Driving device for light emitting device of laser radar and laser radar

Abstract

The present invention provides a driving device for a light-emitting device of a laser radar and a laser radar including the driving device. The driving device includes: a driving control module, which is connected to a power supply and is configured to receive an input pulse signal and a digital control signal and output a control level signal; wherein the digital control signal is used to adjust the magnitude of the control level signal output by the driving control module, and the pulse signal is used to control whether the driving control module outputs the driving level signal; and a driving module, which is connected to the driving control module and the power supply and is used to provide a driving current to the light-emitting device of the laser radar based on the driving level signal to drive the light-emitting device to emit light. The solution of the present invention not only reduces the DC power consumption of the driving circuit, but also solves the problem of inconsistency of multiple pulse light signals emitted by the light-emitting device.

Description

Technical Field

[0001] The present invention relates to the field of laser radar, and more particularly, to a driving device for a light-emitting device of a laser radar and a laser radar including the driving device. Background Art

[0002] With the rapid development of artificial intelligence technology, application scenarios such as autonomous driving, V2R, sweeping robots, logistics vehicles, and unmanned food delivery have gradually matured. LiDAR, as an important three-dimensional imaging sensing device, has become a basic condition for the implementation of these application directions. Figure 1 FIG. 1 is a schematic diagram showing the working principle of an exemplary laser radar 1. Figure 1 As shown in FIG, the laser radar 1 is a multi-beam (such as 40 lines, 64 lines and 128 lines, Figure 1 40 lines) laser radar, which can be along Figure 1 A total of 40 laser beams, L1, L2, ..., L39, and L40, are emitted in the vertical direction (parallel to the axis of rotation) of the laser radar 1. These laser beams are emitted by a light source comprising a plurality of light-emitting devices LD1, LD2, ..., LD39, and LD40 located inside the laser radar 1. By setting the relative arrangement of the plurality of light-emitting devices, the vertical angle of each beam can be selected to achieve the desired vertical angular resolution. For example, for a laser radar with the same vertical angular resolution for each beam, the following can be used: Figure 1 In other cases, the vertical angle resolution of the middle beam of some mechanical radars is denser than that of the two sides, so a light source can be used in which the light emitting devices in the middle part of the multiple light emitting devices are more densely arranged than the light emitting devices at the two ends (not shown in the figure). Of course, in actual multi-line radars, the arrangement of multiple light emitting devices is not limited to the following. Figure 1 The arrangement shown in FIG is one column, but it can be arranged in multiple columns.

[0003] Each laser beam emitted by a light-emitting device corresponds to a channel of the laser radar 1, used to detect the surrounding environment. During detection, the laser radar 1 can rotate along its vertical axis. During this rotation, each light-emitting device LD1, LD2, ..., LD39, and LD40 can sequentially transmit laser beams L1, L2, ..., L39, and L40 through each channel at regular intervals and perform detection, thereby completing a line scan across the vertical field of view. The laser radar 1's receiver receives the echoes reflected from each light-emitting device after encountering an obstacle. By calculating the laser beam's round-trip flight time, it detects the obstacle's distance and orientation, thereby generating point cloud data. The laser radar 1 then transmits and receives the next laser beam at regular intervals in the horizontal field of view (e.g., 0.1 degrees for a radar with a rotation frequency of 10 Hz and 0.2 degrees for a radar with a rotation frequency of 20 Hz). Depending on the working principle of the radar, the order of sending and receiving laser beams can be different. For example, it can be round-robin sending and receiving (that is, one line at a time, or some multiple lines in parallel), or multiple beams can be sent and received simultaneously.

[0004] During the entire rotation process of the laser radar 1, multiple detections can be performed to form complete point cloud data of obstacles, thereby perceiving the conditions of the surrounding environment. Figure 1 The 40-line LiDAR 1 shown rotates one full circle (360 degrees) for scanning and detection, generating one frame of point cloud data. Continuously performing rotational scanning and detection can generate multiple frames of point cloud data. Furthermore, since LiDAR applications may involve multiple LiDARs, crosstalk is a natural problem. To mitigate this, LiDARs can emit multiple pulses per laser.

[0005] As can be seen from the above working principle of the LiDAR, the light-emitting device of the LiDAR is an important component of the entire LiDAR. In order to achieve higher ranging accuracy, longer detection distance, and higher scanning rate, the light-emitting device needs to be able to generate laser pulse signals with fast leading edges, high peak power, and narrow pulse width. The faster the leading edge of the laser pulse signal and the smaller the time error, the smaller the equivalent distance error. The higher the peak power, the longer the distance over which the energy decays to zero, and the narrower the pulse width, the more multiple pulses can be emitted continuously within the same time interval. Since the performance of current light-emitting devices is generally excellent enough to fully meet the requirements of fast leading edges, high power, and narrow pulse width, the performance of the light-emitting device's driving circuit becomes the most important determinant of the radar's pulse signal quality. Summary of the Invention

[0006] In view of this, the present invention proposes a driving device for a light-emitting device of a laser radar and a laser radar including the driving device, which not only reduces the DC power consumption of the driving circuit, but also solves the problem of inconsistency of multiple pulse light signals emitted by the light-emitting device.

[0007] According to one aspect of the present invention, a driving device for a light-emitting device of a laser radar is provided. The driving device includes: a driving control module, connected to a power supply, configured to receive an input pulse signal and a digital control signal, and output a driving level signal; wherein the digital control signal is used to adjust the magnitude of the driving level signal output by the driving control module, and the pulse signal is used to control whether the driving control module outputs the driving level signal; and a driving module, connected to the driving control module and the power supply, configured to provide a driving current to the light-emitting device of the laser radar based on the driving level signal, thereby driving the light-emitting device to emit light.

[0008] In one embodiment, the drive control module includes a plurality of selectable modules connected in parallel with each other and a switch module connected in series with the plurality of selectable modules, wherein the plurality of selectable modules are adapted to receive the digital control signal to control the on or off of each selectable module, thereby controlling the size of the drive level signal output by the drive control module; the switch module is adapted to receive the pulse signal, determine whether to conduct the path between the power supply, the switch module, the selectable module and the ground according to the pulse signal, and provide the drive level signal to the drive module when conducting.

[0009] In one embodiment, each of the multiple selectable modules includes: a gate and a first transistor, wherein the input end of the gate is connected to a high level and a low level, and the output end is connected to the control electrode of the first transistor, and the gate is configured to input the high level or the low level to the control electrode of the first transistor under the control of the corresponding bit in the digital control signal; the control electrode of the first transistor is connected to the gate, the first electrode of the first transistor is grounded, and the second electrode of the first transistor is connected to the switch module; the first transistor is suitable for turning on the path of the switch module to the ground when receiving a high level input from the gate, and turning off the path of the switch module to the ground when receiving a low level input from the gate.

[0010] In one embodiment, the drive control module also includes a level shifter, the switch module includes a second transistor, and the control electrode of the second transistor receives the pulse signal; the level shifter is suitable for providing a voltage drop; the first electrode of the second transistor is connected to the multiple optional modules; the second electrode of the second transistor is connected to the drive module, and is suitable for determining whether to turn on the second transistor based on the pulse signal, and when the second transistor is turned on, the path of the power supply-level shifter-the switch module-the optional module and the ground is turned on to provide the drive level signal to the drive module.

[0011] In one embodiment, the drive control module includes a plurality of selectable modules connected in parallel, a switch module connected in series with the plurality of selectable modules, and a level shifter, wherein the level shifter is suitable for providing a voltage drop; the plurality of selectable modules are suitable for receiving the digital control signal and the pulse signal to control the on or off of each selectable module, thereby controlling the size of the drive level signal output by the drive control module, and wherein the switch module is suitable for receiving the pulse signal, determining whether to conduct the path of the power supply-the level shifter-the switch module-the selectable module and the ground according to the pulse signal, and providing the drive level signal to the drive module when conducting.

