Laser receiving circuit and laser radar

Abstract

The utility model proposes a laser receiving circuit and a laser radar, and the laser receiving circuit comprises a plurality of photoelectric detectors, a plurality of signal amplification circuits, a channel switching circuit, a high-pass filtering circuit, and a negative pulse clamping circuit. The multi-path current signals are converted into voltage echo signals after being amplified, the voltage echo signals are selectively output through the channel switching circuit, the negative pulse clamping circuit clamps a negative pulse signal in the voltage echo signals output by the channel switching circuit, the amplitude of the negative pulse is reduced to a preset amplitude, and the amplitude of the negative pulse is reduced to the preset amplitude. And moreover, the recovery time of the negative pulse signal is shortened, the distance measurement of the next voltage echo signal is not influenced, and the distance measurement accuracy of the next echo is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of laser radar, and in particular relates to a laser receiving circuit and a laser radar. Background Art

[0002] In a multi-line laser radar system, there are multiple groups of one-to-one corresponding lasers and photodetectors. In the laser receiving circuit, in order to facilitate the acquisition and processing of voltage echo signals of different channels and reduce hardware costs, a channel switching circuit is usually set after the photodetector is amplified by the signal amplification circuit to control the time-sharing switching of the signal amplification circuits of different channels, thereby realizing a combined output and reducing the number of channels for subsequent signal processing and acquisition.

[0003] When the channel switch is switched, a common-mode voltage mutation will occur, resulting in a serious voltage step. In order to avoid the voltage step caused by the switch switching causing distortion in the voltage echo signal acquisition, a high-pass filter circuit is usually used in the later stage of the channel switching circuit to eliminate the voltage step caused by the channel switch switching. In order not to affect the voltage echo signal acquisition, the recovery time of the voltage step needs to be shortened as much as possible. Therefore, the cutoff frequency of the high-pass filter needs to be configured to be higher (MHz level) to complete the recovery of the voltage step in a short time (ns level) to avoid affecting the echo ranging time window. However, the ideal voltage echo signal is a Gaussian pulse waveform with no negative pulse on the trailing edge of the waveform. However, affected by the filter circuit, the low-frequency component is attenuated and a negative pulse is generated on the trailing edge of the waveform, which causes the time window occupied by a single voltage echo signal waveform to become longer, affecting the ranging of the next voltage echo signal, resulting in low ranging accuracy of the next echo. Utility Model Content

[0004] The utility model aims to provide a laser receiving circuit, aiming to solve the problem that the traditional laser receiving circuit has negative pulses which leads to low ranging accuracy of the next echo.

[0005] A first aspect of an embodiment of the utility model provides a laser receiving circuit, comprising:

[0006] A plurality of photodetectors, each of the photodetectors being configured to convert a received laser pulse into a current signal;

[0007] A plurality of signal amplifying circuits, each of which is connected to one of the photodetectors, and each of which is configured to amplify the current signal into a voltage echo signal;

[0008] A channel switching circuit, the channel switching circuit comprising a plurality of input terminals and an output terminal, an input terminal of the channel switching circuit being connected to an output terminal of the signal amplifying circuit, the signal amplifying circuit being configured to be triggered by a received selection signal to sequentially select an input terminal and an output terminal of the signal amplifying circuit, and select and output the plurality of voltage echo signals;

[0009] A high-pass filter circuit, connected to the channel switching circuit, and configured to perform high-pass filtering on each of the voltage echo signals;

[0010] The negative pulse clamping circuit is connected to the high-pass filtering circuit and is configured to clamp the amplitude of the negative pulse signal in the filtered voltage echo signal to reduce the amplitude of the negative pulse signal to a preset amplitude and shorten the recovery time of the negative pulse signal.

[0011] Optionally, the photodetector comprises at least one of an avalanche diode, a silicon photomultiplier tube, a single photon avalanche diode and a photodiode.

[0012] Optionally, the signal amplification circuit includes a transimpedance amplifier.

[0013] Optionally, the high-pass filter circuit includes a first resistor and a first capacitor;

[0014] The first end of the first capacitor constitutes the input end of the high-pass filter circuit, the second end of the first capacitor and the first end of the first resistor are connected together to constitute the output end of the high-pass filter circuit, and the second end of the first resistor is grounded.

