A multiple gain control circuit

Abstract

The present invention discloses a multiple gain control circuit, comprising: a first control circuit for performing preliminary stabilization control on an input signal and providing a reference voltage, and a second control circuit for performing advanced stabilization control on the input signal. After the signal enters the first control circuit and completes preliminary processing, it is output to the integrator of the second control circuit as a reference voltage for advanced gain control, and finally output from the output end of the emitter follower, thereby avoiding the situation where the output amplitude is unstable due to the inability of a fixed threshold to cope with dynamic changes in the signal. Multiple gain control circuits are set to work together, thereby enhancing the reliability of the entire circuit system during long-term operation and the stability and accuracy of the output signal.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuit signal control, and in particular relates to a multiple gain control circuit. Background Art

[0002] Commonly used control circuits usually have only one set of gain control mechanisms, and their dynamic range adaptability is limited. When faced with a large range of input signal amplitude changes, their dynamic adjustment capabilities may be insufficient. For example, in a communication system, the signal may fluctuate over a large range due to factors such as transmission distance and obstacles, resulting in insufficient gain improvement when the signal is weak, and the signal cannot be effectively amplified; when the signal is strong, the gain cannot be reduced in time, which easily causes the output signal to be saturated and distorted. On the other hand, there may be defects in accuracy, and the anti-interference ability is weak. When the environment changes are complex or the signal characteristics are diverse, a single adjustment method is difficult to accurately control the gain, and its response speed and flexibility are poor. In addition, the fixed threshold reference voltage makes the circuit inflexible and its scope of application is limited. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present application provides a multiple gain control circuit, which overcomes the above deficiencies of the prior art by performing multiple conditioning of preliminary stabilization control and advanced stabilization control on the input signal.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A multiple gain control circuit is proposed, comprising:

[0006] A first control circuit, used for performing preliminary stability control on an input signal, specifically comprising: a first transimpedance amplifier, an NMOS transistor, a low-pass filter, a second amplifier and a threshold circuit, wherein the first transimpedance amplifier is connected to a source and a drain of the NMOS transistor, an output end of the first transimpedance amplifier is connected to the low-pass filter, a signal processed by the low-pass filter is output to a non-inverting input end of the second amplifier, an inverting input end of the second amplifier is connected to the threshold circuit, and an output end of the second amplifier is connected to a gate of the NMOS transistor, so as to control the first transimpedance amplifier to perform preliminary gain control;

[0007] The second control circuit is used to perform advanced stability control on the input signal, specifically comprising: a second transimpedance amplifier, an emitter follower, a signal conditioning unit and an integrator, wherein the input end of the second transimpedance amplifier is connected to the input end of the first transimpedance amplifier, the output end of the second transimpedance amplifier is connected to the input end of the emitter follower, the output end of the emitter follower is connected to the input end of the signal conditioning unit, the signal conditioning unit conditions the AC signal into a DC signal and detects the peak-to-peak value of the AC signal, the output end of the signal conditioning unit is connected to the integrator, and the integrator controls the second transimpedance amplifier to perform advanced gain control;

[0008] After the signal enters the first control circuit and completes preliminary processing, it is output to the integrator of the second control circuit as a reference voltage for advanced processing and finally output from the output end of the emitter follower. Through the processing of the first control circuit, the gain can be quickly adjusted to keep the output signal amplitude within a relatively stable range, ensuring that the subsequent signal processing links can work normally, stable and reliable, and have a wide range of applicability. In high-precision instrument signal amplification systems, through the advanced control of the second control circuit, the signal gain can be controlled within a very precise range to ensure the accuracy of the results, and has a good inhibitory effect on the long-term drift and slow changes of the signal amplitude, thereby improving the accuracy of the stability of the overall system.

[0009] Preferably, it also includes a timing sampling calculation unit, which is used to perform timing sampling on the output signal of the first control circuit, calculate the average value, and output it to the integrator as a reference voltage. The output end of the first control circuit is electrically connected to the second control circuit through the timing sampling calculation unit. The average value of the signal amplitude is calculated through the timing sampling signal, which reflects the average intensity level of the signal over a period of time, and provides a stable reference voltage for the subsequent advanced automatic gain control, avoiding the transmission of the signal being affected by instantaneous interference, with strong flexibility, and improved accuracy and control efficiency.

