Light detection circuit, light detection method, laser radar and storage medium

Abstract

The present application provides a light detection circuit, a light detection method, a laser radar and a storage medium. The light detection circuit includes: a light detection unit array, including: a plurality of light detection units, for receiving light signals and generating corresponding electrical signals; a switch array, including a plurality of first switch units; each first switch unit is respectively coupled to a light detection unit; each first switch unit is configured to control the working state of the coupled light detection unit so that the signal output end of the coupled light detection unit outputs the electrical signal; a selection unit is used to select the light detection unit in the working state to output the electrical signal. By setting the switch state of each first switch unit respectively, the light detection unit that needs to work is selected to be activated, and the light detection unit that does not need to work is set to be unable to be activated, thereby preventing the measurement channel of the laser radar from being affected by crosstalk caused by external interference light, improving detection accuracy, and avoiding unnecessary energy consumption.

Description

Technical Field

[0001] The present application relates to the field of optical ranging, and in particular to a light detection circuit, a light detection method, a laser radar, and a storage medium. Background Art

[0002] LiDAR is a device that detects external objects by emitting laser light and detecting the echo signal returned by the laser reaching the surface of an obstacle.

[0003] As LiDAR accuracy and resolution improve, multiple detection channels are becoming a mainstream development trend. For example, in LiDARs with 32, 64, or 128 lines, each "line" represents a detection channel. A detection channel consists of at least one laser within the LiDAR that emits laser light and at least one photodetector that detects the laser's return signal.

[0004] The following example illustrates the working principle of a light detector.

[0005] like Figure 1A As shown, a schematic diagram of the structure of the connection between the light detector and the voltage amplifier in an example is shown.

[0006] Figure 1A The photodetector 101 can be implemented as a silicon photomultiplier (SiPM) as shown in the figure. The SiPM is formed by connecting multiple single photon avalanche diodes (SPADs) and corresponding quenching resistors in parallel. The SPAD is an avalanche photon diode (APD) operating in Geiger mode. When a voltage higher than the breakdown voltage V of the SPAD is applied to both ends of the SiPM (ends A and B in the figure), the power supply voltage V th When the reverse bias voltage is V, each SPAD is in Geiger Mode (GM) and can detect light signals. bias , the voltage at terminal A is set to V A , V bias Set to V A -V bias >V th , V A -V bias This is the reverse bias voltage that makes the SiPM work.

[0007] Figure 1AThe voltage amplifier shown in FIG is implemented by a charge sensitive amplifier 102A (CSA). The CSA circuit includes: an operational amplifier; and a capacitor C connected between the negative input terminal and the output terminal of the operational amplifier. F The negative input terminal of the operational amplifier is also coupled to the A terminal of the light detector 101, and the positive input terminal of the operational amplifier is coupled to the ground terminal. The current signal output by the light detector 101 passes through the capacitor C F , for capacitor C F The charge is converted into a voltage signal for output. The CSA's conversion speed is relatively slow; and, as can be seen from the difference between the current signal waveform W1 and the converted voltage signal waveform D, the CSA cannot restore the current signal waveform from the converted voltage signal.

[0008] like Figure 1B As shown, a structural schematic diagram showing the connection between a light detector and a voltage amplifier in another example is shown.

[0009] Figure 1B Example compared to Figure 1A The embodiment differs mainly in that the voltage amplifier is implemented by a trans-impedance amplifier 102B (TIA). The trans-impedance amplifier comprises: an operational amplifier; and a resistor R connected between the negative input terminal and the output terminal of the operational amplifier. F . TIA through the resistor R F The current signal output by the photodetector 101 is converted into a voltage signal. The relationship between the current signal and the voltage signal is U=I*R F Therefore, it can be seen from the waveform comparison of the current signal waveform W1 and the voltage signal waveform W2 that the waveform W2 retains the pulse frequency and width information of the waveform W1.

[0010] As the accuracy and resolution of laser radars increase, laser radars usually use an array of light detectors 101 to detect optical signals in multiple detection channels, using a linear or planar array of light detectors, with each light detector array including multiple light detectors. Each light detector 101 in the light detector 101 array can belong to a different detection channel as needed, and at least one light detector 101 belonging to the same detection channel will be activated and work together. As the number of detection channels increases (e.g., 32, 64, 128, etc.), if the detection results of the detection signals of each detection channel are to be obtained in parallel, a signal processing circuit needs to be set up for each detection channel respectively, which is difficult to implement in actual engineering applications. Therefore, a multiplexer (MUX) is usually used to select the detection signal of the light detector 101 of a certain detection channel, and a shared signal processing circuit is used for time-sharing processing to obtain the detection result of this channel.

[0011] like Figure 2 FIG. 1 is a schematic diagram showing a partial structure of a light detection circuit in a light detector array in an example.

[0012] In this example, the photodetector array 202 includes a plurality of photodetectors 221 (such as SiPMs) and a resistor array 201. Each photodetector 221 is located in a different branch connected in parallel. Each resistor 211 in the resistor array 201 is connected in series with a photodetector 221 in a branch. Each branch is connected to a voltage V DD , to form a reverse bias voltage applied to the photodetector 221 array 202 to activate each photodetector 221 therein. The output end of the photodetector 221 in each branch is coupled to an input end of the multiplexer 203 respectively.

[0013] For example, it is assumed that there are n detection channels, each detection channel corresponds to a light detector 221, which is used to detect the echo signal of the detection channel and convert it into an electrical signal (a voltage signal in this example). n The selection signal selects the output end of the light detector 221 of different detection channels and connects it to the output end of the multiplexer 203 to output the electrical signal of the selected detection channel and convert it into a voltage V through the voltage amplifier 204. o The voltage amplifier 204 may be composed of, for example, Figure 1A The CSA in the example, or Figure 1B TIA implementation in the example. Voltage V o It can be input to the subsequent circuit for processing to obtain the detection result of the selected detection channel.

[0014] However, Figure 2 There are many problems with the light detection circuit in .

[0015] To make the description clearer, the detection channels selected for operation are defined as "measurement channels", and the detection channels not selected for operation are defined as "non-measurement channels". Figure 2 As shown in FIG, each photodetector 221 is always in operation. Although the multiplexer 203 has selected the electrical signal output of the measurement channel, the photodetectors 221 in the non-measurement channels are still detecting optical signals and converting them into electrical signals for transmission to the input of the multiplexer 203. On the one hand, the photodetectors 221 in the non-measurement channels are always in operation, which obviously causes unnecessary and large power consumption. On the other hand, since the multiplexer 203 inevitably has parasitic capacitance, the electrical signals output by the photodetectors 221 in the non-measurement channels are interference signals, which will cause crosstalk to the electrical signals in the measurement channel through the parasitic capacitance of the multiplexer 203 (see FIG). Figure 2 As a result, the electrical signal of the echo signal in the measurement channel (see the echo signal waveform W4 in the figure) will produce burrs after passing through the multiplexer 203 (for example, the waveform W5 of the output signal). 51 Especially when the light detector 221 is implemented as SiPM, the interference will be more obvious due to the high gain of SiPM and its strong detection capability for weak light. DD It is designed for a photodetector 221 with a fixed operating voltage and cannot be adapted to photodetectors 221 with different operating voltages.

[0016] from Figure 2 As can be seen, during detection, only the light detectors in a limited number of channels are activated and in the detection state, while the light detectors in the remaining non-measuring channels are in a standby state. While the light detectors in the standby state can still detect light signals, external interference (such as ambient light) will be detected by the light detectors in the standby state, interfering with the normally detecting measurement channels and affecting the detection results. Furthermore, the light detectors in the standby state generate a significant amount of unnecessary power waste. Summary of the Invention

[0017] In view of the shortcomings of the prior art described above, the present application provides a light detection circuit, a light detection method, a laser radar and a storage medium, which can prevent the measurement channel of the laser radar from being affected by crosstalk caused by external interference light, improve detection accuracy, and avoid unnecessary energy consumption.

[0018] To achieve the above-mentioned objectives and other related objectives, the first aspect of the present application provides a light detection circuit for a laser radar, comprising: a light detection unit array, comprising: a plurality of light detection units, for receiving light signals and generating corresponding electrical signals; a switch array, comprising a plurality of first switch units; each first switch unit is respectively coupled to a light detection unit; each first switch unit is configured to control the working state of the coupled light detection unit so that the signal output end of the coupled light detection unit outputs the electrical signal; a selection unit, for selecting the light detection unit in the working state to output the electrical signal.

