A low-noise continuous wave modulated laser drive source for high-speed laser range finders
By combining modules such as a low phase noise frequency synthesizer and an optical power feedback loop, a fundamental main oscillator signal with low phase noise is generated and transient stability of optical power is achieved, which solves the problems of high phase noise and power instability in laser rangefinders and improves ranging accuracy.
Patent Information
- Application Number
- CN202521877360.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-01
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-09-01
AI Technical Summary
Existing laser rangefinders have high phase noise in their laser drive sources, resulting in low ranging accuracy, and the laser output power is unstable due to factors such as temperature.
The system employs a low-phase-noise frequency synthesizer, a fundamental wave extraction module, an AC coupling module, a high-side current sampling module, an integral regulator, an optical power feedback module, and a voltage-controlled current drive module. Combined with a CDCE L925 series clock chip and a low-noise DC voltage module, it generates a low-phase-noise fundamental wave master oscillator signal and achieves transient stabilization of optical power through an optical power feedback loop.
It effectively reduces random errors in phase difference measurement, improves ranging accuracy, ensures the stability of laser output power, and enhances the accuracy of high-speed phase ranging.
Smart Images
Figure CN224683636U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor laser electronic circuit technology, and specifically to a low-noise continuous wave modulated laser drive source for high-speed laser rangefinders. Background Technology
[0002] Currently, high-speed laser rangefinders have been widely used in industrial production lines, smart warehousing and other fields due to their high precision, high-speed response and strong anti-interference capabilities. Among them, the core of high-precision phase ranging is to calculate the distance by measuring the sinusoidal phase difference between the transmitted and echo signals. The phase difference measurement error is directly converted into the distance error. Therefore, a low phase noise signal source can not only effectively reduce the random error of phase difference measurement, but also make it easier to extract phase changes in weak echo signals.
[0003] In practical applications, the output power of a laser is affected by factors such as temperature. Therefore, continuous wave modulation of the laser amplitude requires overcoming the laser's own power drift (drift, aging, threshold drift) and ensuring transient stability and high linearity of optical power during continuous wave modulation. Based on this, how to provide a laser driver source with low phase noise and transient stability of optical power to reduce the random error of laser rangefinders and improve ranging accuracy has become an urgent problem to be solved. Utility Model Content
[0004] The purpose of this invention is to provide a low-noise continuous wave modulated laser driver for high-speed laser rangefinders, in order to solve the problem of low laser ranging accuracy caused by high phase noise of the laser driver in the prior art.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] In a first aspect, a low-noise continuous-wave modulated laser drive source for a high-speed laser rangefinder is provided, comprising:
[0007] Low phase noise frequency synthesizer, fundamental frequency extraction module and AC coupling module;
[0008] The output of the low phase noise frequency synthesizer is electrically connected to the input of the fundamental wave extraction module, wherein the output of the fundamental wave extraction module is electrically connected to the input of the AC coupling module, and outputs the fundamental wave master oscillation signal for laser continuous wave modulation to the AC coupling module. The low phase noise frequency synthesizer uses a CDCEL925 series clock chip that outputs multiple LVCMOS level signals.
[0009] High-side current sampling module and integral regulator;
[0010] The input terminal of the high-side current sampling module is electrically connected to a low-noise DC voltage module for sampling the bias current of the semiconductor laser. The output terminal of the high-side current sampling module is electrically connected to the input terminal of the main control module, and the output terminal of the main control module is electrically connected to the first input terminal of the integral regulator.
[0011] Optical power feedback module and voltage-controlled current drive module;
[0012] The input terminal of the optical power feedback module is electrically connected to the semiconductor laser, and the output terminal of the optical power feedback module is electrically connected to the second input terminal of the integral regulator. The output terminal of the integral regulator is electrically connected to the input terminal of the voltage-controlled current drive module, and the output terminals of the voltage-controlled current drive module and the AC coupling module are both electrically connected to the semiconductor laser.