[0015] Optionally, the negative pulse clamping circuit includes a first diode;

[0016] The anode of the first diode is connected to the positive power supply terminal and inputs a bias voltage, and the cathode of the first diode is connected to the output terminal of the high-pass filter circuit.

[0017] Optionally, the signal amplification circuit includes a transimpedance amplifier and a differential amplifier;

[0018] The input end of the transimpedance amplifier constitutes the input end of the signal amplification circuit, the output end of the transimpedance amplifier is connected to the non-inverting input end of the differential amplifier, and the non-inverting output end and the inverting output end of the differential amplifier constitute the output end of the signal amplification circuit.

[0019] Optionally, the high-pass filter circuit includes a second resistor, a third resistor, a second capacitor and a third capacitor;

[0020] The first end of the second capacitor and the first end of the third capacitor constitute the first input end and the second input end of the high-pass filter circuit respectively; the second end of the second capacitor is connected to the first end of the second resistor to constitute the first output end of the high-pass filter circuit; the second end of the third capacitor is connected to the second end of the third resistor to constitute the first output end of the high-pass filter circuit; the first end of the second resistor is grounded; the second end of the third resistor is connected to the positive power supply terminal and inputs a bias voltage.

[0021] Optionally, the negative pulse clamping circuit includes a fourth resistor, a fifth resistor and a second diode;

[0022] The first end of the fourth resistor is grounded, the second end of the fourth resistor is connected to the cathode of the second diode to form the positive output end of the negative pulse clamping circuit, the anode of the second diode is connected to the first end of the fifth resistor to form the negative output end of the negative pulse clamping circuit, and the second end of the fifth resistor is connected to the positive power supply end and inputs the bias voltage.

[0023] Optionally, the channel switching circuit includes at least one analog switch, multiple input ends of at least one analog switch are respectively connected to the output end of one of the signal amplifying circuits, and the output ends of each analog switch are connected together to form the output end of the analog switch circuit.

[0024] A second aspect of an embodiment of the utility model proposes a laser radar, comprising a laser transmitting circuit and the laser receiving circuit as described above.

[0025] Compared with the prior art, the embodiments of the utility model have the following beneficial effects: the above-mentioned laser receiving circuit includes multiple photodetectors, multiple signal amplification circuits, a channel switching circuit, a high-pass filtering circuit and a negative pulse clamping circuit; the photodetector performs photoelectric conversion and outputs a current signal; the multiple current signals are respectively converted into voltage echo signals after signal amplification, and are selected for output through the channel switching circuit; the negative pulse clamping circuit clamps the negative pulse signal in the voltage echo signal output by the channel switching circuit, reduces the amplitude of the negative pulse to a preset amplitude, and shortens the recovery time of the negative pulse signal, does not affect the ranging of the next voltage echo signal, and improves the ranging accuracy of the next echo. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 A schematic diagram of the first structure of a laser receiving circuit provided by an embodiment of the utility model;

[0028] Figure 2 A first circuit diagram of a laser receiving circuit provided by an embodiment of the utility model;

[0029] Figure 3 A second structural schematic diagram of a laser receiving circuit provided in an embodiment of the utility model;

[0030] Figure 4 A second circuit diagram of a laser receiving circuit provided by an embodiment of the utility model;

[0031] Figure 5 A third structural schematic diagram of a laser receiving circuit provided in an embodiment of the utility model;

[0032] Figure 6 A schematic diagram of the structure of a laser radar provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0035] The first aspect of the embodiment of the utility model provides a laser receiving circuit 200, such as Figure 6 As shown, the laser receiving circuit 200 is set corresponding to the laser emitting circuit 100. The laser emitting circuit 100 can select to correspond to multiple lasers. The multiple lasers emit laser pulses toward a preset angle according to a preset timing according to a driving signal. At the same time, the laser receiving circuit 200 is set corresponding to the laser emitting circuit 100 to form a multi-line laser radar. The multiple laser pulses are reflected by the object to be measured 1 and returned to the laser receiving circuit 200. The laser receiving circuit 200 performs photoelectric conversion on the laser pulses and outputs multiple voltage echo signals. The voltage echo signals are output to the back-end processing circuit or controller. The processing circuit or controller determines the distance information and reflectivity of the object to be measured 1 according to the voltage echo signals.

