Light receiving device and distance measuring device

Abstract

The optical receiving device according to the present disclosure includes: an optical receiving element that generates a signal in response to receiving a photon; a readout circuit that reads out the signal generated by the optical receiving element; and a protection circuit that is provided between the optical receiving element and the readout circuit and protects the circuit elements of the readout circuit from overvoltage. In addition, the distance measuring device according to the present disclosure includes the optical receiving device of the above configuration.

Description

Technical Field

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

[0002] There is a light receiving device (light detecting device) that uses an element that generates a signal in response to the reception of a photon as a light receiving element (light detecting element). In this type of light receiving device, for example, a time-of-flight (ToF) method that measures the time when light applied from a light source to a distance measuring object is reflected by the distance measuring object and returns is used as a measurement method for measuring the distance to the distance measuring object (measured object).

[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 SPAD element is used by applying a voltage not less than a breakdown voltage to an anode electrode (or cathode electrode) of the SPAD element due to the configuration of the light receiving device (for example, see Patent Document 1).

[0004] Reference List

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-125717 Summary of the invention

[0007] Problems to be solved by the present invention

[0008] Meanwhile, in the case where the SPAD element is irradiated with a large amount of laser light not less than expected (not less than a predetermined amount of light), such as in the case where the SPAD element is directly irradiated with laser light, the SPAD element is strongly affected by photoelectric conversion due to the large amount of light, and thus the internal impedance is greatly reduced. Therefore, an excessively high voltage is applied to a readout circuit that reads out a signal generated by the SPAD element, and circuit elements included in the readout circuit may be damaged.

[0009] The above problem applies not only to SPAD elements but also to all light receiving elements that generate signals in response to receiving photons.

[0010] Therefore, an object of the present disclosure is to provide a light receiving device and a ranging device including the light receiving device, which can protect circuit elements included in a readout circuit at a later stage from overvoltage even when the light receiving element is irradiated with a large amount of light not less than a predetermined amount of light.

[0011] Solution to the problem

[0012] The optical receiving device of the present disclosure for achieving the above-mentioned purpose includes: an optical receiving element that generates a signal in response to receiving photons; a readout circuit that reads out the signal generated by the optical receiving element; and a protection circuit that is arranged between the optical receiving element and the readout circuit and protects the circuit elements of the readout circuit from overvoltage.

[0013] In addition, the distance measuring device of the present invention for achieving the above-mentioned object includes: a light source section that irradiates light to the distance measuring object; and a light receiving device that receives reflected light from the distance measuring object based on the irradiated light from the light source section. Then, the light receiving device includes: a light receiving element that generates a signal in response to receiving a photon; a readout circuit that reads out the signal generated by the light receiving element; and a protection circuit that is provided between the light receiving element and the readout circuit and protects the circuit elements of the readout circuit from overvoltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] [ Figure 1 ] Figure 1 It is a schematic configuration diagram showing an example of a distance measuring device to which the technology according to the present disclosure is applied.

[0015] [Figure 2] Figure 2A and Figure 2B is a block diagram showing an example of a specific configuration of a distance measuring device according to the present application example.

[0016] [ Figure 3 ] Figure 3 is a circuit diagram showing an example of the configuration of a basic pixel circuit using a SPAD element.

[0017] [Figure 4] Figure 4A is a characteristic diagram showing the current-voltage characteristics of the PN junction of the SPAD element, and Figure 4B It is a waveform diagram used to describe the circuit operation of the pixel circuit.

[0018] [ Figure 5 ] Figure 5 It is an exploded perspective view of the stacked chip structure of the sensor chip and the circuit chip of the light receiving device.

[0019] [Figure 6] Fig. 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 a change in the internal impedance of a SPAD element with respect to the amount of incident light, and Figure 6C is the cathode potential V at normal time and under a lot of light CA Waveform diagram of .

[0020] [ Figure 7 ] Figure 7 is a circuit diagram showing a configuration example of a light receiving device according to an embodiment of the present disclosure.

[0021] [ Figure 8 ] Figure 8 is a circuit diagram showing a configuration example of a light receiving device according to Example 1.

[0022] [ Fig. 9 ] Fig. 9 is a waveform diagram describing a clamping operation when an overvoltage occurs in the light receiving device according to Example 1.

[0023] [ Fig.10 ] Fig.10 is a circuit diagram showing an element arrangement example 1 of a SPAD element, a resistance element, a first clamp element, and a second clamp element in a stacked chip structure.

[0024] [ Fig.11 ] Fig.11 is a circuit diagram showing element arrangement example 2 of a SPAD element, a resistance element, a first clamp element, and a second clamp element in a stacked chip structure.

[0025] [ Fig.12 ] Fig.12 is a circuit diagram showing element arrangement example 3 of a SPAD element, a resistance element, a first clamp element, and a second clamp element in a stacked chip structure.

[0026] [ Fig.13 ] Fig.13 is a circuit diagram showing a configuration example of a light receiving device according to Example 2.

[0027] [ Fig.14 ] Fig.14 is a circuit diagram showing a configuration example of a light receiving device according to Example 3.

[0028] [ Fig.15 ] Fig.15 is a circuit diagram showing a configuration example of a light receiving device according to Example 4.

[0029] [ Fig.16 ] Fig.16 is a circuit diagram showing a configuration example of a light receiving device according to Example 5.

[0030] [ Fig.17 ] Fig.17 is a circuit diagram showing a configuration example of a light receiving device according to Example 6.

[0031] [ Fig.18 ] Fig.18 is a circuit diagram showing a configuration example of a light receiving device according to Example 7.

[0032] [ Fig.19 ] Fig.19is a circuit diagram showing a configuration example of a light receiving device according to Example 8.

[0033] [ Fig. 20 ] Fig. 20 is a circuit diagram showing a configuration example of a light receiving device according to Embodiment 9.

[0034] [ Fig.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 body control system to which the technology according to the present disclosure can be applied.

[0035] [ Fig. 22 ] Fig. 22 2 is a diagram showing an example of installation positions of an imaging portion and a vehicle exterior information detection unit. DETAILED DESCRIPTION

[0036] Hereinafter, a mode for implementing the technology of the present disclosure (hereinafter, referred to as an "implementation mode") is described in detail using the accompanying drawings. The technology of the present disclosure is not limited to the implementation mode. In the following description, the same reference numerals are used for the same elements or elements having the same functions, and repeated descriptions are omitted. Note that the description is given in the following order.

[0037] 1. Overview of the light receiving device and distance measuring device disclosed herein

[0038] 2. Distance measuring device using the technology according to the present invention

[0039] 2-1. Specific configuration example of the distance measuring device

[0040] 2-2. Example of a basic pixel circuit using a SPAD element

[0041] 2-3. Circuit Operation Example of Pixel Circuit Using SPAD Element

[0042] 2-4. Overvoltage applied to the readout circuit of the SPAD element

[0043] 3. Light receiving device according to an embodiment of the present disclosure

[0044] 3-1. Example 1 (Example of negative bias configuration: Example in which the protection circuit includes a clamp circuit)

[0045] 3-2. Example 2 (Variation of Example 1: Example in which the second clamping element is omitted)

[0046] 3-3. Example 3 (Example of Negative Bias Configuration: Example in which the Protection Circuit Includes a Resistance Element)

[0047] 3-4. Example 4 (Modification of Example 1: Example in which the first clamp element is configured by using an N-type MOS transistor configured with a diode connection)

[0048] 3-5. Example 5 (Modification of Example 1: Example in which the first clamp element is configured by using a P-type MOS transistor configured with a diode connection)

[0049] 3-6. Example 6 (Variation of Example 5: Example in which a resistor element is provided between the gate and the drain of a P-type MOS transistor)

[0050] 3-7. Example 7 (Example of Forward Bias Configuration: Example in Which the Protection Circuit Includes a Clamp Circuit)

[0051] 3-8. Example 8 (Variation of Example 7: Example in which the second clamping element is omitted)

[0052] 3-9. Example 9 (Example of Forward Bias Configuration: Example in which the Protection Circuit Includes a Resistance Element)

[0053] 4. Modifications

[0054] 5. Application example of technology according to the present disclosure (example of mobile body)

[0055] 6. Configurations that the present disclosure may adopt

[0056] <Overview of the Light Receiving Device and Distance Measuring Device of the Present Disclosure>

[0057] In the light receiving device and the distance measuring device of the present disclosure, the protection circuit may include a clamping circuit that clamps the overvoltage to a certain voltage. Then, the clamping circuit may include: a resistance element, one end of which is connected to the light receiving element; and a first clamping element, connected between the other end of the resistance element and the reference potential node, and the first clamping element may include a clamping diode, in which the cathode electrode is connected to the other end of the resistance element and the anode electrode is connected to the reference potential node.