[0012] In one embodiment, each of the multiple selectable modules includes: a gate and a first transistor, wherein the input end of the gate is connected to the pulse signal and a low level, and the output end is connected to the control electrode of the first transistor, and the gate is configured to determine whether to input the pulse signal to the control electrode of the first transistor under the control of the corresponding bit in the digital control signal; the control electrode of the first transistor is connected to the gate, the first electrode of the first transistor is grounded, and the second electrode of the first transistor is connected to the switch module; the first transistor is suitable for turning on the path of the switch module to the ground when receiving a high level input of the pulse signal from the gate, and turning off the path of the switch module to the ground when receiving a low level input from the gate.

[0013] In one embodiment, the switch module includes a second transistor, the control electrode of which receives a high level or a low level selected by the pulse signal; the first electrode of the second transistor is connected to the multiple selectable modules; the second electrode of the second transistor is connected to the driving module, and is suitable for determining whether to select the second transistor according to the pulse signal, and when the second transistor is selected, the path of the power supply-the level shifter-the switch module-the selectable module and the ground is turned on to provide the driving level signal to the driving module.

[0014] In one embodiment, the first transistor and the second transistor are NMOS transistors, and the control electrodes of the first transistor and the second transistor indicate gates, the first electrodes indicate sources, and the second electrodes indicate drains.

[0015] In one embodiment, the drive control module includes a voltage stabilizing module, an inverter, a switch module and a level shifter, wherein: the level shifter is suitable for providing a voltage drop; the voltage stabilizing module is suitable for receiving a digital control signal for stabilizing the peak value of the pulse signal; the inverter is suitable for inverting the digital control signal when the pulse signal is sufficient to turn on the switch module; the switch module is suitable for receiving the pulse signal, and determining whether to turn on the path between the power supply-the level shifter-the switch module and the ground based on the pulse signal and the inverted digital control signal, and providing the drive level signal to the drive module when turned on.

[0016] In one embodiment, the driving module includes a level shifter and a third transistor, wherein the control electrode of the third transistor is connected to the driving control module, the first electrode of the third transistor is connected to the power supply, and the second electrode of the third transistor is connected to the anode of the light-emitting device, and is suitable for opening and closing under the control of the driving level signal.

[0017] In one embodiment, the level shifter includes a first resistor, one end of which is connected to the control electrode of the third transistor, and the other end is connected to the power supply to cooperate with other components of the drive control module to provide a drive level signal to the control electrode of the third transistor.

[0018] In one embodiment, the third transistor is a PMOS transistor, and the control electrode of the third transistor indicates the gate, the first electrode indicates the source, and the second electrode indicates the drain; or, the third transistor is an NMOS transistor, and the control electrode of the third transistor indicates the gate, the first electrode indicates the drain, and the second electrode indicates the source.

[0019] In one embodiment, the level shifter also includes at least one first diode connected in parallel with the third transistor, the anode of the first diode is connected to the power supply, and the cathode is connected to the drive control module; and / or the level shifter also includes at least one second diode connected in parallel with the third transistor, and the cathode of the second diode is connected to the power supply, and the anode is connected to the drive control module.

[0020] According to another aspect of the present invention, a laser radar is provided. The laser radar comprises: a plurality of driving devices as described above; and a plurality of light-emitting devices; the cathodes of the plurality of light-emitting devices are connected; and one end of each driving device is connected to a power supply and the other end is connected to the anode of the light-emitting device.

[0021] In one embodiment, the laser radar further includes a control unit connected to the drive control module, adapted to generate the pulse signal and the digital control signal according to the ranging requirement, thereby sequentially selecting the multiple light-emitting devices to emit light.

[0022] In one embodiment, the light emitting device includes an edge emitting laser (EEL) or a vertical cavity surface emitting laser (VCSEL). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram illustrating the working principle of an exemplary laser radar is shown;

[0024] Figure 2 A schematic diagram of a narrow pulse width driving circuit that can be used in a laser radar light emitting device is shown;

[0025] Figure 3A and 3B Another functional module diagram and an example circuit diagram of a driving circuit that can be used for a laser radar light-emitting device are shown respectively;

[0026] Figure 4 A schematic structural diagram of a laser radar according to an embodiment of the present invention is shown;

[0027] Figure 5A A schematic structural diagram of a driving device for a light emitting device of a laser radar according to an embodiment of the present invention is shown;

[0028] Figure 5B A functional module diagram of a driving device for a light emitting device of a laser radar according to some embodiments of the present invention is shown;

[0029] Figure 5C Shown Figure 5B An example circuit diagram of the driving device shown;

[0030] Figure 5D and Figure 5E The pulse timing diagrams when the laser radar emits double pulses and triple pulses are shown respectively;

[0031] Figure 5F A schematic diagram showing a simulation of the peak difference when the light emitting device of a current laser radar emits four pulses;

[0032] Figure 6 A functional module diagram of a driving device for a light emitting device of a laser radar according to some embodiments of the present invention is shown;

[0033] Figure 7A Shown Figure 6 An example circuit diagram of the driving device shown;

[0034] Figure 7B Shown Figure 7A A variation of the example circuit diagram shown;

[0035] Figure 8 A functional module diagram of a driving device for a light emitting device of a laser radar according to some other embodiments of the present invention is shown;

[0036] Figure 9A Shown Figure 8 An example circuit diagram of the driving device shown;

[0037] Figure 9B Shown Figure 9A A variation of the example circuit diagram shown;

[0038] Figure 10 Shown Figure 7A Voltage waveform diagrams of key points of the embodiment shown;

[0039] Figure 11 Shown Figure 7A Waveforms of the source-gate voltage of the third transistor and the driving current of the light emitting device in the illustrated embodiment;

[0040] Figure 12 shows a waveform diagram of the driving current of the light-emitting device and the gate voltage of the third transistor when the light-emitting device in the present application emits four pulses;

[0041] Figure 13 Shown Figure 7A A waveform diagram of the drain output voltage of the third transistor when the digital control signal is changed in the embodiment shown; and

[0042] Figure 14 Shown Figure 7A Current flow diagram in the illustrated embodiment.

[0043] In the various drawings, the same or similar reference numerals designate the same or corresponding elements. DETAILED DESCRIPTION

[0044] The following will describe in detail various embodiments of the present invention in conjunction with the accompanying drawings to provide a clearer understanding of the objectives, features and advantages of the present invention. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0045] In the following description, for the purpose of illustrating the various disclosed embodiments, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of these specific details. In other cases, well-known devices, structures, and techniques associated with this application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0046] Unless the context requires otherwise, throughout the specification and claims, the word "comprise" and variations such as "include" and "have" should be construed in an open, inclusive sense, that is, should be interpreted to mean "including, but not limited to."

[0047] Reference throughout this specification to "one embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any manner in one or more embodiments.

[0048] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should be noted that the term "or" is generally employed in its sense including "and / or" unless the context clearly dictates otherwise.

[0049] Figure 2 FIG1 shows a schematic diagram of a narrow pulse width driving circuit that can be used for a laser radar light emitting device. Figure 2 As shown in , the driving circuit includes a power field effect transistor (Power FET), and the pulse driving signal Vin is input into the gate of the Power FET via the gate driver. The source of the Power FET is grounded, and the drain is connected to the laser LD. The current flowing through the laser LD can be changed by controlling the pulse width of the pulse driving signal Vin of the driving circuit or the power supply voltage HV, thereby changing the luminous energy value. Specifically, the pulse width of each pulse driving signal Vin corresponds to the luminous duration of the laser LD. When the pulse driving signal Vin changes from a low level to a high level, the Power FET can be turned on, thereby HV A discharge path is formed among the laser LD, Power FET and ground (GND), and the laser LD starts to emit light.

[0050] Widening the pulse width of the pulse drive signal Vin will limit the interval between adjacent multi-pulses emitted by the laser, increase the measurement dead time (indicating the time during which measurement and point cloud data cannot be obtained), and make it impossible to achieve a high repetition frequency. The luminous energy is equal to the luminous power multiplied by the time width. The luminous power is proportional to the current input to the laser LD. Therefore, changing the pulse width of the input pulse drive signal Vin can proportionally change the luminous energy. When the on-resistance of the laser LD and the Power FET is a constant, changing the power supply voltage HV can change the current flowing into the laser LD, thereby achieving a change in the luminous energy.