[0019] In some embodiments of the first aspect, the optical detection circuit includes: a first power supply end, coupled to a power supply; the first switch unit includes: a first switch element, one end of which is coupled to the first power supply end, and the other end is coupled to one end of a light detection unit; the end of the light detection unit coupled to the first switch element is a signal output end; wherein the switching state of the first switch element corresponds to the on-off state of the path between the first power supply end and the signal output end.

[0020] In some embodiments of the first aspect, each of the first switch units further includes: a second switch element, one end of which is coupled to one end of the light detection unit coupled to the first switch element, and the other end of which is coupled to the ground end; wherein the switching state of the second switch element corresponds to the on-off of the path between the signal output end and the ground end.

[0021] In some embodiments of the first aspect, the switching states of the first switching element and the second switching element are set to be opposite.

[0022] In some embodiments of the first aspect, the light detection circuit includes: a power supply adjustment unit, an output end of which is connected to the first power supply end to provide a variable power supply.

[0023] In some embodiments of the first aspect, the power supply is adjusted to output a plurality of voltage values; the plurality of voltage values ​​are respectively adapted to light detection units with different operating voltages.

[0024] In some embodiments of the first aspect, the light detection circuit includes: a level shift unit, whose input terminal is coupled to the output terminal of the selection unit and is configured to convert a voltage output by the selection unit into a preset voltage range.

[0025] In some embodiments of the first aspect, the level shifting unit includes: at least one second switching unit, a first impedance unit and a current source; each second switching unit includes: a first end coupled to the first power supply end, a second end coupled to one end of the first impedance unit and a control end coupled to the output end of the selection unit; the control end is used to control the on and off of the first end and the second end; the other end of the first impedance unit is coupled to one end of the current source, and the other end of the current source is coupled to the ground end.

[0026] In some embodiments of the first aspect, the current source includes: a first current mirror, including: a first branch and a second branch respectively derived from at least a pair of common-gate transistors, whose gates are coupled to the control end of the current source; a second impedance unit is connected in series in the first branch; one end of the first branch and the second branch is coupled to the second power supply end, and the other end of the first branch is grounded via the second impedance unit; the second power supply end and the first power supply end are connected to different voltages; a second current mirror, including: a third branch and a fourth branch respectively derived from at least a pair of common-gate transistors; one end of the third branch is coupled in series to the other end of the second branch, and the other end of the third branch is coupled to the ground end; one end of the fourth branch is coupled to one end of the first impedance unit, and the other end of the fourth branch is grounded, so that the current flowing through the first impedance unit and the second impedance unit has an adjustable proportional value.

[0027] In some embodiments of the first aspect, the fourth branch includes N branches connected in parallel, N≥2, each branch having a transistor connected in series, wherein the transistor of each branch can be selectively connected or disconnected with the transistor in the third branch to adjust the ratio between the current flowing through the first impedance unit and the second impedance unit.

[0028] In some embodiments of the first aspect, the current source includes: a first current mirror, including: at least one first PMOS and at least one second PMOS connected in common gate and source, the gate is coupled to the control end of the current source, and the source is connected to the second power supply end; the drain of the first PMOS is coupled to the ground end through a second impedance unit; wherein the voltage connected to the second power supply end is different from that of the first power supply end; a second current mirror, including: a first NMOS, whose gate and drain are coupled to the drain of the second PMOS, and whose source is coupled to the ground end; at least one second NMOS, connected in common gate with the first NMOS, whose drain is coupled to one end of the first impedance unit, and whose source is coupled to the ground end.

[0029] In some embodiments of the first aspect, there are N second NMOSs, N≥2; the drain of each second MOS is coupled to each other and coupled to one end of the first impedance unit and the source is coupled to the ground end; the gate of each second NMOS is coupled to the gate of the first NMOS via a third switching element, and coupled to the ground end via a fourth switching element.

[0030] In some embodiments of the first aspect, the current source further includes: an operational amplifier, which includes: a negative input terminal, connected to a reference voltage; a positive input terminal, coupled to one end of the second impedance unit to apply the reference voltage; and an output terminal, used as a control terminal of the current source.

[0031] In some embodiments of the first aspect, the second switch unit includes a third NMOS; the control end, the first end, and the second end of the second switch unit are respectively derived from the gate, the drain, and the source of the third NMOS.

[0032] In some embodiments of the first aspect, the first impedance unit includes one of the following: a variable resistor or a plurality of transistors connected in series.

[0033] In some embodiments of the first aspect, there are multiple second switch units connected in parallel.

[0034] In some embodiments of the first aspect, the light detection circuit includes: an integration operation unit, coupled to the output end of the level shift unit, for performing an integration operation based on the received electrical signal to obtain an operation result; and an analog-to-digital conversion unit, coupled to the output end of the integration operation unit, for performing analog-to-digital conversion based on the operation result.

[0035] In some embodiments of the first aspect, the first switch unit further includes: a variable impedance unit connected in series between the first switch element and one end of the light detection unit.

[0036] In some embodiments of the first aspect, the optical detection circuit includes: a first power supply end, coupled to a power supply; the first switching unit also includes: a transimpedance amplifier unit, which includes a first input end, a second input end, and an output end; the first input end of the transimpedance amplifier unit is coupled to the first switching element to the first power supply end, and coupled to the second switching element to the ground end; the second input end of the transimpedance amplifier unit is coupled to one end of the optical detection unit, and is coupled to the output end of the transimpedance amplifier unit via a third impedance unit; and the output end of the transimpedance amplifier unit is coupled to the signal output end.

[0037] To achieve the above-mentioned objectives and other related objectives, the second aspect of the present application provides a light detection method, which is applied to the light detection circuit described in any one of the first aspects. The light detection method includes: transmitting a switch signal to the switch array to set the switch state of some first switch units to drive the light detection units coupled to some of the first switch units to start and detect light signals; and setting the switch state of the remaining first switch units to turn off the light detection units coupled to the remaining first switch units.

[0038] In some embodiments of the second aspect, applying a switch signal to some of the first switch units in the switch array to drive the coupled light detection units to start includes: applying a switch signal to each of the first switch units in the part of the switch array one by one, and driving each light detection unit to start accordingly.

[0039] To achieve the above-mentioned objectives and other related objectives, the third aspect of the present application provides a laser radar, comprising: a light transmitting module, comprising: a light transmitting unit array, configured to output a transmitting signal; a light detecting module, comprising a light detecting circuit as described in any one of the first aspects; wherein the light detecting unit array is configured to receive an echo signal reflected after the transmitting signal encounters an obstacle; a control module, coupled to the light transmitting module and the light detecting module, configured to transmit a switching signal to the switch array to set the switching state of some first switching units to drive the light detecting units coupled to some first switching units to start to detect light signals; and, set the switching state of the remaining first switching units to turn off the light detecting units coupled to the remaining first switching units.

[0040] To achieve the above objectives and other related objectives, the fourth aspect of the present application provides a computer-readable storage medium storing program instructions, which, when executed, execute the light detection method as described in any one of the second aspects.

[0041] In summary, the present application provides a light detection circuit, a light detection method, a laser radar, and a storage medium, wherein the light detection circuit includes: a light detection unit array, including: a plurality of light detection units, for receiving light signals and generating corresponding electrical signals; a switch array, including a plurality of first switch units; each first switch unit is respectively coupled to a light detection unit; each first switch unit is configured to control the working state of the coupled light detection unit so that the signal output end of the coupled light detection unit outputs the electrical signal; and a selection unit is configured to select the light detection unit in the working state to output the electrical signal. By setting the switch state of each first switch unit separately, the light detection units that need to work together can be activated, and the light detection units that do not need to work can be set to be inactivated, which can prevent the measurement channel of the laser radar from being affected by crosstalk caused by external interference light, improve detection accuracy, and avoid unnecessary energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1A A schematic diagram showing the structure of the connection between a light detector and a voltage amplifier in an example is shown.

[0043] Figure 1B A schematic structural diagram showing the connection between a light detector and a voltage amplifier in yet another example is shown.

[0044] Figure 2 A partial structural schematic diagram of a detection circuit of a photodetector array in an example is shown.

[0045] Figure 3 A partial structural schematic diagram of a light detection circuit in one embodiment of the present application is shown.

[0046] Figure 4A A schematic diagram showing the connection structure of a switch array and a light detection unit array in a light detection circuit in one embodiment of the present application is shown.

