WO2023142315A1 - 脉冲信号的放大电路、回波信号接收系统及激光雷达 - Google Patents

脉冲信号的放大电路、回波信号接收系统及激光雷达 Download PDF

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WO2023142315A1
WO2023142315A1 PCT/CN2022/093944 CN2022093944W WO2023142315A1 WO 2023142315 A1 WO2023142315 A1 WO 2023142315A1 CN 2022093944 W CN2022093944 W CN 2022093944W WO 2023142315 A1 WO2023142315 A1 WO 2023142315A1
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module
pulse signal
current
compensation
voltage
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PCT/CN2022/093944
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English (en)
French (fr)
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李洪鹏
王百戈
郑睿童
沈罗丰
占顺宇
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探维科技(北京)有限公司
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Publication of WO2023142315A1 publication Critical patent/WO2023142315A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/487—Extracting wanted echo signals, e.g. pulse detection

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  • the present disclosure relates to the technical field of electronic circuit design, in particular to a pulse signal amplifying circuit, an echo signal receiving system and a laser radar.
  • Lidar is an active sensor that scans the surface of an object with a laser signal of a specific wavelength (such as a ranging light pulse) to obtain relevant characteristic information on the surface of the object.
  • a laser signal of a specific wavelength such as a ranging light pulse
  • lidar Compared with ordinary microwave radar, lidar has the advantages of high resolution, good concealment, strong anti-interference ability, small size and light weight.
  • the laser radars use pulsed lasers as the time-of-flight (TOF) ranging scheme at the transmitter; correspondingly, the receiver timing based on the received echo pulses to achieve ranging.
  • TOF time-of-flight
  • the laser radar that uses the integral photodetector device as the photoelectric conversion device at the receiving end, when the optical pulse signal of the echo pulse is strong, the falling edge of the waveform corresponding to the electrical signal moves backward, and the waveform widens, thereby affecting the pulse timing. , leading to measurement blind spots.
  • the technical problem to be solved in the present disclosure is to solve the problem of existing measurement blind spots.
  • embodiments of the present disclosure provide a pulse signal amplifying circuit, an echo signal receiving system, and a laser radar.
  • the embodiment of the present disclosure provides a pulse signal amplification circuit, which is characterized in that it includes: a photoelectric conversion module, an amplifier module, a feedback module, and a current compensation module;
  • the amplifier module includes a negative input terminal, a positive input terminal and an output terminal, and the positive input terminal is connected to a bias voltage;
  • the photoelectric conversion module is connected to the negative input terminal of the amplifier module through an electrical connection line; one end of the feedback module is connected to the electrical connection line, and the other end is connected to the output terminal of the amplifier module; the current compensation module is connected to To the electrical connection line;
  • the photoelectric conversion module is configured to convert the light pulse signal into a current pulse signal;
  • the amplifier module is configured to convert the current pulse signal into a voltage pulse signal, and amplifies it according to a preset multiple;
  • the feedback module is configured to control the The gain converted from the current pulse signal to the voltage pulse signal;
  • the current compensation module is set to be turned on when the instantaneous photocurrent in the current pulse signal exceeds the saturation threshold of the amplifier module, and the input compensation current and the feedback module are used The saturation current together constitutes the input current at the negative input terminal, so as to prevent the voltage at the negative input terminal from being pulled down.
  • the amplifier module includes a transimpedance amplifier
  • the feedback module includes a feedback resistor
  • the current compensation module includes a compensation power supply, a compensation diode and a compensation capacitor
  • the anode of the compensation diode is connected to the compensation power supply, and connected to the signal ground through the compensation capacitor; the cathode of the compensation diode is connected to the electrical connection line.
  • the conduction voltage drop of the compensation diode satisfies:
  • V D2 V clamp -V bia
  • V D2 represents the conduction voltage drop of the compensation diode
  • V clamp represents the output voltage of the compensation power supply
  • V bia represents the bias voltage of the positive input terminal.
  • the compensation capacitor has a capacitance within a preset capacitance range.
  • the transimpedance amplifier further includes a power supply terminal and a ground terminal, the power supply terminal is connected to a power supply voltage, and the ground terminal is connected to a signal ground;
  • the supply voltage is twice the bias voltage.
  • the photoelectric conversion module is a single point photodetector, a linear array photodetector or an area array photodetector.
  • the amplifying circuit further includes a shaping module, an analog-to-digital conversion module, and a data processing module;
  • the input end of the shaping module is connected to the output end of the amplifier module, the output end of the shaping module is connected to the input end of the analog-to-digital conversion module, and the output end of the analog-to-digital conversion module is connected to the data processing module;
  • the shaping module is configured to convert the amplified voltage pulse signal into a square wave pulse signal
  • the analog-to-digital conversion module is configured to convert the square wave pulse signal into a digital signal
  • the data processing module is configured to at least based on the The digital signal determines the receiving time of the optical pulse signal.
  • the shaping module includes a comparator
  • the analog-to-digital conversion module includes an analog-to-digital converter
  • the data processing module includes a timer
  • an embodiment of the present disclosure further provides an echo signal receiving system, including any amplification circuit provided in the first aspect.
  • an embodiment of the present disclosure further provides a lidar, including any echo signal receiving system provided in the second aspect.
  • the pulse signal amplifying circuit includes a photoelectric conversion module, an amplifier module, a feedback module, and a current compensation module;
  • the amplifier module includes a negative input terminal , positive input terminal and output terminal, the positive input terminal is connected to the bias voltage;
  • the photoelectric conversion module is connected to the negative input terminal of the amplifier module through the electrical connection line; one end of the feedback module is connected to the electrical connection line, and the other end is connected to the amplifier module.
  • the output terminal; the current compensation module is connected to the electrical connection line; wherein, the photoelectric conversion module is configured to convert the optical pulse signal into a current pulse signal; the amplifier module is configured to convert the current pulse signal into a voltage pulse signal, and amplify according to a preset multiple;
  • the feedback module is set to control the gain of the conversion of the current pulse signal to the voltage pulse signal; the current compensation module is set to be turned on when the instantaneous photocurrent in the current pulse signal exceeds the saturation threshold of the amplifier module, and the input compensation current and the saturation of the feedback module The current together constitutes the input current at the negative input terminal, so as to prevent the voltage at the negative input terminal from being pulled down.
  • the current compensation of the negative input terminal is performed through the current compensation module, so that the voltage of the negative input terminal is not pulled down, thereby avoiding the resulting widening of the output waveform, and then making it still correspond to the optical pulse signal when the energy of the optical pulse signal is strong.
  • the corresponding square wave is generated at the end time, so that the pulse width of the square wave signal is limited to a smaller maximum pulse width range, which reduces the maximum pulse width of the output signal of the comparator output module, which is conducive to improving timing accuracy. Reduce the ranging blind area of the lidar, thereby improving the performance index of the lidar.
  • FIG. 1 is a schematic diagram of a working principle of a laser radar provided by an embodiment of the present disclosure
  • FIG. 2 is a circuit system architecture diagram of a lidar receiving end in the related art
  • FIG. 3 is a schematic diagram of a comparator output waveform in the related art
  • FIG. 4 is a schematic diagram of waveform broadening in the related art
  • FIG. 5 is a schematic structural diagram of an amplifier circuit in the related art
  • FIG. 6 is a schematic structural diagram of an amplifier circuit provided by an embodiment of the present disclosure.
  • FIG. 7 is a schematic structural diagram of another amplifier circuit provided by an embodiment of the present disclosure.
  • FIG. 8 is a schematic structural diagram of another amplifier circuit provided by an embodiment of the present disclosure.