[0058] In the optical receiving device and the ranging device of the present disclosure including the above-mentioned preferred configuration, the clamping circuit may include a second clamping element arranged between the first clamping element and the input terminal of the readout circuit, and the second clamping element may include a MOS transistor connected between the first clamping element and the input terminal of the readout circuit and wherein the gate electrode is connected to the reference potential node.

[0059] In addition, the light receiving device and the 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 including a first semiconductor substrate and a second semiconductor substrate are stacked. Then, the light receiving element may be arranged on the first semiconductor substrate, and the resistance element, the first clamping element and the second clamping element may be arranged on the second semiconductor substrate; alternatively, the light receiving element and the resistance element may be arranged on the first semiconductor substrate, and the first clamping element and the second clamping element may be arranged on the second semiconductor substrate; or, the light receiving element, the resistance element and the first clamping element may be arranged on the first semiconductor substrate, and the second clamping element may be arranged on the second semiconductor substrate.

[0060] Furthermore, in the light receiving device and the distance measuring device of the present disclosure including the above-mentioned preferred configuration, the protection circuit may include a resistance element connected between the light receiving element and the input terminal of the readout circuit. Then, when an N-type MOS transistor connected between the input terminal of the readout circuit and the reference potential node is provided, the resistance element included in the protection circuit may form a clamping circuit together with a body diode present in the N-type MOS transistor.

[0061] In addition, in the light receiving device and the distance measuring device of the present disclosure including the above-mentioned preferred configuration, the first clamping element may include a MOS transistor in a diode connection configuration. Alternatively, the first clamping element may include a second resistance element connected in series to the resistance element and a P-type MOS transistor connected between the output end of the second resistance element and the reference potential node, and the gate electrode of the P-type MOS transistor may be connected to a common connection node between the resistance element and the second resistance element.

[0062] Furthermore, in the light receiving device and the distance measuring device of the present disclosure including the above-described preferred configuration, the readout circuit may include a CMOS inverter circuit.

[0063] Furthermore, in the light receiving device and the distance measuring device of the present disclosure including the above-described preferred configuration, the light receiving element may be an element used to apply a voltage not less than a breakdown voltage. Furthermore, the light receiving element may include an avalanche photodiode operating in a Geiger mode.

[0064] Further, in the light receiving device and the distance measuring device of the present disclosure including the above preferred configuration, the light receiving element preferably includes a single photon avalanche diode. Then, the single photon avalanche diode can be used by applying a negative bias to the anode electrode or a positive bias to the cathode electrode.

[0065] <Distance-measuring device to which the technology according to the present disclosure is applied>

[0066] Figure 1It is a schematic configuration diagram showing an example of a distance measuring device to which the technology according to the present disclosure is applied (ie, the distance measuring device of the present disclosure).

[0067] The distance measuring device 1 according to the present application example adopts a ToF method of measuring distance as a measurement method of measuring the distance from the measured object 10 of the object, and the ToF method measures the flight time when light (for example, laser light having a peak wavelength in the infrared wavelength region) irradiated toward the measured object 10 is reflected and returned by the measured object 10. In order to realize the distance measurement by the ToF method, the distance measuring device 1 according to the present application example includes a light source section 20 and a light receiving device 30. Then, a light receiving device according to an embodiment of the present disclosure described later can be used as the light receiving device 30.

[0068] [Specific configuration example of the distance measuring device]

[0069] Figure 2A and Figure 2B An example of a specific configuration of the distance measuring device 1 according to the present application example is shown. The light source section 20 includes, for example, a laser driving section 21, a laser light source 22, and a diffusion lens 23, and irradiates laser light to the object 10. The laser driving section 21 drives the laser light source 22 under the control of the control section 40. The laser light source 22 includes, for example, a semiconductor laser, and is driven by the laser driving section 21 to emit laser light. The diffusion lens 23 diffuses the laser light emitted from the laser light source 22, and irradiates the laser light to the object 10.

[0070] The light receiving device 30 has a light receiving lens 31, an optical sensor 32 as a light receiving unit, and a signal processing unit 33. The light receiving lens 31 receives the reflected laser light returned after the laser light irradiated from the light source unit 20 is reflected from the object 10. The light receiving lens 31 converges the reflected laser light from the object 10 to the light receiving surface of the optical sensor 32. The optical sensor 32 receives the reflected laser light from the object 10 in units of pixels via the light receiving lens 31 and performs photoelectric conversion. As the optical sensor 32, a two-dimensional array sensor can be used in which pixels each including a light receiving element are two-dimensionally arranged in a matrix (array) form.

[0071] The output signal of the optical sensor 32 is provided to the control unit 40 via the signal processing unit 33. For example, the control unit 40 includes a central processing unit (CPU), etc., and controls the light source unit 20 and the light receiving device 30 to measure the time when the laser light irradiated from the light source unit 20 toward the object 10 is reflected and returned by the object 10. The distance to the object 10 can be obtained based on the measured time.

[0072] As a time measurement method, a timer is started at the timing of irradiating pulse light from the light source section 20, and the timer is stopped at the timing of receiving the pulse light at the light receiving device 30; thus, the time is measured. As another method of time measurement, pulse light can be irradiated from the light source section 20 at a predetermined cycle, and the cycle when the light receiving device 30 receives the pulse light can be detected, and the time can be measured from the phase difference between the cycle of the emitted light and the cycle of the received light. The time measurement is performed multiple times, and the time is measured by detecting the peak position of the ToF histogram in which the time periods obtained by the multiple measurements are accumulated.

[0073] Then, in the distance measuring device 1 according to the present application example, a sensor in which the light receiving element of a pixel includes an element that generates a signal in response to receiving a photon (for example, a single photon avalanche diode (SPAD) element) is used as the optical sensor 32. That is, in the light receiving device 30 in the distance measuring device 1 according to the present application example, a SPAD element is used as the light receiving element of the pixel. The SPAD element operates in a Geiger mode in which the element is operated at a reverse voltage exceeding a breakdown voltage (depression voltage).

[0074] It should be noted that although the SPAD element is given as an example of a light receiving element (light detecting element) of a pixel in this article, the light receiving element is not limited to the SPAD element. That is, as the light receiving element of the pixel, various elements operating in Geiger mode (such as avalanche photodiodes (APDs) and silicon photomultipliers (SiPMs)) as well as SPAD elements can be used.

[0075] [Example of a basic pixel circuit using a SPAD element]

[0076] Figure 3 An example of the configuration of a basic pixel circuit in the light receiving device 30 using the SPAD element is shown. Here, the basic configuration of one pixel is shown.

[0077] In the basic pixel circuit of the pixel 50 using the SPAD element, the cathode electrode of the SPAD element 51 is connected to the terminal 54 via the first control transistor 52 and the current source 53, and the power supply voltage V DD is applied to the terminal 54. The power supply voltage V DD Examples include a voltage of about 3 V. The anode voltage V ano is applied to the anode electrode of the SPAD element 51. As the anode voltage V ano , a large negative voltage is applied for avalanche multiplication, i.e., a voltage not less than the breakdown voltage (e.g., about -20 V) (see Figure 4B ).

[0078] The first control transistor 52 includes, for example, a P-type MOS transistor; and enters a conductive state by the enable signal EN applied to the gate electrode becoming a low level, and transfers current from the current source 53 to the SPAD element 51. The 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 includes, for example, an N-type MOS transistor; and enters a conductive state by a signal xEN inverted from the enable signal EN applied to the gate electrode, sets the voltage applied to the SPAD element 51 to be not greater than the breakdown voltage, and causes the SPAD element 51 to enter an inactive state.

[0079] The signal generated by the SPAD element 51 in response to receiving a photon is used as the cathode potential V CA The data is read out by the readout circuit 56. The readout circuit 56 includes, for example, a P-type MOS transistor Q p and N-type MOS transistor Q n The CMOS inverter circuit of the SPAD element 51 is used to detect 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 section (time digital converter, TDC) 57. Based on the SPAD output, the time measurement section 57 measures the time until the light applied toward the measurement object is reflected by the measurement object and returns.

[0080] As mentioned above, not less than the breakdown voltage V BD A voltage of (eg, about -20 V) is applied to the SPAD element 51. At the breakdown voltage V BD The overvoltage added to the voltage is called excess bias voltage V EX The characteristics of the SPAD element 51 are determined by the applied breakdown voltage V BD The voltage value of the excess bias voltage V EX The voltage value changes.

[0081] Figure 4A The I (current)-V (voltage) characteristics of the PN junction of the SPAD element 51 operating in the Geiger mode are shown. Figure 4A shows the breakdown voltage V BD , Excess bias voltage V EX And the relationship between the operating points of the SPAD element 51.

[0082] [Circuit operation example of pixel circuit using SPAD element]

[0083] Next, use Figure 4B The waveform diagram describes an example of the circuit operation of the pixel circuit configured as described above.