[0051] Therefore, in Figure 2 In the driving circuit shown, if you want to increase the light intensity of the laser LD, you can 1) increase the pulse width of the pulse driving signal Vin or 2) increase the power supply voltage HV. However, for 1), increasing the pulse width of the pulse driving signal Vin will cause the output pulse of the optical signal to become wider, and the pulse widening limits the interval between adjacent pulses, increases the dead time of the measurement, and cannot achieve a higher repetition frequency. In addition, since the peak power current of the output laser pulse does not change, the detection distance corresponding to the non-saturation distortion does not change, so it is impossible to achieve non-saturation distortion detection at far, medium and near distances at the same time. On the other hand, for 2), the power supply voltage HV is generated by a boost circuit. It is necessary to increase HV by controlling the boost circuit, which will make the switching rate of the boost circuit lower, resulting in a longer stabilization time between the two adjustments, and will also make the system control more complicated.

[0052] Figure 3A and 3B The following respectively show a functional module diagram and an example circuit diagram of another driving circuit that can be used for a laser radar light-emitting device.

[0053] like Figure 3A As shown, the input pulse signal Vin is narrowed to a few nanoseconds by the narrow pulse generator 320, then amplified by the intermediate drive link 330 and output to the final inverter 340 for inversion (for example, when the input of the final inverter 340 is 0, the output is 1). The power supply of the final inverter 340 is provided by the voltage follower 310, and the input of the voltage follower 310 comes from the V generated by the digital-to-analog converter 300. REF The peak value of the pulse high level of the final inverter 340 is V REF , drives the power MOSFET 350 through the final inverter 340, and the drain circuit of the power MOSFET 350 outputs to the semiconductor laser 360, which stimulates the semiconductor laser 360 to generate laser pulses. By inputting the digital control signal Din, the output value V of the digital-to-analog converter 300 is changed. REF, that is, the gate voltage of the power MOSFET 350 can be changed when the pulse signal Vin is high, and the current flowing into the semiconductor laser 360 can be changed by changing the gate voltage of the power MOSFET 350, thereby changing the power of the laser emitted by the semiconductor laser 360.

[0054] like Figure 3B As shown, the semiconductor laser 360 includes a laser diode LD, and the digital-to-analog converter 300 uses a voltage DAC, which generates a reference voltage V through the input of the digital control signal Din. REF The voltage follower 310 can be constructed using an operational amplifier (OPA) A1, a PMOS transistor M0, and a filter capacitor C1. According to the principles of an operational amplifier, when negative feedback is established, the input voltages at the positive (+) input and negative (-) input of OPA A1 are equal. At the same time, because the + input of OPA A1 is connected to the drain of PMOS transistor M0, the output current capability is greatly enhanced, which can better drive the final amplifier 340. The narrow pulse generator 320 consists of a current DAC I0, a current-controlled delay unit I1, a non-inverting buffer I2, and a logic AND gate I3. By adjusting the output current of the current DAC I0, the output delay of the current-controlled delay unit I1 can be adjusted. The non-inverting signal and the delayed inverting signal of the input pulse signal Vin are output to the input of AND gate I3. Therefore, the pulse width output by AND gate I3 is the delay difference between the current-controlled delay unit I1 and the non-inverting buffer I2. In other words, the delay difference forms a narrow pulse excitation.

[0055] Narrow pulses drive an intermediate drive chain 330, formed by a cascade of multiple inverters, to amplify the current. The size of each inverter in intermediate drive chain 330 is scaled up in a 1:3 ratio. The inverter at the output of intermediate drive chain 330 is one-third the size of the final inverter 340. Final inverter 340 consists of an NMOS transistor M2 and a PMOS transistor M1, with their gates and drains connected. The source of NMOS transistor M2 is grounded, while the source of PMOS transistor M1 is connected to the output of voltage follower 310 (the drain of PMOS transistor M0). The drains of PMOS transistors M1 and M2 are connected to the gate of power MOSFET 350, an enhancement-mode GaN NMOS FET (eGaN FET). The source of power MOSFET 350 is grounded, and its drain is connected to the cathode of laser diode LD. The semiconductor laser 360 is composed of a laser diode LD, a freewheeling diode D1, a filter capacitor C2, a wiring parasitic capacitor Rp and a high voltage source HV.

[0056] The digital-to-analog converter 300, voltage follower 310, narrow pulse generator 320, intermediate drive link 330, and final inverter 340 are all low-voltage devices (5V), the PMOS transistor M0, PMOS transistor M1, and NMOS transistor M2 are 5V silicon CMOS devices, and the power MOSFET 350 and laser diode 360 ​​are high-voltage devices (60V in this example).

[0057] When the input pulse signal Vin is at a low level, such as the voltage at point A V A =0V, the voltages at points B and C are V B =0V, V C =0V, at this time the power MOSFET 350 is in the off state, no current flows into the laser diode LD, and the semiconductor laser 360 does not emit light; when the input pulse signal Vin is at a high level, such as the voltage V at point A A =5V, the voltage at point B is V B =5V, V REF =V C (voltage at point C) = V E (voltage at point E) = V D (D point voltage), V D is generated by the digital-to-analog converter 300, V D The value is equal to V REF At this time, the current of the laser diode LD is determined by the current-voltage (IV) characteristics of the power MOSFET 350.

[0058] Assume that the threshold voltage of power MOSFET 350 is Vth. REF When Vth is less than Vth, the power MOSFET 350 is in the off state. REF When Vth is greater than Vth, the power MOSFET 350 first enters the subthreshold region, and the current of the power MOSFET 350 and (V REF -Vth) is exponentially related.

[0059] When V REF When Vth is more than tens of mV, the power MOSFET 350 begins to enter the saturation region. When in the saturation region, the current flowing through the power MOSFET 350 can be expressed as:

[0060] I D =β(V REF -V th ) 2 ,

[0061] Where β is the current coefficient when the power MOSFET 350 operates in the saturation region. At the same time, according to the current characteristics of the power supply HV branch from top to bottom, the voltage difference between the drain D and source S of the power MOSFET 350 can be expressed as:

[0062] V DS =HV-I D ×(R P +R LD ),

[0063] Among them, R P R is the parasitic resistance of the wiring between the drain D of the power MOSFET 350 and the power supply HV. LD is the impedance of the laser diode LD when it is turned on, I D is the driving current flowing through the laser diode LD. D As the value of V increases gradually, the drain-source voltage difference V DS Gradually decreases, when the overdrive voltage (V REF -Vth) is greater than V DS When , the working state of the power MOSFET 350 changes from the saturation region to the linear region. D The maximum value of is approximately equal to:

[0064]

[0065] Among them, R DS，on is the impedance of the power MOSFET 350 when it operates in the linear region, and its value is approximately equal to:

[0066]

[0067] Here, K is a constant. Here, those skilled in the art will know that the constant k is a constant determined by the properties of silicon-based devices and depends on the Planck constant.

[0068] for Figure 3B In the example circuit diagram shown, the pulse width of the input pulse signal Vin is tens of ns, the high level is 4V, the leading edge rise time is several ns, the trailing edge fall time is several ns, the delay of the current control delay unit I1 is set to several ns, and the high level V of the gate control voltage of the power MOSFET 350 is changed by the digital control signal Din. D =V REF , V D The voltage value varies from 1V to 7V. Through simulation, it can be seen that the input pulse signal Vin (V A ) has a waveform width of 10ns, and after passing through the narrow pulse generator 320, a waveform V B, V B The pulse width becomes 3ns, V B The high level is fixed at 5V and does not change with the control voltage V D =V REF The voltage value changes, V B After passing through the intermediate drive link 330 and the final inverter 340, a waveform V C , V C The high level peak value increases with V D =V REF The set value changes from 1V to 7V, and then V C The gate of the power MOSFET 350 is controlled so that the drain of the power MOSFET 350 generates a driving current I D Input to the laser diode LD, the peak value of the current waveform of LD changes with V C The voltage peak value changes.

