A low-noise high-precision voltage-controlled current source for semiconductor lasers

Abstract

The application discloses a low-noise high-precision voltage control current source for a semiconductor laser, comprising a voltage control signal generation module, a PID control module and an output current sampling and feedback module, wherein the voltage control signal generation module receives a host computer instruction and generates a voltage control signal of an output current; the PID control module receives and processes the voltage control signal generated by the voltage control signal generation module and the feedback voltage generated by the output current sampling and feedback module, generates a control voltage to control the output current of the output current sampling and feedback module; and the output current sampling and feedback module provides a stable output current for a load and provides the amplified voltage quantity of the current feedback compared with the voltage control signal to the PID control module to provide the feedback voltage for the PID control module. The application can realize accurate and stable current output, the output current is adjustable, and the application can provide stable low-noise high-precision driving current for semiconductor lasers and the like.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic communication technology, specifically relating to a low-noise, high-precision voltage-controlled current source for semiconductor lasers. Background Technology

[0002] Semiconductor lasers are mainly used in fields such as fiber optic communication, optical storage, materials processing, and medical research. These applications have strict requirements for the frequency stability, spectral linewidth, power stability, intensity, and phase noise of lasers.

[0003] For electrically excited semiconductor lasers, variations in the driving current and current noise significantly affect the laser's lasing wavelength, spectral linewidth, output power, and noise. Furthermore, for tunable laser applications, the accuracy of the current determines the wavelength tuning accuracy. Therefore, the laser driving current source must provide a stable, precise, and controllable driving signal to the semiconductor, reducing frequency drift, ensuring laser frequency stability, and possessing characteristics of low noise and high precision. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a low-noise, high-precision voltage-controlled current source for semiconductor lasers. This source can achieve precise and stable current output, and the output current is adjustable. It can provide a stable, low-noise, high-precision drive current for semiconductor lasers and the like, and can be applied to narrow-linewidth lasers, tunable lasers, lidar, etc.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A low-noise, high-precision voltage-controlled current source for semiconductor lasers includes a voltage control signal generation module, a PID control module, and an output current sampling and feedback module. The voltage control signal generation module is electrically connected to the PID control module and the output current sampling and feedback module, respectively, and the PID control module is electrically connected to the output current sampling and feedback module.

[0007] The voltage control signal generation module is used to receive instructions from the host computer and generate a voltage control signal for the output current.

[0008] The PID control module is used to receive and process the voltage control signal generated by the voltage control signal generation module and the feedback voltage generated by the output current sampling and feedback module, and generate a control voltage to control the output current of the output current sampling and feedback module.

[0009] The output current sampling and feedback module is used to provide a stable output current to the load, and to feed the current back as a voltage quantity, compare and amplify it with the voltage control signal, and then provide it to the PID control module to provide feedback voltage to the PID control module.

[0010] To optimize the above technical solution, the specific measures also include:

[0011] The voltage control signal generation module described above uses an MCU as the main control chip; the MCU communicates with the host computer via serial port to receive the load output current value.

[0012] The voltage control signal generation module described above includes a digital potentiometer, a high-precision reference voltage chip, and an operational amplifier A1; the digital potentiometer acts as a voltage divider resistor; the high-precision reference voltage chip provides a reference voltage; and the operational amplifier A1 constitutes a voltage follower.

[0013] The aforementioned digital potentiometer and resistor are connected in series to divide the reference voltage. The digital potentiometer is connected to the MCU, and the MCU controls the resistance value of the digital potentiometer. The voltage division value is the input voltage of the voltage follower, and the output voltage of the voltage follower is the output signal of the voltage control signal generation module.

[0014] The aforementioned digital potentiometer is connected to the reference voltage chip via resistor R13. The digital potentiometer is connected to the non-inverting input terminal of operational amplifier A1 via resistor R14. The inverting input terminal of operational amplifier A1 is connected to the output terminal of operational amplifier A1 via resistor R16. The output terminal of operational amplifier A1 is connected to the PID control module and the output current sampling and feedback module, respectively.