[0047] Figure 4B A schematic diagram showing the connection structure of a switch array and a light detection unit array in a light detection circuit in another embodiment of the present application is shown.

[0048] Figure 5 A schematic structural diagram of a light detection circuit in another embodiment of the present application is shown.

[0049] Figure 6 A schematic diagram showing the circuit principle of a buck or boost switching power supply in one embodiment of the present application is shown.

[0050] Figure 7 A schematic structural diagram of a light detection circuit in yet another embodiment of the present application is shown.

[0051] Figure 8 A schematic diagram showing the circuit principle of a level shifter in one embodiment of the present application is shown.

[0052] Figures 9A to 9E A schematic diagram showing circuit principles of modified examples of level shifters in multiple embodiments of the present application.

[0053] Figure 10 A schematic structural diagram of a light detection circuit in another embodiment of the present application is shown.

[0054] Figure 11A A schematic diagram showing the circuit principle of the RC integral operation unit in one embodiment of the present application is shown.

[0055] Figure 11B A schematic diagram showing the circuit principle of the Gm-C integral operation unit in one embodiment of the present application is shown.

[0056] Figure 12A schematic structural diagram of a light detection circuit in another specific embodiment of the present application is shown.

[0057] Figure 13 A schematic structural diagram of a laser radar in one embodiment of the present application is shown. DETAILED DESCRIPTION

[0058] The following describes the embodiments of the present application through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and application systems without departing from the spirit of the present application. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other unless they conflict.

[0059] The following is a detailed description of the embodiments of the present application with reference to the accompanying drawings so that those skilled in the art can easily implement the present application. The present application can be embodied in many different forms and is not limited to the embodiments described herein.

[0060] In order to clearly describe the present application, components not related to the description are omitted, and the same or similar components throughout the specification are given the same reference numerals.

[0061] Throughout this specification, when a device is said to be "coupled" or "connected" to another device, this includes not only "direct connection" but also "indirect connection" with other elements interposed therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, this does not exclude the other components but rather means that the device may include the other components.

[0062] When a device is said to be "on" another device, it may be directly on the other device, but there may also be other devices between it. In contrast, when a device is said to be "directly on" another device, there are no other devices between it.

[0063] Although the terms first, second, etc. are used in some instances herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, descriptions of a first interface and a second interface, etc. are provided. Furthermore, as used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms "comprise" and "include" indicate the presence of the described features, steps, operations, elements, components, items, types, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, types, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B, or C" or "A, B, and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B, and C." Exceptions to this definition occur only when the combination of elements, functions, steps, or operations is inherently mutually exclusive in some manner.

[0064] The technical terms used herein are intended only to refer to specific embodiments and are not intended to limit this application. The singular form used herein also includes the plural form unless the statement explicitly indicates otherwise. The term "comprising" as used in this specification is intended to specify specific features, regions, integers, steps, operations, elements, and / or components and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0065] Spatially relative terms such as "below" and "above" may be used to more easily explain the relationship of one device to another in the drawings. These terms refer not only to the device in the drawings but also to other aspects of the device during use or operation. For example, if a device in a drawing is turned over, a device previously described as "below" another device may now be described as "above" the other device. Therefore, the exemplary term "below" encompasses both above and below. A device may be rotated 90° or at other angles, and spatially relative terms should be interpreted accordingly.

[0066] Although not defined differently, all terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art to which this application belongs. Terms defined in commonly used dictionaries are to be interpreted as having meanings consistent with the relevant technical literature and current teachings, and unless otherwise defined, they should not be overly interpreted as ideal or highly formalized meanings.

[0067] Typically, in the signal processing circuit of the detection end of the laser radar, a voltage amplifier is set at the front stage to convert the electrical signal (such as current signal) output by the photoelectric conversion of the light detector into a voltage signal for further processing by the back stage. Figure 2 As shown, during the operation of the photodetector array, the photodetectors in the measurement channels work together, while the photodetectors in the non-measurement channels remain in a "waiting" state. Therefore, the photodetectors in the non-measurement channels introduce external interference, causing crosstalk to the measurement channels. Furthermore, the waiting state of the photodetectors in the non-measurement channels also generates a large amount of unnecessary power consumption.

[0068] In view of this, the present application provides a light detection circuit for a lidar in the following embodiments to solve the problems described above.

[0069] like Figure 3 FIG. 1 is a schematic diagram showing a partial structure of a light detection circuit in an embodiment of the present application.

[0070] exist Figure 3 In the embodiment, a light detection circuit is shown including a light detection unit array 301 , a switch array 302 and a selection unit 303 .

[0071] The light detection unit array 301 includes a plurality of light detection units 311, each of which may include at least one light detector. The light detector may be a SiPM or a SPAD. Each light detection unit 311 is configured to receive a light signal and generate a corresponding electrical signal, such as a current signal.

[0072] The switch array 302 includes a plurality of first switch units 321. Each first switch unit 321 is coupled to a corresponding light detection unit 311. Each first switch unit 321 is configured to control the operating state of the coupled light detection unit 311 so that the signal output terminal of the coupled light detection unit 311 outputs the electrical signal. For example, one end of the first switch unit 321 is coupled to the first power supply terminal and connected to the operating voltage. When the first switch unit 321 is turned on, the coupled light detection unit 311 receives the operating voltage and enters the operating state. The measurement channel to which the light detection unit 311 in the operating state belongs is then activated. The other first switch units 321 can be turned off to put the coupled light detection units 311 in the non-operating state, thereby preventing external interference, preventing the generation of interfering electrical signals, and saving power.

[0073] The selection unit 303 is configured to select the light detection unit 311 in working state to output the electrical signal. For example, the selection unit may be implemented as a multiplexer.

[0074] The following Figure 4A and Figure 4B Examples of Figure 3 Possible connection structures between the switch array and the light detection unit array.

[0075] like Figure 4A FIG. 1 is a schematic diagram showing the connection structure of a switch array and a light detection unit array in a light detection circuit according to an embodiment of the present application.

[0076] The figure shows a first power supply terminal, which is coupled to a power supply to provide an operating voltage (such as VDD). The operating voltage is used to generate a reverse bias voltage for activating the light detection units (such as SPAD, SiPM) in the light detection unit array.

[0077] The switch array shown in the figure includes a plurality of first switch units, exemplarily shown as n first switch units, namely S1 to Sn, and corresponding n light detection units D1 to Dn in the light detection unit array.

[0078] The first switch unit S1 is taken as an example for description. The first switch unit includes: a first switch element S 1,1 , one end is coupled to the first power supply end, and the other end is coupled to one end of a light detection unit D1. One end of the light detection unit D1 coupled to the first switch element (corresponding to the negative electrode of D1) is a signal output end, which can be coupled to an input end of the selection unit. The first switch element S 1,1 The switching state corresponds to the on-off state of the path between the first power supply terminal and the signal output terminal, for example, when the first switching element S 1,1 When turned on, the VDD of the first power supply terminal is connected to the V bias circuit to apply a reverse bias voltage to the light detection unit D1 to make it work; or, in the first switching element S 1,1 When disconnected, the line from the first power supply end to the positive electrode of the light detection unit D1 is disconnected, so that the light detection unit D1 is in an inoperative state.

[0079] exist Figure 4A In this example, the positive terminal of the light detection unit D1 can be connected to a bias voltage V bias , with the negative terminal of the light detection unit D1 being connected to the first switching element S 1,1 The voltage formed when the light detection unit D1 is turned on forms a reverse bias voltage (higher than the breakdown voltage V of the light detection unit D1) that makes the light detection unit D1 work. th ). For example, the first switching element S 1,1 It can also be connected through the impedance R IN,1 (such as a resistor) is coupled to one end of the light detection unit D1 to convert the current signal obtained by the light detection unit D1 after converting the light signal into a voltage signal to output from the signal output end.

[0080] Since the reverse bias voltage of the light detection unit is large, there is a problem that causes S 1,1 and R IN,1 To this end, in an optional example, the first switch unit further includes: a second switch element S 2,1 One end of which is coupled to the light detection unit D1 and the first switch element S 1,1 One end of the second switching element S is coupled to the ground end; the other end of the second switching element S is coupled to the ground end; 2,1 The switching state of the second switching element S corresponds to the on-off state of the path between the signal output terminal and the ground terminal. 2,1 When the light detection unit D1 is turned on, the output voltage of the light detection unit D1 can be grounded to prevent overvoltage problems. 2,1 In addition to coupling to the ground terminal, other bias voltages may also be connected, and the other bias voltages do not exceed VDD.

