An adjustable constant current source driving circuit

Abstract

The utility model relates to electronic circuit technical field, concretely relates to an adjustable constant current source drive circuit, in the drive circuit, when the second input end of adjusting circuit receives voltage signal, current sampling circuit perceives the current of load and forms voltage difference at both ends, feedback circuit gathers voltage difference and forms feedback signal input to adjusting circuit, and adjusting circuit exports adjusting signal according to feedback signal and received voltage signal, and the process of adjusting signal and feedback signal, gathering voltage difference, repeatedly perceiving current is repeated until feedback signal and voltage signal are consistent, and load current reaches stable value. The adjustable constant current source drive circuit provided by the utility model embodiment, through the setting of current sampling circuit, feedback circuit, adjusting circuit and control circuit, not only realizes the closed loop control and accurate adjustment of load current, and through double -end sampling, avoids the problem of system power supply noise and unstable influence introduced by single -end sampling.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, specifically to an adjustable constant current source drive circuit. Background Technology

[0002] In the aerospace field, for on-orbit experiments, various devices on each subsystem require a relatively stable constant current power supply. In existing technologies, constant current sources are commonly used to drive semiconductor devices such as lasers and TECs (Thermo Electric Coolers).

[0003] Traditional constant current source circuits often perform single-ended sampling. In addition to the thermal noise of the sampling resistor itself, they also introduce noise from other parts of the system, as well as noise and instability from the system power supply. Utility Model Content

[0004] In view of this, the present invention provides an adjustable constant current source driving circuit to solve the technical problem of noise introduced by single-ended sampling in the prior art.

[0005] The technical solution provided by this utility model embodiment is as follows:

[0006] The first aspect of this utility model provides an adjustable constant current source driving circuit, including: a current sampling circuit, a feedback circuit, an adjustment circuit, and a control circuit;

[0007] One end of the current sampling circuit is connected to the first input terminal of the feedback circuit and an external power supply. The other end of the current sampling circuit is connected to the second input terminal of the feedback circuit and the first terminal of the control circuit. The output terminal of the feedback circuit is connected to the first input terminal of the adjustment circuit. The second input terminal of the adjustment circuit receives a voltage signal. The output terminal of the adjustment circuit is connected to the second terminal of the control circuit. The third terminal of the control circuit is connected to the load.

[0008] When the second input terminal of the regulating circuit receives a voltage signal, the current sampling circuit senses the current flowing through the load and forms a voltage difference across the two terminals. The feedback circuit collects the voltage difference and forms a feedback signal, which is then input to the regulating circuit. The regulating circuit outputs an regulating signal based on the feedback signal and the received voltage signal to regulate the control circuit. The process of sensing the current, collecting the voltage difference, forming the feedback signal, and adjusting the signal is repeated until the feedback signal and the voltage signal are consistent and the load current reaches a stable value.

[0009] In one alternative embodiment, the adjustable constant current source drive circuit further includes a stabilizing circuit connected between the output terminal of the regulating circuit and the second terminal of the control circuit.

[0010] In one optional embodiment, the adjustable constant current source drive circuit further includes a phase compensation circuit connected between the output terminal of the adjustment circuit and the second terminal of the control circuit.

[0011] In one optional embodiment, the adjustable constant current source drive circuit further includes a filter circuit, one end of which is connected to the output terminal of the adjustment circuit and the second terminal of the control circuit, and the other end of which is grounded.

[0012] In one alternative implementation, the current sampling circuit includes a sampling resistor, the control circuit includes a switching transistor, and the adjustment signal is used to adjust the conduction level of the switching transistor.

[0013] In one alternative implementation, the feedback circuit includes an instrumentation amplifier or a differential amplifier circuit consisting of two operational amplifiers; the adjustment circuit includes an operational amplifier.

[0014] In one alternative implementation, the stabilizing circuit includes a gate resistor.

[0015] In one alternative implementation, the phase compensation circuit includes a phase compensation capacitor.

[0016] In one alternative implementation, the filter circuit includes a plurality of capacitors of different capacitance values ​​connected in parallel.

[0017] In one alternative implementation, the filter circuit includes at least three capacitors connected in parallel.