[0015] The aforementioned PID control module employs a high-precision, low-noise operational amplifier A2. The non-inverting input of the operational amplifier A2 is the voltage control signal generated by the voltage control signal generation module, and the inverting input is the feedback voltage of the output current sampling and feedback module. The PID control module performs proportional-integral-differential operations on the difference between the voltage control signal and the feedback voltage and outputs a voltage, which is then provided to the output current sampling and feedback module.

[0016] The aforementioned PID control module includes resistors R2, R7, R8, and R15, capacitors C1, C2, and C3, and operational amplifier A2.

[0017] One end of R2 is connected to the output terminal of the voltage control signal generation module, and the other end is connected to the +IN terminal of the operational amplifier A2.

[0018] One end of R8 is connected to the -IN terminal of operational amplifier A2, and the other end is connected to one end of R15 and the output current sampling and feedback module.

[0019] The other end of R15 is connected to one end of C3;

[0020] One end of R7 is connected to one end of R8, the other end of C3, and one end of C1, while the other end is connected to one end of C2.

[0021] The other end of C2 is connected to the other end of C1 and the output terminal of operational amplifier A2;

[0022] One end of C1 is connected to one end of R7, and the other end is connected to the other end of C2;

[0023] The output terminal of the operational amplifier A2 is connected to the output current sampling and feedback module.

[0024] The aforementioned output current sampling and feedback module includes resistors R1, R5, R3, R4, R6, R9, R10, R11, and R12, operational amplifiers A3 and A4, and transistor Q1.

[0025] One end of R1 is connected to the PID control module, and the other end is connected to the base of the transistor Q1.

[0026] One end of R5 is connected to VCC, and the other end is connected to the collector of the transistor Q1.

[0027] The emitter of transistor Q1 is connected to one end of R3;

[0028] One end of R3 is connected to one end of R4, and the other end is connected to one end of R10 and the load.

[0029] One end of R6 is connected to ground, and the other end is connected to the other end of R4 and the +IN terminal of operational amplifier A4;

[0030] The other end of R10 is connected to one end of R9 and the -IN terminal on operational amplifier A4;

[0031] The other end of R9 is connected to the output of operational amplifier A4;

[0032] The output terminal of operational amplifier A4 is connected to the +IN terminal of operational amplifier A3;

[0033] One end of R11 is connected to one end of resistor R12 and the -IN terminal of operational amplifier A3, and the other end is connected to the output terminal of operational amplifier A3.

[0034] The other end of R12 is connected to the output terminal of the voltage control signal generation module;

[0035] The output of the operational amplifier A3 is connected to the PID control module.

[0036] The present invention has the following beneficial effects:

[0037] This invention provides a high-precision, low-noise voltage control signal to the circuit using a digital potentiometer and a high-precision reference voltage source, thereby ensuring the stability of the input voltage of the PID control module.

[0038] The low-noise, low-offset voltage operational amplifier used in this invention results in low noise in the circuit signals. Since the laser's operating mode is affected by current drive, a stable current source is needed for mode control. The high-precision, low-noise current source of this invention provides a stable current output, precisely controls the laser's mode selection, reduces frequency drift, and ensures the laser's frequency stability.

[0039] In this invention, the output current depends on the voltage control signal, the feedback resistor in the output current sampling and feedback module, and the amplification circuit composed of operational amplifier A4. By changing the resistance value in the circuit, the range and accuracy of the current output can be adjusted. When the voltage control signal is changed, the voltage control signal is inconsistent with the feedback voltage input to the PID control module. Through the negative feedback effect of the feedback module and the PID module, the output current can be quickly stabilized.