[0069] Due to the upgrade of radar products, from the perspectives of ease of assembly, cost, and other aspects, the trend is towards chip-based manufacturing. The laser diodes LD used in subsequent radars are packaged as chips, and the drive circuits can also be packaged as chips. At the same time, the trend of lidar products is to maximize the light-emitting beam or light-emitting density, so the laser needs to be transformed from the original single-particle form to the array form. When processed into a higher-density light-emitting array, due to the limitations of process capabilities, the light-emitting density and light-emitting ability of the common anode laser array are far inferior to those of the common cathode laser array. Therefore, the cathodes of the multiple lasers in the common cathode array need to be made together and grounded (GND). Therefore, no other devices can be set between the cathode and GND of each laser diode LD. Therefore, the drive circuit is either set between the laser and GND, or driven by the anode of the laser.

[0070] However, for the former, the cathodes of multiple lasers are connected and need to share one NMOS for driving and receiving driving signals at the same time. If these multiple lasers are to be selected relative to each other, these multiple lasers should be provided with their own power supply HV respectively and cannot share HV.

[0071] For the latter, since the gate-source voltage of the driving transistor must maintain a fixed voltage difference in order to work, when adjusting the laser light intensity, the current flowing through the laser increases, which will increase the source voltage. The corresponding gate voltage must also increase with negative feedback, making the control solution more complicated.

[0072] Taking the above situation into consideration, the present application proposes a high-side (MOS tube connected to the power supply voltage is called a high-side tube) driving device for a light-emitting device of a laser radar, which controls the voltage / current provided to the light-emitting device by utilizing the input pulse voltage signal and digital control signal to accurately control the light emission of the light-emitting device.

[0073] Figure 4 FIG. 4 shows a schematic structural diagram of a laser radar 4 according to an embodiment of the present invention. Figure 4 As shown in FIG. 5 , the laser radar 4 includes one or more driving devices 10 and one or more light emitting devices 20 according to the present invention, wherein each driving device 10 is used to drive a corresponding light emitting device 20. The driving device 10 is described below in conjunction with FIG. Figure 13 As stated.

[0074] Each driver 10 is connected to a power supply 40 and to the anode (i.e., high-side) of the corresponding light-emitting device 20. The cathode (i.e., low-side) of the light-emitting device 20 is connected to ground (GND). The power supply 40 provides a power supply voltage HVDD1 to the driver 10. The driver 10 receives a pulse signal Vin and a digital control signal Din and generates a drive current Id for output to the light-emitting device 20. The light-emitting device 20 converts the input drive current Id into light energy. The laser radar 4 may also include a control unit 30, which is connected to the driver 10 and can generate a separate pulse signal Vin and digital control signal Din for each driver 10 based on ranging requirements. This allows each light-emitting device 20 to be sequentially selected for illumination, or some light-emitting devices 20 to be selected for simultaneous illumination. The illumination method can be determined based on the specific detection requirements and is not limited here. In other words, the control unit 30 can determine the light-emitting device 20 to be driven and provide the corresponding pulse signal Vin and digital control signal Din to the driver 10 of that light-emitting device 20. The pulse signal Vin represents a continuous signal with a certain time span, and the digital control signal Din represents a signal of 0110... For details, please refer to Figure 5B As shown in . Those skilled in the art will understand that although Figure 4 The input of each driving device 10 is shown as Vin and Din, but depending on different ranging requirements, the pulse signal Vin and digital control signal of each driving device 10 may be

[0075] Here, the pulse signal Vin is a trigger signal of the driving device 10, which is issued each time the radar is ranging (for example, scanning every 1 microsecond). Each pulse signal Vin can include one or several (such as 2-4) narrow pulses, and the pulse width of each narrow pulse is tens of nanoseconds, which is proportional to the luminous power of the light-emitting device 20. The details are as described above and will not be repeated here. The digital control signal Din is a control signal of the driving device 10, which can change as the ranging requirements change. For example, when the environmental obstacle has a high reflectivity surface, its value can be reduced, and when the environmental obstacle has a low reflectivity surface, its value can be increased.

[0076] In addition, although Figure 4 The driving device 10 and the light-emitting device 20 are shown in a one-to-one correspondence, but those skilled in the art will appreciate that, depending on actual conditions, one driving device 10 can drive multiple light-emitting devices 20 .

[0077] The light emitting device 20 may be, for example, an edge emitting laser (EEL) or a vertical cavity surface emitting laser (VCSEL).

[0078] According to the solution of the present invention, one or more driving devices 10 can be packaged on one chip 50 , and one or more light-emitting devices 60 can be packaged on another chip 60 . The chips 50 and 60 can share the same power supply 40 .

[0079] Those skilled in the art will appreciate that other parts of the laser radar 1, such as the receiver, etc., are omitted here for the sake of brevity.

[0080] Figure 5A FIG. 1 shows a schematic structural diagram of a driving device 10 for a light emitting device of a laser radar according to an embodiment of the present invention. Figure 5A As shown in FIG, the driving device 10 may include a driving control module 110 and a driving module 120. The driving control module 110 is configured to receive an input pulse signal Vin and a digital control signal Din, and output a driving level signal Vx. The digital control signal Din can adjust the magnitude of the driving level signal Vx output by the driving control module 110, and the pulse signal Vin can control whether the driving control module 110 outputs the driving level signal Vx. The driving module 120 is connected to the driving control module 110 and the power supply voltage HVDD1, and provides a driving current Id to the light-emitting device 20 of the laser radar based on the driving level signal Vx, thereby driving the light-emitting device 20 to emit light.

[0081] Figure 5B A functional module diagram of a driving device 10 for a light emitting device of a laser radar according to some embodiments of the present invention is shown; Figure 5C Shown Figure 5B An example circuit diagram of the driving device 10 is shown.

[0082] exist Figure 5C There are some Figure 3A and 3B The same parts, such as Figure 5C IDAC in Figure 3B The digital-to-analog converter 300, Figure 5B The LDO and capacitor C1 in the Figure 3B The voltage follower 310 in Figure 5C U2 in Figure 3B The narrow pulse generator 320 in the middle drives the link 330, Figure 5C 11b in corresponds to Figure 3B Regarding the final inverter 340 in FIG. 1 , these same components will not be described in detail here, and may be understood by referring to the above.

[0083] The following will focus on Figure 5B and Figure 5C and Figure 3A and Figure 3B Different components, relative to Figure 3A and Figure 3B , Figure 5B and Figure 5C U4 has been newly added. The switch connected to the light-emitting device LD has been replaced with an LDPMOS transistor U5 instead of a power MOSFET 350. U5's source is connected to the power supply HVDD1, its gate is connected to U4, and its drain is connected to the anode of the LD. U4 is used to provide a driving voltage Vx for U5. Specifically, U4 may include a resistor R1 and an LDNMOS switch (it is understood that an LDPMOS can also be used, and the corresponding connection relationship can be adjusted accordingly). Resistor R1 has one end connected to the power supply HVDD1 and the other end connected to the drain of the LDNMOS switch. The gate of the LDNMOS switch is connected to an inverter U11b, its source is grounded, and its gate is connected to resistor R1. Under the combined control of Vin and Din, the LDNMOS switch is turned on or off. Accordingly, U4 can provide a driving signal to U5 that is high (HV = HVDD1) - low (LV = HVDD1 - I × R1) - high (HV = HVDD1).

[0084] Specifically, when the switch LDNMOS is turned on, the path from HVDD1 to R1 to LDNMOS to GND is connected. If the current flowing in this path is I, due to the voltage drop across R1, the voltage Vx at the gate of the LDNMOS is (HVDD1-I×R1). This voltage is supplied to the gate of U5, driving U5 to turn on, thereby controlling the path from HVDD1 to U5 to LD to GND, and causing the laser to emit light.