[0010] Further preferably, the first transimpedance amplifier comprises: a first amplifier and a first resistor, the first amplifier is a single-ended amplifier, the input end of the first amplifier is connected to one end of the first resistor, and the output end of the first amplifier is connected to the other end of the first resistor and the low-pass filter. The transimpedance amplifier converts the input current signal into an output voltage signal, which is convenient for subsequent signal processing and analysis and is conducive to miniaturized circuit design.

[0011] Further preferably, the second transimpedance amplifier includes: a fourth amplifier and a fourth resistor, the fourth amplifier is a single-ended amplifier, the input end of the fourth amplifier is connected to one end of the fourth resistor, the input end of the first amplifier and one end of the first resistor, and the output end of the fourth amplifier is connected to the other end of the fourth resistor and the input end of the emitter follower. The transimpedance amplifier converts the input current signal into an output voltage signal, which is convenient for subsequent signal processing and analysis and is conducive to miniaturized circuit design.

[0012] Further preferably, the low-pass filter includes a second resistor and a first capacitor, one end of the second resistor is connected to the output end of the first amplifier, the other end of the second resistor is connected to one end of the first capacitor and the in-phase input end of the second amplifier, and the other end of the first capacitor is grounded. The high-frequency component is filtered out, only the low-frequency component is allowed to pass, and the low-frequency signal is transmitted to the in-phase input end of the second amplifier, which is conducive to high-precision signal processing.

[0013] Further preferably, the integrator includes: a fifth resistor, a second capacitor and a fifth amplifier, one end of the fifth resistor is connected to the signal conditioning unit, the other end of the fifth resistor is connected to one end of the second capacitor and the inverting input end of the fifth amplifier, and the other end of the second capacitor is connected to the output end of the fifth amplifier and a control signal line for controlling the resistance value of the fourth resistor. Continuous and smooth gain adjustment is achieved, which can adapt to the scenario of high-precision gain adjustment.

[0014] Further preferably, an input end of the timing sampling calculation unit is connected to an output end of the first amplifier and one end of the second resistor, and an output end of the timing sampling calculation unit is connected to a non-inverting input end of the fifth amplifier.

[0015] Preferably, the threshold circuit includes a third amplifier and a third resistor, the third amplifier is a single-ended amplifier, the input end of the third amplifier is connected to one end of the third resistor, and the other end of the third resistor is connected to the output end of the third amplifier and the inverting input end of the second amplifier. The value of the reference level can be flexibly changed, and the precise triggering and control capabilities can improve the performance of the system.

[0016] Preferably, the emitter follower converts an input single-ended AC signal into an output double-ended AC signal.

[0017] Further preferably, the signal conditioning unit converts the input double-ended AC signal into a single-ended DC signal for output.

[0018] Compared with the prior art, the beneficial results of the present invention are:

[0019] The present invention proposes a multiple gain control circuit, which effectively improves the control circuit's adaptability to signal strength changes and avoids signal distortion by performing multiple conditioning of preliminary stability control and advanced stability control on the input signal. At the same time, a timing sampling calculation unit is added between the preliminary stability and the advanced stability, and the average value is output to the second control circuit, thereby avoiding the output amplitude instability caused by the fixed threshold being unable to cope with the dynamic change of the signal, further enhancing the anti-interference ability, and using the signal processed by the preliminary gain control as the reference signal of the advanced gain control circuit, further improving the accuracy. Regardless of the size of the signal, more accurate gain adjustment can be obtained, the output swing of the transimpedance amplifier can be accurately controlled, and the output signal can be stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings provide further description of the embodiments, and the accompanying drawings are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and are used together with the description to explain the principles of the present invention. It will be easy to recognize other embodiments and many expected advantages of the embodiments, as they become better understood by reference to the following detailed description. Other features, objects and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments made with reference to the following drawings:

[0021] Figure 1 is a circuit diagram of a multiple gain control circuit according to a specific embodiment of the present invention.