[0040] The output current sampling and feedback module in this invention effectively isolates the current source by means of an amplification circuit composed of operational amplifier A4. By utilizing the high input impedance of the operational amplifier, the current source of this invention has a large output impedance, which effectively reduces the impact of environmental and load impedance fluctuations on the output current and improves the stability of the output current. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the principle and modules of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] Although the steps in this invention are arranged by reference numerals, this is not intended to limit the order of the steps. Unless the order of the steps is explicitly stated or the execution of a step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" as used herein refers to and covers any and all possible combinations of one or more of the associated listed items.

[0044] like Figure 1As shown, the present invention provides a low-noise, high-precision voltage-controlled current source for semiconductor lasers, comprising a voltage control signal generation module, a PID control module, and an output current sampling and feedback module.

[0045] The voltage control signal generation module is electrically connected to the PID control module and the output current sampling and feedback module, respectively, and the PID control module is electrically connected to the output current sampling and feedback module.

[0046] The voltage control signal generation module is used to receive instructions from the host computer and generate a control signal for the output current.

[0047] The PID control module is used to receive and process the voltage control signal generated by the voltage control signal generation module and the feedback voltage generated by the output current sampling and feedback module, and generate a control voltage signal to control the output current of the output current sampling and feedback module.

[0048] The output current sampling and feedback module is used to provide a stable output current to the load, and to feed the current back as a voltage quantity, compare and amplify it with the voltage control signal, and then provide it to the PID control module to provide feedback voltage to the PID control module.

[0049] In this embodiment, the voltage control signal generation module uses an MCU as the main control chip; the MCU communicates with the host computer via serial port to receive the laser output current value.

[0050] The voltage control signal generation module includes a digital potentiometer, a high-precision reference voltage chip, and an operational amplifier A1; the digital potentiometer acts as a voltage divider resistor; the high-precision reference voltage chip provides a reference voltage; and the operational amplifier A1 constitutes a voltage follower.

[0051] The digital potentiometer is connected in series with a resistor to divide the reference voltage. The digital potentiometer is connected to the MCU, and the MCU controls the resistance value of the digital potentiometer. The voltage division value is the input voltage of the voltage follower, and the output voltage of the voltage follower is the output signal of the voltage control signal generation module.

[0052] The digital potentiometer is connected to the reference voltage chip via resistor R13. The digital potentiometer is connected to the non-inverting input terminal of operational amplifier A1 via resistor R14. The inverting input terminal of operational amplifier A1 is connected to the output terminal of operational amplifier A1 via resistor R16. The output terminal of operational amplifier A1 is connected to the PID control module and the output current sampling and feedback module, respectively.

[0053] In this embodiment, the PID control module uses a high-precision, low-noise operational amplifier A2;

[0054] The PID control module includes resistors R2, R7, R8, and R15, capacitors C1, C2, and C3, and operational amplifier A2.

[0055] One end of R2 is connected to the output terminal of operational amplifier A1 in the voltage control signal generation module, and the other end is connected to the +IN terminal of operational amplifier A2.

[0056] One end of R8 is connected to the -IN terminal of operational amplifier A2, and the other end is connected to one end of R15 and the output current sampling and feedback module.

[0057] The other end of R15 is connected to one end of C3;

[0058] One end of R7 is connected to one end of R8, the other end of C3, one end of C1, and the -IN terminal of operational amplifier A2, and the other end is connected to one end of C2;

[0059] The other end of C2 is connected to the other end of C1 and the output terminal of operational amplifier A2;

[0060] One end of C1 is connected to one end of R7, and the other end is connected to the other end of C2;

[0061] One end of C3 is connected to R15, and the other end is connected to the -IN terminal of operational amplifier A2; the output terminal of operational amplifier A2 is connected to the output current sampling and feedback module.

[0062] In this embodiment, the non-inverting input of the operational amplifier A2 in the PID control module is the voltage control signal generated by the voltage control signal generation module, and the inverting input is the feedback voltage of the output current sampling and feedback module. The PID control module performs proportional-integral-differential calculations on the difference between the voltage control signal and the feedback voltage and outputs a voltage, which is then provided to the output current sampling and feedback module.