[0084] When no current flows through the SPAD element 51, the value (VDD –V ano ) is applied to the SPAD element 51. This voltage value (V DD -V ano ) is (V BD +V EX ). Then, electrons generated due to the dark electron generation rate DCR (dark count rate) at the PN junction of the SPAD element 51 or light irradiation cause avalanche multiplication, and an avalanche current occurs. This phenomenon occurs randomly even in a light-shielded state (i.e., a state where light is not incident). This is the dark electron generation rate, i.e., the dark count rate (DCR).

[0085] If the cathode potential V CA The voltage between the terminals of the SPAD element 51 decreases and reaches the breakdown voltage V of the PN diode. BD , the avalanche current stops. Then, the electrons generated and accumulated by avalanche multiplication pass through the load 54 (for example, the P-type MOS transistor Q L ) discharge, cathode potential V CA Then, the cathode potential V CA Restore to the power supply voltage V DD , and the state returns to the initial state again.

[0086] If light is incident on the SPAD element 51 and any electron-hole pair is generated, the electron-hole pair acts as a seed and an avalanche current occurs; therefore, the incidence of even one photon can be detected with a certain detection efficiency, ie, photon detection efficiency (PDE).

[0087] Repeat the above operation. Then, in this series of operations, the cathode potential V CA It is subjected to waveform shaping in the readout circuit 56 including a CMOS inverter circuit, and a pulse signal having a pulse width T is output as a SPAD output (pixel output) with the arrival time of one photon as a starting point.

[0088] [Stacked chip structure of optical receiving device]

[0089] The chip structure of the optical receiving device 30 may be a so-called stacked chip structure in which at least two semiconductor substrates of a first semiconductor substrate and a second semiconductor substrate are stacked. Figure 5 As shown, pixels 50 each including a SPAD element 51 are arranged in a two-dimensional array of M rows and N columns on a first semiconductor substrate to form a pixel array section. The first semiconductor substrate on which the pixels 50 are arranged forms a sensor chip 101. The sensor chip 101 corresponds to Figure 2A Optical sensor 32.

[0090] A circuit section 58 is provided for each pixel 50. The pixel 50 includes at least a SPAD element 51. The circuit section 58 includes, for example Figure 3 The first control transistor 52, the current source 53, the second control transistor 55, the readout circuit 56, the time measurement section 57, etc. are shown. The circuit section 58 is arranged in a two-dimensional array of M rows and N columns on the second semiconductor substrate in a manner corresponding to each pixel 50.

[0091] The second semiconductor substrate provided with the circuit section 58 forms the circuit chip 102. The circuit chip 102 is stacked on the sensor chip 101. Thus, in the stacked chip structure of the sensor chip 101 and the circuit chip 102, the circuit section 58 is provided for each pixel 50.

[0092] [Overvoltage applied to the readout circuit of the SPAD element]

[0093] In the above example, the readout circuit 56 for detecting the reaction edge of the SPAD element 51 is directly connected to the cathode electrode of the SPAD element 51 and has a circuit configuration capable of detecting the amplitude change of a voltage set to a Geiger mode (e.g., approximately 3 V) when reflected light is detected.

[0094] Here, use Fig. 6A , Figure 6B and Figure 6C A case where the SPAD element 51 is irradiated with a large amount of laser light of not less than a predetermined amount of light (not less than expected), such as a case where the SPAD element 51 is directly irradiated with laser light, is described.

[0095] Fig. 6A is an equivalent circuit diagram showing a breakdown model and a photoelectric conversion model of the SPAD element 51, Figure 6B is a diagram showing a change in the internal impedance of the SPAD element 51 with respect to the amount of incident light, and Figure 6C The cathode potential V is shown in normal time (solid line) and when the light intensity is large (dashed line). CA Waveform diagram of .

[0096] exist Fig. 6A In the equivalent circuit diagram shown in , the model of the series circuit of the switch SW, the resistor R, and the voltage source E is the SPAD breakdown model; in this article, a model in which the resistance R of the SPAD element 51 is 20 kΩ and the voltage source E is 20 V is shown as an example. In the SPAD breakdown model, the light amount dependence is small; in the case of a normal light amount not greater than a predetermined amount of light, the cathode potential V is determined by this SPAD breakdown model. CA .

[0097] The photoelectric conversion model is the photocurrent I SPAD From the second control transistor 55 (see Figure 3) flows through the internal impedance Z. In this photoelectric conversion model, Figure 6B As shown, when a laser amount not exceeding a predetermined amount of light is applied, the internal impedance Z is normally high, but if the SPAD element 51 is irradiated with a large amount of laser light exceeding the predetermined amount of light, the internal impedance Z of the SPAD element 51 decreases.

[0098] According to the evaluation of the inventors of the present application, for example, it has been found that the internal impedance Z of the SPAD element 51 is about 500 kW / cm 2 When a large amount of light is applied, the cathode potential V CA During calculations, it can become a high potential of -10V or higher.

[0099] Therefore, in the case where the SPAD element 51 is irradiated with a large amount of laser light, the SPAD element 51 is strongly affected by the photoelectric conversion due to the large amount of light, and therefore, the internal impedance Z is greatly reduced. As a result, Figure 6C As shown in FIG. 1 , an excessive voltage (e.g., about several tens of volts) is applied to the readout circuit 56, and this may cause element destruction of circuit elements included in the readout circuit 56. Specifically, due to the application of the excessive voltage, the P-type MOS transistor Q included in the readout circuit 56 is p and N-type MOS transistor Q n Or the first control transistor 52 or the second control transistor 55 may be damaged.

[0100] <Light Receiving Device According to Embodiment of the Present Disclosure>

[0101] Figure 7 1 is a block diagram showing a configuration example of an optical receiving device according to an embodiment of the present disclosure. Figure 7 As shown, in this embodiment, in a light receiving device including a SPAD element 51 that generates a signal in response to receiving 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.

[0102] The protection circuit 60 is an overvoltage protection circuit having a function of protecting the P-type MOS transistor Q included in the readout circuit 56. p and N-type MOS transistor Q n And the first control transistor 52 and the second control transistor 55 are protected from overvoltage occurring when the SPAD element 51 is irradiated with a large amount of laser light.

[0103] Therefore, by providing the protection circuit 60 between the SPAD element 51 and the input terminal of the readout circuit 56, even in the case where the SPAD element 51 is irradiated with a large amount of laser light not less than a predetermined amount of light (not less than expected), the P-type MOS transistor Q included in the readout circuit 56 can be protected by the action of the protection circuit 60. p and N-type MOS transistor Q n And the first control transistor 52 and the second control transistor 55 are protected from overvoltage.

[0104] Hereinafter, a specific example of the protection circuit 60 for protecting circuit elements included in the readout circuit 56 and the like from overvoltage is described.

[0105] [Example 1]

[0106] Example 1 is an example of a negative bias configuration, and is an example in which the protection circuit 60 includes a clamp circuit. Figure 8 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 1 is shown.

[0107] The light receiving device 30 according to Example 1 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 has a configuration in which a clamp circuit 70 that clamps an overvoltage to a certain voltage is used as the protection circuit 60. That is, in the light receiving device 30 according to Example 1, the protection circuit 60 includes the clamp circuit 70 that clamps an overvoltage to a certain voltage.

[0108] like Figure 8 As shown, the clamping circuit 70 includes a resistor element 71, a first clamping element 72, and a second clamping element 73. One end of the resistor element 71 is connected to the cathode electrode of the SPAD element 51. For example, the first clamping element 72 includes a clamping diode, and the cathode electrode is connected to the other end (output end) of the resistor element 71, and the anode electrode is connected to a reference potential node (for example, ground).

[0109] The resistor element 71 is set so that when an overvoltage occurs in the SPAD element 51, the current value flowing through the clamping diode as the first clamping element 72 is limited to not exceed the rated forward current of the clamping diode. When an overvoltage exceeding the clamping voltage occurs in the SPAD element 51, the clamping diode as the first clamping element 72 clamps the overvoltage to a certain voltage (forward voltage V F ).

[0110] Note that the first clamping element 72 is not limited to the clamping diode. For example, examples of the first clamping element 72 may include a Schottky barrier diode or the like in addition to the clamping diode.

[0111] The second clamping element 73 includes, for example, a P-type MOS transistor, and is connected between the first clamping element 72 (specifically, the anode electrode of the clamping diode) and a node N connected to the input terminal of the readout circuit 56. In the P-type MOS transistor as the second clamping element 73, the gate electrode is connected to a reference potential node (for example, ground), and the back gate is connected to the source electrode.