[0085] When the LDNMOS switch is off, both its source and gate terminals are at high voltage HVDD1. The voltage difference is insufficient to turn on U5, and the laser does not emit light. In a specific implementation, HVDD1 can range from 10V to 100V, and LV = 5V. Of course, those skilled in the art can select and set it according to actual conditions.

[0086] In addition, since there are multiple laser radars coexisting in the application scenarios of laser radar, there will inevitably be crosstalk problems. In order to avoid crosstalk, laser radar can alleviate it by emitting n (n ≥ 2) pulse codes for each laser. Figure 5D and Figure 5EThe pulse timing diagrams of the laser radar laser when emitting double pulses and triple pulses are shown respectively. For n pulses, it means that one laser emits n pulses each time, and the encoding indicates that some parameters of at least two of the n pulses are not completely consistent. These parameters can specifically include: the pulse width can be different (for example, refer to Figure 5D The double pulse shown, pulse 1 is smaller than pulse 2), the intervals between the front and back pulses can be different (for example, compare the double pulses shown in FIG5D and Figure 5E The three pulses shown, Δt1≠Δt2≠Δt1"), the amplitude of the pulses can be different (for example Figure 5D Pulse 2 has a higher amplitude than pulse 1), the number of pulses can be different (for example Figure 5D is a double pulse, and Figure 5E is three pulses). By using pulse coding, if LiDAR A sends a double pulse and LiDAR B also sends a double pulse, the interval between the double pulses of the two LiDARs is Δt1" A ≠Δt1" B , so that the laser radar A will only receive or specifically process the interval Δt1 between the two pulses. A The laser radar will not regard the echo of laser radar B as its own echo, thus achieving the effect of anti-interference. In addition, since the rotation frequency of laser radar is very fast, such as 10HZ or 20HZ, the speed of light is even faster, and n pulses are used to correspond to a specific point in the external obstacle, the time interval between any two pulses in n pulses is basically in the order of nanoseconds, such as Δt1=5ns. Moreover, when n pulses are used, the receiving processing end may only determine that the return echo is the pulse emitted by its own laser radar after confirming that the received return echo completely matches each of the n pulses emitted. Therefore, all laser radar companies will pursue the ability of the driving circuit of the transmitting device to control the light-emitting device to emit stable pulses at high speed (in nanoseconds).

[0087] However, when the radar transmits a multi-pulse pulse signal, the peak value difference of the driving current output when the lidar emits each pulse is very large. Figure 5F The figure shows a simulation diagram of the peak difference when the laser radar's light-emitting device emits 4 pulses. Assume that the laser radar originally controls the light-emitting device to emit 4 pulse signals with the same amplitude and 50ns intervals between each other. However, in reality, Figure 5F As shown in the simulation results, the driving currents corresponding to the various pulses are not consistent and vary greatly, with the maximum difference being 169%. Specifically, in 5F, curve 302 is the waveform of the current flowing through the semiconductor laser U6, corresponding to the amplitude of the pulse, and curve 304 is the output voltage of the LDO ( Figure 5CCurve 306 shows the waveform of the power supply voltage HVDD1, and curve 308 shows the waveform of the voltage across semiconductor laser U6. Curve 302 shows that the peak current of the second pulse, corresponding to M32, increases by 169% compared to the peak current of the first pulse, corresponding to M31. There are also differences between M35 and M36.

[0088] Figure 6 A functional module diagram of a driving device 10 for a light emitting device of a laser radar according to some embodiments of the present invention is shown; Figure 7A Shown Figure 6 An example circuit diagram of the driving device 10 is shown; Figure 7B Shown Figure 7A A variation of the example circuit diagram shown.

[0089] like Figure 6 As shown in , the driving control module 110 of the driving device 10 may include a plurality of selectable modules 112 connected in parallel and a switch module 114 connected in series with the plurality of selectable modules 112 .

[0090] The multiple selectable modules 112 can receive a digital control signal Din to control the switching on or off of each selectable module 112. By controlling the number of selectable modules 112 that are switched on, the magnitude of the drive level signal Vx output by the driver control module 110 is controlled. The switch module 114 can receive a pulse signal Vin and, based on the pulse signal Vin, determine whether to conduct a path between the power supply HVDD1 of the driver module 120, the switch module 114, the selectable modules 112, and ground. When conducting, the drive level signal Vx is provided to the driver module 120.

[0091] like Figure 7A As shown in , in one embodiment, each selectable module 112 may include a gate 1122 and a first transistor 1124, and the drains of the first transistors 1124 of the multiple selectable modules 112 are connected in parallel. The input end of the gate 1122 is connected to a high level (such as the power supply voltage VDD5 of the drive control module 110) and a low level (such as 0V, i.e., ground (GND)), and its output end is connected to the control electrode of the first transistor 1124. The gate 1122 is configured to input the high level VDD5 or the low level GND to the control electrode of the first transistor 1124 under the control of the corresponding bit Selx (including Sel 0, Sel 1...Sel 255) in the digital control signal Din. The control electrode of the first transistor 1124 is connected to the gate 1122 to turn on the path from the switch module 114 to the ground when receiving the high level VDD5 input from the gate 1122, and to turn off the path from the switch module 114 to the ground when receiving the low level GND input from the gate 1122.

[0092] In one embodiment, the digital control signal Din is a binary digital sequence, and each binary digital (a bit) in the sequence is used to control the on or off of a selectable module 112. Figure 7A For example, the drive control module 110 may include 256 selectable modules 112, and the digital control signal Din is a digital sequence Sel0, Sel1...Sel255 composed of 256 bits, where each bit is used to control the conduction or shutdown of the corresponding selectable module 112. For example, when Sel0 is 1, the selector 1122 outputs the input high level VDD5 to the control electrode of the first transistor 1124, thereby turning on the first transistor 1124. At this time, if the pulse signal Vin is at its high level, the power supply HVDD1, the first resistor 1222, the second transistor 1142 and the path from the first transistor 1124 to the ground are turned on, thereby driving the third transistor 124. Conversely, when Sel0 is 0, the selector 1122 outputs the input low level GND to the control electrode of the first transistor 1124, thereby turning off the first transistor 1124. Although Figure 7A In the description, an example is given in which the drive control module 110 includes 256 selectable modules 112 and the digital control signal Din includes 256 bits. However, those skilled in the art will appreciate that the number of selectable modules 112 and the number of bits of the digital control signal Din are not limited thereto. For example, the number of selectable modules 112 may also be 300 or 200. In one embodiment of the present invention, the greater the number of selectable modules 112, the finer the control of Vx, and thus the more precise the adjustment of the laser light intensity by the laser radar.

[0093] Furthermore, the number of selectable modules 112 and the number of bits of the digital control signal Din may differ. For example, in some implementations, each bit of the digital control signal Din may control multiple selectable modules 112, such as Sel0 controlling two selectable modules 112. Alternatively, multiple bits of the digital control signal Din may collectively control a single selectable module 112, such as a single selectable module 112 being controlled by both Sel0 and Sel1.

[0094] When a selectable module 112 is turned on, it contributes a current component to the driving module 120 (for example, in a path containing 1000 selectable modules 112, each selectable module 112 contributes 0.1% of the current to the driving module 120). Therefore, by gating and controlling multiple selectable modules 112 through the digital control signal Din, a current-adjustable digitally controlled current source can be formed. Thus, by changing the number of selectable modules 112 that are gated each time, the gate voltage of the third transistor 124 can be changed to adjust the luminous intensity when the light-emitting device 20 is driven on the high side. Specifically, as Figure 7A As shown in , when the digital control signal Din is used to relatively independently control the switching on or off of each selectable module 112, due to the different numbers of the selected modules 112, the corresponding current flowing through the first resistor 1222 is different, and thus the gate voltage input to the third transistor 124 is also different, and the driving current provided to the light-emitting device 20 is also different, thereby adjusting the light intensity.