  • 01 photodetector
  • 02 transimpedance amplifier
  • 03 comparator
  • L01 waveform 1
  • L02 waveform 2
  • L03 waveform 3
  • Amplifying circuit of pulse signal referred to as "amplifying circuit" for short; 100. Electrical connecting wire; 110. Photoelectric conversion module; 120. Amplifier module; 121. Negative input terminal; 122. Positive input terminal; 123. Output terminal; 130. Feedback module; 140. Current compensation module; 150. Shaping module; 160. Analog-to-digital conversion module; 170. Data processing module; 30. Laser radar.
  • the pulse signal amplifying circuit provided by the embodiment of the present disclosure is a photocurrent amplifying circuit with a pulse width limiting function, which is mainly used in the receiving end of the pulsed time-of-flight laser radar, and realizes the limitation of the pulse width by current compensation. In this way, the maximum pulse width of the output signal of the amplifying circuit is limited within a relatively small range, thereby solving the problem of relatively large short-distance blind spots in the TOF laser radar in the related art.
  • the amplifying circuit of the pulse signal, the echo signal receiving system and the laser radar provided by the embodiments of the present disclosure are exemplarily described by comparing with related technologies.
  • FIG. 1 is a schematic diagram of a working principle of a lidar provided by an embodiment of the present disclosure.
  • the pulsed TOF laser radar 30 includes a transmitting end and a receiving end; wherein, the transmitting end sends out a distance-measuring light pulse, and at the same time triggers a timing chip as a START signal, and this moment is recorded as t 0 ; the light pulse passes through the measured target After the diffuse reflection, the echo pulse (that is, the light pulse signal) is detected and received by the receiving end, and after photoelectric conversion, it is used as a STOP signal to trigger the timing chip, and this moment is recorded as t1 ; thus, a distance measurement (timing) is completed .
  • the transmitting end sends out a distance-measuring light pulse, and at the same time triggers a timing chip as a START signal, and this moment is recorded as t 0 ; the light pulse passes through the measured target After the diffuse reflection, the echo pulse (that is, the light pulse signal
  • c represents the light speed of light in the current medium.
  • the photodetector can be a single point detector, a line array detector or an area array detector, such as an area array Avalanche photodiode (Avalanche Photo Diode, APD) detector, etc., and design the corresponding signal processing circuit to realize the processing of pulse signal.
  • APD Automatic Photo Diode
  • the echo signal receiving system in the laser radar can also include a focusing lens or lens group to realize the convergence of echo pulses, thereby improving the signal-to-noise ratio and improving detection accuracy sex.
  • the echo signal system in the lidar may also include other optical path elements or circuit elements known to those skilled in the art, which will not be repeated or limited here.
  • the echo signal system provided by the embodiments of the present disclosure can be applied to other types of radars in addition to the laser radar, so as to realize the corresponding detection, which is not limited herein.
  • FIG. 2 is a circuit system architecture diagram of a lidar receiving end in the related art.
  • this amplifying circuit is made up of photodetector 01, transimpedance amplifier (Trans-Impedance Amplifier, TIA) 02 and comparator 03, the signal that comparator 03 outputs is as the input of post-stage analog-to-digital conversion or timing circuit;
  • TIA Trans-Impedance Amplifier
  • a load resistor RL is used to replace the latter stage circuit in FIG. 2 , and the details thereof are not shown.
  • the photodetector 01 is an example of a common APD device that needs to be applied with a reverse bias voltage (such as -200V ⁇ -300V) and outputs a reverse photocurrent after being triggered by an optical signal.
  • the device corresponds to a wavelength of Triggered by a light pulse, a pulse current as shown in waveform 1 is generated, and the amplitude of the pulse current is on the order of ⁇ A; and then through the current-voltage conversion and amplification of the transimpedance amplifier 02, the signal waveform is converted into The pulse voltage shown in waveform 2, the amplitude of the pulse voltage is in the order of V.
  • the square wave pulse has an amplitude of A voltage signal whose value depends on the output signal specification of the comparator 01, such as a 3.3V or 5V transistor-transistor logic level (Transistor Transistor Logic, TTL) output signal or a 350mV low-voltage differential signal (Low-Voltage Differential Signaling , LVDS) output signal.
  • TTL Transistor Transistor Logic
  • LVDS Low-Voltage Differential Signaling
  • waveform 3 should be a square wave signal in theory, that is, the time of the rising edge and the falling edge are both infinitely small; in practical applications, since the comparator 03 has a fixed slew rate parameter, and it is used in pulsed laser radar
  • the pulse width of the optical pulse is generally small, for example, the pulse width is on the order of ns, which leads to a certain rising and falling edge time in the waveform actually output by the comparator 03 .
  • FIG. 3 is a schematic diagram of a comparator output waveform in the related art.
  • the time between the rising edge and the falling edge of waveform 3 is usually on the order of 100 ps, and the intermediate duration is usually on the order of ns.
  • waveform 3 affects the timing accuracy of the STOP signal. Therefore, accurately timing the waveform 3 and avoiding the aliasing of the waveform 3 of the previous measurement and the waveform 3 of the next measurement as much as possible is very important for the measurement accuracy and range of the laser radar. Specifically, if the duration of the previous waveform 3 is too long, for example, the energy of the echo pulse is too strong, resulting in a longer duration on the time axis (illustrated later in conjunction with FIG.
  • the outgoing panel of the lidar has a certain reflectivity (for example, the reflectivity is in the range of 3% to 5%).
  • the outgoing panel directly reflects part of the outgoing light back to the receiving end, resulting in a
  • the invalid echo with a long duration will simultaneously cause the effective echo generated by the measurement light of the outgoing part to be covered up, thereby creating a measurement blind area in a certain range at a short distance.
  • the amplifier circuit at the receiving end of the lidar needs to be able to provide a waveform 3 with a stable rising edge and a pulse duration as short as possible.
  • the duration of the pulse waveform is usually characterized by "pulse width" (that is, the pulse width).
  • pulse width that is, the pulse width
  • the half-maximum width is often used to represent the pulse width.
  • the timing chip adopts the method of setting thresholds for the rising edge and falling edge respectively for the timing of the pulse. As shown in Figure 3, the rising edge reaches a higher rising edge trigger threshold, and the falling edge reaches a lower falling edge trigger threshold to limit the pulse width. Tw can be used to represent the pulse width of the comparator output waveform.
  • L1 represents waveform 1
  • L2 represents waveform 2
  • L3 represents waveform 3
  • the waveform 2 output by the transimpedance amplifier will gradually enter Saturation state (that is, the maximum voltage reaches its saturated output voltage and cannot be further increased), and with the further increase of the optical pulse signal, the falling edge gradually moves backward, resulting in a continuous increase in pulse width.
  • the pulse width of the waveform 3 output by it will also increase accordingly, thereby affecting the pulse timing and resulting in a measurement blind zone.
  • the fundamental reason why the pulse width of the signal output by the entire amplifying circuit, that is, waveform 3, is widened is that the photodetector receives a strong optical pulse signal, and after being converted and amplified by the transimpedance amplifier, the output voltage signal exceeds the transimpedance The saturation voltage range of the amplifier, and caused the broadening of the output waveform of the transimpedance amplifier (ie, waveform 2).
  • FIG. 5 is a schematic structural diagram of an amplifier circuit in the related art.
