High-precision analog signal processing circuit based on multistage operational amplification

Abstract

The invention discloses a high-precision analog signal processing circuit based on multi-stage operational amplification, which comprises a signal input conditioning module, a main amplification channel and a feedback regulation channel, and the core is to realize signal amplification, filtering and closed-loop control by using an operational amplifier. Precise processing and stable output of complex signals are achieved through differential input, multi-stage amplification, filtering shaping and closed-loop feedback. Signal precision, anti-interference performance and adaptability are effectively improved, and the method is suitable for constant current source feedback, precise instrument and industrial sensing signal processing and power equipment performance upgrading.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a high-precision analog signal processing circuit based on a multi-stage operational amplifier. Background Art

[0002] In the field of precision electronic measurement and automated control, high-precision analog signal processing circuits are the core foundation for building various devices. Especially in devices like constant current sources and precision sensors, signal processing accuracy directly determines the upper limit of system performance. With the development of Industry 4.0 and intelligent manufacturing, higher requirements are being placed on the accuracy, anti-interference capabilities, and adaptability of signal processing circuits.

[0003] Traditional analog signal processing circuits mostly use single-stage or two-stage operational amplifier structures. Although they can achieve basic signal amplification, they have significant limitations:

[0004] Insufficient precision: Single-stage amplification is limited by the operational amplifier's own parameters (such as input offset voltage, noise, etc.), making it difficult to achieve low-noise amplification at high gain (>1000 times), resulting in high signal distortion (typical value >0.5%).

[0005] Weak anti-interference capability: Lack of complete differential processing and multi-stage filtering mechanisms, limited ability to suppress common-mode noise (such as power supply fluctuations, electromagnetic interference), and common-mode rejection ratio (CMRR) is usually less than 60dB, which cannot meet the needs of harsh industrial environments.

[0006] Poor adaptability: Fixed-gain designs cannot adapt to input signals with varying amplitudes. For example, when testing batteries of varying capacities, a constant current source requires frequent changes in the amplifier circuit to match the signal strength, which is cumbersome and prone to introducing errors.

[0007] Imperfect feedback mechanism: Simple feedback structures (such as single-resistor feedback) make it difficult to achieve precise regulation of the output signal. In constant current source applications, they cannot quickly respond to load changes, resulting in output current fluctuations exceeding ±0.1%, affecting the reliability of battery test data.

[0008] To improve performance, some existing technologies use multi-stage amplifier cascade or differential input structures, but problems still exist:

[0009] Multi-stage amplification without optimized inter-stage matching can easily lead to phase distortion and bandwidth compression;

[0010] The differential circuit does not consider the balance between common-mode input range and dynamic response, and its performance drops sharply when a large signal is input.

[0011] The feedback network lacks an adjustable mechanism, making it difficult to strike a balance between stability and response speed.

[0012] In addition, high-end precision instruments (such as semiconductor testers and electrochemical workstations) rely on imported circuit solutions. Domestic similar technologies have obvious gaps in signal processing accuracy (<0.05% error), dynamic response speed (>10kHz) and environmental adaptability, and urgently need to achieve technological breakthroughs through circuit architecture innovation. Summary of the Invention

[0013] The present invention aims to provide a high-precision analog signal processing circuit based on multi-stage operational amplifier to solve the problems raised in the above background technology.

[0014] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0015] A high-precision analog signal processing circuit based on multi-stage operational amplifier includes a signal input conditioning module, a main amplification channel, a feedback adjustment channel and a closed-loop feedback network. Each module works together to complete signal preprocessing, multi-stage amplification, feedback adjustment and stable output. The specific connection relationship and signal flow are as follows Figure 1 shown.

[0016] The signal input conditioning module includes differential input terminals (VF+, VF-), filter capacitor C1, and a voltage-divider and current-limiting resistor network (R10, R12, R15). The differential input terminals receive external differential signals (such as sensor outputs or small signal sources) and utilize the differential input characteristics to suppress common-mode noise. Filter capacitor C1 removes high-frequency noise from the input signal, improving signal purity. Voltage-divider and current-limiting resistors R10 and R12 adjust the signal amplitude to adapt the input signal to the operating range of the subsequent operational amplifier. Balancing resistor R15 ensures symmetry of the differential input and optimizes common-mode rejection.