[0081] For example, when the light detection unit D1 is not required to work, the second switch element S 2,1 The first switching element S can be turned on and 1,1 It can be disconnected to ground the negative electrode of the light detection unit D1 and put D1 into a state where it cannot be activated; when the light detection unit D1 is required to work, the second switch element S 2,1 can be turned off by the first switching element S 1,1 is turned on to enable the light detection unit D1 to be in working state.

[0082] It is understood that, as illustrated above, the switching states of the second switch element and the first switch element correspond to the operating or non-operating state of the corresponding coupled light detection unit. Therefore, in some examples, the switching states of the first switch element and the second switch element can be coordinated with each other, for example, set to opposite states.

[0083] For example, when the light detection unit D1 belongs to the measurement channel, the first switch element S is set 1,1 The second switching element S is turned on 2,1 When the light detection unit D1 is in the non-measurement channel, the first switch element S is set. 1,1 The second switching element S is turned off. 2,1 When the optical detection unit D1 is turned on, it is in an inoperative state, and will not generate additional power consumption, nor will it detect external interference optical signals.

[0084] In a specific implementation example, the first switching element S 1,1 It can be implemented as PMOS; or preferably, it can be implemented as bootstrap NMOS, which has smaller parasitic capacitance and on-resistance and faster switching speed.2,1 Can be implemented for NMOS.

[0085] In the specific implementation example, R IN,1 The impedance value can be fixed or variable (for example, implemented as a variable resistor). IN,1 When configured as a variable impedance, R IN,1 The impedance value (such as resistance value) is adjusted to change the gain of the output signal of the light detection unit. For example, if some measurement channels need to measure far (such as hundreds of meters, such as 150 meters, 250 meters, etc.), by increasing R IN,1 The impedance value is used to increase the gain, so that the pulse amplitude generated by the light detection unit in response to a single photon is increased; when the corresponding measurement channel needs to measure proximity, the R IN,1 In a specific implementation example, when RIN,1 is a variable resistor, its resistance range can be from tens of ohms to hundreds of ohms.

[0086] The connection structure of S2 to Sn can be the same as that of S1, that is, for example, the first switch element S of S2 1,2 , impedance R IN,2 and the second switching element S 2,2 The connection structure is the same as S1, and the same applies to the first switch element S of Sn. 1,n , impedance R IN,n and the second switching element S 2,n . Further optionally, S 1,1 ~S 1,n The configuration is the same between S 2,1 ~S 2,n The configuration is the same between R IN,1 ~R IN,n The configurations are the same. S1 to Sn control the working states of D1 to Dn independently of each other, that is, the working states of D1 to Dn are controlled independently by S1 to Sn in the switch array. When the first switch element (such as S1) in the first switch unit (such as S1) 1,1 ) is turned on, the corresponding measurement channel is selected, so that the corresponding light detection unit (such as D1) detects the light signal and generates the corresponding electrical signal; accordingly, the first switch elements of other first switch units (such as S2 to Sn) can be controlled to be disconnected (the second switch elements can be turned on) to disconnect the light detection units (such as D2 to Dn) of non-measurement channels, so that their power consumption is close to zero and they will not detect light signals.

[0087] In a specific implementation example, in order to meet the requirements of fast switching between multiple measurement channels, non-measurement channels are turned off in real time. The switching time between measurement channels can be, for example, 200ns, and the first switching element and the second switching element in each first switching unit can quickly switch the switching state, with a switching time of 10-20ns.

[0088] Therefore, the operation of the light detection unit array is controlled by the switch array, thereby achieving the purpose of reducing power consumption and reducing crosstalk on the measurement channel.

[0089] In practical examples, the light detection unit array can be in the form of a linear array or a planar array, and each measurement channel may have one or more light detection units. When each measurement channel corresponds to multiple light detection units operating together, the multiple light detection units operating together may be adjacent or dispersed within a column or row of the array, or distributed according to other rules. In all of these cases, the switch array control method described in the above embodiment can be applied to control the light detection unit array to independently control one or more light detection units belonging to the measurement channel to be in an active state and one or more light detection units belonging to non-measurement channels to be in an inactive state, thereby achieving the aforementioned goals of reducing power consumption and mitigating crosstalk between the measurement channels.

[0090] Figure 4A The selection unit in the embodiment selects the signal output end of the light detection unit connected to the measurement channel to output to the subsequent signal processing circuit.

[0091] Figure 4A An example is shown Figure 3 The specific circuit implementation embodiments do not limit the possibility of other embodiments.

[0092] For example, if Figure 4B FIG. 1 is a schematic diagram showing the connection structure of a switch array and a light detection unit array in a light detection circuit according to another embodiment of the present application.

[0093] exist Figure 4B In the embodiment shown, Figure 4A The main difference of the embodiments is that each first switch unit S1-Sn includes a transimpedance amplifier unit (TIA), which includes a first input terminal, a second input terminal and an output terminal. For example, the transimpedance amplifier unit can be implemented by a TIA, and the structure can refer to Figure 1B The first input terminal and the second input terminal may be one of a positive input terminal and the other of a negative input terminal, respectively. According to the “virtual short” principle of an operational amplifier, the voltages of the first input terminal and the second input terminal are the same.

[0094] The first switch units S1 to Sn respectively include a first switch element S 1,1 ~S 1,nand the second switching element S 2,1 ~S 2,n Taking the first switch unit S1 as an example for representative description, the first input terminal of the transresistance amplifier unit is coupled to the first switch element S 1,1 The first power supply terminal (in the example shown in the figure, the operating voltage VDD is connected) is coupled to the second switch element S 2,1 The second input end of the transimpedance amplifier unit is coupled to one end of the light detection unit D1 and is connected to the ground through an impedance unit R IN,1 The output terminal of the transimpedance amplifier unit is coupled to the signal output terminal, and is coupled to an input terminal of the selection unit via the signal output terminal. The connection structure of S2 to Sn is the same as that of S1, and will not be repeated here. Figure 4B The light detection unit Dn of the first switch unit Sn, the impedance unit R IN,n , first switching element S 1,n , the second switching element S 2,n etc. connection structure.

[0095] When the first switching element S 1,1 When the first switch element S is turned on, VDD is conducted to the first input terminal, and the voltage of the second input terminal is also VDD, which is applied to the negative electrode of the coupled light detection unit D1 to put it into working state; or 1,1 The second switching element S is turned off. 2,1 The cathode of the light detection unit D1 is connected to the ground, so that the light detection unit D1 is in an inoperative state.

[0096] In the above embodiment, the selection unit comprises a controllable switch that enables gating of the output signals of the light detection units belonging to different measurement channels. In some examples, the selection unit and the first and second switching elements can be controlled by a clock signal provided by a controller or waveform generator. Specifically, the first switching element can be turned on and the second switching element can be turned off before the gating of the selection unit is controlled. Alternatively, the first switching element can be turned on, the second switching element can be turned off, and the gating of the selection unit can be controlled simultaneously.

[0097] Since different types of light detection units require different operating voltages, if Figure 2 The fixed VDD power supply used in the example cannot adapt to the requirements of different types of light detection units.

[0098] For this reason, Figure 5 FIG. 1 is a schematic diagram showing the structure of a light detection circuit in another embodiment of the present application. Figure 5 In the embodiment of the light detection circuit, Figure 3A power supply adjustment unit 304 is added to the optical detection circuit (optical detection unit array 301, switch array 302, selection unit 303).

[0099] The power supply adjustment unit 304, whose output end is connected to the first power supply end, provides a variable power supply. Specifically, the power supply adjustment unit 304 can provide an adjustable power supply voltage VDD to provide a suitable reverse bias voltage for the light detection units of different measurement channels. Exemplarily, the voltage adjustment range of the power supply adjustment unit 304 can be determined according to the operating voltage of the light detection units (such as one or more SPADs, SiPMs) produced by different manufacturers or processes. The voltage value adjustment of the power supply adjustment unit 304 can be continuous or discontinuous. For example, in the case of continuous voltage value adjustment, the voltage adjustment range can be 4 volts to tens of volts. For another example, in the case of discontinuous voltage value adjustment, multiple discrete voltage values ​​are provided for adjusting VDD, such as 4V, 8V, 12V, etc., which correspond to the operating voltages of different light detection units respectively.

[0100] In some embodiments, the power supply adjustment unit 304 may be implemented by a Buck-Boost switching power supply to achieve a function of adjustable boost or buck.