[0036] In order to reduce the influence of negative pulses, in this embodiment, the laser receiving circuit 200 includes:

[0037] A plurality of photodetectors 10, each of which is configured to convert a received laser pulse into a current signal;

[0038] A plurality of signal amplifying circuits 20, each of which is connected to a photodetector 10, and the signal amplifying circuit 20 is configured to amplify the current signal into a voltage echo signal;

[0039] A channel switching circuit 30, the channel switching circuit 30 includes a plurality of input terminals and an output terminal, an input terminal of the channel switching circuit 30 is connected to an output terminal of a signal amplifying circuit 20, and the signal amplifying circuit 20 is configured to be triggered by a received selection signal to sequentially select an input terminal and an output terminal of itself, and select and output a plurality of voltage echo signals;

[0040] A high-pass filter circuit 40 is connected to the channel switching circuit 30 and is configured to perform high-pass filtering on each voltage echo signal;

[0041] The negative-going pulse clamping circuit 50 is connected to the high-pass filtering circuit 40 and is configured to clamp the amplitude of the negative-going pulse signal in the filtered voltage echo signal to reduce the amplitude of the negative-going pulse signal to a preset amplitude and shorten the recovery time of the negative-going pulse signal.

[0042] In this embodiment, when performing laser ranging, the laser emitting circuit 100 is controlled to emit multiple laser pulses. After the laser pulses are reflected to the object to be measured 1, they are reflected back to the laser receiving circuit 200. The multiple photodetectors 10 respectively perform photoelectric conversion on the reflected multiple laser pulses and output current signals respectively. The signal amplifier circuit 20 at the rear end of each current signal output amplifies the signal and converts it into a voltage echo signal. The voltage echo signal is then output to the channel switching circuit 30 connected to the multiple signal amplifier circuits 20. The channel switching circuit 30 includes multiple input terminals and an output terminal. The channel switching circuit 30 also includes an enable terminal. The enable terminal receives a selection signal. The channel switching circuit 30 selects the internal transmission channel according to the received selection signal, thereby connecting the corresponding input terminal and output terminal, and selecting and outputting each voltage echo signal in sequence according to a preset timing.

[0043] For example, the channel switching circuit 30 includes 8 input terminals, and is respectively connected to a signal amplifying circuit 20. Each signal amplifying circuit 20 outputs a voltage echo signal, and the enable terminals include three. When the selection signal is 000, the channel switching circuit 30 selects its own first input terminal and output terminal, and the voltage echo signal input to the first input terminal is selected by the channel switching circuit 30 to be output to the high-pass filter circuit 40 at the rear end. When the selection signal is 001, the channel switching circuit 30 selects its own second input terminal and output terminal, and the voltage echo signal input to the second input terminal is selected by the channel switching circuit 30 to be output to the high-pass filter circuit 40 at the rear end. Similarly, the voltage echo signals input to the 8 input terminals of the channel switching circuit 30 can be selected and output in sequence under the control of the selection signal, thereby realizing the merging of multiple different voltage echo signals into one output.

[0044] The high-pass filter circuit 40 is used to perform high-pass filtering on each voltage echo signal to eliminate the voltage step generated when the channel switch of the channel switching circuit 30 is switched. Figure 3 As shown, there are positive pulse signals and negative pulse signals in the voltage echo signal after high-pass filtering. When the positive pulse signal is input to the negative pulse clamping circuit 50, the negative pulse clamping circuit 50 has no clamping effect, and the positive pulse signal is normally output through the negative pulse clamping circuit 50. When the negative pulse signal is output to the negative pulse clamping circuit 50, the negative pulse clamping circuit 50 implements clamping limitation, and reduces the amplitude of the negative pulse signal to a preset amplitude. The negative pulse amplitude is reduced and the recovery time is shortened, thereby achieving the purpose of eliminating the negative pulse, avoiding affecting the detection work of the next voltage echo signal, and improving the ranging accuracy of the next echo.

[0045] The photodetector 10 may be of a corresponding type. In an optional embodiment, the photodetector 10 includes at least one of an avalanche diode, a silicon photomultiplier tube, a single photon avalanche diode, and a photodiode.

[0046] The channel switching circuit 30 is used to realize the gated output of the voltage echo signal, and the analog switch U2 of the corresponding structure can be selected. In an optional embodiment, as shown in FIG. Figure 2 or Figure 4 As shown, the channel switching circuit 30 includes at least one analog switch U2, and multiple input terminals of at least one analog switch U2 are respectively connected to the output terminal of a signal amplifying circuit 20, and the output terminals of each analog switch U2 are connected together to form the output terminal of the analog switch U2 circuit.