[0018] The technical solution of this utility model has the following advantages:

[0019] The adjustable constant current source drive circuit provided in this embodiment of the utility model, through the setting of current sampling circuit, feedback circuit, adjustment circuit and control circuit, not only realizes closed-loop control and precise adjustment of load current, but also avoids the problems of system power supply noise and instability introduced by single-ended sampling by using dual-ended sampling.

[0020] The adjustable constant current source drive circuit provided in this embodiment of the utility model uses an instrumentation amplifier as a feedback circuit. Based on its function of suppressing common-mode noise and reducing drift, it can avoid the drift problem generated in common operational amplifiers and improve measurement accuracy.

[0021] The adjustable constant current source drive circuit provided in this embodiment of the invention can adjust the response value and response speed of the adjustment signal output by the adjustment circuit by setting the gate resistor. For example, it can limit the rate of change of the adjustment signal, thereby improving circuit stability. Setting a phase compensation capacitor can control the circuit feedback polarity, adjust the circuit phase, and improve the circuit phase margin to prevent high-frequency oscillation. When both the gate resistor and the phase compensation capacitor are set, they form an adjustment network to adjust the open-loop gain and phase response of the system.

[0022] The adjustable constant current source drive circuit provided in this embodiment of the invention achieves circuit stability by setting a filter circuit to filter out noise of different frequencies in the circuit and limit the bandwidth of the control signal. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a structural block diagram of the adjustable constant current source drive circuit in an embodiment of this utility model;

[0025] Figure 2 This is a schematic diagram of the adjustable constant current source drive circuit in an embodiment of this utility model. Detailed Implementation

[0026] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0027] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0030] This utility model embodiment provides an adjustable constant current source drive circuit, such as Figure 1 As shown, it includes: a current sampling circuit 10, a feedback circuit 20, an adjustment circuit 30, and a control circuit 40; one end of the current sampling circuit 10 is connected to the first input terminal of the feedback circuit 20 and an external power supply, the other end of the current sampling circuit 10 is connected to the second input terminal of the feedback circuit 20 and the first terminal of the control circuit 40, the output terminal of the feedback circuit 20 is connected to the first input terminal of the adjustment circuit 30, the second input terminal of the adjustment circuit 30 receives a voltage signal, the output terminal of the adjustment circuit 30 is connected to the second terminal of the control circuit 40, the third terminal of the control circuit 40 is connected to the first terminal of a load 50, and the other end of the load 50 is grounded;

[0031] When the second input terminal of the regulating circuit 30 receives a voltage signal, the current sampling circuit 10 senses the current flowing through the load 50 and forms a voltage difference across the two terminals. The feedback circuit 20 collects the voltage difference and forms a feedback signal, which is input to the regulating circuit 30. The regulating circuit 30 outputs an regulating signal based on the feedback signal and the received voltage signal to regulate the control circuit 40. The process of sensing the current, collecting the voltage difference, forming the feedback signal, and adjusting the signal is repeated until the feedback signal and the voltage signal are consistent and the current of the load 50 reaches a stable value.

[0032] In this adjustable constant current source drive circuit, the current sampling circuit is connected in series with the load via a control circuit, meaning the current flowing through the current sampling circuit and the load is the same, thus achieving load current sensing. Simultaneously, a feedback circuit is connected across the current sampling circuit to collect the voltage difference across it, achieving dual-ended sampling. The feedback circuit outputs a feedback signal to the adjustment circuit based on the sampled voltage difference. The adjustment circuit then outputs an adjustment signal to regulate the control circuit based on the relationship between the feedback signal and the voltage signal, thereby changing the current in the load. Furthermore, when the current in the load changes, the current flowing through the current sampling circuit changes, and the voltage difference across it changes. This changes the feedback signal output by the feedback circuit, which in turn changes the adjustment signal output by the adjustment circuit, further adjusting the load current through the control circuit. Therefore, in this adjustable constant current drive circuit, a closed-loop control is formed through the current sampling circuit, feedback circuit, adjustment circuit, and control circuit.