[0101] like Figure 6 FIG. 1 is a schematic diagram showing the circuit principle of a Buck-Boost switching power supply in one embodiment of the present application.

[0102] The Buck-Boost switching power supply includes a voltage source V, a switch S, a diode D, an inductor L, a capacitor C, and a resistor R.

[0103] One end of the voltage source is coupled to one end of a switch S. The other end of the switch S is coupled to one end of an inductor L and the cathode of a diode D. The anode of the diode D is coupled to one end of a capacitor C and a resistor R. The other ends of the inductor L, capacitor C, and resistor R are coupled to the other end of the voltage source. The output voltage of the buck-boost switching power supply is the voltage across R.

[0104] When switch S is on, voltage source V stores energy through inductor L, causing capacitor C to discharge and supply power to load R, achieving a step-down function. When switch S is off, a reverse electromotive force is generated in inductor L, causing diode D to switch from cutoff to conduction. Inductor L supplies power to load R and charges capacitor C, ultimately maintaining the output voltage constant and achieving a step-up function.

[0105] It should be noted that Figure 6The circuit structure of the switching power supply is merely an example. In other embodiments, the power supply adjustment unit may also be implemented using other types of adjustable switching power supplies or linear power supplies, such as a low-dropout linear regulator (LDO). However, it should be noted that switching power supplies are more suitable for applications such as lidar applications where SiPM-based light detection circuits require a high voltage drop.

[0106] Continue to refer Figure 7 , shows a schematic diagram of the structure of the light detection circuit in another embodiment of the present application. In this embodiment, compared to Figure 5 The light detection circuit in the embodiment (light detection unit array 301 , switch array 302 , selection unit 303 , power supply adjustment unit 304 ) is further provided with a level shift unit 305 .

[0107] The level shift unit 305 has an input terminal coupled to the output terminal of the selection unit 303 and is configured to convert the voltage output by the selection unit into a predetermined voltage range. Specifically, the predetermined voltage range is determined by the operating voltage limit of the subsequent signal processing circuit of the selection unit.

[0108] On the one hand, since the operating voltage of the light detection unit array is high voltage, the corresponding electrical signal selected and output by the selection unit 303 is also a high voltage signal. The signal processing circuit after the selection unit may have a low voltage circuit, so the high voltage to low voltage conversion is performed by the level shift unit 305. For example, the operating voltage of SiPM is usually relatively high, and the typical value can reach more than 10V. Please refer to the subsequent Figure 10 The signal processing circuit after the selection unit may include an integration operation unit 306. In order to achieve sufficient speed, the integration operation unit 306 is usually implemented using a low-voltage device. For example, its typical withstand voltage is 1.8V, which is a low-voltage component. The output signal with an amplitude of tens of volts is converted into a 1.8V signal through the level shift unit 305 and then input into the integration operation unit 306.

[0109] On the other hand, due to the voltage regulation function of the power supply regulation unit, for example, the change of VDD will cause the voltage change of the output signal of the light detection unit, which will cause the voltage of the input and output signals of the subsequent signal processing circuit to be unstable, making the design difficulty of the components in the subsequent signal processing circuit. By setting the level shift unit 305, the design difficulty of the components in the subsequent signal processing circuit can be further reduced. For example, please refer to the subsequent Figure 10An analog-to-digital converter (ADC) 307 is provided after the integral operation unit 306. The voltage of the input signal is reduced by the level shifter 305 before the integral operation unit 306, which reduces the design difficulty of the subsequent analog-to-digital converter 307 and improves measurement accuracy. For example, if the ADC has an accuracy of 1mV, its input voltage needs to be maintained at 1V. If the voltage is unstable and the ADC input voltage becomes 3V, while the number of effective bits for the same ADC remains unchanged, such as 10 bits, this reduces measurement accuracy. These problems can be solved by using the level shifter 305 to convert the output signal of the selection unit into an input signal with a stable voltage value before the integral operation unit 306 enters the integral operation unit 306.

[0110] like Figure 8 FIG. 1 is a schematic diagram showing the circuit principle of a level shift unit in an embodiment of the present application.

[0111] The level shift unit includes: at least one second switch unit 801 , a first impedance unit 802 and a current source 803 .

[0112] Each second switch unit 801 includes: a first end coupled to the first power supply end, a second end coupled to one end of the first impedance unit 802, and a control end coupled to the output end of the selection unit 303; the control end is used to control the on and off of the first end and the second end; the other end of the first impedance unit 802 is coupled to one end of the current source 803, and the other end of the current source 803 is coupled to the ground end.

[0113] Figure 8 The level shifter unit illustrated in the figure is a voltage follower. The figure schematically illustrates current source 803 as a variable current source with self-adjustable output current. By adjusting the current in current source 803, different level shifts are achieved. As the voltage of the light detection unit's output signal changes, the level shifter unit follows suit, maintaining its output voltage range unchanged.

[0114] In some embodiments, the second switch unit 801 can be implemented by a MOS, for example, as schematically shown in the figure as an NMOS, wherein the drain is a first terminal, the source is a second terminal, and the gate is a control terminal (which can be coupled to the output terminal of the previous stage selection unit). In some embodiments, the first impedance unit 802 can be implemented by a resistor or multiple MOSs connected in series. The impedance value (such as the resistance value) of the first impedance unit 802 is fixed or variable; the current source 803 can also be a current source whose output current changes with the change of the resistance value of the first impedance unit 802 to match the variable impedance value of the first impedance unit 802, or a variable current source whose output current can be actively adjusted to match the fixed impedance value of the first impedance unit 802.

[0115] The following describes various possible variations of the circuit structure of the level shift unit through a plurality of embodiments and drawings.

[0116] like Figures 9A to 9E , which respectively show schematic diagrams of various modified circuit structures of the level shift unit in the embodiment of the present application.

[0117] exist Figure 9A In FIG. 1 , the second switch unit 901A is implemented as an NMOS, the first impedance unit 902A is implemented as a variable resistor R, and the current source 903A is a current source. Thus, the output voltage of the level shift unit can be adjusted by setting the variable resistor R.

[0118] exist Figure 9B In the figure, the second switch unit 901B is implemented as an NMOS, the first impedance unit 902B is implemented as a variable resistor R, and the current source 903B is a variable current source. Therefore, the variable resistor and the variable current source can be set at the same time to adjust the output voltage of the level shift power supply.

[0119] exist Figure 9C In the figure, the second switch unit 901C is implemented as multiple parallel-connected NMOS transistors, with their sources connected in common and their drains coupled to the first power supply terminal, which receives VDD. The first impedance unit 902C is implemented as a non-variable resistor R, and the output current of the current source 903C depends on the first impedance unit 902C. The output voltage of the level shift unit can be adjusted by adjusting the number of NMOS transistors.

[0120] exist Figure 9D In FIG. 1 , the second switch unit 901D is implemented as an NMOS. The first impedance unit 902D can be implemented by a transistor. Specifically, the transistor can be a field effect transistor (such as a PMOS or NMOS). Figure 9DThe first impedance unit 902D is exemplarily shown as being implemented by a plurality of NMOSs connected in series, with different numbers of NMOSs corresponding to different impedance values, thereby replacing the variable resistor. Specifically, the connection method of the plurality of NMOSs in the first impedance unit 902D in series refers to: the gate and source of each NMOS are coupled, the gate of the first NMOS is connected to the source of the NMOS of the second switch unit 901D, and the source of the last NMOS is coupled to one end of the current source; and the gate of each NMOS other than the first and last is coupled to the source of the previous NMOS. In this example, the output current of the current source 903D depends on the impedance of the first impedance unit 902D. The output voltage of the level shift unit can be adjusted by adjusting the number of NMOSs.

[0121] Figures 9A to 9D The examples shown here are merely illustrative and non-exhaustive of several possible variations of the first impedance unit. It is understood that various permutations and combinations of the implementation of the second switch unit of the level shift unit, the implementation / variable / unvariable of the first impedance unit, and the implementation / variable / unvariable of the current source are all within the scope of protection of this application and are not listed here.

[0122] For example Figure 9E , which is a schematic diagram showing a circuit principle of a level shift unit including a specific circuit structure of a current source.

[0123] In this illustrated embodiment, the current source includes a first current mirror and a second current mirror.