[0047] In this embodiment, the analog switch U2 also includes an enable terminal, which receives a selection signal. The analog switch U2 selects the internal transmission channel according to the received selection signal, thereby connecting the corresponding input terminal and output terminal, and selects and outputs each voltage echo signal in sequence according to a preset timing.

[0048] For example, the analog switch U2 includes 8 input terminals, and is respectively connected to a signal amplifying circuit 20. Each signal amplifying circuit 20 outputs a voltage echo signal, and includes three enable terminals. When the selection signal is 000, the analog switch U2 selects its own first input terminal and output terminal, and the voltage echo signal input to the first input terminal is selected and output to the high-pass filter circuit 40 at the back end through the analog switch U2. When the selection signal is 001, the analog switch U2 selects its own second input terminal and output terminal, and the voltage echo signal input to the second input terminal is selected and output to the high-pass filter circuit 40 at the back end through the analog switch U2. Similarly, the voltage echo signals input to the 8 input terminals of the analog switch U2 can be selected and output in sequence under the control of the selection signal, thereby realizing the merging of multiple different voltage echo signals into one output.

[0049] Among them, the number of analog switches U2 can be set according to the number of paths of the voltage echo signal and the number of its own input terminals. For example, the analog switch U2 includes 8 input terminals. When the number of paths of the photodetector 10 is less than 8, the number of analog switches U2 is 1. When the number of paths of the photodetector 10 is greater than 8, the number of analog switches U2 needs to be greater than 1. For example, when the number of paths of the photodetector 10 is 20, the analog switches U2 include at least 3. The number of signal amplification circuits 20 connected to the 3 analog switches U2 can be 8, 8, 4, 7, 7, 6, 6, 6, 8, etc. respectively. The number of signal amplification circuits 20 connected to each analog switch U2 can be set according to the needs. At the same time, when multiple analog switches U2 are included, the multiple analog switches U2 respectively select and output their own voltage echo signals according to the received selection signals, so that the multi-path voltage echo signals are selected and output according to the preset timing, and high-pass filtering, negative pulse clamping and other operations are performed.

[0050] The signal amplifying circuit 20 may be at least one of a transimpedance amplifier U1, a signal amplifier, etc. In an optional embodiment, as Figure 2 As shown, the signal amplifying circuit 20 includes a transimpedance amplifier U1.

[0051] The high-pass filter circuit 40 includes a first resistor R1 and a first capacitor C1;

[0052] The first end of the first capacitor C1 constitutes the input end of the high-pass filter circuit 40 , the second end of the first capacitor C1 and the first end of the first resistor R1 are connected together to constitute the output end of the high-pass filter circuit 40 , and the second end of the first resistor R1 is grounded.

[0053] The negative pulse clamp circuit 50 includes a first diode D1;

[0054] An anode of the first diode D1 is connected to the positive power supply terminal and inputs the bias voltage VBIAS, and a cathode of the first diode D1 is connected to the output terminal of the high-pass filter circuit 40 .

[0055] In this embodiment, Figure 2 and Figure 3 As shown, the photodetector 10 converts different echo light signals into current signals respectively, and the transimpedance amplifier U1 converts the current signal output by the photodetector 10 into a voltage signal. At the same time, multiple transimpedance amplifiers U1 are respectively connected to an input end of the analog switch U2. The analog switch U2 triggers the selection signal to select the corresponding internal transmission channel, and selects and outputs each voltage echo signal in turn, thereby realizing the merging of multiple different voltage echo signals into one output.

[0056] Each voltage echo signal is output to the high-pass filter circuit 40. The first resistor R1 and the first capacitor C1 form a first-order high-pass filter. The voltage step recovery time is proportional to the RC time constant formed by the first resistor R1 and the first capacitor C1. In order to speed up the voltage step recovery time and not affect the ranging of the echo signal, the size of the first resistor R1 and the first capacitor C1 should be as small as possible.