[0013] Based on the above disclosure, this invention uses a CDCE L925 series clock chip to generate a clock signal, which, after passing through a fundamental frequency extraction module, generates a fundamental main oscillator signal for laser continuous wave modulation. The CDCE L925 series clock chip can output multiple LVCMOS level signals, and compared to other frequency synthesis techniques, it can generate clock signals with lower phase noise, thus generating a low-phase-noise fundamental main oscillator signal. Simultaneously, this invention provides a low-noise DC voltage module to generate the laser's bias current. Therefore, combining the low-noise bias current with the AC-coupled low-phase-noise fundamental main oscillator signal, a low-phase-noise laser driver source can be formed. Laser continuous wave modulation is performed; based on this, the random error of phase difference measurement can be effectively reduced. In addition, this invention also sets up an optical power feedback loop, that is, the power of the laser is fed back through the optical power feedback module and fed back to the integral regulator. The integral regulator can output corresponding control signals based on the feedback value and the output of the main control module to adjust the bias current of the laser circuit until balance is reached. In this way, the transient stability of optical power during continuous wave modulation can be achieved through the optical power feedback loop, thereby further improving the ranging accuracy. Therefore, this invention provides a laser driver source with low phase noise and transient stability of optical power, which can effectively improve the ranging accuracy in high-speed phase ranging.
[0014] In one possible design, the fundamental frequency extraction module includes a multi-stage filtering circuit, wherein the input of the multi-stage filtering circuit is electrically connected to the output of the low phase noise frequency synthesizer, and the output of the multi-stage filtering circuit outputs a sinusoidal output signal to the AC coupling module, and the sinusoidal output signal serves as the fundamental frequency main oscillation signal.
[0015] In one possible design, the multi-stage filter circuit includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, a first inductor, a second inductor, and a third inductor;
[0016] One end of the second capacitor serves as the input terminal of the multi-stage filter circuit and is electrically connected to the output terminal of the low phase noise frequency synthesizer. One end of the second capacitor is also electrically connected to one end of the first capacitor and one end of the first inductor, and the other end of the second capacitor is electrically connected to the other end of the first inductor, one end of the second inductor, one end of the third capacitor, and one end of the fourth capacitor.
[0017] The other end of the fourth capacitor is electrically connected to the other end of the second inductor, one end of the third inductor, one end of the fifth capacitor, and one end of the sixth capacitor, respectively; and the other end of the sixth capacitor is electrically connected to the other end of the third inductor and one end of the seventh capacitor, respectively.
[0018] The other end of the sixth capacitor also serves as the output terminal of the multi-stage filter circuit, electrically connected to the AC coupling module, and the other ends of the first capacitor, the third capacitor, the fifth capacitor, and the seventh capacitor are respectively grounded.
[0019] In one possible design, the high-side current sampling module includes: a sampling resistor, a resistor array, and a first operational amplifier;
[0020] The sampling resistor serves as the input terminal of the high-side current sampling module and is electrically connected to the low-noise DC voltage module. The two ends of the sampling resistor are electrically connected to the non-inverting input terminal and the inverting input terminal of the first operational amplifier through the resistor array, and the output terminal of the first operational amplifier is electrically connected to the input terminal of the main control module.
[0021] In one possible design, the high-side current sampling module further includes an eighth capacitor, wherein the inverting input of the first operational amplifier is electrically connected to one end of the eighth capacitor, the other end of the eighth capacitor is electrically connected to the resistor array and the output of the first operational amplifier, and the eighth capacitor and the resistor array constitute a low-pass filter.
[0022] In one possible design, the low-noise DC voltage module includes: a DC-DC power supply and a multiplier filter circuit;
[0023] The input terminal of the multiplication filter circuit is electrically connected to the DC-DC power supply, and the output terminal of the multiplication filter circuit is electrically connected to the input terminal of the high-side current sampling module, providing a low-noise DC voltage to the high-side current sampling module.
[0024] In one possible design, the multiplication filter circuit includes: a first transistor, a first resistor, and a ninth capacitor;
[0025] The collector of the first transistor is electrically connected to the DC-DC power supply and one end of the first resistor, respectively. The base of the first transistor is electrically connected to the other end of the first resistor and one end of the ninth capacitor, respectively. The emitter of the first transistor is electrically connected to the input terminal of the high-side current sampling module.