[0095] The multiple optional modules 112 can be relatively consistent devices or different devices. In one embodiment of the present invention, the performance of the multiple optional modules 112 is relatively consistent. The more the number of optional modules 112, the finer the regulation of the current provided to the driving module 120. However, the more the number of optional modules 112, the larger the volume occupied, so depending on the application scenario, a compromise can be selected between fineness and volume. For example, for the laser radar used for ranging in the present application, the number of optional modules 112 can be about 300, such as 256. In addition, in actual applications, the overall size of about 300 optional modules 112 is about the same as that of one third crystal 124, because relatively more optional modules 112 can be used to drive one light-emitting device 20. In such as Figure 7A In the illustrated embodiment, the first transistor 1124 may be an NMOS transistor, wherein the gate serves as a control electrode, the source is grounded, and the drain is connected to the switch module 114 .

[0096] In addition, the switch module 114 may include a second transistor 1142 , a control electrode of which receives the pulse signal Vin.

[0097] In such Figure 7AIn the illustrated embodiment, the second transistor 1142 may be an NMOS transistor, wherein the gate serves as a control electrode, and the source is connected to a plurality of selectable modules 112 to adjust and change the drive level signal Vx. The gate is connected to the gate of the third transistor 124 to drive the opening and closing of the third transistor 124 by outputting the drive level signal Vx. The drain of the second transistor 1142 is connected to the driver module 120, and whether to select the second transistor 1142 can be determined based on the pulse signal Vin. When the second transistor 1142 is selected, the path between the power supply HVDD1 of the driver module 120, the switch module 114, the selection module 112 and the ground is connected to provide the drive level signal Vx to the driver module 120. Figure 7A The switch module 114 is described in the example of NMOS transistor, but those skilled in the art will appreciate that the switch module 114 can be implemented in other forms, such as PMOS transistor, PNP transistor, NPN transistor, or in the form of a mechanical switch. Figure 2 As can be seen from the description above, due to the current-voltage (IV) characteristics of the switch module, the peak voltage of the pulse signal Vin is also related to the on-state current flowing through the switch module 114. Therefore, the pulse signal Vin determines whether to turn on the switch module, and thus whether to drive the level signal. Furthermore, the peak value of the pulse signal Vin and the digital control signal Din can both affect the on-state current flowing through the switch module 114, and thus the magnitude of the driven level signal.

[0098] like Figure 6 As shown in , the drive control module further includes a level shifter 122 for providing a voltage drop. The drive module 120 may include a third transistor 124. Specifically, the control electrode of the third transistor 124 is connected to the drive control module 110, and the level shifter 122 is connected to the drive control module 110, the control electrode of the third transistor 124, and the power supply HVDD1 of the drive module 120 to control the opening and closing of the third transistor 124.

[0099] like Figure 7A As shown, the level shifter 122 may include a first resistor 1222, wherein one end of the first resistor 1222 is connected to the control electrode of the third transistor 124, and the other end is connected to the power supply HVDD1 of the driving module 120 to provide a driving signal to the control electrode of the third transistor 124. When the second transistor 1142 and the first transistor 1124 below the first resistor 1222 are both turned on, this branch is turned on, and the conducted current forms a voltage drop across the resistor connected in parallel with the first resistor 1222 and the first transistor 1124 (to accelerate the flow of the conducted current). After passing through the first resistor 1222 (and the first diode 1224 connected in parallel therewith), the conducted current I generates a voltage Vx at the gate of the third transistor 124:

[0100] Vx=HVDD1-R1×I,

[0101] Wherein HVDD1 is the power supply voltage, R1 is the resistance value of the first resistor 1222 , and I is the current value flowing through the first resistor 1222 , the second transistor 1142 , the first transistor 1124 , and the ground.

[0102] It can be seen that in Figure 7A In the illustrated embodiment, when the pulse signal Vin and the digital control signal Din turn on both the first transistor 1124 and the second transistor 1142, a path is formed between the power supply HVDD1, the first resistor 1222, the second transistor 1142, and the first transistor 1124 to ground. The pulse signal Vin determines whether the second transistor 1142 is turned on. The digital control signal Din and the pulse signal Vin jointly determine the current value I during the on-state period, which in turn determines the gate voltage of the third transistor 124 (i.e., the aforementioned voltage Vx). This voltage turns on the third transistor 124, thereby determining the magnitude of the drive current provided to the light-emitting device 20 and the light-emitting power of the light-emitting device 20.

[0103] When the pulse signal Vin and the digital control signal Din cause one of the first transistor 1124 and the second transistor 1142 to be non-conductive, the aforementioned path is not formed. At this time, the gate voltage of the third transistor 124 is its power supply voltage HVDD1, so the third transistor 124 is turned off, and the light-emitting device 20 is turned off. At this time, there is no DC path from the power supply HVDD1 to GND, and no DC power consumption is generated.

[0104] Furthermore, in some embodiments, the level shifter 122 may further include at least one first diode 1224 connected in parallel with the third transistor 124. The anode of the first diode 1224 is connected to the power supply HVDD1 of the driver module 120, and the cathode is connected to the driver control module 110. More specifically, the cathode of the first diode 1224 is connected to the drain of the second transistor 1142. Utilizing the first diode 1224 can accelerate the conduction between the first transistor 1124 and the second transistor 1142.

[0105] Furthermore, in some embodiments, the level shifter 122 may further include at least one second diode 1226 connected in parallel with the third transistor 124. The cathode of the second diode 1226 is connected to the power supply HVDD1 of the driver module 120, and the anode is connected to the driver control module 110. More specifically, the anode of the second diode 1226 is connected to the drain of the second transistor 1142. The second transistor 1226 can be used to limit the drive level signal Vx from the driver control module 110 to prevent it from being too high and thereby damaging the light-emitting device 20.

[0106] In such Figure 7AIn the illustrated embodiment, the third transistor 124 may be implemented as a PMOS transistor, wherein the gate serves as a control electrode, the source is connected to the power supply HVDD1 of the driving module 120 , and the drain is connected to the anode of the light emitting device 20 .

[0107] In such Figure 7B In the illustrated embodiment, the third transistor 124 may be implemented as an NMOS transistor, wherein the gate serves as a control electrode, the drain is connected to the power supply HVDD1 of the driving module 120 , and the source is connected to the anode of the light emitting device 20 .

[0108] It can be seen that Figure 7A and 7B The main difference of the embodiment shown is the different implementation of the third transistor 124. Figure 7A In the embodiment, the third transistor 124 is implemented as a PMOS tube, and Figure 7B In the embodiment, the third transistor 124 is implemented as an NMOS transistor. Since the gate voltage of the NMOS transistor is relatively more difficult to control, Figure 7A The PMOS transistor 124 shown is generally superior to Figure 7B The NMOS tube shown.

[0109] Here, the MOS tube refers to a MOSFET, namely a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), the PMOS tube refers to a P-channel MOS tube, and the NMOS tube refers to an N-channel MOS tube.

[0110] In addition, if Figure 7A and 7B As shown, each selectable module 112 may further include a first driving link 1126 connected to the gate of the first transistor 1124 for driving the first transistor 1124 to be turned on or off. For example, the first driving link 1126 may enhance its driving capability when the input pulse signal Vin is small.

[0111] In addition, if Figure 7A As shown, the switch module 114 may further include a second drive link 1144 connected to the gate of the second transistor 1142 to drive the second transistor 1142 to turn on or off. The second drive link 1144 may further narrow the width of Vin, thereby more accurately controlling the light-emitting duration of the light-emitting device 20.

[0112] In addition, if Figure 7A and 7B As shown, the driving control module 110 may further include a second resistor R2 for stabilizing the drain voltage of the first transistor 1124 at 0.

[0113] Figure 8 A functional module diagram of a driving device 10 for a light emitting device of a laser radar according to other embodiments of the present invention is shown; Figure 9A Shown Figure 8 An example circuit diagram of the driving device 10 is shown; Figure 9B Shown Figure 9A A variation of the example circuit diagram shown. Figure 8 、 Figure 9A and Figure 9B Examples and Figure 6 、 Figure 7A 、 Figure 7B The main difference lies in the different control methods of the selectable module 112 and the switch module 114, so the following description only focuses on the difference between them.