  • NHV stands for negative high voltage, which is used to provide reverse bias voltage for photodetectors such as APD
  • D1 stands for photodetector
  • C1 stands for TIA input capacitance mainly based on the junction capacitance of photodetector
  • TIA stands for transimpedance amplifier ( That is, transimpedance amplifier)
  • RF represents the feedback resistance required by TIA, which is used to control the gain of current-voltage conversion
  • Vbia represents the DC bias voltage
  • C2 and RL represent the AC coupling load, which is used to simulate the post-stage circuit
  • I represents the light Current, the direction arrow represents the current flow
  • Vo represents the output signal of the TIA, corresponding to the aforementioned waveform 2
  • VCC represents the TIA single power supply voltage.
  • V o V bia +I ⁇ RF ,V o ⁇ VCC
  • the photocurrent I continues to increase until it is greater than the saturation value I 0 , the equilibrium state of the transimpedance amplifier is broken, the deep negative feedback fails, and the photocurrent I on the photodetector D1 continues to increase.
  • the feedback resistor The current of RF also needs to increase accordingly, and the voltage of the output signal Vo cannot be further increased, which will cause the voltage of the negative input terminal of the transimpedance amplifier to be pulled down, which will cause the positive input terminal and negative input terminal of the transimpedance amplifier to be pulled down. pressure difference between them.
  • the output signal Vo will remain saturated for a period of time until the feedback current drops to 0 under the negative feedback loop, that is, the feedback regulation of the feedback resistor RF, and the voltage of the positive input terminal and the negative input terminal Restore equal position.
  • the output waveform of the transimpedance amplifier is broadened, and the specific amount of broadening is determined by the energy of the photocurrent. The greater the energy of the photocurrent, the greater the amount of broadening.
  • an embodiment of the present disclosure proposes a photocurrent amplifier circuit with a pulse width limiting function, that is, an amplifier circuit for pulse signals.
  • the improvement points mainly focus on the control of the waveform of the output signal of the transimpedance amplifier.
  • the pulse width of the square wave signal output by the comparator module can still be limited to a smaller one when the energy of the optical pulse signal is strong.
  • the amplifying circuit of the pulse signal provided by the embodiment of the present disclosure will be exemplarily described below with reference to FIGS. 6-8 .
  • FIG. 6 is a schematic structural diagram of an amplification circuit provided by an embodiment of the present disclosure.
  • the amplifying circuit 10 of the pulse signal includes: a photoelectric conversion module 110, an amplifier module 120, a feedback module 130 and a current compensation module 140;
  • the amplifier module 120 includes a negative input terminal 121, a positive input terminal 122 and an output terminal 123, The positive input terminal 122 is connected to the bias voltage;
  • the photoelectric conversion module 110 is connected to the negative input terminal 121 of the amplifier module 120 through the electrical connection line 100; one end of the feedback module 130 is connected to the electrical connection line 100, and the other end is connected to the amplifier module 120.
  • the current compensation module 140 is connected to the electrical connection line 100; wherein, the photoelectric conversion module 110 is set to convert the light pulse signal into a current pulse signal; the amplifier module 120 is set to convert the current pulse signal into a voltage pulse signal, and according to the preset Set the multiple amplification; the feedback module 130 is set to control the gain of the current pulse signal to the voltage pulse signal conversion; the current compensation module 140 is set to be turned on when the instantaneous photocurrent in the current pulse signal exceeds the saturation threshold of the amplifier module 120, using the input
  • the compensation current and the saturation current of the feedback module 130 jointly constitute the input current of the negative input terminal 121 to prevent the voltage of the negative input terminal 121 from being pulled down.
  • the pulse signal may also be called an optical pulse signal, or an echo pulse;
  • the amplifying circuit of the pulse signal may also be called a photocurrent amplifying circuit, or an optical pulse amplifying circuit, which is not limited herein.
  • the photoelectric conversion module 110 can convert the light pulse signal into a current pulse signal, that is, realize photoelectric conversion, and transmit the current pulse signal to the comparator module 120 .
  • the amplifier module 120 can convert the current pulse signal into a voltage pulse signal, and amplify according to a preset multiple, that is, realize current-voltage gain amplification, and output it to the subsequent stage circuit; wherein, the preset multiple is determined by the feedback module 130, It can be any value that satisfies the requirement of gain amplification, and is not limited here.
  • the feedback module 130 can control the gain of converting the current pulse signal to the voltage pulse signal, that is, determine a preset multiple.
  • the current compensation module 140 can be turned on when the instantaneous photocurrent in the current pulse signal exceeds the saturation threshold of the amplifier module 120, and the input current of the negative input terminal 121 is formed jointly by the input compensation current and the saturation current of the feedback module 130, so as to avoid The voltage at the negative input 121 is pulled low.
  • the current compensation is performed through the current compensation module 140, so that the voltage of the negative input terminal 121 is not pulled down, thereby avoiding the resulting widening of the output waveform, and thus making the optical pulse signal energy stronger
  • the corresponding square wave is still generated corresponding to the end time of the optical pulse signal, so that the pulse width of the square wave signal is limited within a smaller maximum pulse width range, reducing the maximum pulse width of the output signal of the comparator output module, It is beneficial to improve the timing accuracy, reduce the ranging blind area of the lidar, and then improve the performance indicators such as the ranging range of the lidar.
  • FIG. 7 is a schematic structural diagram of another amplifier circuit provided by an embodiment of the present disclosure.
  • the amplifier module 120 includes a transimpedance amplifier TIA
  • the feedback module 130 includes a feedback resistor RF
  • the current compensation module 140 includes a compensation power supply Vclamp, a compensation diode D2 and a compensation capacitor C3; the anode of the compensation diode D2 It is connected to the compensation power supply Vclamp, and connected to the signal ground through the compensation capacitor C3; the cathode of the compensation diode D2 is connected to the electrical connection line 100 .
  • the amplifying circuit provided by the embodiment of the present disclosure can be applied to improve the amplifying circuit in the related art, so as to improve the applicability of the technical solution while limiting the pulse width and reduce the improvement cost.
  • a current compensation module is added on the basis of the amplification circuit shown in Figure 5, that is, a compensation power supply Vclamp, a compensation capacitor and a compensation diode D2 are added; wherein, the compensation capacitor C3 can provide instantaneous current and simultaneously act as a bypass The role of capacitance.
  • the compensation diode D2 starts to conduct, generating a compensation current I 1 , which is connected to the feedback resistor RF
  • the saturation current I 0 together constitutes the photocurrent I, so as to avoid the voltage of the negative input terminal of the transimpedance amplifier TIA from being pulled down, or even if it is pulled down, it can recover in a short time, thereby avoiding the resulting transimpedance amplifier TIA
  • the output waveform is widened to achieve pulse width limitation.
  • the conduction voltage drop of the compensation diode satisfies:
  • V D2 V clamp -V bia
  • V D2 represents the conduction voltage drop of the compensation diode
  • V clamp represents the output voltage of the compensation power supply
  • V bia represents the bias voltage of the positive input terminal 122 .
  • the voltage of the compensation diode D2 can make the compensation diode D2 turn on when the photocurrent I exceeds the saturation threshold I0, that is, the voltage at the negative input terminal is pulled down, and the current compensation is realized immediately, thereby avoiding the voltage at the negative input terminal of the transimpedance amplifier TIA. is continuously pulled low to avoid the resulting widening of the output waveform of the transimpedance amplifier TIA, thereby realizing pulse width limitation.
  • the voltage value of the compensation power supply Vclamp can also be obtained based on the above calculation formula.
  • the capacitance of the compensation capacitor C3 is within a preset capacitance range.
  • the capacitance value of the compensation capacitor D3 cannot be too large to ensure a faster discharge speed, thereby confirming that the compensation speed of the compensation current I1 is faster; at the same time, the capacitance value of the compensation capacitor D3 cannot be too small to ensure that it can store enough charge, thus providing sufficient compensation current I 1 .