[0017] The main amplification channel is composed of a first operational amplifier unit (U1), a second operational amplifier unit (U2), and a third operational amplifier unit (U3) which are cascaded in sequence to achieve multi-stage amplification and filtering and shaping of the signal;

[0018] The first operational amplifier unit (U1) comprises an operational amplifier (U1), the inverting input of which is connected to a voltage divider resistor R4, and the non-inverting input of which is connected to a voltage divider resistor R6, thereby providing a stable operating bias for the operational amplifier; a feedback network is formed by a capacitor (C2) and a resistor (R1) connected in parallel, and is connected to the output of (U1) and the inverting input, thereby forming an amplifier circuit with a low-pass filtering characteristic, which can filter out high-frequency interference of a specific frequency while amplifying the signal, thereby preliminarily regulating the signal amplitude and frequency.

[0019] The second operational amplifier unit (U2) is combined with a resistor (R2) and a capacitor (C3) to form a resistor-capacitor network to perform secondary amplification and frequency shaping (such as compensating for signal bandwidth and adjusting phase characteristics) on the signal processed by U1, further optimizing signal quality and preparing for output.

[0020] The third operational amplifier unit (U3) uses an operational amplifier (U3), whose feedback resistor (R7) is connected to the output terminal and the inverting input terminal to form a voltage follower structure. The low output impedance characteristic of the operational amplifier is utilized to enhance the circuit's load capacity, stabilize the output VOUT, and drive the subsequent load (such as test equipment and actuators).

[0021] The feedback adjustment channel includes a fourth operational amplifier unit (U4) and a fifth operational amplifier unit (U5), which realize differential amplification and gain adjustment of the input signal:

[0022] The fourth operational amplifier unit (U4) is composed of an operational amplifier (U4) and differential input resistors (R10), (R12), and a balancing resistor (R15); the differential input resistors (R10) and (R12) have equal resistance values, and the balancing resistor (R15) matches the differential input resistors, forming a differential amplifier circuit that can effectively suppress common-mode noise (such as power supply fluctuations and environmental interference), achieve a common-mode rejection ratio of ≥80dB, perform preliminary amplification on the differential input signal, and output a cleaner signal to the subsequent stage.

[0023] The fifth operational amplifier unit (U5) includes an operational amplifier (U5) and a feedback resistor network (R9, R11, R13, and R14). An adjustable resistor (R11) is introduced into the feedback resistor network. By adjusting its resistance value, a dynamic gain adjustment of 0 to 50 times can be achieved, allowing the circuit to adapt to input signals of different amplitude ranges to meet the needs of diverse scenarios.

[0024] The closed-loop feedback network consists of a feedback path connecting the output of the fifth operational amplifier unit (U5) and the input of the second operational amplifier unit (U2) in the main amplifier channel, with a voltage divider resistor (R3) placed in the path. Its function is to transmit the feedback signal output by (U5) back to the main amplifier channel, forming a closed-loop control system with the main channel signal. By monitoring the feedback signal (reflecting the system output status, such as the current signal in a constant current source scenario), the amplification parameters of the main amplifier channel are adjusted in real time to ensure the stability of the output VOUT (for example, in a constant current source application, the output current accuracy is ≤±0.05%). The voltage divider resistor (R3) can flexibly adjust the feedback signal strength to optimize the closed-loop control effect.

[0025] Beneficial effects

[0026] High-precision signal processing:

[0027] It adopts differential input and multi-stage operational amplifier design, combined with low-pass filtering, differential amplification and other technologies to effectively suppress common-mode noise and high-frequency interference, achieve adjustable signal gain (0-50 times), low signal distortion rate, and ensure high output signal accuracy. It is suitable for scenarios with strict requirements on signal quality, such as precision instruments and constant current sources.

[0028] Strong anti-interference ability:

[0029] The differential input structure and multi-stage filtering network work together to achieve a common-mode rejection ratio of ≥80dB, which can resist environmental noise such as power supply fluctuations and electromagnetic interference, and improve the stability and reliability of the circuit under complex working conditions.

[0030] High adaptability:

[0031] The adjustable gain design (0-50 times) adapts to input signals of different amplitudes (0.1mV-10V), covering various application scenarios such as sensor signals and constant current source control signals; the closed-loop feedback network adjusts the output in real time to adapt to load changes and enhance the versatility of the circuit.

