistive element and a MOS transistor.

[0095] <Application examples of the technology disclosed herein> The technology according to the present disclosure can be applied to various products. More specific application examples will be described below. For example, the technology according to the present disclosure may be realized as a distance measuring device mounted on any type of moving object such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility, an airplane, a drone, a ship, a robot, a construction machine, or an agricultural machine (tractor).

[0096] [Mobile object] 21 is a block diagram showing a schematic configuration example of a vehicle control system 7000 which is an example of a mobile object control system to which the technology according to the present disclosure can be applied. The vehicle control system 7000 includes a plurality of electronic control units connected via a communication network 7010. In the example shown in FIG. 21, the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an outside-vehicle information detection unit 7400, an inside-vehicle information detection unit 7500, and an integrated control unit 7600. The communication network 7010 connecting these multiple control units may be an in-vehicle communication network conforming to any standard such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), or FlexRay (registered trademark).

[0097] Each control unit includes a microcomputer that performs arithmetic processing according to various programs, a storage unit that stores the programs executed by the microcomputer or parameters used in various calculations, and a drive circuit that drives various control target devices. Each control unit includes a network I / F for communicating with other control units via a communication network 7010, and a communication I / F for communicating with devices or sensors inside and outside the vehicle by wired communication or wireless communication. In FIG. 21, a microcomputer 7610, a general-purpose communication I / F 7620, a dedicated communication I / F 7630, a positioning unit 7640, a beacon receiving unit 7650, an in-vehicle device I / F 7660, an audio / video output unit 7670, an in-vehicle network I / F 7680, and a storage unit 7690 are illustrated as the functional configuration of the integrated control unit 7600. Other control units also include a microcomputer, a communication I / F, a storage unit, and the like.

[0098] The drivetrain control unit 7100 controls the operation of devices related to the drivetrain of the vehicle according to various programs. For example, the drivetrain control unit 7100 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle. The drivetrain control unit 7100 may also function as a control device such as an ABS (Antilock Brake System) or an ESC (Electronic Stability Control).

[0099] A vehicle state detection unit 7110 is connected to the drive system control unit 7100. The vehicle state detection unit 7110 includes at least one of a gyro sensor that detects the angular velocity of the axial rotational motion of the vehicle body, an acceleration sensor that detects the acceleration of the vehicle, or a sensor for detecting the amount of operation of an accelerator pedal, the amount of operation of a brake pedal, the steering angle of a steering wheel, the engine rotation speed, or the rotation speed of wheels, for example. The drive system control unit 7100 performs arithmetic processing using signals input from the vehicle state detection unit 7110, and controls the internal combustion engine, the drive motor, the electric power steering device, the brake device, etc.

[0100] The body system control unit 7200 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 7200 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as head lamps, back lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals of various switches transmitted from a portable device that replaces a key may be input to the body system control unit 7200. The body system control unit 7200 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, and the like of the vehicle.

[0101] The battery control unit 7300 controls the secondary battery 7310, which is a power supply source for the drive motor, according to various programs. For example, information such as battery temperature, battery output voltage, or remaining capacity of the battery is input to the battery control unit 7300 from a battery device equipped with the secondary battery 7310. The battery control unit 7300 performs calculation processing using these signals, and controls the temperature regulation of the secondary battery 7310 or controls a cooling device or the like equipped in the battery device.

[0102] The outside-vehicle information detection unit 7400 detects information outside the vehicle equipped with the vehicle control system 7000. For example, at least one of an imaging unit 7410 and an outside-vehicle information detection unit 7420 is connected to the outside-vehicle information detection unit 7400. The imaging unit 7410 includes at least one of a ToF (Time Of Flight) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The outside-vehicle information detection unit 7420 includes at least one of an environmental sensor for detecting the current weather or climate, or a surrounding information detection sensor for detecting other vehicles, obstacles, pedestrians, and the like around the vehicle equipped with the vehicle control system 7000.