[0124] The first current mirror includes: a first branch and a second branch respectively derived from at least a pair of common-gate transistors M1 and M2, whose gates are coupled to the control terminal of the current source; a second impedance unit R2 is connected in series in the first branch; one end of the first branch and the second branch is coupled to the second power supply terminal, and the other end of the first branch is grounded via the second impedance unit; the second power supply terminal and the first power supply terminal are connected to different voltages. In an optional example, if Figure 9E As shown in the figure, the pair of common-gate transistors M1 and M2 in the first current mirror are specifically implemented as at least one first PMOS and at least one second PMOS connected with common gate and common source, that is, the branches where the transistors M1 and M2 are located are the first branch and the second branch respectively. They are connected with common gate and the gate is coupled to the control end of the current source, and the source of the common source connection is connected to the second power supply end; the drain of the first PMOS is coupled to the ground end through the second impedance unit; wherein the voltage connected to the second power supply end is different from that connected to the first power supply end. For example, the VDD connected to the first power supply end in the figure is the high voltage HV, while the voltage connected to the second power supply end is the low voltage LV.

[0125] The second current mirror comprises: at least one pair of common-gate transistors (M3 and M4 connected in parallel) 4,1 ~M 4,n ) are respectively led out of the third branch and the fourth branch; one end of the third branch is coupled in series to the other end of the second branch, and the other end of the third branch is coupled to the ground end; one end of the fourth branch is coupled to one end of the first impedance unit R1, and the other end of the fourth branch is grounded, so as to form a proportional relationship between the currents flowing through the second impedance unit R2 and the first impedance unit R1. In an optional example, the pair of common-gate transistors in the second current mirror are specifically implemented as a first NMOS with common gate and common source connection (which can be one in the example shown in the figure, or multiple in parallel, i.e., M3), and at least one second NMOS (shown as multiple in parallel, i.e., M in the figure). 4,1 ~M 4,n ), M3 and M 4,1 ~M 4,n The gate and drain of M3 are coupled to the drain of the second PMOS (M2), and the source of M3 is coupled to the ground terminal; 4,1 ~M 4,n The transistor is connected to the M3 in common gate connection, has a drain coupled to one end of the first impedance unit R1 , and has a source coupled to the ground.

[0126] The fourth branch includes n (n≥2) branches, each of which has a transistor (i.e., a second NMOS, M 4,1 ~M 4,n ), wherein the transistor of each branch can be selectively connected or disconnected with the transistor in the third branch to adjust the ratio between the current flowing through the first impedance unit and the second impedance unit. In a specific implementation example, for example Figure 9E As shown, M 4,1 ~M 4,n The drains of the first and second resistors R1 are coupled to each other and to form an output voltage V out .

[0127] M 4,1 ~M 4,n Constitute the transistor array M4. 4,2 ~M 4,n The gates of the M 4,1 and coupled to the ground via the fourth switch element S4.

[0128] Optionally, the current source further includes an operational amplifier, which includes: a negative input terminal connected to a reference voltage V REF; A positive input terminal coupled to one end of the second impedance unit R2 to apply the reference voltage, and the other end of the second impedance unit R2 is grounded; an output terminal used as a control terminal of the current source. In a specific example, V REF Typically 1V-1.2V, with high accuracy and independent of temperature, the negative feedback loop composed of the operational amplifier and the first PMOS (i.e. M1) makes the voltage V1 = V REF .

[0129] The current generated in each branch of the current mirror is related to the ratio of the number of MOS transistors in each branch. It should be noted that although the illustrated example shows one M1, M2, M3, and M5, the actual number can vary. For example, multiple MOS transistors can be connected in parallel, as shown in Figure 9, for example, 901C.

[0130] For example, in the first current mirror, M1 and M2 have the same device parameters and are equal in number, so the current flowing through the second branch where M2 is located is equal to the current flowing through R2 in the first branch.

[0131] In the second current mirror, M3 is the same as M 4,1 ~M 4,n The device parameters of each NMOS are the same, and the number ratio is 1:n. Therefore, the current ratio of R2 and R1 is 1:n, and the voltage across the first impedance unit R1 is n*V REF / R2*R1, the value of n is adjusted by turning on or off switches S3 and S4 to adjust the current proportional relationship and achieve precise control of the voltage across R1. In addition, through the stable V REF , so that V out Stable output. The gate of the second switching unit M5 is connected to the output terminal of the selection unit and receives the voltage signal output by the light detection unit of the selected measurement channel. The voltage of the first power supply terminal is VDD as previously described, and its amplitude can be 12V. The amplitude of the voltage LV of the second power supply terminal can be 1.8V or 5V, etc.

[0132] V IN With V out The voltage between the gate and source voltages of the second switch element M5 is not shown in the figure and can be expressed as V GS ) and the voltage across the first impedance unit R1. GSThis is only relevant to the current flowing through the first impedance unit R1, which is determined by the ratio of the number of transistors in M3 and M4. By adjusting the switching state of each transistor in M4, precise control of the voltage regulation of the level shift unit can be achieved. Specifically, when S3, connected to the gate of a transistor in M4, is on and S4 is off, the transistor is in the on state, and current flows through the branch path where it is located. Alternatively, when S3, connected to the gate of a transistor in M4, is off and S4 is on, the transistor is in the off state, and no current flows through the branch path where it is located. Therefore, when more transistors in M4 are on, the current flowing through the first impedance unit R1 increases, causing the voltage across R1 to increase. Conversely, when fewer transistors in M4 are on, the voltage across R1 decreases.

[0133] A first PMOS (M1), a second PMOS (M2), a first NMOS (M3) and at least one second NMOS (M 4,1 ~M 4,n ), and the second switching element (M5), can all be high-voltage resistant transistors.

[0134] In some embodiments, different types of light detection units (such as SiPMs or SPADs) have different operating voltages, such as 4V, 8V, and 12V. In practical applications, the operating voltage parameters of each light detection unit can be pre-measured. For example, the operating voltage of light detection unit D1 is 4V, and the operating voltage of light detection unit D3 is 12V. The measured operating voltage parameters are stored in a storage medium (such as a register, RAM, ROM, hard disk, etc.) for retrieval and used to control the power supply adjustment unit to provide an adaptive voltage value VDD to the light detection unit corresponding to each measurement channel, thereby providing the light detection unit with a suitable reverse bias voltage to activate its operation.

[0135] In addition, in some embodiments, a temperature sensor may be added to the light detection circuit to detect the circuit's ambient temperature, enabling further calculation of the light detection unit's reverse breakdown voltage compensation in response to changes in the detected temperature. Specifically, the breakdown voltage values ​​obtained at different temperatures are fed back to a storage medium, which may pre-associate and store the reverse breakdown voltage change values ​​and the matching reverse bias voltage values. This allows for providing an appropriate reverse bias voltage value based on the reverse breakdown voltage change values, allowing the power supply adjustment unit to set the compensated VDD. In some examples, a lookup table may also be provided to associate and store the reverse breakdown voltage change values ​​with the matching reverse bias voltage values, allowing for querying the reverse bias voltage value.

[0136] like Figure 10 FIG. 1 is a schematic diagram showing the structure of a light detection circuit in another embodiment of the present application.

[0137] Compared to Figure 7 , Figure 10 The signal processing circuit shown in FIG. 3 further includes an integration operation unit 306 and an analog-to-digital conversion unit 307 after the level shift unit.

[0138] The integration operation unit 306 is coupled to the output terminal of the level shift unit 305 and is configured to perform an integration operation based on the received electrical signal to obtain an operation result. In some embodiments, the integration operation unit 306 may include an integrator. The integrator may be a low-voltage device with an operating voltage of, for example, 1.8V or 5V. The output signal of the selection unit is converted from a high voltage to a low voltage suitable for the integrator by the level shift unit 305 of the preceding stage, and then input into the integrator for integration operation.

[0139] In an application example, a power supply adjustment unit provides a suitable operating voltage to the optical detection unit array, thereby generating a suitable reverse bias voltage to enable the optical detection units to operate normally. When detecting echo signals, a switch control signal turns on at least one first switch element corresponding to a measurement channel in the switch array (and optionally turns off the second switch element simultaneously), thereby activating the coupled at least one optical detection unit belonging to the measurement channel. Furthermore, a first switch element corresponding to a non-measurement channel is turned off (and optionally turns on the second switch element simultaneously), thereby deactivating the coupled at least one optical detection unit belonging to the non-measurement channel. Consequently, the at least one optical detection unit belonging to the non-measurement channel neither consumes unnecessary power nor detects external interference light that could cause crosstalk to the measurement channel.