[0022] The meaning of the numbers in the figure are: A1-first amplifier; A2-second amplifier; A3-third amplifier; A4-fourth amplifier; A5-fifth amplifier; R1-first resistor; R2-second resistor; R3-third resistor; R4-fourth resistor; R5-fifth resistor; C1-first capacitor; C2-second capacitor; N1-NMOS transistor. DETAILED DESCRIPTION

[0023] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0024] In the description of the present invention, it should be noted that the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. The terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Figure 1 A circuit diagram of a multiple gain control circuit according to a specific embodiment of the present invention is shown. Figure 1 As shown, a multiple gain control circuit includes: a first control circuit, a second control circuit and a timing sampling calculation unit; the principle of a multiple gain control circuit of the present invention is described below in conjunction with a specific embodiment:

[0027] In a specific embodiment, the first control circuit specifically includes: a first amplifier A1, a first resistor R1, an NMOS (N-Metal-Oxide-Semiconductor) transistor N1, a second resistor R2, a first capacitor C1, a second amplifier A2, a third amplifier A3 and a third resistor R3. The first amplifier A1 and the first resistor R1 constitute a first transimpedance amplifier to obtain a mid-frequency band transimpedance gain. When the first transimpedance amplifier receives a relatively large input current, it can autonomously reduce the circuit gain to keep the output voltage amplitude unchanged. The second resistor R2 and the first capacitor C1 constitute a low-pass filter, which performs filtering and amplitude sampling on the output signal of the first transimpedance amplifier. The first amplifier A1 is a single-ended amplifier, the input end of the first amplifier A1 is connected to one end of the first resistor R1, the output end of the first amplifier A1 is connected to the other end of the first resistor R1 and one end of the second resistor R2, the other end of the second resistor R2 is connected to one end of the first capacitor C1 and the in-phase input end of the second amplifier A2, the other end of the first capacitor C1 is grounded, the source and drain of the NMOS transistor are connected to the first resistor R1 and the two ends of the first amplifier A1, the second amplifier A2 is an error amplifier, and the output end of the second amplifier A2 regulates the gate voltage of the NMOS transistor N1.

[0028] The first transimpedance amplifier converts the input current signal IN into a voltage signal. Since the gain of the first amplifier A1 is positive, when the input current input to the first transimpedance amplifier increases, the voltage output from the first amplifier increases. Then, a low-pass filter composed of the second resistor R2 and the first capacitor C1 is used to remove the high-frequency component, so that the signal becomes smoother, continuous and stable. The low-frequency component is input to the in-phase input terminal of the second amplifier A2. When the output voltage of the first transimpedance amplifier is greater than the threshold voltage of the second amplifier A2, the second amplifier A2 amplifies and outputs the difference, controls the gate voltage of the NMOS transistor N1, and the threshold circuit connected to the inverting input terminal of the second amplifier A2 includes a third amplifier A3 and a third resistor R3. The third amplifier A3 is a single-ended amplifier. The input terminal of the third amplifier A3 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the output terminal of the third amplifier A3 and the inverting input terminal of the second amplifier A2.

[0029] When the NMOS transistor N1 operates in the linear region, the on-resistance formula is:

[0030]

[0031] Among them, μ n represents the electron mobility, C oxrepresents the gate oxide capacitance per unit area, W represents the channel width, L represents the channel length, V GS Represents the voltage between the gate and the source, V TH represents the threshold voltage, R ON Represents the on-resistance of the transistor.

[0032] It can be seen from the above formula that when the current input into the first control circuit increases, the output voltage of the second amplifier A2 will increase, causing the gate voltage of the NMOS transistor N1 to increase, and the on-resistance of the NMOS transistor N1 will decrease, and then the resistance of the first resistor R1 will decrease, and the transimpedance gain of the first transimpedance amplifier will decrease, thereby achieving the effect of preliminary gain control. However, in the scenario where high-precision signals are required, the preliminary gain control effect achieved only by the first control circuit is insufficient. The present invention adds a timing sampling calculation unit to the output end of the first transimpedance amplifier.

[0033] In a specific embodiment, the input end of the timing sampling calculation unit is connected to the output end of the first amplifier and one end of the second resistor. The timing sampling calculation unit performs sampling based on a certain time interval and triggers the sampling operation through a timer. Optionally, the timer can be set to generate a trigger signal every 1 millisecond. When the trigger signal arrives, the sampling circuit starts working, samples the input signal, and obtains the instantaneous value of the input signal. The sampled data will be stored in a data register inside the unit. The voltage value obtained by each sampling will be stored in an array in turn. This array will be continuously updated for subsequent calculations and analysis. After a certain number of sampled data have been accumulated, the timing sampling calculation unit will start to calculate the average value, add all the sampled data, and then divide it by the number of sampled data to obtain the average value. After being processed by a high-precision voltage source, the analog signal is output with high resolution as the reference voltage of the integrator in the second control circuit for subsequent signal processing. The integrator will gradually adjust the gain according to the difference between this reference average value and the actual signal amplitude, so that the entire system can better adapt to changes in signal amplitude and maintain the stability and accuracy of signal processing.