[0103] The environmental sensor may be, for example, at least one of a raindrop sensor that detects rain, a fog sensor that detects fog, a sunshine sensor that detects the degree of sunshine, and a snow sensor that detects snowfall. The surrounding information detection sensor may be at least one of an ultrasonic sensor, a radar device, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device. The imaging unit 7410 and the outside vehicle information detection unit 7420 may be provided as independent sensors or devices, or may be provided as a device in which multiple sensors or devices are integrated.

[0104] Here, FIG. 22 shows an example of the installation positions of the imaging unit 7410 and the vehicle exterior information detection unit 7420. The imaging units 7910, 7912, 7914, 7916, and 7918 are provided, for example, at least one of the front nose, side mirrors, rear bumper, back door, and upper part of the windshield in the vehicle interior of the vehicle 7900. The imaging unit 7910 provided on the front nose and the imaging unit 7918 provided on the upper part of the windshield in the vehicle interior mainly acquire images of the front of the vehicle 7900. The imaging units 7912 and 7914 provided on the side mirrors mainly acquire images of the sides of the vehicle 7900. The imaging unit 7916 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 7900. The imaging unit 7918 provided on the upper part of the windshield in the vehicle interior is mainly used to detect a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

[0105] 22 shows an example of the imaging ranges of the imaging units 7910, 7912, 7914, and 7916. Imaging range a indicates the imaging range of the imaging unit 7910 provided on the front nose, imaging ranges b and c indicate the imaging ranges of the imaging units 7912 and 7914 provided on the side mirrors, and imaging range d indicates the imaging range of the imaging unit 7916 provided on the rear bumper or back door. For example, image data captured by the imaging units 7910, 7912, 7914, and 7916 are superimposed to obtain an overhead image of the vehicle 7900.

[0106] The outside information detection units 7920, 7922, 7924, 7926, 7928, and 7930 provided on the front, rear, sides, and corners of the vehicle 7900 and on the upper part of the windshield inside the vehicle cabin may be, for example, ultrasonic sensors or radar devices. The outside information detection units 7920, 7926, and 7930 provided on the front nose, rear bumper, back door, and on the upper part of the windshield inside the vehicle cabin of the vehicle 7900 may be, for example, LIDAR devices. These outside information detection units 7920 to 7930 are mainly used to detect preceding vehicles, pedestrians, obstacles, and the like.

[0107] Returning to FIG. 21, the description will be continued. The outside-vehicle information detection unit 7400 causes the imaging unit 7410 to capture an image outside the vehicle, and receives the captured image data. The outside-vehicle information detection unit 7400 also receives detection information from the outside-vehicle information detection unit 7420 connected thereto. When the outside-vehicle information detection unit 7420 is an ultrasonic sensor, a radar device, or a LIDAR device, the outside-vehicle information detection unit 7400 transmits ultrasonic waves or electromagnetic waves, and receives information on the received reflected waves. The outside-vehicle information detection unit 7400 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, or characters on the road surface, based on the received information. The outside-vehicle information detection unit 7400 may perform environment recognition processing for recognizing rainfall, fog, road surface conditions, and the like, based on the received information. The outside-vehicle information detection unit 7400 may calculate the distance to an object outside the vehicle based on the received information.

[0108] Furthermore, the outside vehicle information detection unit 7400 may perform image recognition processing or distance detection processing to recognize people, cars, obstacles, signs, or characters on the road surface, based on the received image data. The outside vehicle information detection unit 7400 may perform processing such as distortion correction or position adjustment on the received image data, and may generate an overhead image or a panoramic image by synthesizing image data captured by different imaging units 7410. The outside vehicle information detection unit 7400 may perform viewpoint conversion processing using image data captured by different imaging units 7410.