[0032] Reliable drive and protection:

[0033] The voltage follower structure of the third operational amplifier unit (U3) enhances its load capacity and stably drives subsequent devices. Optional protection diodes, decoupling capacitors, and other designs further enhance the circuit's resistance to overvoltage and power supply noise, ensuring long-term stable operation.

[0034] By optimizing the circuit architecture and module design, the present invention solves the accuracy, anti-interference and adaptability problems of traditional analog signal processing circuits, provides a reliable signal processing solution for high-precision electronic equipment, and promotes technological upgrades in the fields of constant current sources and precision instruments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the overall principle diagram of the high-precision analog signal processing circuit of the present invention. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0037] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words “including” or “comprising” and the like used in this disclosure mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The words “connected” or “connected” and the like are not limited to physical or mechanical connections, but may also include electrical connections, whether direct or indirect. “Up”, “down”, “left”, “right” and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0038] In the field of precision electronic measurement and automated control, high-precision analog signal processing circuits are the core foundation for building various devices. This is especially true in devices like constant current sources and precision sensors, where signal processing accuracy directly determines the upper limit of system performance. While traditional analog signal processing circuits can achieve basic signal amplification, they have significant limitations: insufficient accuracy, weak anti-interference capabilities, poor adaptability, and imperfect feedback mechanisms.

[0039] To address these challenges, the present invention provides a high-precision analog signal processing circuit based on a multi-stage operational amplifier, comprising a signal input conditioning module, a main amplification channel, and a feedback regulation channel. The core of the circuit is the use of op amps for signal amplification, filtering, and closed-loop control. Through differential input, multi-stage amplification, filtering and shaping, and closed-loop feedback, it enables precise processing and stable output of complex signals. This circuit effectively improves signal accuracy, interference resistance, and adaptability, making it suitable for constant current source feedback, precision instrumentation, and industrial sensor signal processing, helping to upgrade equipment performance.

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0041] Figure 1 The figure shows an overall principle diagram of a high-precision analog signal processing circuit based on multi-stage operational amplifier according to an embodiment of the present invention.

[0042] like Figure 1 As shown, the high-precision analog signal processing circuit includes a signal input conditioning module, a main amplification channel, a feedback adjustment channel and a closed-loop feedback network.

[0043] Specifically, the signal input conditioning module is composed of differential input terminals VF+ and VF-, a filter capacitor (C1), and voltage-dividing and current-limiting resistors (R10), (R12), and (R15), and is used to filter and amplitude-condition the external input differential signal.

[0044] Specifically, the main amplification channel is composed of a cascade of three operational amplifier units: the first operational amplifier unit (U1) obtains a bias voltage through voltage-dividing resistors (R4) and (R6), and uses a feedback network formed by a capacitor (C2) and a resistor (R1) in parallel to achieve low-pass filtering and signal amplification; the second operational amplifier unit (U2) combines a resistor-capacitor network (R2) and (C3) to perform secondary amplification and frequency shaping on the signal; the third operational amplifier unit (U3) forms a voltage follower structure through a feedback resistor (R7), thereby enhancing the signal driving capability and stabilizing the output VOUT.

[0045] Specifically, the feedback regulation channel includes a fourth operational amplifier unit (U4) and a fifth operational amplifier unit (U5): (U4) forms a differential amplifier circuit through differential input resistors (R10), (R12) and a balancing resistor (R15) to suppress common-mode noise; (U5) uses a feedback resistor network (R9), (R11), (R13), and (R14) to achieve 0-50 times adjustable gain, and feeds back the conditioned signal to the input end (U2) of the main amplifier channel through a voltage divider resistor (R3), forming a closed-loop control system.

[0046] Specifically, in the signal processing flow, the differential signal is fed from VF+ and VF-, filtered by (C1) and differentially amplified by (U4). Gain adjustment is performed by (U5), and the signal is then fed back to the main amplifier channel via a closed-loop feedback network. Simultaneously, the VIN signal is low-pass filtered and amplified by (U1), then superimposed with the feedback signal in (U2), ultimately outputting a stable VOUT signal via (U3). This circuit, through its multi-stage amplification and closed-loop feedback design, achieves high-precision processing capabilities with a signal distortion rate of ≤0.1% and a common-mode rejection ratio of ≥80dB. It is suitable for controlling output fluctuations within ±0.05% when the constant current source load varies.

[0047] The embodiments of the present invention have been described in detail with reference to the accompanying drawings. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods described in the embodiments; those skilled in the art may easily modify or replace them.