[0033] Furthermore, the regulating circuit outputs a regulating signal based on the relationship between the feedback signal and the voltage signal. Therefore, when the voltage signal input to the regulating circuit is changed, the constant current ultimately formed in the load will also change. Thus, the voltage signal input to the regulating circuit can be determined based on the final required load current. The type of load can be determined according to the actual situation; for example, it could be a laser or a semiconductor device such as a semiconductor cooler, or other devices. This embodiment does not limit this.

[0034] In this invention, by setting up a current sampling circuit, a feedback circuit, an adjustment circuit, and a control circuit, not only is closed-loop control and precise adjustment of the load current achieved, but also the dual-ended sampling avoids the problems of system power supply noise and instability introduced by single-ended sampling.

[0035] In one alternative implementation, such as Figure 2 As shown, the current sampling circuit includes a sampling resistor R1, the control circuit includes a switching transistor M1, and the adjustment signal is used to adjust the conduction level of the switching transistor. The feedback circuit includes an instrumentation amplifier or a differential amplifier circuit composed of two operational amplifiers; the adjustment circuit includes an operational amplifier U1.

[0036] Specifically, by setting a sampling resistor R1 in the current sampling circuit, this resistor R1 can sample the current flowing through the load LOAD in real time and convert it into a voltage signal (voltage difference) for subsequent detection (feedback circuit). The control circuit uses a switching transistor M1, which can be a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), for example, a PMOS transistor. When a PMOS transistor is used, the source of the PMOS transistor is connected to one end of the sampling resistor, the drain is connected to the positive input terminal of the load, and the gate is connected to the control node (output terminal of the adjustment circuit). When the signal received by the gate of the PMOS transistor changes, its conduction level changes, thereby adjusting the magnitude of the current flowing through the load.

[0037] The feedback circuit includes an instrumentation amplifier or a differential amplifier circuit composed of two operational amplifiers. The instrumentation amplifier internally uses a differential amplifier circuit, which has common-mode noise suppression capabilities. The differential signal experiences less drift after passing through the instrumentation amplifier, and its primary function is to measure differential signals, making it more suitable for high-precision signal measurements. Therefore, using an instrumentation amplifier in the feedback circuit can avoid the drift problems commonly found in operational amplifiers, improving measurement accuracy. Specifically, the inverting input of the instrumentation amplifier U2 is connected to the lower end of the sampling resistor (the end connected to the PMOS transistor), and the non-inverting input is connected to the upper end of the sampling resistor (the end connected to the external power supply). The instrumentation amplifier converts the voltage difference across the sampling resistor into a feedback signal.

[0038] The adjustment circuit includes an operational amplifier U1. The inverting input of the operational amplifier receives the externally input voltage signal V1, the non-inverting input receives the feedback signal, and the output is connected to the control node. This forms a feedback loop between the operational amplifier and the instrumentation amplifier. When the operational amplifier receives the voltage signal and the feedback signal, it compares the difference between them and outputs an adjustment signal to adjust the conduction level of the PMOS tank.

[0039] It should be noted that the above-described structural configurations of the current sampling circuit, feedback circuit, regulation circuit, and control circuit are merely illustrative examples. In practical applications, other structures can also be incorporated into these circuits. For instance, for the feedback circuit and regulation circuit, peripheral structures for instrumentation amplifiers or operational amplifiers can be included. The control circuit can also be implemented using other types of switching transistors, and so on. This embodiment does not impose specific limitations on these aspects.

[0040] In one alternative implementation, such as Figure 2As shown, the adjustable constant current source drive circuit further includes a stabilizing circuit and a phase compensation circuit. The stabilizing circuit is connected between the output terminal of the regulating circuit and the second terminal of the control circuit, and the phase compensation circuit is connected between the output terminal of the regulating circuit and the second terminal of the control circuit. The stabilizing circuit includes a gate resistor R2. The phase compensation circuit includes a phase compensation capacitor C1.

[0041] Specifically, by using a gate resistor R2 as a stabilizing circuit connected between the output of the regulating circuit and the second terminal of the control circuit, the response value and response speed of the regulating signal output by the regulating circuit can be adjusted. For example, the rate of change of the regulating signal can be limited, thereby improving circuit stability. In addition to the gate resistor, a phase compensation capacitor C1 can be set between the output of the regulating circuit and the second terminal of the control circuit. This phase compensation capacitor C1 can control the circuit feedback polarity, adjust the circuit phase, and improve the circuit phase margin to prevent high-frequency oscillation.