[0109] The in-vehicle information detection unit 7500 detects information inside the vehicle. For example, a driver state detection unit 7510 that detects the state of the driver is connected to the in-vehicle information detection unit 7500. The driver state detection unit 7510 may include a camera that captures an image of the driver, a biosensor that detects the bioinformation of the driver, or a microphone that collects sound in the vehicle cabin. The biosensor is provided, for example, on the seat or steering wheel, and detects the bioinformation of a passenger sitting in the seat or a driver gripping the steering wheel. The in-vehicle information detection unit 7500 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 7510, or may determine whether the driver is dozing. The in-vehicle information detection unit 7500 may perform processing such as noise canceling processing on the collected sound signal.

[0110] The integrated control unit 7600 controls the overall operation of the vehicle control system 7000 according to various programs. The input unit 7800 is connected to the integrated control unit 7600. The input unit 7800 is realized by a device that can be operated by an occupant to input, such as a touch panel, a button, a microphone, a switch, or a lever. Data obtained by voice recognition of a voice input by a microphone may be input to the integrated control unit 7600. The input unit 7800 may be, for example, a remote control device using infrared or other radio waves, or an externally connected device such as a mobile phone or a PDA (Personal Digital Assistant) that supports the operation of the vehicle control system 7000. The input unit 7800 may be, for example, a camera, in which case the occupant can input information by gestures. Alternatively, data obtained by detecting the movement of a wearable device worn by the occupant may be input. Furthermore, the input unit 7800 may include, for example, an input control circuit that generates an input signal based on information input by the occupant using the above-mentioned input unit 7800 and outputs the input signal to the integrated control unit 7600. A passenger or the like operates the input unit 7800 to input various data to the vehicle control system 7000 and to instruct processing operations.

[0111] The storage unit 7690 may include a ROM (Read Only Memory) that stores various programs executed by the microcomputer, and a RAM (Random Access Memory) that stores various parameters, calculation results, sensor values, etc. The storage unit 7690 may be realized by a magnetic storage device such as an HDD (Hard Disc Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device, etc.

[0112] The general-purpose communication I / F 7620 is a general-purpose communication I / F that mediates communication between various devices present in the external environment 7750. The general-purpose communication I / F 7620 may implement a cellular communication protocol such as GSM (registered trademark), WiMAX, LTE (Long Term Evolution), or LTE-Advanced (LTE-A), or other wireless communication protocols such as wireless LAN (also called Wi-Fi (registered trademark)) and Bluetooth (registered trademark). The general-purpose communication I / F 7620 may connect to a device (e.g., an application server or a control server) present on an external network (e.g., the Internet, a cloud network, or a carrier-specific network) via, for example, a base station or an access point. The general-purpose communication I / F 7620 may also connect to a terminal (e.g., a driver's, pedestrian's, or store's terminal, or a MTC (Machine Type Communication) terminal) present in the vicinity of the vehicle using, for example, a P2P (Peer To Peer) technology.

[0113] The dedicated communication I / F 7630 is a communication I / F that supports a communication protocol designed for use in a vehicle. The dedicated communication I / F 7630 may implement a standard protocol such as WAVE (Wireless Access in Vehicle Environment), which is a combination of a lower layer IEEE802.11p and a higher layer IEEE1609, DSRC (Dedicated Short Range Communications), or a cellular communication protocol. The dedicated communication I / F 7630 typically performs V2X communication, which is a concept including one or more of vehicle-to-vehicle communication, vehicle-to-infrastructure communication, vehicle-to-home communication, and vehicle-to-pedestrian communication.

[0114] The positioning unit 7640 performs positioning by receiving, for example, a GNSS signal from a Global Navigation Satellite System (GNSS) satellite (for example, a GPS signal from a Global Positioning System (GPS) satellite) and generates position information including the latitude, longitude, and altitude of the vehicle. The positioning unit 7640 may identify the current position by exchanging signals with a wireless access point, or may obtain position information from a terminal such as a mobile phone, PHS, or smartphone having a positioning function.