[0026] The emitter of the first transistor is also electrically connected to one end of the tenth capacitor and one end of the eleventh capacitor, respectively, and the other ends of the ninth capacitor, the tenth capacitor, and the eleventh capacitor are grounded.
[0027] In one possible design, the voltage-controlled current drive module includes: a second operational amplifier and a second transistor;
[0028] The non-inverting input terminal of the second operational amplifier is electrically connected to the output terminal of the integral regulator through a second resistor, a third resistor, and a fourth resistor connected in series. The inverting input terminal of the second operational amplifier is electrically connected to the output terminal of the second operational amplifier through a twelfth capacitor, and a fifth resistor is connected in parallel across the two ends of the twelfth capacitor.
[0029] The output of the second operational amplifier is electrically connected to the base of the second transistor through a sixth resistor. The emitter of the second transistor is electrically connected to the low side of the sampling resistor in the high-side current sampling module, and the collector of the second transistor is electrically connected to the semiconductor laser.
[0030] In one possible design, the output of the low-noise DC voltage module is electrically connected to the input of the high-side current sampling module via a soft-start protection circuit.
[0031] In one possible design, the output of the fundamental frequency extraction module is electrically connected to the input of the AC coupling module via an RF amplifier.
[0032] Beneficial effects:
[0033] (1) This utility model provides a laser driving source with low phase noise and transient stability of optical power, which can effectively improve the ranging accuracy in high-speed phase ranging. Attached Figure Description
[0034] Figure 1 A schematic diagram of a low-noise continuous-wave modulated laser drive source for a high-speed laser rangefinder provided for an embodiment of this utility model;
[0035] Figure 2 A detailed circuit diagram of the multi-stage filter circuit provided in this embodiment of the utility model;
[0036] Figure 3A detailed circuit diagram of the multiplication filter circuit provided in the embodiments of the present invention;
[0037] Figure 4 A detailed circuit diagram of the high-side current sampling module provided in this embodiment of the utility model;
[0038] Figure 5 The connection circuit diagram between the voltage-controlled current drive module and the optical power feedback module provided in this embodiment of the utility model and the semiconductor laser;
[0039] Figure 6 A specific circuit diagram of the radio frequency amplifier provided in the embodiments of the present invention;
[0040] Figure 7 A schematic diagram of a laser continuous wave modulation curve provided for an embodiment of this utility model. Detailed Implementation
[0041] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the present utility model will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is used to help understand this utility model, but does not constitute a limitation on this utility model.
[0042] It should be understood that although the terms first, second, etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, the first unit may be referred to as the second unit, and similarly, the second unit may be referred to as the first unit, without departing from the scope of the exemplary embodiments of this utility model.
[0043] It should be understood that the term "and / or" that may appear in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" that may appear in this document describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this document generally indicates that the related objects before and after it are in an "or" relationship.
[0044] Example:
[0045] See Figures 1 to 7As shown, the low-noise continuous wave modulated laser drive source for high-speed laser rangefinders provided in this embodiment may include, but is not limited to, a low-noise DC voltage module, a high-side current sampling module, an integral regulator, a voltage-controlled current drive module, an optical power feedback module, a low phase noise frequency synthesizer, a fundamental wave extraction module, an AC coupling module, and a main control module.
[0046] The low-phase-noise frequency synthesizer, fundamental wave extraction module, and AC coupling module are used to provide the fundamental main oscillator signal for laser continuous wave modulation. The low-noise DC voltage module is used to provide a low-noise DC voltage. The high-side current sampling module is used to generate the bias current of the semiconductor laser. The integral regulator and optical power feedback module form an optical power feedback loop, which, combined with the optical power setting value output by the main control module, controls the voltage-controlled current drive module to adjust the bias current. Finally, it is superimposed with the AC-coupled fundamental main oscillator signal to perform laser continuous wave modulation.