[0057] The first-order high-pass filter is used to perform high-pass filtering on each voltage echo signal to eliminate the voltage step generated when the analog switch U2 is switched. Figure 3 As shown, there are positive pulse signals and negative pulse signals in the voltage echo signal after high-pass filtering, wherein the first diode D1 is a high-frequency Schottky diode, and the bias voltage VBIAS is set to the forward conduction start-up voltage of the first diode D1. When the positive pulse signal is input, the first diode D1 is in a cut-off state, and the equivalent resistance of the first diode D1 is large. Therefore, the negative pulse clamping circuit 50 has no clamping effect, and the positive pulse signal is normally output through the negative pulse clamping circuit 50. When the negative pulse signal is output to the negative pulse clamping circuit 50, the first diode D1 is in a forward conduction state, and the equivalent resistance of the first diode D1 is small, so the negative pulse is clamped and limited, and the amplitude of the negative pulse signal is reduced to a preset amplitude. The negative pulse amplitude is reduced and the recovery time is shortened, so as to achieve the purpose of eliminating the negative pulse, avoid affecting the detection work of the next voltage echo signal, and improve the ranging accuracy of the next echo.

[0058] like Figure 4 As shown, in another optional embodiment, the signal amplification circuit 20 includes a transimpedance amplifier U1 and a differential amplifier U3;

[0059] The input end of the transimpedance amplifier U1 constitutes the input end of the signal amplification circuit 20 , the output end of the transimpedance amplifier U1 is connected to the non-inverting input end of the differential amplifier U3 , and the non-inverting output end and the inverting output end of the differential amplifier U3 constitute the output end of the signal amplification circuit 20 .

[0060] The high-pass filter circuit 40 includes a second resistor R2, a third resistor R3, a second capacitor C2 and a third capacitor C3;

[0061] The first end of the second capacitor C2 and the first end of the third capacitor C3 constitute the first input end and the second input end of the high-pass filter circuit 40 respectively. The second end of the second capacitor C2 is connected to the first end of the second resistor R2 to constitute the first output end of the high-pass filter circuit 40. The second end of the third capacitor C3 is connected to the second end of the third resistor R3 to constitute the first output end of the high-pass filter circuit 40. The first end of the second resistor R2 is grounded, and the second end of the third resistor R3 is connected to the positive power supply terminal and inputs the bias voltage VBIAS.

[0062] The negative pulse clamp circuit 50 includes a fourth resistor R4, a fifth resistor R5 and a second diode D2;

[0063] The first end of the fourth resistor R4 is grounded, the second end of the fourth resistor R4 is connected to the cathode of the second diode D2 to form the positive output end of the negative pulse clamping circuit 50, the anode of the second diode D2 is connected to the first end of the fifth resistor R5 to form the negative output end of the negative pulse clamping circuit 50, and the second end of the fifth resistor R5 is connected to the positive power supply end and inputs the bias voltage VBIAS.

[0064] In this embodiment, Figure 4 and Figure 5 As shown, the photodetector 10 converts different echo light signals into current signals respectively, the transimpedance amplifier U1 converts the current signal output by the photodetector 10 into a voltage signal, and the differential amplifier U3 converts the voltage echo signal into a differential voltage echo signal. At the same time, the analog switch U2 includes multiple differential signal input terminals and a signal output terminal, and the multiple differential amplifiers U3 are respectively connected to a differential signal input terminal of the analog switch U2. The analog switch U2 triggers the selection signal to select the corresponding differential signal transmission channel inside, and selects and outputs each voltage echo signal in turn, thereby realizing the merging of multiple different voltage echo signals into one output.

[0065] Each voltage echo signal is output to the high-pass filter circuit 40. The second resistor R2 and the second capacitor C2 form a first-order high-pass filter, and the third resistor R3 and the third capacitor C3 form a first-order high-pass filter, which respectively perform high-pass filtering on the differential voltage echo signal output by the analog switch U2. The voltage step recovery time is proportional to the size of the RC time constant composed of the second resistor R2 and the second capacitor C2, and the size of the RC time constant composed of the third resistor R3 and the third capacitor C3. In order to speed up the recovery time of the voltage step and not affect the ranging of the echo signal, the size of the second resistor R2, the second capacitor C2, the third resistor R3 and the third capacitor C3 should be as small as possible.