[0112] Here, as an example, use Fig. 9 The waveform diagram of FIG. 7 describes the clamping operation in the case where an overvoltage of several tens of volts negative occurs in the SPAD element 51. The clamping diode as the first clamping element 72 clamps the overvoltage that has occurred in the SPAD element 51 to a certain voltage (forward voltage V F ). By this clamping operation, the overvoltage that has occurred in the SPAD element 51 is clamped to a negative voltage of, for example, approximately -1 V to -3 V.

[0113] Here, based on the fact that a negative voltage appears by the clamping operation of the first clamping element 72, the negative voltage may exceed the breakdown voltage of the MOS transistor at a later stage. In order to solve the problem of this negative voltage, the second clamping element 73 is provided. That is, the second clamping element 73 clamps the voltage of the node N to which the input terminal of the readout circuit 56 is connected to the gate-source voltage V gs (For example, about 0.5 V.) Therefore, the problem of negative voltage can be solved by the clamping operation of the first clamping element 72.

[0114] As described above, by using the light receiving device 30 of Example 1, due to the action of the clamp circuit 70 provided as the protection circuit 60, the overvoltage generated when the SPAD element 51 is irradiated with light of not less than a predetermined amount can be clamped to a certain voltage. As a result, the P-type MOS transistor Q included in the readout circuit 56 can be protected. p and N-type MOS transistor Q n And the first control transistor 52 and the second control transistor 55 are protected from overvoltage.

[0115] Next, a description is given of a case where the optical receiving device 30 according to Example 1 of the above configuration has a stacked chip structure (see Figure 5 ) in which the sensor chip 101 and the circuit chip 102 are stacked as the upper chip and the lower chip.

[0116] (Component arrangement example 1)

[0117] Fig.10is a circuit diagram showing an element arrangement example 1 of the SPAD element 51 , the resistance element 71 , the first clamp element 72 , and the second clamp element 73 in the stacked chip structure.

[0118] In the stacked chip structure according to element arrangement example 1, only the SPAD element 51 is arranged on the sensor chip 101 (which is the upper chip), and the resistance element 71, the first clamping element 72 and the second clamping element 73 as well as the first control transistor 52, the current source 53, the second control transistor 55 and the readout circuit 56 are arranged on the circuit chip 102 (which is the lower chip).

[0119] (Component arrangement example 2)

[0120] Fig.11 is a circuit diagram showing an element arrangement example 2 of the SPAD element 51 , the resistance element 71 , the first clamp element 72 , and the second clamp element 73 in the stacked chip structure.

[0121] In the stacked chip structure according to element arrangement example 2, the SPAD element 51 and the resistor element 71 are arranged on the sensor chip 101 (which is the upper chip), and the first clamping element 72 and the second clamping element 73 as well as the first control transistor 52, the current source 53, the second control transistor 55 and the readout circuit 56 are arranged on the circuit chip 102 (which is the lower chip).

[0122] (Component arrangement example 3)

[0123] Fig.12 is a circuit diagram showing element arrangement example 3 of the SPAD element 51 , the resistance element 71 , the first clamp element 72 , and the second clamp element 73 in the stacked chip structure.

[0124] In the stacked chip structure according to element arrangement example 3, the SPAD element 51, the resistor element 71 and the first clamping element 72 are arranged on the sensor chip 101 (which is the upper chip) and the second clamping element 73, and the first control transistor 52, the current source 53, the second control transistor 55 and the readout circuit 56 are arranged on the circuit chip 102 (which is the lower chip).

[0125] [Example 2]

[0126] Example 2 is a modification of Example 1, and is an example in which the second clamping element is omitted. Fig.13 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 2 is shown.

[0127] In the light receiving device 30 according to Example 2, the clamp circuit 70 includes a resistance element 71 and a first clamp element 72. That is, in the light receiving device 30 according to Example 2, the second clamp element 73 serving as a constituent element of the clamp circuit 70 in Example 1 is omitted.

[0128] In the case of the light receiving device 30 of Example 2 according to the above configuration, the action and effect of the second clamping element 73 of Example 1 cannot be obtained, and the voltage of the node N becomes a negative voltage; however, this voltage is much lower than the overvoltage (negative tens of volts). Therefore, even in the case where the SPAD element 51 is irradiated with a large amount of light not less than a predetermined amount of light and an overvoltage occurs, the P-type MOS transistor Q included in the readout circuit 56 can be protected. p and N-type MOS transistor Q n And the first control transistor 52 and the second control transistor 55 are protected from overvoltage.

[0129] [Example 3]

[0130] Example 3 is an example of a negative bias configuration, and is an example in which the protection circuit 60 includes a resistance element. Fig.14 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 3.

[0131] In the optical receiving device 30 according to Example 3, the protection circuit 60 includes a resistance element 71 connected between the SPAD element 51 and the input terminal (i.e., node N) of the readout circuit 56. That is, in the optical receiving device 30 according to Example 3, the first clamping element 72 and the second clamping element 73 serving as constituent elements of the clamping circuit 70 in Example 1 are omitted.

[0132] In the light receiving device 30 according to Example 3, the resistance element 71 forms a clamp circuit together with a body diode present in an N-type MOS transistor connected as the second control transistor 55 between a node N to which the input terminal of the readout circuit 56 is connected and a reference potential node (e.g., ground). Here, the “body diode” is a built-in diode formed by a PN junction between the source and the drain due to the structure of the MOSFET.

[0133] By using the light receiving device 30 according to Example 3 of the above configuration, when the SPAD element 51 is irradiated with a large amount of light not less than a predetermined amount of light and an overvoltage occurs, due to the voltage drop of the resistance element 71 and the clamping action of the body diode of the N-type MOS transistor, a voltage much lower than the overvoltage (negative tens of volts) is applied to the node N. Therefore, even in the case where the SPAD element 51 is irradiated with a large amount of light not less than a predetermined amount of light and an overvoltage occurs, the P-type MOS transistor Q included in the readout circuit 56 can be protected. p and N-type MOS transistor Qn And the first control transistor 52 and the second control transistor 55 are protected from overvoltage.

[0134] [Example 4]

[0135] Example 4 is a modification of Example 1, and is an example in which the first clamp element 73 is configured by using an N-type MOS transistor configured in a diode connection. Fig.15 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 4.

[0136] In the light receiving device 30 according to Example 4, in the clamping circuit 70 including the resistance element 71, the first clamping element 72, and the second clamping element 73, the first clamping element 72 includes an N-type MOS transistor. The N-type MOS transistor is connected between the other end (output end) of the resistance element 71 and a reference potential node (for example, ground), and has a diode connection configuration in which a gate electrode and a drain electrode are commonly connected.

[0137] As described above, in the light receiving device 30 according to Example 4, the N-type MOS transistor in the diode connection configuration is used as the first clamping element 72 included in the clamping circuit 70, instead of the clamping diode of Example 1. Therefore, even if the N-type MOS transistor in the diode connection configuration is used as the configuration of the first clamping element 72, it is possible to obtain an action and effect similar to that in the case of Example 1, that is, when the SPAD element 51 is irradiated with a large amount of light not less than a predetermined amount of light and an overvoltage occurs, circuit elements such as the readout circuit 56 at a later stage can be protected from the overvoltage.

[0138] [Example 5]

[0139] Example 5 is a modification of Example 1, and is an example in which the first clamp element 73 is configured by using a P-type MOS transistor configured in a diode connection. Fig.16 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 5 is shown.

[0140] In the light receiving device 30 according to Example 5, in the clamping circuit 70 including the resistance element 71, the first clamping element 72, and the second clamping element 73, the first clamping element 72 includes a P-type MOS transistor. The P-type MOS transistor is connected between the other end (output end) of the resistance element 71 and a reference potential node (for example, ground), and has a diode connection configuration in which a gate electrode and a source electrode are commonly connected.

[0141] As described above, in the light receiving device 30 according to Example 5, the P-type MOS transistor in the diode connection configuration is used as the first clamping element 72 included in the clamping circuit 70, instead of the clamping diode of Example 1. Therefore, even if the P-type MOS transistor in the diode connection configuration is used as the configuration of the first clamping element 72, it is possible to obtain an action and effect similar to that in the case of Example 1, that is, when the SPAD element 51 is irradiated with a large amount of light not less than a predetermined amount of light and an overvoltage occurs, circuit elements such as the readout circuit 56 at a later stage can be protected from the overvoltage.

[0142] [Example 6]

[0143] 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 resistance element is provided between the gate and the drain of the P-type MOS transistor. Fig.17 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 6 is shown.

[0144] In the light receiving device 30 according to Example 6, in the clamping circuit 70 including the resistance element 71, the first clamping element 72, and the second clamping element 73, the first clamping element 72 includes the second resistance element 74 connected in series with the resistance element 71 and a P-type MOS transistor connected between the output terminal of the second resistance element 74 and a reference potential node (for example, ground). In the P-type MOS transistor, the gate electrode is connected to the common connection node between the resistance element 71 and the second resistance element 74.