[0042] Specifically, setting a gate resistor and a phase compensation capacitor in the circuit can compensate for the system's phase margin and introduce a lag phase. Essentially, this introduces new poles into the circuit, allowing the phase margin to stabilize around 45°. The most direct result is stable output without oscillation or static error. The specific resistance and capacitance values ​​need to be configured based on system parameters (load parameters, switching transistor parameters, etc.).

[0043] In one optional embodiment, the adjustable constant current source drive circuit further includes a filter circuit. One end of the filter circuit is connected to the output terminal of the adjustment circuit and the second terminal of the control circuit, and the other end of the filter circuit is grounded. The filter circuit includes multiple capacitors of different capacitance values ​​connected in parallel. Specifically, one end of each of the multiple filter capacitors is connected to the control node, and the other end is grounded. When the capacitance values ​​of the multiple capacitors are set to be different, noise of different frequencies in the circuit can be filtered out and the bandwidth of the adjustment signal can be limited, thereby further improving the circuit's anti-interference capability and stability. Figure 2 As shown, this embodiment includes three filter capacitors: the second capacitor C2, the third capacitor C3, and the fourth capacitor C4.

[0044] As a specific application embodiment of this utility model, the adjustable constant current source driving circuit includes:

[0045] A sampling resistor, connected in series between the positive terminal of the power supply and the source of the driving field-effect transistor, is used to sample the load current and the resulting voltage drop.

[0046] A metal-oxide-semiconductor field-effect transistor, specifically a PMOS transistor, has its source connected to the lower end of the sampling resistor, its drain connected to the positive input terminal of the load, and its gate connected to the control node. It is used to regulate the current flowing through the load to maintain a constant current output.

[0047] The first amplifier is an operational amplifier. The inverting input of the first amplifier receives the set voltage signal, the non-inverting input receives the feedback signal, and the output of the first amplifier is connected to the control node. The first amplifier is used to compare the difference between the set voltage and the feedback signal and output a control signal to adjust the conduction degree of the driving field-effect transistor.

[0048] The second amplifier is an instrumentation amplifier. The inverting input of the instrumentation amplifier is connected to the lower end of the sampling resistor, and the non-inverting input is connected to the upper end of the sampling resistor. The instrumentation amplifier is used to convert the voltage difference across the sampling resistor into a feedback signal and output the feedback signal to the non-inverting input of the first amplifier to form a feedback loop.

[0049] The gate resistor is connected at one end to the output of the first amplifier and at the other end to the gate of the driving field-effect transistor. It is used to adjust the response value and response speed of the control signal and improve circuit stability.

[0050] A phase compensation capacitor is connected in parallel across the gate resistor to control the circuit feedback polarity, adjust the circuit phase, and improve the circuit phase margin to prevent high-frequency oscillation. Furthermore, the phase compensation capacitor and the gate resistor form an adjustment network to adjust the system's open-loop gain and phase response.

[0051] The filter capacitors, the second capacitor, the third capacitor, and the fourth capacitor are filter capacitors, which are connected to the control node and grounded respectively. They are used to filter out noise of different frequencies in the circuit and limit the bandwidth of the control signal, thereby achieving circuit stability.

[0052] The control node is a common node connecting the gate of the driving field-effect transistor, the gate resistor, and the phase compensation capacitor, and is used to receive the control signal output by the first amplifier.

[0053] The load is a semiconductor load. Its positive input terminal is connected to the drain of the driving MOSFET, and its negative input terminal is connected to the circuit ground to receive the constant current input from the driving MOSFET.