[0063] The output voltage of the PID control module is the base input of the transistor Q1 in the output current sampling and feedback module, thereby controlling the collector current, i.e., the output current.

[0064] In this embodiment, the output current sampling and feedback module includes resistors R1, R5, R3, R4, R6, R9, R10, R11, and R12, operational amplifiers A3 and A4, and transistor Q1.

[0065] One end of R1 is connected to the PID control module, and the other end is connected to the base of the transistor Q1.

[0066] One end of R5 is connected to VCC, and the other end is connected to the collector of the transistor Q1.

[0067] The collector of transistor Q1 is connected to R5, the base is connected to R1, and the emitter is connected to one end of R3.

[0068] One end of R3 is connected to one end of R4 and the emitter of transistor Q1, and the other end is connected to one end of R10 and the load.

[0069] One end of R6 is connected to ground, and the other end is connected to the other end of R4 and the +IN terminal of operational amplifier A4;

[0070] One end of R4 is connected to R3, and the other end is connected to the +IN terminal of the operational amplifier;

[0071] One end of R10 is connected to R3 and the load, and the other end is connected to one end of R9 and the -IN terminal of operational amplifier A4.

[0072] One end of R9 is connected to the other end of R10, and the other end is connected to the output terminal of operational amplifier A4.

[0073] The output terminal of operational amplifier A4 is connected to the +IN terminal of operational amplifier A3;

[0074] One end of R11 is connected to one end of resistor R12 and the -IN terminal of operational amplifier A3, and the other end is connected to the output terminal of operational amplifier A3.

[0075] The other end of R12 is connected to the output terminal of the voltage control signal generation module;

[0076] The output of the operational amplifier A3 is connected to the PID control module.

[0077] When driving the current source, the required current value is first input to the computer via host computer software. After software processing, it is then connected to the circuit board via an RS232 programmable line for serial communication, inputting the corresponding command to the MCU in the control signal generation module. The MCU communicates with the digital potentiometer via the SPI communication protocol, thereby changing the resistance value of the digital potentiometer. Since the digital potentiometer and resistor are connected in series to divide the reference voltage, changing the resistance value of the digital potentiometer controls the input voltage, thereby changing the voltage at the non-inverting input of the operational amplifier in the PID control module, and thus changing the output voltage of the operational amplifier. This voltage serves as the base input of the subsequent transistor, thereby changing the collector current and controlling the output current. Since the load is connected in series with the feedback resistor, the feedback resistor feeds back the output current as a feedback voltage, which is then compared and amplified with the voltage control signal in the voltage control signal generation module. Its output serves as the feedback signal for the PID control module. When the output current changes slightly due to temperature variations, a difference arises between the voltage control signal of the PID control module and the feedback signal. Therefore, the PID control module performs proportional-integral-differential amplification on the difference between the two, thereby quickly changing the output voltage to stabilize the output current. The proportional-integral-derivative (PI) parameters are changed by selecting resistors R7, R8, and R15, and capacitors C1, C2, and C3. Current accuracy is determined by the value of the feedback resistor and the subsequent operational amplifier circuit.