[0115] The beacon receiving unit 7650 receives, for example, radio waves or electromagnetic waves transmitted from radio stations or the like installed on the road, and acquires information such as the current location, congestion, road closure, required time, etc. The function of the beacon receiving unit 7650 may be included in the dedicated communication I / F 7630 described above.

[0116] The in-vehicle device I / F 7660 is a communication interface that mediates a connection between the microcomputer 7610 and various in-vehicle devices 7760 present in the vehicle. The in-vehicle device I / F 7660 may establish a wireless connection using a wireless communication protocol such as wireless LAN, Bluetooth (registered trademark), NFC (Near Field Communication), or WUSB (Wireless USB). The in-vehicle device I / F 7660 may also establish a wired connection such as USB (Universal Serial Bus), HDMI (High-Definition Multimedia Interface), or MHL (Mobile High-definition Link) via a connection terminal (and a cable, if necessary) not shown. The in-vehicle device 7760 may include at least one of a mobile device or a wearable device owned by a passenger, or an information device carried or attached to a vehicle. The in-vehicle device 7760 may also include a navigation device that searches for a route to an arbitrary destination. The in-vehicle equipment I / F 7660 exchanges control signals and data signals with these in-vehicle equipment 7760.

[0117] The in-vehicle network I / F 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network I / F 7680 transmits and receives signals in accordance with a predetermined protocol supported by the communication network 7010.

[0118] The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 according to various programs based on information acquired through at least one of the general-purpose communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the in-vehicle device I / F 7660, and the in-vehicle network I / F 7680. For example, the microcomputer 7610 may calculate a control target value of a driving force generating device, a steering mechanism, or a braking device based on the acquired information inside and outside the vehicle, and output a control command to the drive system control unit 7100. For example, the microcomputer 7610 may perform cooperative control for the purpose of realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc. In addition, the microcomputer 7610 may perform cooperative control for the purpose of autonomous driving, in which the vehicle travels autonomously without relying on driver operation, by controlling a driving force generating device, a steering mechanism, a braking device, etc. based on information acquired about the vehicle's surroundings.

[0119] The microcomputer 7610 may generate three-dimensional distance information between the vehicle and objects such as surrounding structures and people, and create local map information including peripheral information of the current position of the vehicle, based on information acquired via at least one of the general-purpose communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the in-vehicle device I / F 7660, and the in-vehicle network I / F 7680. The microcomputer 7610 may also predict dangers such as vehicle collisions, the approach of pedestrians, or entry into a closed road, based on the acquired information, and generate a warning signal. The warning signal may be, for example, a signal for generating a warning sound or turning on a warning lamp.

[0120] The audio / image output unit 7670 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle of information. In the example of FIG. 21, an audio speaker 7710, a display unit 7720, and an instrument panel 7730 are illustrated as output devices. The display unit 7720 may include, for example, at least one of an on-board display and a head-up display. The display unit 7720 may have an AR (Augmented Reality) display function. The output device may be other devices such as headphones, a wearable device such as a glasses-type display worn by the passenger, a projector, or a lamp, other than these devices. When the output device is a display device, the display device visually displays the results obtained by various processes performed by the microcomputer 7610 or information received from other control units in various formats such as text, image, table, graph, etc. When the output device is an audio output device, the audio output device converts an audio signal consisting of reproduced audio data or acoustic data into an analog signal and audibly outputs it.

[0121] In the example shown in FIG. 21, at least two control units connected via the communication network 7010 may be integrated into one control unit. Alternatively, each control unit may be composed of multiple control units. Furthermore, the vehicle control system 7000 may include another control unit not shown. In the above description, some or all of the functions performed by any control unit may be provided by another control unit. In other words, as long as information is transmitted and received via the communication network 7010, a predetermined arithmetic processing may be performed by any control unit. Similarly, a sensor or device connected to any control unit may be connected to another control unit, and multiple control units may transmit and receive detection information to each other via the communication network 7010.