[0114] like Figure 8 As shown in , the driving control module 110 of the driving device 10 may include a plurality of selectable modules 112 connected in parallel and a switch module 114 connected in series with the plurality of selectable modules 112 .

[0115] Multiple selectable modules 112 can receive a pulse signal Vin and a digital control signal Din to control the switching on or off of each selectable module 112. By controlling the number of selectable modules 112 that are enabled, the magnitude of the drive level signal Vx output by the driver control module 110 is controlled. The switch module 114 can receive a pulse signal Vin and, based on the pulse signal Vin, determine whether to connect the power supply HVDD1 of the driver module 120, the switch module 114, the selectable modules 112, and ground. When connected, the drive level signal Vx is provided to the driver module 120.

[0116] like Figure 9A As shown in , in one embodiment, with Figure 7A and 7B Similarly, each of the selectable modules 112 may include a selector 1122 and a first transistor 1124, and the drains of the first transistors 1124 of the plurality of selectable modules 112 are connected in parallel. Figure 7A and 7BIn contrast, the input of the gate 1122 is connected to the pulse signal Vin and a low level (e.g., 0V, i.e., ground (GND)), and its output is connected to the control electrode of the first transistor 1124. The gate 1122 is configured to input the pulse signal Vin or the low level GND to the control electrode of the first transistor 1124 under the control of the corresponding bit Selx (including Sel0, Sel1...Sel300) in the digital control signal Din. The control electrode of the first transistor 1124 is connected to the gate 1122 to connect the switch module 114 to the ground when receiving the high level pulse signal Vin from the gate 1122, and to disconnect the switch module 114 from the ground when receiving the low level GND from the gate 1122.

[0117] Similarly, the digital control signal Din can be a binary digital sequence, and each binary digital (one bit) in the sequence together with the pulse signal Vin controls the on or off of a selectable module 112. Figure 9A For example, the drive control module 110 may include 301 selectable modules 112, and the digital control signal Din is a digital sequence Sel0, Sel1... Sel300 composed of 301 bits, wherein each bit is used to control the on or off of the corresponding selectable module 112 together with the pulse signal Vin. For example, when Sel0 is 1 and the pulse signal Vin is at a high level, the selector 1122 outputs the high level of the input pulse signal Vin to the control electrode of the first transistor 1124, thereby turning on the first transistor 1124. Conversely, when Sel0 is 0 or when Sel0 is 1 and the pulse signal Vin is at a low potential, the selector 1122 outputs the low level GND of the input to the control electrode of the first transistor 1124, thereby turning off the first transistor 1124. Although Figure 9A The example in which the drive control module 110 includes 301 selectable modules 112 and the digital control signal Din includes 301 bits is used for description. However, those skilled in the art will appreciate that the number of selectable modules 112 and the number of bits of the digital control signal Din are not limited to this. Furthermore, the manner in which the pulse signal Vin and the digital control signal Din control the selectable modules 112 is not limited to that shown in the figure. For example, in some implementations, each bit of the digital control signal Din can be used together with the pulse signal Vin to control multiple selectable modules 112, or multiple bits of the digital control signal Din can be used together with the pulse signal Vin to control a single selectable module 112. Furthermore, if the pulse signal Vin is a multi-pulse signal, the digital control signal Din can be combined with the number of pulses in the pulse signal Vin to control the selectable modules 112. Generally, the greater the number of selectable modules 112, the more precisely Vx is controlled, and thus the more accurately the laser radar adjusts the laser light intensity.

[0118] In such Figure 9A In the illustrated embodiment, the first transistor 1124 may be an NMOS transistor, wherein the gate serves as a control electrode, the source is grounded, and the drain is connected to the switch module 114 .

[0119] In addition, the switch module 114 may include a second transistor 1142, whose control electrode receives a high level or a low level selected by the pulse signal Vin. Specifically, the drive control module 110 may include a second gate 116, whose input end is connected to a high level (such as the power supply voltage VDD5 of the drive control module) and a low level (such as 0V, i.e., ground (GND)), and its output end is connected to the control electrode of the second transistor 1142. When the pulse signal Vin is at a high level, the second gate 116 selects its high level input VDD5 and outputs the high level VDD5 to the gate of the second transistor 1142 to turn on the second transistor 1142. Conversely, when the pulse signal Vin is at a low level, the second gate 116 selects its low level input GND and outputs the low level GDN to the gate of the second transistor 1142 to turn off the second transistor 1142.

[0120] In such Figure 9A In the illustrated embodiment, the second transistor 1142 may be an NMOS transistor, wherein the gate serves as a control electrode and the source is connected to the plurality of selectable modules 112 to receive the drive level signal Vx. The drain of the second transistor 1142 is connected to the driver module 120, and whether to select the second transistor 1142 may be determined based on the pulse signal Vin. When the second transistor 1142 is selected, the power supply HVDD1 of the driver module 120, the switch module 114, the selection module 112, and the ground path are connected to provide the drive level signal Vx to the driver module 120. Figure 9A The switch module 114 is described using an NMOS transistor as an example, but those skilled in the art will appreciate that the switch module 114 may be implemented in other forms, such as a PMOS transistor, a PNP transistor, an NPN transistor, or in the form of a mechanical switch.

[0121] exist Figure 8 、 Figure 9A and Figure 9B In the example shown, the driving modules 120 are respectively Figure 6 , Figure 7A and Figure 7B It is similar to the above, so I will not repeat it here.

[0122] also, Figure 9A and Figure 9B In addition to the different implementations of the third transistor 124, the example also shows the case where the digital control signal Din contains different bits. Figure 9AIn the embodiment shown, the digital control signal Din includes Sel0, Sel1, ..., Sel300, a total of 301 bits. Accordingly, the number of the selectable modules 112 is 301. Figure 9B In the illustrated embodiment, the digital control signal Din includes Sel0 , Sel1 , . . . Sel200 , which are 201 bits in total. Accordingly, the number of the selectable modules 112 is 201.

[0123] In addition, if Figure 9A and 9B As shown in , each selectable module 112 may further include a first driving link 1126 connected to the gate of the first transistor 1124 for driving the first transistor 1124 to be turned on or off. For example, the first driving link 1126 may enhance its driving capability when the input pulse signal Vin is small.

[0124] Simulation Results

[0125] The inventors conducted simulations on various solutions according to the present invention. Figure 10 Shown Figure 7A Voltage waveform diagram 1000 of key points of the embodiment shown; Figure 11 Shown Figure 7A A waveform diagram 2000 of the source-gate voltage of the third transistor 142 and the driving current of the light emitting device 20 in the illustrated embodiment; Figure 12 A waveform diagram 3000 is shown showing the driving current of the light emitting device 20 and the gate voltage of the third transistor 142 when the light emitting device of the present application emits four pulses; Figure 13 Shown Figure 7A The waveform diagram 4000 of the drain output voltage of the third transistor 142 when the digital control signal Din is changed in the embodiment shown.

[0126] like Figure 10 As shown, assuming that the pulse signal Vin is a 4-pulse signal with the same amplitude and an interval of 50ns, curve 1100 shows the voltage waveform of the pulse signal Vin, curve 1200 shows the waveform of the gate voltage of the second transistor 1142, curve 1300 shows the waveform of the drain voltage of the first transistor 1124, curve 1400 shows the waveform of the drain voltage of the second transistor 1142 (that is, the driving level signal Vx), curve 1500 shows the waveform of the power supply voltage HVDD1 of the driving module 120, and curve 1600 shows the waveform of the drain voltage of the third transistor 124.

[0127] like Figure 11 As shown in , a curve 2100 indicates a waveform diagram of the source-gate voltage of the third transistor 142 , and a curve 2200 indicates a waveform diagram of the driving current of the light emitting device 20 .

[0128] It can be seen that using the solution of the present invention, for a four-pulse pulse signal Vin, the drive currents when the four pulses are emitted are almost equal, and the amplitudes of the corresponding four pulses are also almost the same. This overcomes the problem of large differences in the peak drive currents between pulses in the prior art for multi-pulse pulse signals, making the solution of the present invention particularly suitable for multi-pulse application scenarios.