[0078] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0079] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-noise, high-precision voltage-controlled current source for semiconductor lasers, comprising a voltage control signal generation module, a PID control module, and an output current sampling and feedback module, wherein the voltage control signal generation module is electrically connected to both the PID control module and the output current sampling and feedback module, and the PID control module is electrically connected to the output current sampling and feedback module, characterized in that: The voltage control signal generation module is used to receive instructions from the host computer and generate a voltage control signal for the output current. The PID control module is used to receive and process the voltage control signal generated by the voltage control signal generation module and the feedback voltage generated by the output current sampling and feedback module, and generate a control voltage to control the output current of the output current sampling and feedback module. The output current sampling and feedback module is used to provide a stable output current to the load, and to feed the current back as a voltage quantity, compare and amplify it with the voltage control signal, and then provide it to the PID control module to provide feedback voltage to the PID control module. The PID control module uses a high-precision, low-noise operational amplifier A2. The non-inverting input of the operational amplifier A2 is the voltage control signal generated by the voltage control signal generation module, and the inverting input is the feedback voltage of the output current sampling and feedback module. The PID control module performs proportional-integral-differential operations on the difference between the voltage control signal and the feedback voltage and outputs the voltage, which is then provided to the output current sampling and feedback module. The PID control module includes resistors R2, R7, R8, and R15, capacitors C1, C2, and C3, and operational amplifier A2. One end of R2 is connected to the output terminal of the voltage control signal generation module, and the other end is connected to the +IN terminal of operational amplifier A2. One end of R8 is connected to the -IN terminal of operational amplifier A2, and the other end is connected to one end of R15 and the output current sampling and feedback module. The other end of R15 is connected to one end of C3. One end of R7 is connected to one end of R8, the other end of C3, and one end of C1, and the other end is connected to one end of C2. The other end of C2 is connected to the other end of C1 and the output terminal of operational amplifier A2. One end of C1 is connected to one end of R7, and the other end is connected to the other end of C2. The output terminal of operational amplifier A2 is connected to the output current sampling and feedback module. The output current sampling and feedback module includes resistors R1, R5, R3, R4, R6, R9, R10, R11, and R12, operational amplifiers A3 and A4, and transistor Q1. One end of R1 is connected to the PID control module, and the other end is connected to the base of transistor Q1. One end of R5 is connected to VCC, and the other end is connected to the collector of transistor Q1. The emitter of transistor Q1 is connected to one end of R3. One end of R3 is connected to one end of R4, and the other end is connected to one end of R10 and the load. One end of R6 is connected to ground, and the other end is connected to the other end of R4. One end of R10 is connected to the +IN terminal of operational amplifier A4; the other end of R10 is connected to one end of R9 and the -IN terminal of operational amplifier A4; the other end of R9 is connected to the output terminal of operational amplifier A4; the output terminal of operational amplifier A4 is connected to the +IN terminal of operational amplifier A3; one end of R11 is connected to one end of resistor R12 and the -IN terminal of operational amplifier A3, and the other end is connected to the output terminal of operational amplifier A3; the other end of R12 is connected to the output terminal of the voltage control signal generation module; the output terminal of operational amplifier A3 is connected to the PID control module.

2. A low-noise, high-precision voltage-controlled current source for semiconductor lasers according to claim 1, characterized in that, The voltage control signal generation module uses an MCU as the main control chip; the MCU communicates with the host computer via serial port to receive the load output current value.

3. The low-noise, high-precision voltage-controlled current source for semiconductor lasers according to claim 2, characterized in that, The voltage control signal generation module includes a digital potentiometer, a high-precision reference voltage chip, and an operational amplifier A1; the digital potentiometer acts as a voltage divider resistor; the high-precision reference voltage chip provides a reference voltage; and the operational amplifier A1 constitutes a voltage follower.

4. The low-noise, high-precision voltage-controlled current source for semiconductor lasers according to claim 3, characterized in that, The digital potentiometer is connected in series with a resistor to divide the reference voltage. The digital potentiometer is connected to the MCU, and the MCU controls the resistance value of the digital potentiometer. The voltage division value is the input voltage of the voltage follower, and the output voltage of the voltage follower is the output signal of the voltage control signal generation module.

5. A low-noise, high-precision voltage-controlled current source for semiconductor lasers according to claim 4, characterized in that, The digital potentiometer is connected to the reference voltage chip via resistor R13. The digital potentiometer is connected to the non-inverting input terminal of operational amplifier A1 via resistor R14. The inverting input terminal of operational amplifier A1 is connected to the output terminal of operational amplifier A1 via resistor R16. The output terminal of operational amplifier A1 is connected to the PID control module and the output current sampling and feedback module, respectively.

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