[0122] An example of a vehicle control system to which the technology according to the present disclosure can be applied has been described above. In the technology according to the present disclosure, when, for example, the imaging unit 7410 or the vehicle outside information detection unit 7420 includes a ToF camera (ToF sensor) among the components described above, the light receiving device according to the above-mentioned embodiment can be used as the ToF camera. By mounting the light receiving device as the ToF camera of the distance measuring device, for example, when a large amount of light equal to or greater than a predetermined amount of light is irradiated onto the light receiving element and an overvoltage occurs in the light receiving element, it is possible to prevent element destruction due to the overvoltage, and therefore a highly reliable vehicle control system can be constructed.

[0123] <Configurations that the present disclosure can take> The present disclosure may also be configured as follows.

[0124] ≪A. Light receiving device≫ [A-1] a photodetector that generates a signal in response to receiving a photon; a readout circuit for reading out a signal generated by the light receiving element; and a protection circuit provided between the light receiving element and an input terminal of the readout circuit for protecting a circuit element of the readout circuit from an overvoltage; A light receiving device comprising: [A-2] The protection circuit consists of a clamp circuit that clamps the overvoltage to a constant voltage. The light receiving device described in [A-1] above. [A-3] The clamp circuit is a resistive element having one end connected to the light receiving element; and a first clamp element connected between the other end of the resistive element and a reference potential node; having The light receiving device described in [A-2] above. [A-4] The first clamp element is composed of a clamp diode having a cathode electrode connected to the other end of the resistance element and an anode electrode connected to a reference potential node. The light receiving device described in [A-3] above. [A-5] The clamp circuit includes a second clamp element provided between the first clamp element and the input terminal of the readout circuit; having The light receiving device according to the above [A-3] or [A-4]. [A-6] The second clamp element is connected between the first clamp element and the input terminal of the readout circuit, and is composed of a MOS transistor having a gate electrode connected to a reference potential node; The light receiving device described in [A-5] above. [A-7] A stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked, The light receiving element is disposed on a first semiconductor substrate; the resistive element, the first clamp element, and the second clamp element are disposed on a second semiconductor substrate. The light receiving device according to the above [A-5] or [A-6]. [A-8] A stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked, the light receiving element and the resistor element are disposed on a first semiconductor substrate; the first clamping element and the second clamping element are disposed on a second semiconductor substrate. The light receiving device according to the above [A-5] or [A-6]. [A-9] A stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked, the light receiving element, the resistor element, and the first clamp element are disposed on a first semiconductor substrate; the second clamping element is disposed on the second semiconductor substrate; The light receiving device according to the above [A-5] or [A-6]. [A-10] The protection circuit comprises a resistive element connected between the light receiving element and the input terminal of the readout circuit; The light receiving device described in [A-1] above. [A-11] An N-type MOS transistor is connected between the input terminal of the read circuit and a reference potential node, The resistor element that constitutes the protection circuit constitutes a clamp circuit together with the body diode in the N-type MOS transistor. The light receiving device described in [A-10] above. [A-12] The first clamp element is composed of a MOS transistor in a diode-connected configuration; The light receiving device described in [A-3] above. [A-13] The first clamp element is a second resistive element connected in series with the resistive element; and a P-type MOS transistor connected between an output terminal of the second resistance element and a reference potential node; a gate electrode of the P-type MOS transistor is connected to a common connection node of the resistance element and the second resistance element; The light receiving device described in [A-3] above. [A-14] The readout circuit is composed of a CMOS inverter circuit. The light receiving device according to any one of [A-1] to [A-13] above. [A-15] The light receiving element is an element that is used by applying a voltage equal to or higher than the breakdown voltage. The light receiving device according to any one of [A-1] to [A-14] above. [A-16] The light receiving element is an avalanche photodiode operating in Geiger mode. The light receiving device described in [A-15] above. [A-17] The light receiving element is composed of a single photon avalanche diode. The light receiving device described in [A-16] above. [A-18] Single-photon avalanche diodes are used with a negative bias voltage applied to the anode electrode. The light receiving device described in [A-17] above. [A-19] Single-photon avalanche diodes are used with a positive bias voltage applied to the cathode electrode. The light receiving device described in [A-17] above.