[0047] Furthermore, the detailed working process of each of the aforementioned modules is disclosed below:
[0048] In this embodiment, the output of the low phase noise frequency synthesizer is electrically connected to the input of the fundamental wave extraction module, and the output of the fundamental wave extraction module is electrically connected to the input of the AC coupling module, outputting the fundamental wave master oscillator signal for laser continuous wave modulation to the AC coupling module. The AC coupling module performs AC coupling of the fundamental wave master oscillator signal so that it can be superimposed on the bias current output by the voltage-controlled current drive module. Specifically, the fundamental wave extraction module performs fundamental wave filtering on the clock signal to convert the square wave into a sine wave output signal (i.e., the fundamental wave master oscillator signal), while the AC coupling module removes the DC component from the sine wave output signal to ensure that only the AC signal is superimposed on the bias current of the laser. The AC coupling module is usually implemented using capacitive coupling, which is a common circuit for laser modulation, and its structure will not be described in detail.
[0049] Additionally, see Figure 1 As shown, for example, the output of the fundamental frequency extraction module is electrically connected to the input of the AC coupling module through an RF amplifier. This allows the RF amplifier to amplify the fundamental frequency oscillator signal, providing sufficient gain to drive subsequent circuitry. The specific circuit diagram of the RF amplifier can be found in [reference needed]. Figure 6 As shown, it will not be elaborated further here.
[0050] In this embodiment, the low phase noise frequency synthesizer uses a CDCEL925 series clock chip that outputs multiple signals conforming to LVCMOS (a logic level standard). In practical applications, common frequency synthesis techniques include direct frequency synthesis, phase-locked loop (PLL) frequency synthesis, and direct digital frequency synthesis (DDS). This embodiment uses PLL-based frequency synthesis, which utilizes a programmable multi-channel LVCMOS output clock chip (i.e., a CDCEL925xx series clock chip, such as the CDCEL92513 or CDCEL92525) to output a clock signal. This signal is then provided to the fundamental frequency extraction module for fundamental frequency filtering to obtain a sinusoidal output signal. Compared to other frequency synthesis techniques, this method can generate a clock signal with lower phase noise, thus generating a low-phase-noise fundamental oscillator signal.
[0051] Thus, after generating the fundamental main oscillator signal, the bias current can be sampled, and the process is as follows:
[0052] The input of the high-side current sampling module is electrically connected to a low-noise DC voltage module for sampling the bias current of the semiconductor laser. The output of the high-side current sampling module is electrically connected to the input of the main control module, and the output of the main control module is electrically connected to the first input of the integral regulator for outputting a power setpoint to the integral regulator. Simultaneously, the input of the optical power feedback module is electrically connected to the semiconductor laser, and the output of the optical power feedback module is electrically connected to the second input of the integral regulator. Thus, the integral regulator can output a corresponding control signal to the voltage-controlled current drive module based on the optical power feedback value output by the optical power feedback module and the power setpoint output by the main control module. That is, the output of the integral regulator is electrically connected to the input of the voltage-controlled current drive module for controlling the bias current of the laser circuit in the feedback adjustment of the voltage-controlled current drive module. Finally, the adjusted bias current is superimposed on the aforementioned AC-coupled fundamental main oscillator signal and input to the semiconductor laser. That is, the outputs of both the voltage-controlled current drive module and the AC coupling module are electrically connected to the semiconductor laser to achieve continuous wave modulation of the semiconductor laser.
[0053] In this embodiment, the main control module described herein may, but is not limited to, be a microcontroller.
[0054] Therefore, through the aforementioned design, this embodiment utilizes the CDCEL925 series clock chip, combined with a low-noise DC voltage module and an optical power feedback loop, to provide a laser drive source with low phase noise and transiently stable optical power. In this way, the ranging accuracy can be effectively improved during high-speed phase ranging.
[0055] In one possible design, the detailed circuit structure of each of the aforementioned modules is provided below in this embodiment:
[0056] First, let's disclose one specific circuit structure of the fundamental frequency extraction module:
[0057] In this embodiment, the fundamental wave extraction module may include, but is not limited to, a multi-stage filtering circuit. The input terminal of the multi-stage filtering circuit is electrically connected to the output terminal of the low phase noise frequency synthesizer to receive the clock signal output by the low phase noise frequency synthesizer. The output terminal of the multi-stage filtering circuit outputs a sinusoidal output signal to the AC coupling module and uses it as the fundamental wave main oscillation signal so that it can be superimposed with the bias current after AC coupling to realize laser continuous wave modulation.