[0145] As described above, in the light receiving device 30 according to Example 6, the second resistance element 74 is connected in series to the resistance element 71, and the gate electrode of the P-type MOS transistor is connected to the common connection node between the resistance element 71 and the second resistance element 74. With this configuration, since the P-type MOS transistor can be completely turned into a conductive state (on-state), the voltage of the common connection node between the source electrode of the P-type MOS transistor and the output end of the second resistance element 74 does not become a negative voltage. Therefore, in the case of Example 6, the second clamping element 73 can be omitted.

[0146] [Example 7]

[0147] Example 7 is an example of a forward bias configuration, and is an example in which the protection circuit 60 includes a clamp circuit. Fig.18 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 7 is shown.

[0148] The light receiving device 30 according to Example 7 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 a clamp circuit 70 that clamps an overvoltage to a certain voltage is used as the protection circuit 60. That is, the light receiving device 30 of Example 7 according to the positive bias configuration has a circuit configuration corresponding to the light receiving device 30 of Example 1 according to the negative bias configuration.

[0149] like Fig.18 As shown, the clamping circuit 70 includes a resistor element 71, a first clamping element 72, and a second clamping element 73. One end of the resistor element 71 is connected to the anode electrode of the SPAD element 51. For example, the first clamping element 72 includes a clamping diode, and the anode electrode is connected to the other end (output end) of the resistor element 71, and the cathode electrode is connected to the power supply voltage V DD The second clamping element 73 includes, for example, an N-type MOS transistor, and is connected between the first clamping element 72 and the node N, and the gate electrode is connected to the power supply voltage V DD Node.

[0150] By using the light receiving device 30 according to Example 7 of the above configuration, even in a case where the SPAD element 51 is irradiated with a large amount of light not less than a predetermined amount of light and an overvoltage occurs, the readout circuit 56 in a later stage 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 included in the readout circuit 56 can be protected. p and N-type MOS transistor Q n And the first control transistor 52 and the second control transistor 55 are protected from overvoltage.

[0151] [Example 8]

[0152] Example 8 is a modified example of Example 7, and is an example in which the second clamping element is omitted. Fig.19 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 8 is shown.

[0153] In the light receiving device 30 according to Example 8, the clamp circuit 70 includes a resistance element 71 and a first clamp element 72. That is, the light receiving device 30 according to Example 8 has a configuration in which the second clamp element 73 serving as a constituent element of the clamp circuit 70 in Example 7 is omitted, and has a circuit configuration corresponding to the light receiving device 30 of Example 2 according to the negative bias configuration. Therefore, by using the light receiving device 30 according to Example 8, actions and effects substantially similar to those in the case of the light receiving device 30 according to Example 2 can be obtained.

[0154] [Example 9]

[0155] Example 9 is an example of a forward bias configuration, and is an example in which the protection circuit 60 includes a resistance element. Fig. 20 A circuit diagram showing a configuration example of a light receiving device 30 according to Example 9 is shown.

[0156] In the light receiving device 30 according to Example 9, the protection circuit 60 includes a resistance element 71 connected between the SPAD element 51 and the input terminal (i.e., node N) of the readout circuit 56. That is, the light receiving device 30 according to Example 3 has a configuration in which the first clamp element 72 and the second clamp element 73 serving as constituent elements of the clamp circuit 70 in Example 1 are omitted, and has a circuit configuration corresponding to the light receiving device 30 of Example 3 according to the negative bias configuration. Therefore, by using the light receiving device 30 according to Example 9, actions and effects substantially similar to those in the case of the light receiving device 30 according to Example 3 can be obtained.

[0157] <Modification>

[0158] In the above, the technology according to the present disclosure is described based on the preferred embodiment; however, the technology according to the present disclosure is not limited to the embodiment. The configuration and structure of the light receiving device and the distance measuring device described in the above embodiment are examples, and the light receiving device and the distance measuring device can be appropriately changed.

[0159] For example, also in the light receiving device 30 according to Example 7 of the positive bias configuration, the first clamping element 72 may have a configuration similar to that of the light receiving device 30 according to any one of Examples 4 to 6 of the negative bias configuration. That is, the first clamping element 72 may have a configuration using a MOS transistor in a diode connection configuration, or a configuration including a combination of a second resistance element and a MOS transistor.

[0160] <Application Examples of Technology According to the Present Disclosure>

[0161] The technology according to the present disclosure can be applied to various products. In the following, more specific application examples will be described. For example, the technology according to the present disclosure can be implemented as a distance measuring device installed on any type of mobile body (such as a car, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, a construction machine, and an agricultural machine (tractor)).

[0162] [Mobile body]

[0163] Fig.21 7000 is a block diagram showing an example of a schematic configuration of a vehicle control system 7000 as an example of a mobile body control system to which the technology according to the embodiment of the present disclosure can be applied. The vehicle control system 7000 includes a plurality of electronic control units connected to each other via a communication network 7010. Fig.21 In the example described in , the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an external information detection unit 7400, an internal information detection unit 7500, and an integrated control unit 7600. For example, the communication network 7010 connecting the plurality of control units to each other may be an in-vehicle communication network conforming to any standard, such as a controller area network (CAN), a local interconnect network (LIN), a local area network (LAN), FlexRay (registered trademark), and the like.

[0164] Each control unit includes: a microcomputer that performs calculations according to various programs; a storage unit that stores programs executed by the microcomputer, parameters for various operations, etc.; and a drive circuit that drives various control object devices. Each control unit also includes: a network interface (I / F) for communicating with other control units via the communication network 7010; and a communication I / F for communicating with devices, sensors, etc. inside and outside the vehicle through wired communication or radio communication. Fig.21 The functional configuration of the integrated control unit 7600 shown includes a microcomputer 7610, a general communication I / F 7620, a dedicated communication I / F 7630, a positioning section 7640, a beacon receiving section 7650, an in-vehicle device I / F 7660, a sound / image output section 7670, an in-vehicle network I / F 7680, and a storage section 7690. Other control units similarly include a microcomputer, a communication I / F, a storage section, and the like.

[0165] The drive system control unit 7100 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 7100 is used as a control device for a drive force generating device (such as an internal combustion engine, a drive motor, etc.) for generating the drive force of the vehicle, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating the braking force of the vehicle, etc. The drive system control unit 7100 may have a function as a control device for an anti-lock braking system (ABS), an electronic stability control (ESC), etc.

[0166] The drive system control unit 7100 is connected to the vehicle state detection unit 7110. The vehicle state detection unit 7110 includes, for example, a gyro sensor for detecting the angular velocity of the axial rotational motion of the vehicle body, an acceleration sensor for detecting the acceleration of the vehicle, and at least one of a sensor for detecting the amount of operation of the accelerator pedal, the amount of operation of the brake pedal, the steering angle of the steering wheel, the engine speed, or the speed of the wheels. The drive system control unit 7100 performs calculation processing using the signal input from the vehicle state detection unit 7110 to control the internal combustion engine, the drive motor, the electric power steering device, the brake device, and the like.

[0167] The body system control unit 7200 controls the operation of various devices provided in the body according to various programs. For example, the body system control unit 7200 is used as a control device for a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a backup light, a brake light, a turn signal, a fog light, etc. In this case, a radio wave emitted from a mobile device may be input to the body system control unit 7200 as a substitute for a signal of a key or various switches. The body system control unit 7200 receives these input radio waves or signals and controls a door lock device, a power window device, lights, etc. of the vehicle.

[0168] The battery control unit 7300 controls the secondary battery 7310 as a power source for driving the motor according to various programs. For example, information about the battery temperature, the battery output voltage, the amount of charge remaining in the battery, etc. is supplied to the battery control unit 7300 from the battery device including the secondary battery 7310. The battery control unit 7300 performs arithmetic operation processing using these signals, and performs control for adjusting the temperature of the secondary battery 7310 or controls a cooling device provided to the battery device, etc.

[0169] The vehicle exterior information detection unit 7400 detects information outside the vehicle including the vehicle control system 7000. For example, the vehicle exterior information detection unit 7400 is connected to at least one of the imaging unit 7410 and the vehicle exterior information detection unit 7420. The imaging unit 7410 includes at least one of a time-of-flight (ToF) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. For example, the vehicle exterior information detection unit 7420 includes at least one of an environmental sensor for detecting current atmospheric conditions or weather conditions and a peripheral information detection sensor for detecting other vehicles, obstacles, pedestrians, etc., in the periphery of the vehicle including the vehicle control system 7000.