  • the capacitance of the compensation capacitor C3 is strongly related to the magnitude of the photocurrent of the photoelectric conversion module 110; when the photocurrent is on the order of ⁇ A, the capacitance of the compensation capacitor C3 is on the order of 10 pF.
  • the capacitance of the compensation capacitor C3 will also change, as long as it meets the above requirements, its specific value is not limited here.
  • the compensation current I1 starts current compensation immediately to ensure that the current I0 of the path where the feedback resistor RF is located remains unchanged, and then the feedback of the transimpedance amplifier TIA
  • the voltage to the input terminal that is, the negative input terminal
  • I 0 instantaneously follows the decrease, therefore, the output signal of the output terminal of the transimpedance amplifier TIA
  • the pulse amplitude will drop immediately, and then the pulse width will not be widened, so as to realize the pulse width limitation of the output waveform of the transimpedance amplifier TIA (that is, the waveform 2 above), so as to realize the amplification circuit of the pulse signal the pulse width limit.
  • the minimum pulse width of the waveform 2 will not be smaller than the pulse width of the optical pulse signal (corresponding to the waveform 1).
  • the minimum pulse width of waveform 2 can only be 10ns, which is even better than the pulse width when it is in a saturated state; If it is steeper, the minimum pulse width of the actual saturation waveform will be slightly greater than 10ns, for example, it can reach 11-12ns or even larger, which is not limited here.
  • the transimpedance amplifier further includes a power terminal and a ground terminal, the power terminal is connected to the power supply voltage VCC, and the ground terminal is connected to the signal ground; wherein the power supply voltage VCC is twice the bias voltage Vbia.
  • the bias voltage for a single power supply voltage, by setting the bias voltage to half of the power supply voltage, the maximum up and down swing of the output signal can be guaranteed, thereby ensuring accurate waveform output.
  • bias voltage and the power supply voltage can also be set, which can be set based on the requirements of the amplifier circuit, and are not limited here.
  • the photoelectric conversion module 110 is a single point photodetector, a linear array photodetector or an area array photodetector.
  • the photoelectric conversion module is exemplarily described by taking the photodetector that needs to be applied with a reverse bias voltage and outputs a reverse photocurrent after being triggered by a light pulse signal as an example.
  • the photodetector in the photoelectric conversion module does not require the polarity and amplitude of the bias voltage and the polarity of the electrical signal after photoelectric conversion, and only needs to ensure that the output signal after conversion is a pulse
  • the electric current is sufficient, and is not limited here.
  • the photoelectric conversion module 110 can be correspondingly configured as a single point, line array or area array structure, so as to receive corresponding echo pulses.
  • the maximum pulse width of the output signal of the optical pulse amplifying circuit is limited within a smaller maximum pulse width range, such as 20ns, 10ns, 5ns, 3ns or a smaller pulse width range, thereby improving timing Accuracy, reducing the ranging blind area of the radar, and improving the performance index of the ranging range of the radar.
  • the pulse width can be further compressed by setting at least one of the compensation diode D2 and the compensation capacitor C3 , which is not limited herein.
  • FIG. 8 is a schematic structural diagram of another amplifier circuit provided by an embodiment of the present disclosure.
  • this amplifying circuit 10 can also comprise: shaping module 150, analog-to-digital conversion module 160 and data processing module 170;
  • the output end of 150 is connected to the input end of analog-to-digital conversion module 160, and the output end of analog-to-digital conversion module 160 is connected to data processing module 170;
  • Shaping module 150 is set to convert the amplified voltage pulse signal into a square wave pulse signal, and the analog-to-digital conversion
  • the module 160 is configured to convert the square wave pulse signal into a digital signal
  • the data processing module 170 is configured to determine the reception time of the optical pulse signal based at least on the digital signal.
  • the amplifier module 120 transmits the amplified voltage pulse signal to the shaping module 150; correspondingly, the shaping module 150 receives the amplified voltage pulse signal, and can convert the amplified voltage pulse signal into a square wave pulse signal; then The analog-to-digital conversion module 160 can convert the square wave pulse signal into a digital signal, and the data processing module 170 can at least determine the receiving time of the optical pulse signal based on the digital signal, so as to realize precise timing.
  • the shaping module 150 includes a comparator
  • the analog-to-digital conversion module 160 includes an analog-to-digital converter
  • the data processing module 170 includes a timer
  • the comparator performs waveform shaping on the amplified voltage pulse signal to generate a square wave signal; the analog-to-digital converter performs 01 conversion based on the square wave signal, the high level signal corresponds to 1, and the low level signal corresponds to 0 to generate a digital signal ; The timer counts based on the digital signal.
  • the above functional modules may also include other circuit elements known to those skilled in the art, or may be replaced with circuit modules having the same function known to those skilled in the art, which is not limited herein.
  • an embodiment of the present disclosure also provides an echo signal receiving system, the echo signal receiving system includes any amplifying circuit in the above-mentioned embodiments, and has corresponding beneficial effects. repeat.
  • an embodiment of the present disclosure also provides a laser radar, which includes any echo signal receiving system in the above-mentioned embodiments, and can use the pulse width-limited pulse signal to accurately locate the received signal. The time of the echo signal, thereby improving the detection accuracy and improving the problem of detection blind spots.
  • the lidar may also include a pulse signal transmitting system, and other structural components known to those skilled in the art, such as supporting components, optical components, and electrical components, which will not be repeated or limited here.
  • the current compensation of the negative input terminal is performed through the current compensation module, so that the voltage of the negative input terminal is not pulled down, thereby avoiding the widening of the output waveform caused by it , so that when the energy of the optical pulse signal is strong, the corresponding square wave is still generated corresponding to the end time of the optical pulse signal, so that the pulse width of the square wave signal is limited within a smaller maximum pulse width range, which reduces the comparison
  • the maximum pulse width of the output signal of the device output module is beneficial to improve the timing accuracy, reduce the ranging blind zone of the lidar, and then improve the performance index of the lidar.