[0066] Two first-order high-pass filters perform high-pass filtering on each differential voltage echo signal to eliminate the voltage step generated when the analog switch U2 is switched. Figure 5 As shown, there are positive pulse signals and negative pulse signals in the differential voltage echo signal after high-pass filtering, wherein the second diode D2 is a high-frequency Schottky diode, connected across the inverting output terminal of the positive output terminal of the negative pulse clamp circuit 50, the fourth resistor R4 and the fifth resistor R5 respectively provide DC bias for the inverting output terminal of the positive output terminal of the negative pulse clamp circuit 50, the bias voltage VBIAS is the critical conduction voltage of the second diode D2, when there is no differential voltage echo signal, the voltage at the inverting output terminal of the negative pulse clamp circuit 50 is the bias voltage VBIAS, and the voltage at the positive output terminal of the negative pulse clamp circuit 50 is 0. At this time, the second diode D2 is critically turned on. When the positive pulse differential signal is input, the second diode D2 is in a non-conducting state. The equivalent resistance of the second diode D2 is large, and the negative pulse clamping circuit 50 has no effect on the positive pulse differential signal. When the negative pulse differential signal appears, the second diode D2 completely enters the forward conduction state. The equivalent resistance of the second diode D2 is small, and the negative pulse is clamped and limited, and the amplitude of the negative pulse signal is reduced to a preset amplitude. The negative pulse amplitude is reduced and the recovery time is shortened, thereby achieving the purpose of eliminating the negative pulse, avoiding affecting the detection of the next voltage echo signal, and improving the ranging accuracy of the next echo.

[0067] In order to simplify the circuit structure, the second resistor R2 and the fourth resistor R4 can be combined into a sixth resistor, the third resistor R3 and the fifth resistor R5 can be combined into a seventh resistor, and the sixth resistor and the seventh resistor can achieve high-pass filtering and potential biasing.

[0068] Compared with the prior art, the embodiment of the utility model has the following beneficial effects: the above-mentioned laser receiving circuit 200 includes multiple photodetectors 10, multiple signal amplification circuits 20, a channel switching circuit 30, a high-pass filter circuit 40 and a negative pulse clamping circuit 50; the photodetector 10 performs photoelectric conversion and outputs a current signal; the multiple current signals are respectively converted into voltage echo signals after signal amplification, and are selected for output through the channel switching circuit 30; the negative pulse clamping circuit 50 clamps the negative pulse signal in the voltage echo signal output by the channel switching circuit 30, reduces the amplitude of the negative pulse to a preset amplitude, and shortens the recovery time of the negative pulse signal, does not affect the ranging of the next voltage echo signal, and improves the ranging accuracy of the next echo.

[0069] like Figure 6 As shown, the second aspect of the embodiment of the utility model proposes a laser radar, including a laser transmitting circuit 100 and the above laser receiving circuit 200.

[0070] In this embodiment, the laser receiving circuit 200 is configured corresponding to the laser transmitting circuit 100. The laser transmitting circuit 100 transmits multiple laser pulses toward a preset angle according to a preset timing. At the same time, the laser receiving circuit 200 is configured corresponding to the laser transmitting circuit 100 to form a multi-line laser radar. The multiple laser pulses are reflected by the object to be measured 1 and return to the laser receiving circuit 200. The laser receiving circuit 200 performs photoelectric conversion on the laser pulses and outputs multiple voltage echo signals. The voltage echo signals are output to the back-end processing circuit or controller. The processing circuit or controller determines the distance information and reflectivity of the object to be measured 1 according to the voltage echo signals.

[0071] The laser emitting circuit 100 can select a corresponding laser. In an optional embodiment, the laser emitting circuit 100 includes multiple lasers, and the multiple lasers are correspondingly arranged with the multiple photodetectors 10 of the laser receiving circuit 200. The multiple lasers emit laser pulses according to a preset timing and a preset angle under the drive of the driving signal. The laser pulses are reflected back to the corresponding photodetector 10 by the object to be measured 1, and are converted into current signals by the photodetector 10. The current signals are processed by the signal amplification circuits 20, the high-pass filter circuit 40 and the negative pulse clamping circuit 50 at the back end to output voltage echo signals. The processing circuit or controller determines the distance information and reflectivity according to the transmission and reception time of the laser pulse and the size of the voltage echo signal.

[0072] The laser emitting circuit 100 may further include a laser driving circuit, which is connected to a plurality of lasers. The laser driving circuit outputs a driving signal to each laser according to a control signal, thereby driving each laser to emit a laser pulse.