[0170] For example, the environmental sensor may be at least one of a raindrop sensor for detecting rain, a fog sensor for detecting fog, a sunlight sensor for detecting the degree of sunlight, and a snow sensor for detecting snowfall. The peripheral information detection sensor may be at least one of an ultrasonic sensor, a radar device, and a LIDAR device (a light detection and ranging device, or a laser imaging detection and ranging device). Each of the imaging portion 7410 and the vehicle exterior information detection unit 7420 may be provided as an independent sensor or device, or may be provided as a device in which a plurality of sensors or devices are integrated.

[0171] Here, Fig. 22An example of the installation position of the imaging section 7410 and the vehicle exterior information detection unit 7420 is described. The imaging sections 7910, 7912, 7914, 7916, and 7918 are, for example, provided at least one of the positions on the front nose, side mirrors, rear bumper, and rear door of the vehicle 7900 and the position on the upper part of the windshield in the vehicle interior. The imaging section 7910 provided at the front nose and the imaging section 7918 provided at the upper part of the windshield in the vehicle interior mainly obtain an image in front of the vehicle 7900. The imaging sections 7912 and 7914 provided at the side mirrors mainly obtain an image of the side of the vehicle 7900. The imaging section 7916 provided at the rear bumper or rear door mainly obtains an image of the rear of the vehicle 7900. The imaging section 7918 provided at the upper part of the windshield in the vehicle interior is mainly used to detect a front vehicle, pedestrians, obstacles, signals, traffic signs, lanes, etc.

[0172] By the way, Fig. 22 An example of the imaging range of each imaging unit 7910, 7912, 7914, and 7916 is described. Imaging range a represents the imaging range of the imaging unit 7910 set to the front nose. Imaging ranges b and c respectively represent the imaging ranges of the imaging units 7912 and 7914 set to the side mirrors. Imaging range d represents the imaging range of the imaging unit 7916 set to the rear bumper or the rear door. For example, by superimposing image data imaged by the imaging units 7910, 7912, 7914, and 7916, a bird's-eye view image of the vehicle 7900 viewed from above can be obtained.

[0173] The vehicle exterior information detection units 7920, 7922, 7924, 7926, 7928, 7930 provided at the front, rear, side, corners, and upper portion of the windshield inside the vehicle 7900 may also be, for example, ultrasonic sensors or radar devices. The vehicle exterior information detection units 7920, 7926, 7930 provided at the front nose, rear bumper, rear door of the vehicle 7900, and upper portion of the windshield inside the vehicle may also be, for example, LIDAR devices. These vehicle exterior information detection units 7920 to 7930 are mainly used to detect vehicles ahead, pedestrians, obstacles, and the like.

[0174] return Fig.21, will continue to describe. The vehicle exterior information detection unit 7400 enables the imaging unit 7410 to image the image outside the vehicle and receive the image data of the image. In addition, the vehicle exterior information detection unit 7400 receives detection information from the vehicle exterior information detection unit 7420 connected to the vehicle exterior information detection unit 7400. In the case where the vehicle exterior information detection unit 7420 is an ultrasonic sensor, a radar device, or a LIDAR device, the vehicle exterior information detection unit 7400 sends ultrasonic waves, electromagnetic waves, etc., and receives information of the received reflected waves. Based on the received information, the vehicle exterior information detection unit 7400 can perform processing for detecting objects such as humans, vehicles, obstacles, signs, and text on the road surface, or processing for detecting the distance between the objects. In addition, the vehicle exterior information detection unit 7400 can also perform environmental recognition processing for identifying rainfall, fog, road conditions, etc. based on the received information. The vehicle exterior information detection unit 7400 can calculate the distance to objects outside the vehicle based on the received information.

[0175] In addition, the vehicle exterior information detection unit 7400 can perform image recognition processing to identify humans, vehicles, obstacles, signs, text on the road surface, etc., or detect the distance thereto based on the received image data. The vehicle exterior information detection unit 7400 can perform processing such as distortion correction, alignment, etc. on the received image data, and combine the image data imaged by multiple different imaging units 7410 to generate a bird's-eye view image or a panoramic image. The vehicle exterior information detection unit 7400 can perform viewpoint transformation processing using the image data captured by the imaging unit 7410, which includes different imaging units.

[0176] The vehicle-mounted information detection unit 7500 detects information about the interior of the vehicle. For example, the vehicle-mounted information detection unit 7500 is connected to a driver state detection unit 7510 that detects the state of the driver. The driver state detection unit 7510 may include a camera that images the driver, a biosensor that detects the driver's biometric information, a microphone that collects sounds inside the vehicle, and the like. The biosensor is, for example, arranged in a seat surface, a steering wheel, and the like, and detects biometric information of a passenger sitting on the seat or a driver holding the steering wheel. Based on the detection information input from the driver state detection unit 7510, the vehicle-mounted information detection unit 7500 can calculate the driver's fatigue or the driver's concentration, or can determine whether the driver is dozing off. The vehicle-mounted information detection unit 7500 may subject the audio signal obtained by collecting the sound to processing such as noise elimination processing.

[0177] The integrated control unit 7600 controls the overall operation within the vehicle control system 7000 according to various programs. The integrated control unit 7600 is connected to the input unit 7800. The input unit 7800 is implemented by a device such as a touch panel, a button, a microphone, a switch, a joystick, etc. that can be input by the occupant. The integrated control unit 7600 can be supplied with data obtained by voice recognition of the voice input through the microphone. The input unit 7800 can be, for example, a remote control device using infrared or other radio waves, or an external connection device that supports the operation of the vehicle control system 7000, such as a mobile phone, a personal digital assistant (PDA), etc. The input unit 7800 can be, for example, a camera. In this case, the occupant can input information through gestures. Alternatively, data obtained by detecting the movement of a wearable device worn by the occupant can be input. In addition, the input unit 7800 can include, for example, an input control circuit, etc., which generates an input signal based on the information input by the occupant, etc. using the above-mentioned input unit 7800, and outputs the generated input signal to the integrated control unit 7600. The occupants and the like input various data or instruct processing operations to the vehicle control system 7000 by operating the input unit 7800 .

[0178] The storage unit 7690 may include a read-only memory (ROM) storing various programs executed by the microcomputer and a random access memory (RAM) storing various parameters, operation results, sensor values, etc. In addition, the storage unit 7690 may be implemented by a magnetic storage device such as a hard disk drive (HDD), a semiconductor storage device, an optical storage device, a magneto-optical storage device, etc.

[0179] The general communication I / F 7620 is a widely used communication I / F that relays communication with various devices existing in the external environment 7750. The general communication I / F 7620 can implement a cellular communication protocol such as Global System for Mobile Communications (GSM (registered trademark)), WiMAX, Long Term Evolution (LTE), LTE-Advanced (LTE-A), etc., or another wireless communication protocol such as a wireless LAN (also known as Wireless Fidelity (Wi-Fi (registered trademark)), Bluetooth (registered trademark), etc. For example, the general communication I / F 7620 can be connected to a device (e.g., an application server or a control server) existing on an external network (e.g., the Internet, a cloud network, or a company-specific network) via a base station or an access point. In addition, for example, the general communication I / F 7620 can be connected to a terminal existing near the vehicle (the terminal is, for example, a driver's terminal, a pedestrian or a store, or a machine type communication (MTC) terminal) using a peer-to-peer (P2P) technology.

[0180] The dedicated communication I / F 7630 is a communication I / F that supports the development of a communication protocol for use in a vehicle. The dedicated communication I / F 7630 may implement a standard protocol such as Wireless Access in Vehicular Environments (WAVE) (which is a combination of Institute of Electrical and Electronics Engineers (IEEE) 802.11p as a lower layer and IEEE 1609 as a higher layer), Dedicated Short Range Communication (DSRC), or a cellular communication protocol. The dedicated communication I / F 7630 generally performs V2X communication as a concept including one or more of the following: communication between vehicles and vehicles (vehicle to vehicle), communication between roads and vehicles (vehicle to infrastructure), communication between vehicles and homes (vehicle to home), and communication between pedestrians and vehicles (vehicle to pedestrians).

[0181] The positioning unit 7640 performs positioning, for example, by receiving a global navigation satellite system (GNSS) signal (e.g., a GPS signal from a global positioning system (GPS) satellite) from a GNSS satellite, and generates position information including the latitude, longitude, and altitude of the vehicle. Incidentally, 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, a personal handyphone system (PHS), or a smart phone having a positioning function.

[0182] For example, the beacon receiving section 7650 receives radio waves or electromagnetic waves emitted from a radio station installed on a road or the like, and thereby obtains information on the current position, congestion, closed roads, necessary time, etc. Incidentally, the function of the beacon receiving section 7650 may be included in the above-mentioned dedicated communication I / F 7630.