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Abstract

本公开涉及脉冲信号的放大电路、回波信号接收系统及激光雷达，该放大电路包括光电转换模块、放大器模块、反馈模块以及电流补偿模块；放大器模块的正输入端接入偏置电压；光电转换模块通过电连接线连接至放大器模块的负输入端，反馈模块连接在电连接线与放大器模块的输出端之间，电流补偿模块连接至电连接线；光电转换模块将光脉冲信号转换为电流脉冲信号；放大器模块将电流脉冲信号转换为电压脉冲信号并放大；反馈模块控制电流脉冲信号向电压脉冲信号转换的增益；电流补偿模块在电流脉冲信号中的瞬时光电流超过放大器模块的饱和阈值时导通，利用输入的补偿电流进行电流补偿，以免负输入端的电压被拉低，避免脉宽展宽，进而限制脉宽，改善盲区。

Description

脉冲信号的放大电路、回波信号接收系统及激光雷达
本公开要求于2022年01月28日提交中国专利局、申请号为202210103783.0、发明名称为“脉冲信号的放大电路、回波信号接收系统及激光雷达”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及电子电路设计技术领域，尤其涉及一种脉冲信号的放大电路、回波信号接收系统及激光雷达。
背景技术
激光雷达是一种主动式传感器，其利用特定波长的激光信号(例如测距光脉冲)对物体表面进行扫描来获取物体表面的相关特性信息。与普通微波雷达相比，激光雷达具有分辨率高、隐蔽性好、抗干扰能力强、体积小以及质量轻等优点。
目前，激光雷达大都采用脉冲激光器作为发射端的飞行时间法(Time Of Flight，TOF)的测距方案；对应的，接收端基于接收到的回波脉冲计时，以实现测距。其中，在采用积分式光电探测器件作为接收端的光电转换器件的激光雷达中，由于回波脉冲的光脉冲信号较强时，电信号对应的波形的下降沿后移，波形展宽，从而影响脉冲计时，导致测量盲区。
发明内容
(一)要解决的技术问题
本公开要解决的技术问题是解决现有的测量盲区的问题。
(二)技术方案
为了解决上述技术问题，本公开实施例提供了一种脉冲信号的放大电路、回波信号接收系统及激光雷达。
第一方面，本公开实施例提供了一种脉冲信号的放大电路，其特征在于，包括：光电转换模块、放大器模块、反馈模块以及电流补偿模块；
所述放大器模块包括负输入端、正输入端和输出端，所述正输入端接入偏置电压；
所述光电转换模块通过电连接线连接至所述放大器模块的负输入端；所述反馈模块的一端连接至电连接线，另一端连接至所述放大器模块的输出端；所述电流补偿模块连接至电连接线；
其中，所述光电转换模块设置为将光脉冲信号转换为电流脉冲信号；所述放大器模块设置为将电流脉冲信号转换为电压脉冲信号，并按照预设倍数放大；所述反馈模块设置为控制所述电流脉冲信号向所述电压脉冲信号转换的增益；所述电流补偿模块设置为在电流脉冲信号中的瞬时光电流超过所述放大器模块的饱和阈值时导通，利用输入的补偿电流与反馈模块的饱和电流共同构成负输入端的输入电流，以免负输入端的电压被拉低。
在一些实施例中，所述放大器模块包括跨阻放大器，所述反馈模块包括反馈电阻，所述电流补偿模块包括补偿电源、补偿二极管和补偿电容；
所述补偿二极管的正极连接至所述补偿电源，并通过所述补偿电容连接信号地；所述补偿二极管的负极连接至所述电连接线。
在一些实施例中，所述补偿二极管的导通压降满足：
V D2＝V clamp-V bia
其中，V D2代表补偿二极管的导通压降，V clamp代补偿电源的输出电压，V bia代表正输入端的偏置电压。
在一些实施例中，所述补偿电容的容值在预设电容范围内。
在一些实施例中，所述跨阻放大器还包括电源端和接地端，所述电源端接入供电电压，所述接地端连接信号地；
其中，所述供电电压为所述偏置电压的2倍。
在一些实施例中，所述光电转换模块为单点光电探测器、线阵光电探测器或面阵光电探测器。
在一些实施例中，该放大电路还包括整形模块、模数转换模块和数据处理模块；
所述整形模块的输入端连接所述放大器模块的输出端，所述整形模块的输出端连接所述模数转换模块的输入端，所述模数转换模块的输出端连接所述数据处理模块；
所述整形模块设置为将放大后的电压脉冲信号转换为方波脉冲信号，所述模数转换模块设置为将所述方波脉冲信号转换为数字信号，所述数据处理模块设置为至少基于所述数字信号确定光脉冲信号的接收时间。
在一些实施例中，所述整形模块包括比较器，所述模数转换模块包括模数转换器，所述数据处理模块包括计时器。
第二方面，本公开实施例还提供了一种回波信号接收系统，包括第一方面提供的任一种放大电路。
第三方面，本公开实施例还提供了一种激光雷达，包括第二方面提供的任一种回波信号接收系统。
(三)有益效果
本公开实施例提供的上述技术方案与现有技术相比具有如下优点：
本公开实施例提供的该脉冲信号的放大电路、回波信号接收系统及激光雷达中，该脉冲信号的放大电路包括光电转换模块、放大器模块、反馈模块以及电流补偿模块；放大器模块包括负输入端、正输入端和输出端，正输入端接入偏置电压；光电转换模块通过电连接线连接至放大器模块的负输入端；反馈模块的一端连接至电连接线，另一端连接至放大器模块的输出端；电流补偿模块连接至电连接线；其中，光电转换模块设置为将光脉冲信号转换为电流脉冲信号；放大器模块设置为将电流脉冲信号转换为电压脉冲信号，并按照预设倍数放大；反馈模块设置为控制电流脉冲信号向电压脉冲信号转换的增益；电流补偿模块设置为在电流脉冲信号中的瞬时光电流超过放大器模块的饱和阈值时导通，利用输入的补偿电流与反馈模块的饱和电流共同构成负输入端的输入电流，以免负输入端的电压被拉低。由此，通过电流 补偿模块进行负输入端的电流补偿，使得负输入端的电压不被拉低，从而避免由此导致的输出波形展宽，进而使得在光脉冲信号能量较强时依旧对应于光脉冲信号的结束时间生成对应的方波，从而使得方波信号脉宽限制在一个较小的最大脉宽范围之内，减小了比较器输出模块的输出信号的最大脉宽，利于提高计时精准性，减小激光雷达的测距盲区，进而提升激光雷达性能指标。
应当理解的是，以上的一般描述和后文的细节描述仅是示例性和解释性的，并不能限制本公开。
附图说明
此处的附图被并入说明书中并构成本说明书的一部分，示出了符合本公开的实施例，并与说明书一起用于解释本公开的原理。
为了更清楚地说明本公开实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，对于本领域普通技术人员而言，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为本公开实施例提供的一种激光雷达的工作原理示意图；
图2为相关技术中激光雷达接收端的电路系统架构图；
图3为相关技术中比较器输出波形示意图；
图4为相关技术中波形展宽示意图；
图5为相关技术中放大电路的结构示意图；
图6为本公开实施例提供的一种放大电路的结构示意图；
图7为本公开实施例提供的另一种放大电路的结构示意图；
图8为本公开实施例提供的又一种放大电路的结构示意图。
其中，相关技术中：01、光电探测器；02、跨阻放大器；03、比较器；L01、波形1；L02、波形2；L03、波形3；
本公开实施例中：10、脉冲信号的放大电路，简称为“放大电路”；100、电连接线；110、光电转换模块；120、放大器模块；121、负输入端；122、正输入端；123、输出端；130、反馈模块；140、电流补偿模块；150、整形模块；160、模数转换模块；170、数据处理模块；30、激光雷达。
具体实施方式