[0048] Unless otherwise indicated, the numerical parameters in this specification and the accompanying examples are approximate and can vary depending on the desired properties obtained through the teachings of the present invention. Specifically, all numbers used in the specification and examples to indicate composition amounts, reaction conditions, and the like should be understood to be modified by the term "about" in all cases. Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in the examples. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0049] The ordinal numbers used in the specification and embodiments, such as "first," "second," "third," etc., to modify the corresponding elements, do not in themselves mean that the elements have any ordinal number, nor do they represent the order of one element relative to another, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish one element with a certain name from another element with the same name.

[0050] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the scope of the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the spirit and scope of protection of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present invention.

Claims

1. A high-precision analog signal processing circuit based on multi-stage operational amplifier, characterized in that: include: Signal input conditioning module: It consists of differential input terminals (VF+, VF-), filter capacitor (C1) and voltage-dividing and current-limiting resistor network (R10, R12, R15), and is used to receive and pre-process differential input signals; Main amplification channel: a first operational amplifier unit (U1), a second operational amplifier unit (U2), and a third operational amplifier unit (U3) cascaded in sequence, for multi-stage amplification and filtering and shaping of signals; A feedback regulation channel comprises a fourth operational amplifier unit (U4) and a fifth operational amplifier unit (U5), wherein the fourth operational amplifier unit (U4) receives a differential input signal and performs differential amplification, and the fifth operational amplifier unit (U5) performs gain regulation on the output of the fourth operational amplifier unit (U4); Closed-loop feedback network: Feeds back the output signal of the fifth operational amplifier unit (U5) to the input end of the second operational amplifier unit (U2) of the main amplifier channel to form a closed-loop control system.

2. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The first operational amplifier unit (U1) includes: An operational amplifier (U1) and a voltage divider resistor (R4) connected to its inverting input terminal and a voltage divider resistor (R6) connected to its non-inverting input terminal; A feedback network consisting of a capacitor (C2) and a resistor (R1) connected in parallel connects the output terminal and the inverting input terminal of the operational amplifier U1 to form an amplifier circuit with low-pass filtering characteristics.

3. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The fourth operational amplifier unit (U4) includes: Operational amplifier (U4) and its differential input resistors (R10, R12), and balancing resistor (R15); The differential input resistors (R10, R12) have equal resistance values, and the balancing resistor (R15) has a resistance value that matches the differential input resistor, forming a differential amplifier circuit.

4. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The fifth operational amplifier unit (U5) includes: Operational amplifier (U5) and its feedback resistor network (R9, R11, R13, R14); The feedback resistor network includes an adjustable resistor (R11), and the gain can be adjusted from 0 to 50 times by adjusting the adjustable resistor (R11).

5. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The third operational amplifier unit (U3) includes: An operational amplifier (U3) and a feedback resistor (R7) thereof, wherein the feedback resistor (R7) is connected to the output terminal and the inverting input terminal of the operational amplifier (U3) to form a voltage follower structure for enhancing the output driving capability.

6. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The closed-loop feedback network includes: a feedback path connecting the output end of the fifth operational amplifier unit (U5) and the input end of the second operational amplifier unit (U2); A voltage divider resistor (R3) is provided on the feedback path to adjust the feedback signal strength.

7. A high-precision analog signal processing circuit based on multi-stage operational amplifier according to any one of claims 1 to 6, characterized in that: The circuit is used for: The feedback control circuit of the constant current source device monitors the output current signal and adjusts the feedback to achieve a current accuracy of ≤±0.05% within the range of ±1000A; Precision sensor signal conditioning circuit for processing differential input signals in the range of 0.1mV-10V; Signal amplification and filtering circuits in industrial automation control systems.

8. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The signal input conditioning module also includes: Protection diodes (D1, D2) connected between the differential input terminals (VF+, VF-) and ground prevent input signal overvoltage from damaging the circuit.

9. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The main amplifying channel is provided between the operational amplifying units of each level: The coupling capacitor (C3) is used to isolate the DC bias and pass only the AC signal component.

10. The high-precision analog signal processing circuit based on multi-stage operational amplifier according to claim 1, characterized in that: The power supply terminal of the circuit is set as follows: Decoupling capacitors (C4, C5) connected in parallel, wherein the decoupling capacitor (C4) is a ceramic capacitor and the decoupling capacitor (C5) is a tantalum capacitor, are used to stabilize the power supply voltage.

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