[0183] The vehicle-mounted device I / F 7660 is a communication interface for relaying the connection between the microcomputer 7610 and various vehicle-mounted devices 7760 present in the vehicle. The vehicle-mounted device I / F 7660 can establish a wireless connection using a wireless communication protocol such as wireless LAN, Bluetooth (registered trademark), near field communication (NFC), or wireless universal serial bus (WUSB). In addition, the vehicle-mounted device I / F 7660 can establish a wired connection via a universal serial bus (USB), a high-definition multimedia interface (HDMI (registered trademark)), a mobile high-definition link (MHL), etc. via a connection terminal (and a cable, if necessary) not shown in the figure. The vehicle-mounted device 7760 may, for example, include at least one of a mobile device and a wearable device owned by an occupant and an information device carried or attached to the vehicle. The vehicle-mounted device 7760 may also include a navigation device that searches for a path to an arbitrary destination. The vehicle-mounted device I / F 7660 exchanges control signals or data signals with these vehicle-mounted devices 7760.

[0184] The in-vehicle network I / F 7680 is an interface that relays communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network I / F 7680 transmits and receives signals and the like according to a predetermined protocol supported by the communication network 7010.

[0185] The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 according to various programs based on information obtained via at least one of the general communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the vehicle-mounted device I / F 7660, and the vehicle-mounted network I / F 7680. For example, the microcomputer 7610 may calculate a control target value of a driving force generation device, a steering mechanism, or a braking device based on the obtained information about the inside and outside of the vehicle, and output a control command to the drive system control unit 7100. For example, the microcomputer 7610 may perform cooperative control aimed at realizing functions of an advanced driver assistance system (ADAS), including collision prevention or shock absorption for a vehicle, follow-up driving based on a following distance, vehicle speed maintenance for driving, warning of a vehicle collision, warning of a vehicle leaving a lane, and the like. In addition, microcomputer 7610 can perform cooperative control intended for autonomous driving by controlling a drive force generating device, a steering mechanism, a braking device, etc. based on information obtained about the vehicle's surroundings, thereby enabling the vehicle to travel automatically without relying on the driver's operation, etc.

[0186] The microcomputer 7610 may generate three-dimensional distance information between the vehicle and objects such as surrounding structures, people, etc., based on information obtained via at least one of the general communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the vehicle-mounted device I / F 7660, and the vehicle-mounted network I / F 7680, and generate local map information including information about the surroundings of the current position of the vehicle. In addition, the microcomputer 7610 may predict dangers such as collision of the vehicle, approach of pedestrians, etc., entering a closed road, etc., based on the obtained information, and generate a warning signal. The warning signal may be, for example, a signal for generating a warning sound or lighting a warning lamp.

[0187] The sound / image output unit 7670 sends an output signal of at least one of sound and image to an output device, which can visually or auditorily notify the occupants of the vehicle or the outside of the vehicle of information. Fig.21In the example, the audio speaker 7710, the display unit 7720, and the instrument panel 7730 are shown as output devices. For example, the display unit 7720 may include at least one of an in-vehicle display and a head-up display. The display unit 7720 may have an augmented reality (AR) display function. The output device may be different from these devices and may be another device such as headphones, a wearable device such as a glasses-type display worn by a passenger or the like, a projector, a lamp, or the like. In the case where the output device is a display device, the display device visually displays, in various forms such as text, image, table, graph, etc., the results obtained through various processes executed by the microcomputer 7610 or the information received from another control unit. Further, in the case where the output device is an audio output device, the audio output device converts an audio signal composed of reproduced audio data, sound data, or the like into an analog signal and outputs the analog signal auditorily.

[0188] Incidentally, in Fig.21 the example described, at least two control units connected to each other via the communication network 7010 may be integrated into one control unit. Alternatively, each individual control unit may include a plurality of control units. Further, the vehicle control system 7000 may include another control unit not shown in the figure. Additionally, part or all of the functions executed by one of the control units in the above description may be assigned to another control unit. That is, as long as information is transmitted and received via the communication network 7010, predetermined arithmetic processing may be executed by any control unit. Similarly, a sensor or device connected to one of the control units may be connected to another control unit, and the plurality of control units may transmit and receive detection information to and from each other via the communication network 7010.

[0189] Above, an example of a vehicle control system to which the technology according to the present disclosure can be applied has been described. Among the above components, for example, in the case where the imaging unit 7410 or the out-of-vehicle information detection unit 7420 includes a ToF camera (ToF sensor), the light receiving device in any of the above embodiments of the technology according to the present disclosure can be used as a ToF camera. By installing a ToF camera that uses the light receiving device as a distance measuring device, for example, when irradiating the light receiving element with not less than a predetermined amount of light and an overvoltage is generated in the light receiving element, element damage caused by the overvoltage can be prevented, and a highly reliable vehicle control system can be configured.

[0190] <Configurations that the present disclosure can adopt>

[0191] It should be noted that the present disclosure may have the following configurations.

[0192] <<A. Light receiving device>>

[0193] [A-1] A light receiving device, comprising:

[0194] a light receiving element that generates a signal in response to receiving a photon;

[0195] a readout circuit that reads out a signal generated by the light receiving element; and

[0196] The protection circuit is provided between the light receiving element and the input terminal of the readout circuit and protects the circuit elements of the readout circuit from an overvoltage.

[0197] [A-2] The light receiving device according to [A-1], wherein

[0198] The protection circuit includes a clamping circuit for clamping the overvoltage to a certain voltage.

[0199] [A-3] The light receiving device according to [A-2], wherein:

[0200] The clamping circuit includes:

[0201] a resistor element having one end connected to the light receiving element; and

[0202] The first clamping element is connected between the other end of the resistance element and the reference potential node.

[0203] [A-4] The light receiving device according to [A-3], wherein:

[0204] The first clamping element includes a clamping diode in which a cathode electrode is connected to the other end of the resistance element and an anode electrode is connected to a reference potential node.

[0205] [A-5] The light receiving device according to [A-3] or [A-4], wherein

[0206] The clamping circuit includes a second clamping element arranged between the first clamping element and the input terminal of the readout circuit.

[0207] [A-6] The light receiving device according to [A-5], wherein:

[0208] The second clamping element includes a MOS transistor connected between the first clamping element and an input terminal of the readout circuit, and wherein a gate electrode of the MOS transistor is connected to a reference potential node.

[0209] [A-7] The light receiving device according to [A-5] or [A-6],

[0210] a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked,

[0211] wherein the light receiving element is arranged on the first semiconductor substrate, and

[0212] The resistance element, the first clamping element, and the second clamping element are arranged on the second semiconductor substrate.

[0213] [A-8] The light receiving device according to [A-5] or [A-6],

[0214] a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked,

[0215] wherein the light receiving element and the resistance element are arranged on the first semiconductor substrate, and

[0216] The first clamping element and the second clamping element are disposed on the second semiconductor substrate.

[0217] [A-9] The light receiving device according to [A-5] or [A-6],

[0218] a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked,

[0219] wherein the light receiving element is arranged on the first semiconductor substrate, and

[0220] The resistance element, the first clamping element, and the second clamping element are arranged on the second semiconductor substrate.

[0221] [A-10] The light receiving device according to [A-1], wherein

[0222] The protection circuit includes a resistance element connected between the light receiving element and an input terminal of the readout circuit.

[0223] [A-11] The optical receiving device according to [A-10], further comprising:

[0224] N-type MOS transistor, the N-type MOS transistor is connected between the input terminal of the readout circuit and the reference potential node,

[0225] Here, the resistance element included in the protection circuit forms a clamping circuit together with the body diode existing in the N-type MOS transistor.

[0226] [A-12] The light receiving device according to [A-3], wherein:

[0227] The first clamping element includes a MOS transistor in a diode-connected configuration.

[0228] [A-13] The light receiving device according to [A-3], wherein

[0229] The first clamping element comprises:

[0230] A second resistor element connected in series with a resistor element; and

[0231] A P-type MOS transistor connected between the output terminal of the second resistor element and a reference potential node, and

[0232] The gate electrode of the P-type MOS transistor is connected to a common connection node between the resistor element and the second resistor element.

[0233] [A-14] The optical receiving device according to any one of [A-1] to [A-13], wherein

[0234] The readout circuit includes a CMOS inverter circuit.

[0235] [A-15] The optical receiving device according to any one of [A-1] to [A-14], wherein

[0236] The optical receiving element is an element used under a voltage not less than the breakdown voltage.

[0237] [A-16] The optical receiving device according to [A-15], wherein

[0238] The optical receiving element includes an avalanche photodiode operating in Geiger mode.

[0239] [A-17] The optical receiving device according to [A-16], wherein

[0240] The optical receiving element includes a single-photon avalanche diode.

[0241] [A-18] The optical receiving device according to [A-17], wherein

[0242] The single-photon avalanche diode is used by applying a negative bias voltage to the anode electrode.