[0129] like Figure 12 As shown, curve 3100 shows the waveform of the driving current of the light emitting device 20 when the multi-pulse repetition frequency of the pulse signal Vin increases, and curve 3200 shows the waveform of the gate voltage of the third transistor 142 when the multi-pulse repetition frequency of the pulse signal Vin increases. Specifically, four pulses are emitted with a time interval of about 50ns. Figure 5F and Figure 10 、 Figure 11 、 Figure 12 It can be seen that the same 4 pulses are sent with an interval of about 50ns. Figure 11 and Figure 12 The currents of the four pulses are almost equal when they are emitted. When the multi-pulse repetition frequency (4 times) increases, the amplitudes of multiple consecutive pulse signals become more consistent. For example, the peak current of the first pulse 3101 of curve 3100 is 193.89mA, and the peak current of the second pulse 3102 is 211.79mA. The corresponding heights of the first pulse 3201, the second pulse 3202, the third pulse 3203 and the fourth pulse 3204 of curve 3200 are almost the same, all about 1.25V. Figure 5F In the example, the peak currents between different pulses differ by 169%. Therefore, the drive circuit of the present application can overcome the defects of the existing solutions.

[0130] like Figure 13 As shown, curve 4100 shows the waveform 4100 of the drain output voltage of the third transistor 142 when the digital control signal Din selects Sel0 ... Sel49 (a total of 50 selectable modules 112 are selected); curve 4200 shows the waveform 4200 of the drain output voltage of the third transistor 142 when the digital control signal Din selects Sel0 ... Sel4 (a total of 5 selectable modules 112 are selected). It can be seen that the peak value of waveform 4200 is higher than the peak value of waveform 4100. Therefore, the more selectable modules 112 are selected, the higher the output voltage of the third transistor 142, thereby increasing the driving current provided to the light-emitting device 20.

[0131] In addition, this solution does not have a circuit such as an LDO that generates static loss. Instead, it uses an NMOS tube in structure and adopts a gating method in operation, thus overcoming the defect of static loss and saving power consumption. Figure 14 Shown Figure 7A Referring to FIG14 , using the solution of the present invention, when one of the first transistor 1124 and the second transistor 1142 is not conducting, the gate voltage of transistor 1142 is 0V, the source voltage of transistor 1142 is also 0V, the current flowing through resistor 1222 can only be 0A, and the third transistor 124 is turned off, thereby turning off the light-emitting device 20, thereby preventing high-voltage DC power consumption.

[0132] Those skilled in the art will appreciate that, depending on different application scenarios, the solutions according to the inventive concept of the present invention can be easily implemented as hardware circuits (such as FPGA or ASIC), driving methods or corresponding driver programs.

[0133] Various aspects of the embodiments of the present invention have been described above with reference to the accompanying drawings. It should be understood that the above description is merely exemplary, and the present invention is not limited to the specific implementations described above and shown in the accompanying drawings. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the embodiments described. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to the technology in the market, or to enable other persons skilled in the art to understand the embodiments disclosed herein.

Claims

1. A driving device for a light-emitting device of a laser radar, wherein the driving device is connected to an anode of the light-emitting device, and the driving device comprises: a drive control module connected to a power supply, configured to receive an input pulse signal and a digital control signal, and output a drive level signal; wherein the pulse signal is used to control whether the drive control module outputs the drive level signal, and the digital control signal is used to adjust the magnitude of the drive level signal output by the drive control module; and a driving module connected to the driving control module and a power supply, and configured to provide a driving current to the light-emitting device of the laser radar based on the driving level signal, so as to drive the light-emitting device to emit light; The drive control module includes a plurality of selectable modules connected in parallel with each other, a switch module connected in series with the plurality of selectable modules, and a level shifter, wherein The plurality of selectable modules are adapted to receive the digital control signal to control the on or off of each selectable module, thereby controlling the magnitude of the driving level signal output by the driving control module; The switch module is adapted to receive the pulse signal, determine whether to conduct the path between the power supply, the switch module, the selectable module and the ground according to the pulse signal, and provide the driving level signal to the driving module when conducting; The level shifter is suitable for providing a voltage drop. The level shifter includes a first resistor and a first diode connected in parallel between the output end of the drive control module and the power supply voltage of the drive module. The anode of the first diode is connected to the power supply, and the cathode is connected to the drive control module.

2. The driving device according to claim 1, wherein: The driving module includes a third transistor, wherein The control electrode of the third transistor is connected to the drive control module, the first electrode of the third transistor is connected to the power supply, and the second electrode of the third transistor is connected to the anode of the light emitting device, and is suitable for opening and closing under the control of the drive level signal.

3. The driving device according to claim 2, wherein: Each of the plurality of gate-through modules comprises: a gate and a first transistor, wherein The input end of the gate is connected to a high level and a low level, and the output end thereof is connected to the control electrode of the first transistor, and the gate is configured to input the high level or the low level to the control electrode of the first transistor under the control of a corresponding bit in the digital control signal; The control electrode of the first transistor is connected to the gate, the first electrode of the first transistor is grounded, and the second electrode of the first transistor is connected to the switch module; The first transistor is adapted to connect the path from the switch module to the ground when receiving a high-level input from the gate, and disconnect the path from the switch module to the ground when receiving a low-level input from the gate.

4. The driving device according to claim 3, wherein: The switch module includes a second transistor, and a control electrode of the second transistor receives the pulse signal; A first electrode of the second transistor is connected to the plurality of selectable modules; The second electrode of the second transistor is connected to the driving module, and is suitable for determining whether to turn on the second transistor according to the pulse signal, and when the second transistor is turned on, turning on the path of the power supply-the level shifter-the switch module-the selectable module and the ground to provide the driving level signal to the driving module.

5. The driving device according to claim 4, wherein one end of the first resistor is connected to the control electrode of the third transistor, and the other end is connected to the power supply, so as to cooperate with other components of the driving control module to provide the driving level signal to the control electrode of the third transistor.

6. The driving device according to claim 5, wherein the level shifter further comprises at least one first diode connected in parallel with the third transistor; and / or The level shifter further includes at least one second diode connected in parallel with the third transistor, and the cathode of the second diode is connected to the power supply, and the anode of the second diode is connected to the drive control module. 7 . The driving device according to claim 4 , wherein the first transistor and the second transistor are NMOS transistors, and the control electrodes of the first transistor and the second transistor indicate gates, the first electrodes indicate sources, and the second electrodes indicate drains.

8. The driving device according to claim 2, wherein the third transistor is a PMOS transistor, and the control electrode of the third transistor indicates the gate, the first electrode indicates the source, and the second electrode indicates the drain; or The third transistor is an NMOS transistor, and the control electrode of the third transistor indicates the gate, the first electrode indicates the drain, and the second electrode indicates the source.

9. The driving device according to claim 1, wherein the driving control module further comprises a voltage stabilizing module and an inverter, wherein: The voltage stabilizing module is adapted to receive a digital control signal for stabilizing the peak value of the pulse signal; The inverter is adapted to invert the digital control signal when the pulse signal is sufficient to turn on the switch module; The switch module is adapted to receive the pulse signal, determine whether to conduct the path between the power supply-the level shifter-the switch module and the ground according to the pulse signal and the inverted digital control signal, and provide the driving level signal to the driving module when conducting.

10. A laser radar comprising: A plurality of drive devices according to any one of claims 1 to 9; and a plurality of light emitting devices; The cathodes of the multiple light-emitting devices are connected; One end of each driving device is connected to a power source, and the other end is connected to the anode of the light emitting device.

11. The laser radar as claimed in claim 10 further includes a control unit, which is connected to the drive control module and is suitable for generating the pulse signal and the digital control signal according to the ranging requirements, so as to select the multiple light-emitting devices in turn to emit light.

12. The laser radar according to claim 10 or 11, wherein: The light emitting device includes an edge emitting laser (EEL) or a vertical cavity surface emitting laser (VCSEL).

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