[0125] ≪B. Distance measuring device≫ [B-1] A light source unit that irradiates light onto an object to be measured; and a light receiving device that receives reflected light from an object to be measured based on light emitted from a light source unit; Equipped with The light receiving device is a light receiving element that generates a signal in response to receiving a photon; a readout circuit for reading out a signal generated by the light receiving element; and a protection circuit provided between the light receiving element and the readout circuit for protecting a circuit element of the readout circuit from an overvoltage; A distance measuring device comprising: [B-2] The protection circuit consists of a clamp circuit that clamps the overvoltage to a constant voltage. The distance measuring device described in [B-1] above. [B-3] The clamp circuit is a resistive element having one end connected to the light receiving element; and a first clamp element connected between the other end of the resistive element and a reference potential node; having The distance measuring device described in [B-2] above. [B-4] The first clamp element is composed of a clamp diode having a cathode electrode connected to the other end of the resistance element and an anode electrode connected to a reference potential node; The distance measuring device described in [B-3] above. [B-5] The clamp circuit includes a second clamp element provided between the first clamp element and the input terminal of the readout circuit; having A distance measuring device according to the above [B-3] or [B-4]. [B-6] The second clamp element is connected between the first clamp element and the input terminal of the readout circuit, and is composed of a MOS transistor having a gate electrode connected to a reference potential node; The distance measuring device described in [B-5] above. [B-7] A stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked, The light receiving element is disposed on a first semiconductor substrate; the resistive element, the first clamp element, and the second clamp element are disposed on a second semiconductor substrate. A distance measuring device according to the above [B-5] or [B-6]. [B-8] A stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked, the light receiving element and the resistor element are disposed on a first semiconductor substrate; the first clamping element and the second clamping element are disposed on a second semiconductor substrate. A distance measuring device according to the above [B-5] or [B-6]. [B-9] A stacked chip structure in which at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, are stacked, the light receiving element, the resistor element, and the first clamp element are disposed on a first semiconductor substrate; the second clamping element is disposed on the second semiconductor substrate; A distance measuring device according to the above [B-5] or [B-6]. [B-10] The protection circuit comprises a resistive element connected between the light receiving element and the input terminal of the readout circuit; The distance measuring device described in [B-1] above. [B-11] An N-type MOS transistor is connected between the input terminal of the read circuit and a reference potential node, The resistor element that constitutes the protection circuit constitutes a clamp circuit together with the body diode in the N-type MOS transistor. The distance measuring device according to [B-10] above. [B-12] The first clamp element is composed of a MOS transistor in a diode-connected configuration; The distance measuring device described in [B-3] above. [B-13] The first clamp element is a second resistive element connected in series with the resistive element; and a P-type MOS transistor connected between an output terminal of the second resistance element and a reference potential node; a gate electrode of the P-type MOS transistor is connected to a common connection node of the resistance element and the second resistance element; The distance measuring device described in [B-3] above. [B-14] The readout circuit is composed of a CMOS inverter circuit. A distance measuring device according to any one of [B-1] to [B-13] above. [B-15] The light receiving element is an element that is used by applying a voltage equal to or higher than the breakdown voltage. A distance measuring device according to any one of [B-1] to [B-14] above. [B-16] The light receiving element is an avalanche photodiode operating in Geiger mode. The distance measuring device according to [B-15] above. [B-17] The light receiving element is a single-photon avalanche diode. The distance measuring device according to [B-16] above. [B-18] Single-photon avalanche diodes are used with a negative bias voltage applied to the anode electrode. The distance measuring device according to [B-17] above. [B-19] Single-photon avalanche diodes are used with a positive bias voltage applied to the cathode electrode. The distance measuring device according to [B-17] above. [Explanation of symbols]