[0058] Furthermore, the circuit construction of the multi-stage filter circuit is disclosed below:
[0059] In specific applications, the multi-stage filter circuit described in the example may include, but is not limited to: a first capacitor C5, a second capacitor C9, a third capacitor C6, a fourth capacitor C10, a fifth capacitor C7, a sixth capacitor C12, a seventh capacitor C8, a first inductor L1, a second inductor L2, and a third inductor L3; wherein the connection structure of the aforementioned capacitors and inductors is as follows:
[0060] See Figure 2 As shown, one end of the second capacitor C9 serves as the input terminal of the multi-stage filter circuit and is electrically connected to the output terminal of the low phase noise frequency synthesizer. Figure 2 In the PLL OUT section, the output terminal of the low phase noise frequency synthesizer is indicated. One end of the second capacitor C9 is also electrically connected to one end of the first capacitor C5 and one end of the first inductor L1, and the other end of the second capacitor C9 is electrically connected to the other end of the first inductor L1, one end of the second inductor L2, one end of the third capacitor C6, and one end of the fourth capacitor C10.
[0061] Meanwhile, the other end of the fourth capacitor C10 is electrically connected to the other end of the second inductor L2, one end of the third inductor L3, one end of the fifth capacitor C7, and one end of the sixth capacitor C12, respectively. The other end of the sixth capacitor C12 is electrically connected to the other end of the third inductor L3 and one end of the seventh capacitor C8, respectively. The other end of the sixth capacitor C12 also serves as the output terminal of the multi-stage filter circuit, electrically connected to the AC coupling module. The other ends of the first capacitor C5, the third capacitor C6, the fifth capacitor C7, and the seventh capacitor C8 are grounded, respectively.
[0062] In this embodiment, the first inductor L1, the second inductor L2, and the third inductor L3 are radio frequency signal inductors, and the first to seventh capacitors are MLCC capacitors. Through the synergistic effect of multiple capacitors and multiple inductors, the fundamental frequency of the clock signal can be filtered out to obtain a sinusoidal output signal other than the fundamental frequency.
[0063] After describing the circuit of the fundamental frequency extraction module, the circuit of the bias current sampling module will be described below.
[0064] Optionally, one implementation circuit of the low-noise DC voltage module may be provided first.
[0065] In this embodiment, the low-noise DC voltage module may include, but is not limited to, a DC-DC power supply and a multiplier filter circuit, wherein the input terminal of the multiplier filter circuit is electrically connected to the DC-DC power supply, and the output terminal of the multiplier filter circuit is electrically connected to the input terminal of the high-side current sampling module, thereby providing a low-noise DC voltage to the high-side current sampling module.
[0066] Meanwhile, the example multiplier filter circuit may include, but is not limited to, a first transistor Q1, a first resistor R1, and a ninth capacitor C3; wherein the connection structure of the aforementioned electronic components is as follows:
[0067] See Figure 3 As shown, the collector of the first transistor Q1 is electrically connected to the DC-DC power supply and one end of the first resistor R1, respectively. The base of the first transistor Q1 is electrically connected to the other end of the first resistor R1 and one end of the ninth capacitor C3, respectively. The emitter of the first transistor Q1 is electrically connected to the input terminal of the high-side current sampling module. At the same time, the emitter of the first transistor Q1 is also electrically connected to one end of the tenth capacitor C1 and one end of the eleventh capacitor C2, respectively. The other ends of the ninth capacitor C3, the tenth capacitor C1, and the eleventh capacitor C2 are respectively grounded.
[0068] In practical applications, Figure 3 VIN in the diagram represents the DC voltage after DC-DC power conversion, and VOUT represents the low-noise DC voltage after being filtered by the multiplier capacitor. R1 not only provides charging current for C3 and base current for the transistor, but R1 and C3 also form a low-pass filter, which can smooth out small fluctuations in the base voltage and control the load current of the emitter stage with the base current. Thus, after the capacitor multiplier filter, the noise floor of the output voltage can be greatly improved.