[0054] Specifically, most constant current circuits in related technologies employ linear voltage regulation or simple feedback control structures, which cannot achieve a balance between high bandwidth and low noise. They lack effective phase compensation and bandwidth limiting mechanisms, making the system prone to oscillation or overshoot. Influenced by noise from various parts of the system, the output current is unstable, making it difficult to meet the requirements of applications with high stability requirements. In this embodiment, by setting up structures such as sampling resistors, PMOS transistors, instrumentation amplifiers, operational amplifiers, gate resistors, phase compensation capacitors, and filter capacitors, and by using dual-ended sampling to avoid noise sources, phase margin compensation, bandwidth limiting, and the selection of high-precision components, the problems of not being able to achieve a balance between high bandwidth and low noise, lacking effective phase compensation and bandwidth limiting mechanisms, and being prone to oscillation or overshoot in related technologies are solved. This results in a stable output current, meeting the requirements of applications with high stability requirements.

[0055] While exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions, and modifications to these embodiments without departing from the spirit of this invention and the scope of protection defined by the appended claims. Such modifications and variations all fall within the scope defined by the appended claims. For other examples, those skilled in the art should readily understand that the order of process steps can be changed while remaining within the scope of protection of this invention.

[0056] Furthermore, the scope of application of this utility model is not limited to the processes, mechanisms, manufacturing methods, material compositions, means, methods, and steps of the specific embodiments described in the specification. From the disclosure of this utility model, those skilled in the art will readily understand that existing or future-developed processes, mechanisms, manufacturing methods, material compositions, means, methods, or steps that perform substantially the same function or achieve substantially the same results as the corresponding embodiments described in this utility model can be applied according to this utility model. Therefore, the appended claims of this utility model aim to include these processes, mechanisms, manufacturing methods, material compositions, means, methods, or steps within their scope of protection.

Claims

1. An adjustable constant current source drive circuit, characterized by comprising: include: Current sampling circuit, feedback circuit, adjustment circuit and control circuit; One end of the current sampling circuit is connected to the first input terminal of the feedback circuit and an external power supply. The other end of the current sampling circuit is connected to the second input terminal of the feedback circuit and the first terminal of the control circuit. The output terminal of the feedback circuit is connected to the first input terminal of the adjustment circuit. The second input terminal of the adjustment circuit receives a voltage signal. The output terminal of the adjustment circuit is connected to the second terminal of the control circuit. The third terminal of the control circuit is connected to the load. When the second input terminal of the regulating circuit receives a voltage signal, the current sampling circuit senses the current flowing through the load and forms a voltage difference across the two terminals. The feedback circuit collects the voltage difference and forms a feedback signal, which is then input to the regulating circuit. The regulating circuit outputs an regulating signal based on the feedback signal and the received voltage signal to regulate the control circuit. The process of sensing the current, collecting the voltage difference, forming the feedback signal, and adjusting the signal is repeated until the feedback signal and the voltage signal are consistent and the load current reaches a stable value.

2. The adjustable constant current source drive circuit of claim 1, wherein, Also includes: A stabilizing circuit is connected between the output terminal of the regulating circuit and the second terminal of the control circuit.

3. The adjustable constant current source drive circuit according to claim 1 or 2, characterized in that, Also includes: A phase compensation circuit is connected between the output terminal of the adjustment circuit and the second terminal of the control circuit.

4. The adjustable constant current source drive circuit of claim 1, wherein, Also includes: A filter circuit, one end of which is connected to the output terminal of the adjustment circuit and the second terminal of the control circuit, and the other end of which is grounded.

5. The adjustable constant current source drive circuit of claim 1, wherein, The current sampling circuit includes a sampling resistor, the control circuit includes a switching transistor, and the adjustment signal is used to adjust the conduction level of the switching transistor.

6. The adjustable constant current source drive circuit of claim 1, wherein, The feedback circuit includes an instrumentation amplifier or a differential amplifier circuit consisting of two operational amplifiers; the adjustment circuit includes an operational amplifier.

7. The adjustable constant current source drive circuit of claim 2, wherein, The stabilizing circuit includes a gate resistor.

8. The adjustable constant current source drive circuit according to claim 3, characterized in that, The phase compensation circuit includes a phase compensation capacitor.

9. The adjustable constant current source drive circuit according to claim 4, characterized in that, The filter circuit includes multiple capacitors of different capacitance values ​​connected in parallel.

10. The adjustable constant current source drive circuit according to claim 9, characterized in that, The filter circuit includes at least three capacitors connected in parallel.

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