为使本公开实施例的目的、技术方案和优点更加清楚，下面将对本公开实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本公开的一部分实施例，而不是全部的实施例。基于本公开中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都属于本公开保护的范围。
本公开实施例提供的脉冲信号的放大电路为具有脉宽限制功能的光电流放大电路，主要应用于脉冲式时间飞行法激光雷达的接收端中，通过电流补偿，实现对脉宽展宽的限制，从而将放大电路的输出信号的最大脉宽限制在一个较小的范围之内，进而解决相关技术中TOF激光雷达存在的近距离盲区较大的问题。
下面，通过与相关技术的对比，对本公开实施例提供的脉冲信号的放大电路、回波信号接收系统及激光雷达进行示例性说明。
示例性的，图1为本公开实施例提供的一种激光雷达的工作原理示意图。参照图1，该脉冲式TOF激光雷达30包括发射端和接收端；其中，发射端发出测距光脉冲，并同时作为START信号触发计时芯片，该时刻记录为t 0；光脉冲经过被测目标的漫反射之后，回波脉冲(即光脉冲信号)被接收端探测接收，经过光电转换之后，作为STOP信号触发计时芯片，该时刻记录为t 1；如此，便完成了一次测距(计时)。
其中，△t＝t 1-t 0即为本次计时中，光脉冲的飞行时间，利用光速进行“时间-距离转换”即可获得最终的测距结果，即：l＝△t×c/2。其中，c代表光在当前介质中的光速。
对于上述激光雷达中的接收端，至少需要一片符合激光雷达对于探测单元数需求的光电探测器，该光电探测器可为单点探测器、线阵探测器或面阵探测器，例如面阵的雪崩光电二极管(Avalanche Photo Diode，APD)探测器等，并设计对应的信号处理电路，以实现对脉冲信号的处理。
在一些实施例中，激光雷达中的回波信号接收系统除包括光电探测器之外，还可包括聚焦透镜或透镜组，以实现对回波脉冲的汇聚，进而提高信噪比，提高探测精准性。
在其他实施方式中，激光雷达中的回波信号系统还可包括本领域技术人员可知的其他光路元件或电路元件，在此不赘述也不限定。
本公开实施例提供的回波信号系统除应用于激光雷达中之外，还可应用于其他类型的雷达中，以实现对应的探测，在此不限定。
下面，通过与相关技术的对比，说明本公开实施例提供的放大电路的改进点及对应的有益效果。
示例性的，图2为相关技术中激光雷达接收端的电路系统架构图。参照图2，该放大电路由光电探测器01、跨阻放大器(Trans-Impedance Amplifier，TIA)02以及比较器03组成，比较器03输出的信号作为后级模数转换或计时电路的输入；因为本公开实施例的改进点与后级电路无关，因此，图2中采用一个负载电阻RL替代后级电路，而未展示其中的细节。
示例性的，光电探测器01以常见的需要施加反向偏置电压(如-200V～-300V)，在被光信号触发后输出反向光电流的APD器件为例，该器件在外界对应波长的光脉冲触发之下，产生如波形1所示的脉冲电流，该脉冲电流的幅值约在μA量级；而后经过跨阻放大器02的电流-电压转换以及放大，该信号波形被转换为如波形2所示的脉冲电压，该脉冲电压的幅值约在V量级，波形2经过比较器03进行波形整形后，再次转换为如波形3所示的方波脉冲，该方波脉冲为幅值随比较器01的输出信号规格而定的电压信号，如3.3V或5V的晶体管-晶体管逻辑电平(Transistor Transistor Logic，TTL)的输出信号或350mV的低电压差分信号(Low-Voltage Differential Signaling，LVDS)的输出信号。
其中，波形3在理论上应为方波信号，即上升沿和下降沿的时间均无限小；而实际应用中，由于比较器03均存在一个固定的摆率参数，且应用于脉冲式激光雷达的光脉冲通常脉宽较小，例如脉宽在ns量级，这就导致比较器03实际输出的波形存在一定的上升沿和下降沿时间。
示例性的，图3为相关技术中比较器输出波形示意图。参照图3，在激光雷达中，波形3的上升沿与下降沿的时间通常在100ps量级，而中间持续时间通常在ns量级。
对于TOF激光雷达而言，每次测量所获取的距离信息就是由波形 3所携带，具体的，波形3影响着STOP信号的计时精度。由此，准确地对波形3进行计时，同时尽可能避免前一次测量的波形3与后一次测量的波形3产生混叠，对于激光雷达的测量精度以及测距范围至关重要。具体的，如果前一次波形3持续时间过长，例如回波脉冲的能量过强导致其在时间轴上产生较长的持续时间(后文中结合图4进行示例性说明)，以至于后一次测量的波形3整体或上升沿被其覆盖或影响，会导致后一次测量无法进行计时或无法进行准确计时，从而导致后一次测量精度下降，甚至会产生测量盲区，即后一次测量与前一次测量一定距离范围内时均无法进行计时，相当于这个距离范围内雷达无法获取任何物体的测量信息，由此产生测量盲区。
上述情况通常出现在激光雷达的出射面板存在一定的反射率(例如反射率在3％～5％范围内)的场景下，此时，出射面板将出射光的一部分直接反射回接收端，产生一个持续时间较长的无效回波，同时导致出射部分的测量光产生的有效回波被掩盖，进而产生近距离一定范围的测量盲区。
针对此，为减小测距盲区，需要激光雷达的接收端的放大电路能够提供上升沿稳定、脉冲持续时间尽可能短的波形3。
下面结合图3、图4和图5，对波形展宽的原因进行示例性说明。
首先，脉冲波形的持续时间通常采用“脉宽”(即脉冲宽度)进行表征，在数据分析中，常用半高宽代表脉宽。但在雷达系统(例如激光雷达)中，为了避免误触发，计时芯片对于脉冲的计时采用上升沿和下降沿分别设定阈值的方式。如图3所示，以上升沿达到一个较高的上升沿触发阈值，下降沿达到一个较低的下降沿触发阈值来限定脉宽，即可采用Tw表示比较器输出波形的脉宽。
对于积分式光电探测器件，即光能量与被转换成的电能量线性相关，光信号能量越强，输出的电信号幅值也越大的光电转换器件，例如APD、增益较低的PIN(Positive Intrinsic-Negative)光电二极管等，其波形展宽示意图如图4所示。其中，L1代表波形1，L2代表波形2，L3代表波形3；基于三个波形之间的转换关系可知，随着接收到的光脉冲信号逐渐增大，跨阻放大器输出的波形2会逐渐进入饱和状态(即 电压最大值达到其饱和输出电压，无法进一步提升)，并随着光脉冲信号的进一步增大，下降沿逐渐后移，从而导致脉宽持续增大。由前述比较器的触发原理可知，其输出的波形3的脉宽也会随之增大，进而影响到脉冲计时，导致测量盲区。
由此，整个放大电路输出的信号，即波形3，其脉宽被展宽的根本原因是光电探测器接收到较强的光脉冲信号，经过跨阻放大器转换放大之后，输出的电压信号超过跨阻放大器的饱和电压范围，并引起了跨阻放大器输出波形(即波形2)的展宽。
具体的，图5为相关技术中放大电路的结构示意图。其中，NHV代表负高压，用于给APD等光电探测器提供反向偏置电压；D1代表光电探测器；C1代表以光电探测器的结电容为主的TIA输入电容；TIA代表互阻抗放大器(即跨阻放大器)；RF代表TIA所需的反馈电阻，用于控制电流-电压转换的增益；Vbia代表直流偏置电压；C2和RL代表交流耦合负载，用于模拟后级电路；I代表光电流，方向箭头代表电流流向；Vo代表TIA的输出信号，对应前述的波形2；VCC代表TIA单电源供电电压。
由图5的示意图可知，跨阻放大器的输出信号Vo表示为：
V o＝V bia+I×R F，V o≤VCC
由上式可知，光电流I增大，输出信号Vo会同步增大，但受限于单电源供电电压VCC，输出信号Vo的最大值只能达到单电源供电电压VCC，因而光电流I存在一个饱和值，如下：