[0140] Furthermore, the output signal of the measurement channel is selected by the selection unit 303 and input to the level shift unit 305 for level conversion, such as converting from a high voltage to a low voltage signal suitable for the subsequent integration operation unit 306, and then input to the integration operation unit 306. The integration operation unit 306 calculates the energy information of the echo signal obtained by the measurement channel based on the input signal to obtain an analog signal form of the energy information. The analog-to-digital conversion unit 307 converts the energy information into a digital signal, and then sends it to the control module 308, such as a laser radar, for calculating the detection result of the measurement channel.

[0141] In some embodiments, the circuit implementation of the integration operation unit 306 can be, for example, Figure 11A and Figure 11B shown.

[0142] Figure 11AA schematic diagram of an RC integrator unit in one embodiment of the present application is shown. The RC integrator unit includes an operational amplifier. The positive input terminal (+) of the operational amplifier is coupled to a resistor R and one end of a capacitor C. The negative input terminal (-) of the operational amplifier can be coupled to a reference voltage. The other end of capacitor C is coupled to the output terminal of the operational amplifier. The other end of resistor R (i.e., the left end in the figure) is used to input the output signal of the previous level shifter unit.

[0143] Figure 11B The schematic diagram of the Gm-C integration unit in one embodiment of the present application is shown. Gm is a transconductance amplifier, whose output is coupled to one end of capacitor C, the other end of which is grounded. The input of Gm is fed with the output signal of the previous level shift unit.

[0144] The analog-to-digital conversion unit is coupled to the output end of the integral operation unit and is used to perform analog-to-digital conversion according to the operation result. In some embodiments, the analog-to-digital conversion unit may include an analog-to-digital converter (ADC) for converting analog signals into digital signals.

[0145] In some examples, the output end of the analog-to-digital conversion unit can be coupled to a control module of the lidar, and the control module can be implemented by a field-programmable gate array (FPGA), a system on chip (SoC), or other processing circuits.

[0146] like Figure 12 , which shows a structural diagram of a light detection circuit in another specific embodiment of the present application.

[0147] Figure 12 For Figure 10 The circuit structure is based on the following, and provides the structure of a possible specific embodiment, including a light detection unit array 1201, a switch array 1202, a selection unit 1203, a voltage adjustment unit 1204, a level shift unit 1205, an integration unit 1206, and an analog-to-digital conversion unit 1207. The calculation result of the digital signal output by the analog-to-digital conversion unit 1207 can be transmitted to the control module 1208, so that the control module 1208 can calculate the light energy information of the echo signal.

[0148] Specifically, the power supply adjustment unit 1204 can be implemented by a Buck-Boost switching power supply, and the switch array 1202 and the light detection unit array 1201 can be as follows: Figure 4A The implementation of the embodiment; the level shift unit 1205 can be exemplarily shown as Figure 8 The variable current source can also be in the form of Figure 9EImplementation; the integral operation unit 1206 is exemplarily implemented by an RC integral operation unit, and a switch can be exemplarily connected in parallel at both ends of the capacitor to select the bypass capacitor, and a switch is connected in series in the connection line between the input end corresponding to one end of the resistor and the output end of the level shift unit 1205 of the previous stage to control the on-off connection between the integral operation unit 1206 and the previous stage.

[0149] It is understandable that Figure 12 The structure of the specific light detection circuit shown is only an example and can be changed as needed, and is not a limitation to its implementation.

[0150] like Figure 13 As shown, a schematic diagram of the structure of the laser radar in one embodiment of the present application is shown.

[0151] In this example, the laser radar 1300 includes a light emitting module 1301, a light detection module 1302, and a control module 1303. The light emitting module 1301 includes a light emitting unit array 1311, which includes a plurality of light emitting units 13111. The light emitting unit 13111 can be implemented by at least one light emitter, which can be a laser, such as a vertical cavity surface emitting laser (VCSEL) or an edge emitting laser (EEL).

[0152] The light emitting module 1301 may further include a transmitting lens 1312 and a driving circuit 1313 for the light emitting unit array 1311 .

[0153] The light detection module 1302 includes a light detection circuit 1320. The light detection circuit 1320 can refer to the previous Figure 3 、 Figure 5 、 Figure 7 、 Figure 10 or Figure 12 The light detection circuit implementation in the embodiment. The light detection circuit 1320 includes a light detection unit array 1321 and a multi-stage signal processing circuit for reading its output signal (such as a switch array, a selection unit, a supply voltage adjustment unit 1, a level shift unit, an integration unit, and an analog-to-digital conversion unit, and may or may not have a processing module). The light detection unit array 1321 includes multiple light detection units 13211, and the light detection unit 13211 may include at least one light detector (such as a SiPM or a SPAD).

[0154] Each light emitting unit 13111 outputs a transmission signal, which is then emitted from the laser radar 1300 after passing through the transmitting lens 1312 (e.g., shaping / collimating). Upon encountering obstacle A, the signal is reflected to form an echo signal. This echo signal enters the laser radar 1300 and passes through the receiving lens 1322 (e.g., shaping / focusing) before being detected by each light detection unit 13211 in the light detection unit array 1321. In some embodiments, one light emitting unit 13111 and one light detection unit 13211 constitute a detection channel. That is, the echo signal formed by the reflection of the transmission signal from one light emitting unit 13111 is detected by one light detection unit 13211. If there are N pairs of light emitting units 13111 and light detection units 13211, N detection channels can be formed, each corresponding to a different field of view. Optionally, the fields of view of the detection channels can overlap or not overlap. The detection channel selected for operation is the aforementioned measurement channel, while the remaining unselected channels are non-measurement channels.

[0155] The control module 1303 is coupled to the optical transmitter module 1301 and the optical detection module 1302, and is configured to transmit a switch signal to the switch array to set the switch state of some of the first switch units to drive the optical detection units coupled to some of the first switch units to start detecting optical signals; and set the switch state of the remaining first switch units to turn off the optical detection units coupled to the remaining first switch units. Specifically, the control module can be implemented by FPGA, SoC, or other processing circuits. In the above embodiments, for example Figure 10 or Figure 12 The processing module 308 or 1208 described in the foregoing may be located in the control module 1303 , or may be integrated into the light detection module 1302 and be in communication with the control module 1303 .

[0156] The present application also provides a light detection method. This light detection method can be applied to the laser radar described in the previous embodiment to control the operation of the light detection circuit. Specifically, the method can be executed by a control module in the laser radar, or implemented in an EDA software simulation of the light detection circuit design.

[0157] The light detection method may include:

[0158] A switch signal is transmitted to the switch array to set the switch state of some of the first switch units to drive the light detection units (belonging to the measurement channel) coupled to some of the first switch units to start detecting light signals; and the switch state of the remaining first switch units is set to turn off the light detection units (belonging to the non-measurement channel) coupled to the first switch units, so that they are in an inoperative state.

[0159] In some embodiments, applying a switch signal to some of the first switch units in the switch array to drive the coupled light detection units to start up includes: applying a switch signal to each of the first switch units in the switch array one by one to drive each light detection unit to start up accordingly.

[0160] The above-mentioned process of activating each light detection unit one by one is illustrated by an example. For example, in a linear or planar array of light detection units, during each detection, one or more light detection units (which may correspond to one or more measurement channels) are activated simultaneously (possibly simultaneously) to perform detection. The next time, another one or more light detection units (corresponding to another one or more measurement channels) are activated to perform detection, and so on, until all light detection units (each detection channel) have been activated in turn, and then the cycle begins again.

[0161] The multiple light detection units activated together can be a column of light detection units, a portion of light detection units in a column, a row of light detection units, or a portion of light detection units in a row in the light detection unit array. Alternatively, the same light detection units in the light detection array can be grouped based on their spatial proximity, and the multiple light detection units activated together can also be from different light detection unit groups. Each light detection unit group can correspond to a channel. In this way, the multiple light detection units operating together in different channels are relatively far apart in spatial locations, thereby reducing crosstalk between channels.

[0162] In an embodiment of the present application, a computer-readable storage medium may be provided, storing program instructions, which, when executed, perform the light detection method. Specifically, the steps of the light detection method may be implemented as program instructions (e.g., software or computer code) that can be stored in a readable storage medium (e.g., a CDROM, RAM, floppy disk, hard disk, or magneto-optical disk), or as program instructions originally stored in a remote recording medium or a non-transitory machine-readable storage medium downloaded over a network and then stored in a local recording medium, so that the program instructions can be read and executed by a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (e.g., an SoC or FPGA) to implement the light detection method.