[0243] [A-19] The optical receiving device according to [A-17], wherein

[0244] The single-photon avalanche diode is used by applying a positive bias voltage to the cathode electrode.

[0245] <<B. Distance Measuring Device>>

[0246] [B-1] A distance measuring device, comprising:

[0247] A light source unit that irradiates light to a distance measurement target; and

[0248] An optical receiving device that receives reflected light from the distance measurement target based on the irradiated light from the light source unit,

[0249] wherein the optical receiving device includes:

[0250] a light receiving element that generates a signal in response to receiving a photon;

[0251] a readout circuit that reads out a signal generated by the light receiving element; and

[0252] The protection circuit is provided between the light receiving element and the readout circuit and protects the circuit elements of the readout circuit from an overvoltage.

[0253] [B-2] The distance measuring device according to [B-1], wherein:

[0254] The protection circuit includes a clamping circuit for clamping the overvoltage to a certain voltage.

[0255] [B-3] The distance measuring device according to [B-2], wherein:

[0256] The clamping circuit includes:

[0257] a resistor element having one end connected to the light receiving element; and

[0258] The first clamping element is connected between the other end of the resistance element and the reference potential node.

[0259] [B-4] The distance measuring device according to [B-3], wherein:

[0260] The first clamping element includes a clamping diode in which a cathode electrode is connected to the other end of the resistance element and an anode electrode is connected to a reference potential node.

[0261] [B-5] The distance measuring device according to [B-3] or [B-4], wherein:

[0262] The clamping circuit includes:

[0263] The second clamping element is arranged between the first clamping element and the input terminal of the readout circuit.

[0264] [B-6] The distance measuring device according to [B-5], wherein:

[0265] The second clamping element includes a MOS transistor connected between the first clamping element and an input terminal of the readout circuit, and wherein a gate electrode of the MOS transistor is connected to a reference potential node.

[0266] [B-7] The distance measuring device according to [B-5] or [B-6],

[0267] a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked,

[0268] wherein the light receiving element is arranged on the first semiconductor substrate, and

[0269] The resistance element, the first clamping element, and the second clamping element are arranged on the second semiconductor substrate.

[0270] [B-8] The distance measuring device according to [B-5] or [B-6],

[0271] a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked,

[0272] wherein the light receiving element and the resistance element are arranged on the first semiconductor substrate, and

[0273] The first clamping element and the second clamping element are disposed on the second semiconductor substrate.

[0274] [B-9] The distance measuring device according to [B-5] or [B-6],

[0275] a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked,

[0276] wherein the light receiving element is arranged on the first semiconductor substrate, and

[0277] The resistance element, the first clamping element, and the second clamping element are arranged on the second semiconductor substrate.

[0278] [B-10] The distance measuring device according to [B-1], wherein:

[0279] The protection circuit includes a resistance element connected between the light receiving element and an input terminal of the readout circuit.

[0280] [B-11] The distance measuring device according to [B-10], further comprising:

[0281] N-type MOS transistor, the N-type MOS transistor is connected between the input terminal of the readout circuit and the reference potential node,

[0282] Here, the resistance element included in the protection circuit forms a clamping circuit together with the body diode existing in the N-type MOS transistor.

[0283] [B-12] The distance measuring device according to [B-3], wherein:

[0284] The first clamping element includes a MOS transistor in a diode-connected configuration.

[0285] [B-13] The distance measuring device according to [B-3], wherein:

[0286] The first clamping element comprises:

[0287] a second resistive element connected in series with the resistive element; and

[0288] A P-type MOS transistor connected between the output terminal of the second resistor element and the reference potential node, and

[0289] A gate electrode of the P-type MOS transistor is connected to a common connection node between the resistance element and the second resistance element.

[0290] [B-14] The distance measuring device according to any one of [B-1] to [B-13], wherein:

[0291] The readout circuit includes a CMOS inverter circuit.

[0292] [B-15] The distance measuring device according to any one of [B-1] to [B-14], wherein:

[0293] The light receiving element is an element used under application of a voltage not less than a breakdown voltage.

[0294] [B-16] The distance measuring device according to [B-15], wherein:

[0295] The light receiving element includes an avalanche photodiode operating in a Geiger mode.

[0296] [B-17] The distance measuring device according to [B-16], wherein:

[0297] The light receiving element includes a single photon avalanche diode.

[0298] [B-18] The distance measuring device according to [B-17], wherein:

[0299] A single photon avalanche diode is used by applying a negative bias voltage to the anode.

[0300] [B-19] The distance measuring device according to [B-17], wherein:

[0301] A single photon avalanche diode is used by applying a positive bias voltage to the cathode electrode.

[0302] Reference numerals list

[0303] 1 Distance measuring device

[0304] 10 Test object

[0305] 20 Light source

[0306] 21 Laser drive unit

[0307] 22 Laser light source

[0308] 23. Diffuser lens

[0309] 30 Light receiving device

[0310] 31 Light receiving lens

[0311] 32 Optical Sensors

[0312] 33 Signal Processing Unit

[0313] 40 Control Department

[0314] 50 pixels

[0315] 51 SPAD element

[0316] 56 Readout circuit

[0317] 57 Time measurement unit (TDC)

[0318] 60 Protection circuit

[0319] 70 Clamp Circuit

Claims

1. A light receiving device, comprising: a light receiving element that generates a signal in response to receiving a photon; a readout circuit that reads out a signal generated by the light receiving element; as well as a protection circuit disposed between the light receiving element and the input terminal of the readout circuit and protecting the circuit elements of the readout circuit from negative overvoltage occurring at the light receiving element, wherein: The protection circuit includes a clamping circuit for clamping the overvoltage to a certain positive voltage. The clamping circuit comprises: a resistance element having one end connected to the light receiving element; and a first clamping element connected between the other end of the resistance element and a reference potential node to perform a first clamping operation of clamping the overvoltage occurring in the light receiving element to a negative voltage, The second clamping element is provided between the first clamping element and the input terminal of the readout circuit to perform a second clamping operation on the negative voltage to clamp the negative voltage to the certain positive voltage.

2. The light receiving device according to claim 1, wherein: The first clamping element includes a clamping diode having a cathode electrode connected to the other end of the resistance element and an anode electrode connected to the reference potential node.

3. The light receiving device according to claim 1, wherein The second clamping element includes a MOS transistor connected between the first clamping element and the input terminal of the readout circuit, and wherein a gate electrode of the MOS transistor is connected to the reference potential node.

4. The light receiving device according to claim 1, a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked, in, The light receiving element is arranged on the first semiconductor substrate, and the resistance element, the first clamping element, and the second clamping element are arranged on the second semiconductor substrate.

5. The light receiving device according to claim 1, a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked, in, The light receiving element and the resistance element are arranged on the first semiconductor substrate, and The first clamping element and the second clamping element are arranged on the second semiconductor substrate.

6. The light receiving device according to claim 1, a stacked chip structure having at least two semiconductor substrates in which a first semiconductor substrate and a second semiconductor substrate are stacked, in, The light receiving element, the resistance element, and the first clamping element are arranged on the first semiconductor substrate, and The second clamping element is disposed on the second semiconductor substrate.

7. The light receiving device according to claim 1, wherein: The first clamping element includes a MOS transistor in a diode-connected configuration.

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

9. The light receiving device according to claim 1, wherein: The readout circuit includes a CMOS inverter circuit.

10. The light receiving device according to claim 1, wherein The light receiving element is an element used under application of a voltage not less than a breakdown voltage.

11. The light receiving device according to claim 10, wherein: The light receiving element includes an avalanche photodiode operating in a Geiger mode.

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

13. The light receiving device according to claim 12, wherein: The single photon avalanche diode is used by applying a negative bias voltage to the anode electrode.

14. The light receiving device according to claim 12, wherein: The single photon avalanche diode is used by applying a positive bias voltage to a cathode electrode.

15. A distance measuring device, comprising: A light source unit irradiates light to the distance measurement object; as well as a light receiving device for receiving light reflected from the distance measurement object according to the irradiation light from the light source unit, Wherein, the light receiving device comprises: a light receiving element that generates a signal in response to receiving a photon; a readout circuit that reads out a signal generated by the light receiving element; and a protection circuit provided between the light receiving element and the readout circuit and protecting the circuit elements of the readout circuit from a negative overvoltage occurring at the light receiving element, The protection circuit includes a clamping circuit for clamping the overvoltage to a certain positive voltage. The clamping circuit comprises: a resistance element having one end connected to the light receiving element; and a first clamping element connected between the other end of the resistance element and a reference potential node to perform a first clamping operation of clamping the overvoltage occurring in the light receiving element to a negative voltage, The second clamping element is provided between the first clamping element and the input terminal of the readout circuit to perform a second clamping operation on the negative voltage to clamp the negative voltage to the certain positive voltage.

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