[0034] In a specific embodiment, the second control circuit specifically includes: a fourth amplifier A4, a fourth resistor R4, an emitter follower, a signal conditioning unit, a fifth resistor R5, a second capacitor C2 and a fifth amplifier A5. The fourth amplifier A4 and the fourth resistor R4 constitute a second transimpedance amplifier, which converts the input current signal IN into a voltage signal, and then through the emitter follower, reduces the mutual interference between the front and rear stage circuits, provides a stable signal voltage for the rear stage circuit, and outputs a two-terminal AC signal, uses balanced transmission to reduce noise and distortion during signal transmission, and ensures high-quality signal transmission. The fourth amplifier A4 is a single-ended amplifier, the input end of the fourth amplifier A4 is connected to one end of the fourth resistor R4, the output end of the fourth amplifier A4 is connected to the other end of the fourth resistor R4 and the input end of the emitter follower, the output end of the emitter follower is two outputs OUTA and OUTB, and is also connected to the signal conditioning unit, converts the two-terminal AC signal output by the emitter follower into a DC signal, and detects the peak-to-peak value of the input two-terminal AC signal.

[0035] In a specific embodiment, the fifth resistor R5, the second capacitor C2 and the fifth amplifier A5 constitute an integrator to integrate the DC signal output by the signal conditioning unit to avoid voltage mutations. One end of the fifth resistor R5 is connected to the signal conditioning unit, the other end of the fifth resistor R5 is connected to one end of the second capacitor C2 and the inverting input end of the fifth amplifier A5, and the other end of the second capacitor C2 is connected to the output end of the fifth amplifier A5 and the control signal line that controls the resistance value of the fourth resistor R4. The output signal of the first control circuit is processed by the timing sampling calculation unit and then input into the non-inverting input terminal of the fifth amplifier A5 as a reference voltage. When the signal output by the signal conditioning unit and entering the inverting input terminal of the fifth amplifier A5 is greater than the reference voltage, the voltage output by the integrator becomes smaller, thereby controlling the resistance value of the fourth resistor R4 to decrease, and then reducing the output swing through the second transimpedance amplifier until the signal input to the inverting input terminal of the fifth amplifier A5 is less than the reference voltage, thereby achieving stable control of the output terminal OUTA and the output terminal OUTB signals. When the signal output by the signal conditioning unit and entering the inverting input terminal of the fifth amplifier A5 is less than the reference voltage, the voltage output by the integrator becomes larger, thereby controlling the resistance value of the fourth resistor R4 to increase, and then reducing the output swing through the second transimpedance amplifier until the signal input to the inverting input terminal of the fifth amplifier A5 increases to the reference voltage, thereby achieving stable control of the output terminal OUTA and the output terminal OUTB signals, effectively reducing the distortion of the signal during transmission, and ensuring the quality of the signal.

[0036] A multiple gain control circuit proposed in the present invention provides a solid guarantee for system stability by performing multiple conditioning of preliminary stability control and advanced stability control on the input signal. A timing sampling calculation unit is added between the preliminary stability and the advanced stability, and the average value is output to the second control circuit. The signal processed by the preliminary gain control is used as the reference signal of the advanced gain control circuit. Therefore, whether the signal is slowly changing or fluctuating in the short term, the circuit can flexibly adapt so that the gain is always closely matched with the actual situation of the signal, avoiding the output amplitude instability caused by the inability of the fixed threshold to cope with the dynamic change of the signal; the preliminary first control circuit can quickly process the large fluctuation or abnormal peak of the signal to prevent it from causing impact on the subsequent circuit; the advanced second control circuit further optimizes the gain based on a more accurate reference signal. The two work together to reduce the probability of signal distortion, overload and false triggering, and greatly enhance the reliability of the entire circuit system during long-term operation. Since it does not rely on a fixed reference voltage, the multiple gain control circuit can be widely used in various types of signal processing tasks, without the need to frequently adjust circuit parameters for different signals, greatly improving the flexibility of circuit design and application.