[0073] The laser radar may also include a controller, which is used to drive the laser emitting circuit 100 to emit laser pulses and simultaneously receive the voltage echo signal output by the laser receiving circuit 200, and determine the flight time of the voltage echo signal, as well as the distance information and reflectivity according to the echo pulse width and pulse arrival time of the voltage echo signal.

[0074] The controller and the processing circuit may be the same module or separated into different modules. The specific setting is selected according to the structure and cost. The corresponding structures may be ADC or TDC, FPGA or SoC.

[0075] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A laser receiving circuit, characterized in that: include: A plurality of photodetectors, each of the photodetectors being configured to convert a received laser pulse into a current signal; A plurality of signal amplifying circuits, each of which is connected to one of the photodetectors, and each of which is configured to amplify the current signal into a voltage echo signal; A channel switching circuit, the channel switching circuit comprising a plurality of input terminals and an output terminal, an input terminal of the channel switching circuit being connected to an output terminal of the signal amplifying circuit, the signal amplifying circuit being configured to be triggered by a received selection signal to sequentially select an input terminal and an output terminal of the signal amplifying circuit, and select and output the plurality of voltage echo signals; A high-pass filter circuit, connected to the channel switching circuit, and configured to perform high-pass filtering on each of the voltage echo signals; The negative pulse clamping circuit is connected to the high-pass filtering circuit and is configured to clamp the amplitude of the negative pulse signal in the filtered voltage echo signal to reduce the amplitude of the negative pulse signal to a preset amplitude and shorten the recovery time of the negative pulse signal.

2. The laser receiving circuit according to claim 1, characterized in that: The photodetector includes at least one of an avalanche diode, a silicon photomultiplier tube, a single photon avalanche diode, and a photodiode.

3. The laser receiving circuit according to claim 1, characterized in that: The signal amplifying circuit includes a transimpedance amplifier.

4. The laser receiving circuit according to claim 3, characterized in that: The high-pass filter circuit includes a first resistor and a first capacitor; The first end of the first capacitor constitutes the input end of the high-pass filter circuit, the second end of the first capacitor and the first end of the first resistor are connected together to constitute the output end of the high-pass filter circuit, and the second end of the first resistor is grounded.

5. The laser receiving circuit according to claim 4, characterized in that: The negative pulse clamping circuit includes a first diode; The anode of the first diode is connected to the positive power supply terminal and inputs a bias voltage, and the cathode of the first diode is connected to the output terminal of the high-pass filter circuit.

6. The laser receiving circuit according to claim 1, characterized in that: The signal amplification circuit includes a transimpedance amplifier and a differential amplifier; The input end of the transimpedance amplifier constitutes the input end of the signal amplification circuit, the output end of the transimpedance amplifier is connected to the non-inverting input end of the differential amplifier, and the non-inverting output end and the inverting output end of the differential amplifier constitute the output end of the signal amplification circuit.

7. The laser receiving circuit according to claim 6, characterized in that: The high-pass filter circuit includes a second resistor, a third resistor, a second capacitor and a third capacitor; The first end of the second capacitor and the first end of the third capacitor constitute the first input end and the second input end of the high-pass filter circuit respectively; the second end of the second capacitor is connected to the first end of the second resistor to constitute the first output end of the high-pass filter circuit; the second end of the third capacitor is connected to the second end of the third resistor to constitute the first output end of the high-pass filter circuit; the first end of the second resistor is grounded; the second end of the third resistor is connected to the positive power supply terminal and inputs a bias voltage.

8. The laser receiving circuit according to claim 7, characterized in that: The negative pulse clamping circuit comprises a fourth resistor, a fifth resistor and a second diode; The first end of the fourth resistor is grounded, the second end of the fourth resistor is connected to the cathode of the second diode to form the positive phase output end of the negative pulse clamping circuit, and the anode of the second diode is connected to the The first end of the fifth resistor is connected to the inverting output end of the negative pulse clamping circuit, and the second end of the fifth resistor is connected to the positive power supply end and inputs a bias voltage.

9. The laser receiving circuit according to claim 1, characterized in that: The channel switching circuit includes at least one analog switch, and multiple input terminals of at least one analog switch are respectively connected to the output terminal of a signal amplifying circuit, and the output terminals of each analog switch are connected together to form the output terminal of the analog switch circuit.

10. A laser radar, characterized in that: The invention comprises a laser transmitting circuit and a laser receiving circuit as claimed in any one of claims 1 to 9.

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