Figure PCTCN2022093944-appb-000001
而当光电流I持续增大直到大于饱和值I 0后，跨阻放大器的平衡状态被打破，深度负反馈失效，光电探测器D1上的光电流I还在持续增大，此时，反馈电阻RF的电流随之也需要增大，而输出信号Vo的电压已经无法进一步增大，从而会导致跨阻放大器的负输入端的电压被拉低，进而导致跨阻放大器的正输入端和负输入端之间产生压差。因而即使光脉冲信号的持续时间已经结束，输出信号Vo仍然会保持饱和一段时间，直到在负反馈回路，即反馈电阻RF的反馈调节下，反馈电 流降为0，正输入端和负输入端的电压恢复相等位置。由此，导致了跨阻放大器的输出波形产生展宽，具体的展宽量，则由光电流的能量大小来决定，光电流的能量越大，展宽量越大。
为了解决上述脉冲式激光雷达由于脉宽展宽带来的测距盲区问题，本公开实施例提出了一种具有脉宽限制功能的光电流放大电路，即脉冲信号的放大电路，其相对于相关技术的改进点主要集中于对于跨阻放大器的输出信号的波形的控制上，通过电流补偿，可以在光脉冲信号能量较强时依旧将比较器模块输出的方波信号脉宽限制在一个较小的最大脉宽范围之内，从而减小了比较器输出模块的输出信号的最大脉宽，有利于提高计时精准性，减小激光雷达的测距盲区，进而提升激光雷达的测距范围等性能指标。
下面结合图6-图8，对本公开实施例提供的脉冲信号的放大电路进行示例性说明。
在一些实施例中，图6为本公开实施例提供的一种放大电路的结构示意图。参照图6，该脉冲信号的放大电路10，包括：光电转换模块110、放大器模块120、反馈模块130以及电流补偿模块140；放大器模块120包括负输入端121、正输入端122和输出端123，正输入端122接入偏置电压；光电转换模块110通过电连接线100连接至放大器模块120的负输入端121；反馈模块130的一端连接至电连接线100，另一端连接至放大器模块120的输出端；电流补偿模块140连接至电连接线100；其中，光电转换模块110设置为将光脉冲信号转换为电流脉冲信号；放大器模块120设置为将电流脉冲信号转换为电压脉冲信号，并按照预设倍数放大；反馈模块130设置为控制电流脉冲信号向电压脉冲信号转换的增益；电流补偿模块140设置为在电流脉冲信号中的瞬时光电流超过放大器模块120的饱和阈值时导通，利用输入的补偿电流与反馈模块130的饱和电流共同构成负输入端121的输入电流，以免负输入端121的电压被拉低。
其中，脉冲信号也可称为光脉冲信号，或者称为回波脉冲；脉冲信号的放大电路也可称为光电流放大电路，或者称为光脉冲放大电路，在此不限定。
其中，该放大电路10中，光电转换模块110能够将光脉冲信号转换为电流脉冲信号，即实现光电转换，并将电流脉冲信号传输至比较器模块120。继而，放大器模块120能够将电流脉冲信号转换为电压脉冲信号，并按照预设倍数放大，即实现电流-电压的增益放大，并输出至后级电路；其中，预设倍数由反馈模块130决定，可为满足增益放大需求的任意数值，在此不限定。
其中，反馈模块130能够控制电流脉冲信号向电压脉冲信号转换的增益，即决定预设倍数。
其中，电流补偿模块140能够在电流脉冲信号中的瞬时光电流超过放大器模块120的饱和阈值时导通，利用输入的补偿电流与反馈模块130的饱和电流共同构成负输入端121的输入电流，以免负输入端121的电压被拉低。
结合上文，若放大器模块120的负输入端121的电压被拉低，则会导致放大器模块120的正输入端122和负输入端121之间产生压差，进而导致即使光脉冲信号的持续时间已经结束，放大器模块120的输出端123的输出信号仍然会保持饱和一段时间，进而导致脉宽展宽。
由此，本公开实施例中，通过电流补偿模块140进行电流补偿，使得负输入端121的电压不被拉低，从而避免由此导致的输出波形展宽，进而使得在光脉冲信号能量较强时依旧对应于光脉冲信号的结束时间生成对应的方波，从而使得方波信号脉宽限制在一个较小的最大脉宽范围之内，减小了比较器输出模块的输出信号的最大脉宽，利于提高计时精准性，减小激光雷达的测距盲区，进而提升激光雷达的测距范围等性能指标。
在一些实施例中，图7为本公开实施例提供的另一种放大电路的结构示意图。在图6的基础上，参照图7，放大器模块120包括跨阻放大器TIA，反馈模块130包括反馈电阻RF，电流补偿模块140包括补偿电源Vclamp、补偿二极管D2和补偿电容C3；补偿二极管D2的正极连接至补偿电源Vclamp，并通过补偿电容C3连接信号地；补偿二极管D2的负极连接至电连接线100。
将图7与图5进行对比可知，本公开实施例提供的放大电路，可 应用于对相关技术中的放大电路进行改进，以在限制脉宽的同时，提高该技术方案的适用性，降低改进成本。
具体的，在图5示出的放大电路的基础上增加电流补偿模块，即增加一个补偿电源Vclamp、一个补偿电容和一个补偿二极管D2；其中，补偿电容C3能够提供瞬时电流，同时起到旁路电容的作用。在该放大电路中，当光电流I超过饱和阈值I 0，导致负输入端的电压被拉低时，补偿二极管D2开始导通，产生一个补偿电流I 1，该补偿电流I 1与反馈电阻RF上的饱和电流I 0共同组成光电流I，从而避免跨阻放大器TIA的负输入端的电压被拉低，或其即使被拉低也能在短时间内恢复，从而避免由此导致的跨阻放大器TIA的输出波形展宽，进而实现脉宽限制。
在一些实施例中，补偿二极管的导通压降满足：
V D2＝V clamp-V bia
其中，V D2代表补偿二极管的导通压降，V clamp代补偿电源的输出电压，V bia代表正输入端122的偏置电压。
其中，补偿二极管D2的电压能够使得补偿二极管D2在光电流I超过饱和阈值I0，即负输入端的电压被拉低的瞬间导通，即刻实现电流补偿，进而避免跨阻放大器TIA的负输入端的电压被持续拉低，避免由此导致的跨阻放大器TIA的输出波形展宽，进而实现脉宽限制。
在一些实施例中，当补偿二极管D2的导通压降为已知量时，还可基于上述计算公式得到补偿电源Vclamp的电压值。
在一些实施例中，补偿电容C3的容值在预设电容范围内。
其中，补偿电容D3的容值不能过大，以确保较快的放电速度，从而确证补偿电流I 1的补偿速度较快；同时，补偿电容D3的容值不能过小，以确保能够存储足够的电荷量，从而提供足够的补偿电流I 1。
示例性的，补偿电容C3的容值与光电转换模块110的光电流的大小强相关；当光电流为μA量级时，补偿电容C3的容值为10pF量级。
在其他实施方式中，随着放大电路中的其他功能模块或电路元件的器件参数变化，补偿电容C3的容值也会发生变化，满足上述需求即可，在此对其具体取值不作限定。
本公开实施例中，当光电流I的值达到饱和电流值或以上，补偿电流I 1开始立刻进行电流补偿，保证反馈电阻RF所在通路的电流I 0保持不变，进而跨阻放大器TIA的反向输入端(即负输入端)的电压保持不变；而当光电流I的值减小到饱和电流值以下时，I 0瞬时跟随减小，因此，跨阻放大器TIA的输出端的输出信号的脉冲幅度会立刻随之下降，进而脉宽不会产生展宽，从而实现对跨阻放大器TIA的输出波形(即上文中的波形2)脉宽限制的作用，由此可实现对脉冲信号的放大电路的脉宽限制。
能够理解的是，波形2的脉宽最小不会小于光脉冲信号(对应于波形1)的脉宽。例如，光脉冲信号的实际脉宽为10ns时，波形2的脉宽最小只能为10ns，甚至优于其处于饱和态时的脉宽；其上升/下降沿相较理想高斯脉冲形态的光脉冲较陡，实际饱和波形的脉宽最小也会略大于10ns，如可达到11～12ns甚至更大，在此不限定。
在一些实施例中，继续参照图7，跨阻放大器还包括电源端和接地端，电源端接入供电电压VCC，接地端连接信号地；其中，供电电压VCC为偏置电压Vbia的2倍。