[0126] REFERENCE SIGNS LIST 1 distance measuring device, 10 subject, 20 light source section, 21 laser driving section, 22 laser light source, 23 diffusion lens, 30 light receiving device, 31 light receiving lens, 32 optical sensor, 33 signal processing section, 40 control section, 50 pixel, 51 SPAD element, 56 readout circuit, 57 time measurement section (TDC), 60 protection circuit, 70 clamp circuit

Claims

1. a light receiving element that generates a signal in response to receiving a photon; a readout circuit for reading out a signal generated by the light receiving element; and a protection circuit provided between the light receiving element and an input terminal of the readout circuit for protecting a circuit element of the readout circuit from an overvoltage; Equipped with The protection circuit consists of a clamp circuit that clamps the overvoltage to a fixed voltage, The clamp circuit is a resistive element having one end connected to the light receiving element; a first clamp element connected between the other end of the resistive element and a reference potential node; and a second clamp element provided between the first clamp element and the input of the read circuit; having Light receiving device.

2. the first clamp element is composed of a clamp diode having a cathode electrode connected to the other end of the resistance element and an anode electrode connected to a reference potential node; The light receiving device according to claim 1 .

3. the second clamp element is connected between the first clamp element and the input terminal of the read circuit, and is composed of a MOS transistor having a gate electrode connected to a reference potential node; The light receiving device according to claim 1 .

4. A stacked chip structure is formed by stacking at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, The light receiving element is disposed on the first semiconductor substrate; the resistive element, the first clamp element, and the second clamp element are disposed on a second semiconductor substrate; The light receiving device according to claim 1 .

5. A stacked chip structure is formed by stacking at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, the light receiving element and the resistor element are disposed on a first semiconductor substrate; the first clamping element and the second clamping element are disposed on a second semiconductor substrate; The light receiving device according to claim 1 .

6. A stacked chip structure is formed by stacking at least two semiconductor substrates, a first semiconductor substrate and a second semiconductor substrate, the light receiving element, the resistor element, and the first clamp element are disposed on a first semiconductor substrate; the second clamping element is disposed on the second semiconductor substrate; The light receiving device according to claim 1 .

7. The first clamp element is a MOS transistor in a diode-connected configuration. The light receiving device according to claim 1 .

8. The first clamping element comprises: a second resistive element connected in series with the resistive element; and a P-type MOS transistor connected between an output terminal of the second resistance element and a reference potential node; a gate electrode of the P-type MOS transistor is connected to a common connection node of the resistance element and the second resistance element; The light receiving device according to claim 1 .

9. The read circuit is composed of a CMOS inverter circuit. The light receiving device according to claim 1 .

10. The light receiving element is an element that is used by applying a voltage equal to or higher than the breakdown voltage. The light receiving device according to claim 1 .

11. The light receiving element consists of an avalanche photodiode operating in Geiger mode. The light receiving device according to claim 10.

12. The light receiving element is a single photon avalanche diode. The light receiving device according to claim 11.

13. Single-photon avalanche diodes are used with a negative bias voltage applied to the anode electrode. The light receiving device according to claim 12.

14. Single-photon avalanche diodes are used with a positive bias voltage applied to the cathode electrode. The light receiving device according to claim 12.

15. A light source unit that irradiates light onto an object to be measured; and a light receiving device that receives reflected light from an object to be measured based on light emitted from a light source unit; Equipped with The light receiving device is a light receiving element that generates a signal in response to receiving a photon; a readout circuit for reading out a signal generated by the light receiving element; and a protection circuit provided between the light receiving element and the readout circuit for protecting a circuit element of the readout circuit from an overvoltage; Equipped with The protection circuit consists of a clamp circuit that clamps the overvoltage to a fixed voltage, The clamp circuit is a resistive element having one end connected to the light receiving element; a first clamp element connected between the other end of the resistive element and a reference potential node; and a second clamp element provided between the first clamp element and the input of the read circuit; having Ranging device.

Images