[0037] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above invention concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

Claims

1. A multiple gain control circuit, characterized in that: include: A first control circuit, used for performing preliminary stability control on an input signal, specifically comprising: a first transimpedance amplifier, an NMOS transistor, a low-pass filter, a second amplifier and a threshold circuit, wherein the first transimpedance amplifier is connected to a source and a drain of the NMOS transistor, an output end of the first transimpedance amplifier is connected to the low-pass filter, a signal processed by the low-pass filter is output to a non-inverting input end of the second amplifier, an inverting input end of the second amplifier is connected to the threshold circuit, and an output end of the second amplifier is connected to a gate of the NMOS transistor, so as to control the first transimpedance amplifier to perform preliminary gain control; The second control circuit is used to perform advanced stability control on the input signal, specifically comprising: a second transimpedance amplifier, an emitter follower, a signal conditioning unit and an integrator, wherein the input end of the second transimpedance amplifier is connected to the input end of the first transimpedance amplifier, the output end of the second transimpedance amplifier is connected to the input end of the emitter follower, the output end of the emitter follower is connected to the input end of the signal conditioning unit, the signal conditioning unit conditions the AC signal into a DC signal and detects the peak-to-peak value of the AC signal, the output end of the signal conditioning unit is connected to the integrator, and the integrator controls the second transimpedance amplifier to perform advanced gain control; After the signal enters the first control circuit and completes preliminary processing, it is output to the integrator of the second control circuit as a reference voltage for advanced processing and finally output from the output end of the emitter follower.

2. A multiple gain control circuit according to claim 1, characterized in that: It also includes a timing sampling calculation unit, which is used to perform timing sampling on the output signal of the first control circuit, calculate the average value, and output it to the integrator as a reference voltage. The output end of the first control circuit is electrically connected to the second control circuit through the timing sampling calculation unit.

3. A multiple gain control circuit according to claim 2, characterized in that: The first transimpedance amplifier includes: a first amplifier and a first resistor, the first amplifier is a single-ended amplifier, the input end of the first amplifier is connected to one end of the first resistor, and the output end of the first amplifier is connected to the other end of the first resistor and the low-pass filter.

4. A multiple gain control circuit according to claim 3, characterized in that: The second transimpedance amplifier includes: a fourth amplifier and a fourth resistor, the fourth amplifier is a single-ended amplifier, the input end of the fourth amplifier is connected to one end of the fourth resistor, the input end of the first amplifier and one end of the first resistor, and the output end of the fourth amplifier is connected to the other end of the fourth resistor and the input end of the emitter follower.

5. A multiple gain control circuit according to claim 4, characterized in that: The low-pass filter includes a second resistor and a first capacitor, one end of the second resistor is connected to the output end of the first amplifier, the other end of the second resistor is connected to one end of the first capacitor and the in-phase input end of the second amplifier, and the other end of the first capacitor is grounded.

6. A multiple gain control circuit according to claim 5, characterized in that: The integrator includes: a fifth resistor, a second capacitor and a fifth amplifier, one end of the fifth resistor is connected to the signal conditioning unit, the other end of the fifth resistor is connected to one end of the second capacitor and the inverting input end of the fifth amplifier, and the other end of the second capacitor is connected to the output end of the fifth amplifier and a control signal line that controls the resistance value of the fourth resistor.

7. A multiple gain control circuit according to claim 6, characterized in that: An input end of the timing sampling calculation unit is connected to an output end of the first amplifier and one end of the second resistor, and an output end of the timing sampling calculation unit is connected to a non-inverting input end of the fifth amplifier.

8. The multiple gain control circuit according to claim 1, characterized in that: The threshold circuit includes a third amplifier and a third resistor. The third amplifier is a single-ended amplifier. The input end of the third amplifier is connected to one end of the third resistor, and the other end of the third resistor is connected to the output end of the third amplifier and the inverting input end of the second amplifier.

9. The multiple gain control circuit according to claim 1, characterized in that: The emitter follower converts the input single-ended AC signal into a double-ended AC signal for output.

10. The multiple gain control circuit according to claim 2, characterized in that: The signal conditioning unit converts the input double-ended AC signal into a single-ended DC signal for output.

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