其中，对于单电源供电电压，通过将偏置电压设置为供电电压的一半，能够保证输出信号的上下摆幅最大，从而确保波形精准输出。
在其他实施方式中，当采用其他电源供电方式时，还可设置偏置电压与供电电压之间满足其他的倍数关系，可基于放大电路的需求设置，在此不限定。
在一些实施例中，光电转换模块110为单点光电探测器、线阵光电探测器或面阵光电探测器。
上文中，以需要施加反向偏置电压，且在被光脉冲信号触发后输出反向光电流的光电探测器为例，对光电转换模块进行了示例性说明。
在其他实施方式中，光电转换模块中的光电探测器，对于偏置电压的极性、幅值以及光电转换后电信号的极性均不做要求，仅需保证其转换后输出的信号为脉冲电流即可，在此不限定。
同时，基于发射端的探测光脉冲的类型，光电转换模块110可对应设置为单点、线阵或面阵结构，以实现接收对应的回波脉冲。
本公开实施例中，将光脉冲放大电路的输出信号最大脉宽限制在一个较小的最大脉宽范围之内，例如20ns、10ns、5ns、3ns或更小的脉宽范围，从而提高了计时精度，减小了雷达的测距盲区，提升了雷达的测距范围性能指标。
在其他实施方式中，还可以通过对补偿二极管D2和补偿电容C3中的至少一者的设置，进一步压缩脉宽，在此不限定。
在一些实施例中，图8为本公开实施例提供的又一种放大电路的结构示意图。在图6的基础上，参照图8，该放大电路10还可包括：整形模块150、模数转换模块160和数据处理模块170；整形模块150的输入端连接放大器模块120的输出端，整形模块150的输出端连接模数转换模块160的输入端，模数转换模块160的输出端连接数据处理模块170；整形模块150设置为将放大后的电压脉冲信号转换为方波脉冲信号，模数转换模块160设置为将方波脉冲信号转换为数字信号，数据处理模块170设置为至少基于数字信号确定光脉冲信号的接收时间。
其中，放大器模块120将放大后的电压脉冲信号传输至整形模块150；对应的，整形模块150接收该放大后的电压脉冲信号，并能够将放大后的电压脉冲信号转换为方波脉冲信号；继而，模数转换模块160能够将方波脉冲信号转换为数字信号，数据处理模块170能够至少基于数字信号确定光脉冲信号的接收时间，从而实现精准计时。
在一些实施例中，整形模块150包括比较器，模数转换模块160包括模数转换器，数据处理模块170包括计时器。
其中，比较器将放大后的电压脉冲信号进行波形整形，生成方波信号；模数转换器基于方波信号进行01转换，高电平信号对应1，低电平信号对应0，以生成数字信号；计时器基于数字信号进行计时。
在其他实施方式中，上述各功能模块还可包括本领域技术人员可知的其他电路元件，或者可替换为本领域技术人员可知的具有相同功能的电路模块，在此不限定。
在上述实施方式的基础上，本公开实施例还提供了一种回波信号接收系统，该回波信号接收系统包括上述实施方式中的任一种放大电 路，具有对应的有益效果，在此不赘述。
在上述实施方式的基础上，本公开实施例还提供了一种激光雷达，该激光雷达包括上述实施方式中的任一种回波信号接收系统，能够利用脉宽限制的脉冲信号精准定位接收到回波信号的时间，从而提高探测准确性，改善探测盲区的问题。
在其他实施方式中，激光雷达还可包括脉冲信号发射系统，以及其他支撑部件、光学元件以及电学元件等本领域技术人员可知的结构部件，在此不赘述也不限定。
需要说明的是，在本文中，诸如“第一”和“第二”等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
以上所述仅是本公开的具体实施方式，使本领域技术人员能够理解或实现本公开。对这些实施例的多种修改对本领域的技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本公开的精神或范围的情况下，在其它实施例中实现。因此，本公开将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。
工业实用性
本公开公开的脉冲信号的放大电路、回波信号接收系统及激光雷达中，通过电流补偿模块进行负输入端的电流补偿，使得负输入端的电压不被拉低，从而避免由此导致的输出波形展宽，进而使得在光脉 冲信号能量较强时依旧对应于光脉冲信号的结束时间生成对应的方波，从而使得方波信号脉宽限制在一个较小的最大脉宽范围之内，减小了比较器输出模块的输出信号的最大脉宽，利于提高计时精准性，减小激光雷达的测距盲区，进而提升激光雷达性能指标。

Claims (10)

  1. 一种脉冲信号的放大电路，包括：光电转换模块、放大器模块、反馈模块以及电流补偿模块；
    所述放大器模块包括负输入端、正输入端和输出端，所述正输入端接入偏置电压；
    所述光电转换模块通过电连接线连接至所述放大器模块的负输入端；所述反馈模块的一端连接至电连接线，另一端连接至所述放大器模块的输出端；所述电流补偿模块连接至电连接线；
    其中，所述光电转换模块设置为将光脉冲信号转换为电流脉冲信号；所述放大器模块设置为将电流脉冲信号转换为电压脉冲信号，并按照预设倍数放大；所述反馈模块设置为控制所述电流脉冲信号向所述电压脉冲信号转换的增益；所述电流补偿模块设置为在电流脉冲信号中的瞬时光电流超过所述放大器模块的饱和阈值时导通，利用输入的补偿电流与反馈模块的饱和电流共同构成负输入端的输入电流，以免负输入端的电压被拉低。
  2. 根据权利要求1所述的放大电路，其中，所述放大器模块包括跨阻放大器，所述反馈模块包括反馈电阻，所述电流补偿模块包括补偿电源、补偿二极管和补偿电容；
    所述补偿二极管的正极连接至所述补偿电源，并通过所述补偿电容连接信号地；所述补偿二极管的负极连接至所述电连接线。
  3. 根据权利要求2所述的放大电路，其中，所述补偿二极管的导通压降满足：
    V D2＝V clamp-V bia
    其中，V D2代表补偿二极管的导通压降，V clamp代补偿电源的输出电压，V bia代表正输入端的偏置电压。
  4. 根据权利要求2所述的放大电路，其中，所述补偿电容的容值在预设电容范围内。
  5. 根据权利要求2所述的放大电路，其中，所述跨阻放大器还包括电源端和接地端，所述电源端接入供电电压，所述接地端连接信号 地；
    其中，所述供电电压为所述偏置电压的2倍。
  6. 根据权利要求1-5任一项所述的放大电路，其中，所述光电转换模块为单点光电探测器、线阵光电探测器或面阵光电探测器。
  7. 根据权利要求1-5任一项所述的放大电路，还包括整形模块、模数转换模块和数据处理模块；
    所述整形模块的输入端连接所述放大器模块的输出端，所述整形模块的输出端连接所述模数转换模块的输入端，所述模数转换模块的输出端连接所述数据处理模块；
    所述整形模块设置为将放大后的电压脉冲信号转换为方波脉冲信号，所述模数转换模块设置为将所述方波脉冲信号转换为数字信号，所述数据处理模块设置为至少基于所述数字信号确定光脉冲信号的接收时间。
  8. 根据权利要求7所述的放大电路，其中，所述整形模块包括比较器，所述模数转换模块包括模数转换器，所述数据处理模块包括计时器。
  9. 一种回波信号接收系统，包括权利要求1-8任一项所述的放大电路。
  10. 一种激光雷达，包括权利要求9所述的回波信号接收系统。
PCT/CN2022/093944 2022-01-28 2022-05-19 脉冲信号的放大电路、回波信号接收系统及激光雷达 WO2023142315A1 (zh)

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