[0069] After generating a low-noise DC voltage, a high-side current sampling module can be used to sample the current, thereby obtaining the bias current of the semiconductor laser. The specific circuit structure of the high-side current sampling module is as follows:
[0070] In this embodiment, the high-side current sampling module may include, but is not limited to, a sampling resistor R9, a resistor array R10, and a first operational amplifier U1; wherein, see Figure 4 As shown, the sampling resistor R9 serves as the input terminal of the high-side current sampling module and is electrically connected to the low-noise DC voltage module; specifically, one end of the sampling resistor R9 is electrically connected to the output terminal of the aforementioned low-noise DC voltage module (i.e., Figure 4 In this context, VDD represents the low-noise DC voltage output by the low-noise DC voltage module. The other end of the sampling resistor R9 serves as the low side of the sampling resistor and is connected to the voltage-controlled current drive module. Meanwhile, the two ends of the sampling resistor R9 are electrically connected to the non-inverting input and inverting input of the first operational amplifier U1 through the resistor array R10, and the output of the first operational amplifier U1 is electrically connected to the input of the main control module.
[0071] In practical implementation, after sampling the current through the sampling resistor R9, the signal is differentially amplified by the first operational amplifier U1 and converted into a single-ended voltage signal, which is then output to the main control module for reading, thereby outputting the power setting value to the integral regulator. At the same time, for example, the inverting input terminal of the first operational amplifier U1 is also electrically connected to one end of the eighth capacitor C13, and the other end of the eighth capacitor C13 is electrically connected to the resistor array R10 and the output terminal of the first operational amplifier U1, respectively. The eighth capacitor C13 and the resistor array R10 constitute a low-pass filter, thus realizing low-pass filtering of the single-ended voltage signal.
[0072] Furthermore, in this embodiment, a soft-start protection circuit is provided between the low-noise DC voltage module and the high-side current sampling module, for example, see [link to relevant documentation]. Figure 1 As shown, the output terminal of the low-noise DC voltage module is electrically connected to the input terminal of the high-side current sampling module through a soft-start protection circuit. The soft-start protection circuit includes power-on soft-start and surge protection for surges generated during startup. This prevents damage to the laser caused by voltage overshoot or transient peak current overshoot during startup.
[0073] After the bias current is sampled based on the high-side current sampling module, the bias current can be adjusted through the aforementioned optical power feedback loop; wherein, the optical power feedback module may include, but is not limited to, the third operational amplifier U3.
[0074] See Figure 5As shown, the inverting input of the third operational amplifier U3 is connected to the PD optical power feedback pin of the semiconductor laser D1 through resistor R11, and the non-inverting input of the third operational amplifier U3 is electrically connected to one end of resistor R12. The other end of resistor R12 is electrically connected to the VCC power supply. The other end of resistor R12 is also electrically connected to the PD optical power feedback pin of the semiconductor laser D1 through resistor R13 and grounded through capacitor C11. The output of the third operational amplifier U3 is electrically connected to the second input of the integral regulator. In this way, the integral regulator can output a control signal to the voltage-controlled current drive module according to the output of the optical power feedback module and the set value output of the main control module, so as to control the voltage-controlled current drive module to adjust the bias current.
[0075] The process of feedback adjustment of the bias current in the laser circuit is as follows: when the optical power decreases, the bias current increases, and the power increases; when the optical power increases, the bias current decreases, and the power decreases.
[0076] Furthermore, one of the circuit structures of the voltage-controlled current drive module is disclosed below.