[0163] In summary, the present application provides a light detection circuit, a light detection method, a laser radar, and a storage medium, wherein the light detection circuit includes: a light detection unit array, including: a plurality of light detection units, for receiving light signals and generating corresponding electrical signals; a switch array, including a plurality of first switch units; each first switch unit is respectively coupled to a light detection unit; each first switch unit is configured to control the working state of the coupled light detection unit so that the signal output end of the coupled light detection unit outputs the electrical signal; and a selection unit is configured to select the light detection unit in the working state to output the electrical signal. By setting the switch state of each first switch unit in the switch array in the light detection circuit, the light detection units that need to work together can be selected to be activated, and the light detection units that do not need to work can be set to an inactivated state, thereby avoiding interference from external ambient light, improving the detection accuracy of the laser radar, and avoiding unnecessary energy consumption.

[0164] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed in this application shall be covered by the claims of this application.

Claims

1. A light detection circuit for laser radar, characterized in that: include: The light detection unit array comprises: a plurality of light detection units configured to receive light signals and generate corresponding electrical signals; A switch array, comprising a plurality of first switch units; each first switch unit is respectively coupled to a light detection unit; each first switch unit is configured to control the working state of the coupled light detection unit so that the signal output end of the coupled light detection unit outputs the electrical signal; wherein the first switch unit comprises a first switch element and a second switch element; a first end of the first switch element is coupled to a first power supply end, and the other end of the first switch element is coupled to the first end of the light detection unit, and the end of the light detection unit coupled to the first switch element is the signal output end; the switching state of the first switch element corresponds to the on-off of the path between the first power supply end and the signal output end; a first end of the second switch element is coupled to the end of the light detection unit coupled to the first switch element, and the other end of the second switch element is used to connect to other bias voltages; the switching state of the second switch element corresponds to the on-off of the path between the signal output end and the other bias voltage; the first power supply end is used to couple a power supply voltage, and the other bias voltage does not exceed the power supply voltage; The selection unit is coupled to the output ends of the plurality of light detection units and is used to select a light detection unit in a working state to output the electrical signal, and output the electrical signal to a subsequent circuit.

2. The light detection circuit according to claim 1, wherein: The switching states of the first switching element and the second switching element are set to be opposite.

3. The light detection circuit according to claim 1, wherein: include: The power supply regulating unit has an output end connected to the first power supply end and provides a variable power supply.

4. The light detection circuit according to claim 3, wherein: The power supply is adjusted to output a variety of voltage values; The multiple voltage values ​​are respectively adapted to light detection units with different operating voltages.

5. The light detection circuit according to claim 3, wherein: include: The level shift unit has an input terminal coupled to the output terminal of the selection unit and is configured to convert the voltage output by the selection unit into a preset voltage range.

6. The light detection circuit according to claim 5, wherein: The level shift unit includes: at least one second switch unit, a first impedance unit and a current source; Each of the second switch units includes: a first end coupled to the first power supply end, a second end coupled to one end of the first impedance unit, and a control end coupled to the output end of the selection unit; the control end is used to control the on and off of the first end and the second end; The other end of the first impedance unit is coupled to one end of the current source, and the other end of the current source is coupled to the ground.

7. The light detection circuit according to claim 6, wherein: The current source comprises: The first current mirror comprises: a first branch and a second branch respectively derived from at least a pair of common-gate transistors, wherein the gates of the first branch and the second branch are coupled to a control terminal of a current source; a second impedance unit is connected in series with the first branch; one end of the first branch and the second branch are coupled to a second power supply terminal, and the other end of the first branch is grounded via the second impedance unit; the second power supply terminal and the first power supply terminal are connected to different voltages; The second current mirror includes: a third branch and a fourth branch respectively led out by at least a pair of common-gate transistors; one end of the third branch is coupled in series to the other end of the second branch, and the other end of the third branch is coupled to the ground end; one end of the fourth branch is coupled to one end of the first impedance unit, and the other end of the fourth branch is grounded, so that the currents flowing through the first impedance unit and the second impedance unit have an adjustable proportional value.

8. The light detection circuit according to claim 7, wherein: The fourth branch includes N branches connected in parallel, N≥2, and each branch is connected in series with a transistor, wherein the transistor of each branch can be selectively connected or disconnected with the transistor in the third branch to adjust the ratio between the current flowing through the first impedance unit and the second impedance unit.

9. The light detection circuit according to claim 7, wherein: The current source comprises: The first current mirror comprises: at least one first PMOS transistor and at least one second PMOS transistor connected in common gate and common source mode, wherein the gate is coupled to the control terminal of the current source and the source is connected to the second power supply terminal; the drain of the first PMOS transistor is coupled to the ground terminal via a second impedance unit; wherein the second power supply terminal and the first power supply terminal are connected to different voltages; The second current mirror includes: a first NMOS, whose gate and drain are coupled to the drain of the second PMOS, and whose source is coupled to the ground end; at least one second NMOS, connected to the first NMOS with a common gate, whose drain is coupled to one end of the first impedance unit, and whose source is coupled to the ground end.

10. The light detection circuit according to claim 9, wherein: There are N second NMOSs, N≥2; the drain of each second MOS is coupled to each other and coupled to one end of the first impedance unit and the source is coupled to the ground end; the gate of each second NMOS is coupled to the gate of the first NMOS through the third switching element, and coupled to the ground end through the fourth switching element.

11. The light detection circuit according to claim 7 or 9, characterized in that: The current source further includes an operational amplifier comprising: Negative input terminal, connected to the reference voltage; The positive input terminal is coupled to one end of the second impedance unit to apply the reference voltage; the output terminal is used as a control terminal of the current source.

12. The light detection circuit according to claim 6, wherein: The second switch unit includes a third NMOS; the control terminal, the first terminal and the second terminal of the second switch unit are respectively led out from the gate, the drain and the source of the third NMOS.

13. The light detection circuit according to claim 6, wherein: The first impedance unit includes one of the following: a variable resistor or a plurality of transistors connected in series.

14. The light detection circuit according to claim 6, wherein: There are multiple second switch units connected in parallel.

15. The light detection circuit according to claim 5, wherein: include: an integral operation unit, coupled to the output end of the level shift unit, and configured to perform an integral operation according to the received electrical signal to obtain an operation result; The analog-to-digital conversion unit is coupled to the output end of the integral operation unit and is used for performing analog-to-digital conversion according to the operation result.

16. The light detection circuit according to claim 1, wherein: The first switch unit further includes a variable impedance unit connected in series between the first switch element and the light detection unit.

17. The light detection circuit according to claim 1, wherein: include: A first power supply terminal coupled to a power supply; The first switch unit further includes: The transimpedance amplifier unit includes a first input terminal, a second input terminal and an output terminal; the first input terminal of the transimpedance amplifier unit is coupled to the first switching element to the first power supply terminal, and is coupled to the second switching element to the ground terminal; the second input terminal of the transimpedance amplifier unit is coupled to one end of the light detection unit, and is coupled to the transimpedance amplifier unit through the third impedance unit. The output end of the amplifying unit is coupled to the signal output end.

18. A light detection method, characterized in that: Applied to controlling the light detection circuit according to any one of claims 1 to 17, the light detection method comprising: A switch signal is transmitted to the switch array to set the switch state of some of the first switch units to drive the light detection units coupled to some of the first switch units to start detecting light signals; and the switch state of the remaining first switch units is set to turn off the light detection units coupled to the remaining first switch units.

19. The light detection method according to claim 18, wherein: Applying a switch signal to some first switch units in the switch array to drive the coupled light detection units to start, including: A switch signal is applied to each first switch unit in a part of the switch array one by one to drive each light detection unit to start accordingly.

20. A laser radar, characterized in that: include: The optical transmission module includes: an optical transmission unit array configured to output a transmission signal; A light detection module comprising the light detection circuit according to any one of claims 1 to 17; wherein the light detection unit array is configured to receive an echo signal reflected by the transmitted signal after encountering an obstacle; The control module is coupled to the optical transmission module and the optical detection module and is configured to transmit a switch signal to the switch array to set the switch state of some of the first switch units to drive the optical detection units coupled to some of the first switch units to start detecting optical signals; and to set the switch state of the remaining first switch units to turn off the optical detection units coupled to the remaining first switch units.

21. A computer-readable storage medium, characterized in that Program instructions are stored, and when the program instructions are executed, the light detection method according to claim 18 or 19 is executed.

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