[0077] In this embodiment, the voltage-controlled current drive module may include, but is not limited to, a second operational amplifier U2 and a second transistor Q2; wherein the connection structure of the aforementioned electronic devices is as follows:
[0078] See Figure 5 As shown, the non-inverting input terminal of the second operational amplifier U2 is electrically connected to the output terminal of the integral regulator via a second resistor R3, a third resistor R4, and a fourth resistor R5 connected in series. The non-inverting input terminal of the second operational amplifier U2, the common connection terminal of the second resistor R3 and the third resistor R4, and the common connection terminal of the third resistor R4 and the fourth resistor R5 are each grounded through a capacitor. Figure 5 In the configuration (C15-C17), the inverting input terminal of the second operational amplifier U2 is electrically connected to the output terminal of the second operational amplifier U2 through the twelfth capacitor C19, and the fifth resistor R7 is connected in parallel across the two ends of the twelfth capacitor C19; simultaneously, the output terminal of the second operational amplifier U2 is electrically connected to the base of the second transistor Q2 through the sixth resistor R6, the emitter of the second transistor Q2 is electrically connected to the low side of the sampling resistor in the high-side current sampling module (i.e., the other end of the sampling resistor R9), and the collector of the second transistor Q2 is electrically connected to the semiconductor laser to output an adjusted bias current to the semiconductor laser.
[0079] Thus, through the aforementioned second operational amplifier U2 and second transistor Q2, the bias current of the laser circuit can be adjusted by feedback under the control of the PWM control signal output by the integral regulator, thereby achieving transient stability of the optical power during the modulation process.
[0080] After adjusting the bias current, the aforementioned AC-coupled fundamental main oscillator signal can be superimposed and output to the semiconductor laser for continuous wave modulation. For example, the modulation wavelength of the semiconductor laser is 650 nm, and a schematic diagram of the continuous wave modulation curve can be found [link to schematic diagram]. Figure 7 As shown; in addition, in this embodiment, the integral regulator is a commonly used circuit in feedback control, and its structure will not be described in detail.
[0081] Thus, based on the foregoing description, this utility model provides a laser driving source with low phase noise and transiently stable optical power, which can effectively improve ranging accuracy in high-speed phase ranging.
[0082] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.
Claims
1. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder, characterized in that, include: Low phase noise frequency synthesizer, fundamental frequency extraction module and AC coupling module; The output of the low phase noise frequency synthesizer is electrically connected to the input of the fundamental wave extraction module, wherein the output of the fundamental wave extraction module is electrically connected to the input of the AC coupling module, and outputs the fundamental wave master oscillation signal for laser continuous wave modulation to the AC coupling module. The low phase noise frequency synthesizer uses a CDCEL925 series clock chip that outputs multiple LVCMOS level signals. High-side current sampling module and integral regulator; The input terminal of the high-side current sampling module is electrically connected to a low-noise DC voltage module for sampling the bias current of the semiconductor laser. The output terminal of the high-side current sampling module is electrically connected to the input terminal of the main control module, and the output terminal of the main control module is electrically connected to the first input terminal of the integral regulator. Optical power feedback module and voltage-controlled current drive module; The input terminal of the optical power feedback module is electrically connected to the semiconductor laser, and the output terminal of the optical power feedback module is electrically connected to the second input terminal of the integral regulator. The output terminal of the integral regulator is electrically connected to the input terminal of the voltage-controlled current drive module, and the output terminals of the voltage-controlled current drive module and the AC coupling module are both electrically connected to the semiconductor laser.
2. The low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 1, characterized in that, The fundamental frequency extraction module includes a multi-stage filtering circuit, wherein the input terminal of the multi-stage filtering circuit is electrically connected to the output terminal of the low phase noise frequency synthesizer, and the output terminal of the multi-stage filtering circuit outputs a sinusoidal output signal to the AC coupling module, and the sinusoidal output signal serves as the fundamental frequency main oscillation signal.
3. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 2, characterized in that, The multi-stage filter circuit includes: a first capacitor (C5), a second capacitor (C9), a third capacitor (C6), a fourth capacitor (C10), a fifth capacitor (C7), a sixth capacitor (C12), a seventh capacitor (C8), a first inductor (L1), a second inductor (L2), and a third inductor (L3). One end of the second capacitor (C9) serves as the input terminal of the multi-stage filter circuit and is electrically connected to the output terminal of the low phase noise frequency synthesizer. One end of the second capacitor (C9) is also electrically connected to one end of the first capacitor (C5) and one end of the first inductor (L1), and the other end of the second capacitor (C9) is electrically connected to the other end of the first inductor (L1), one end of the second inductor (L2), one end of the third capacitor (C6), and one end of the fourth capacitor (C10). The other end of the fourth capacitor (C10) is electrically connected to the other end of the second inductor (L2), one end of the third inductor (L3), one end of the fifth capacitor (C7), and one end of the sixth capacitor (C12), and the other end of the sixth capacitor (C12) is electrically connected to the other end of the third inductor (L3) and one end of the seventh capacitor (C8). The other end of the sixth capacitor (C12) also serves as the output terminal of the multi-stage filter circuit, electrically connected to the AC coupling module, and the other ends of the first capacitor (C5), the third capacitor (C6), the fifth capacitor (C7), and the seventh capacitor (C8) are respectively grounded.
4. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 1, characterized in that, The high-side current sampling module includes: a sampling resistor (R9), a resistor array (R10), and a first operational amplifier (U1); The sampling resistor (R9) serves as the input terminal of the high-side current sampling module and is electrically connected to the low-noise DC voltage module. The two ends of the sampling resistor (R9) are electrically connected to the non-inverting input terminal and the inverting input terminal of the first operational amplifier (U1) through the resistor array (R10), and the output terminal of the first operational amplifier (U1) is electrically connected to the input terminal of the main control module.
5. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 4, characterized in that, The high-side current sampling module also includes an eighth capacitor (C13), wherein the inverting input terminal of the first operational amplifier (U1) is electrically connected to one end of the eighth capacitor (C13), and the other end of the eighth capacitor (C13) is electrically connected to the resistor array (R10) and the output terminal of the first operational amplifier (U1), and the eighth capacitor (C13) and the resistor array (R10) constitute a low-pass filter.
6. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 1, characterized in that, The low-noise DC voltage module includes: a DC-DC power supply and a multiplier filter circuit; The input terminal of the multiplication filter circuit is electrically connected to the DC-DC power supply, and the output terminal of the multiplication filter circuit is electrically connected to the input terminal of the high-side current sampling module, providing a low-noise DC voltage to the high-side current sampling module.
7. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 6, characterized in that, The multiplication filter circuit includes: a first transistor (Q1), a first resistor (R1), and a ninth capacitor (C3); The collector of the first transistor (Q1) is electrically connected to the DC-DC power supply and one end of the first resistor (R1), the base of the first transistor (Q1) is electrically connected to the other end of the first resistor (R1) and one end of the ninth capacitor (C3), and the emitter of the first transistor (Q1) is electrically connected to the input terminal of the high-side current sampling module. The emitter of the first transistor (Q1) is also electrically connected to one end of the tenth capacitor (C1) and one end of the eleventh capacitor (C2), and the other ends of the ninth capacitor (C3), the tenth capacitor (C1) and the eleventh capacitor (C2) are respectively grounded.
8. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 1, characterized in that, The voltage-controlled current drive module includes: a second operational amplifier (U2) and a second transistor (Q2); The non-inverting input terminal of the second operational amplifier (U2) is electrically connected to the output terminal of the integral regulator through a second resistor (R3), a third resistor (R4), and a fourth resistor (R5) connected in series. The inverting input terminal of the second operational amplifier (U2) is electrically connected to the output terminal of the second operational amplifier (U2) through a twelfth capacitor (C19), and a fifth resistor (R7) is connected in parallel across the two ends of the twelfth capacitor (C19). The output of the second operational amplifier (U2) is electrically connected to the base of the second transistor (Q2) through the sixth resistor (R6). The emitter of the second transistor (Q2) is electrically connected to the low side of the sampling resistor in the high-side current sampling module, and the collector of the second transistor (Q2) is electrically connected to the semiconductor laser.
9. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 1, characterized in that, The output terminal of the low-noise DC voltage module is electrically connected to the input terminal of the high-side current sampling module through a soft-start protection circuit.
10. A low-noise continuous-wave modulated laser driving source for a high-speed laser rangefinder according to claim 1, characterized in that, The output of the fundamental frequency extraction module is electrically connected to the input of the AC coupling module via a radio frequency amplifier.