A high-precision analog signal processing circuit based on multi-stage operational amplification

Abstract

This utility model discloses a high-precision analog signal processing circuit based on multi-stage operational amplifiers, including a signal input conditioning module, a main amplification channel, and a feedback conditioning channel. The core functionality utilizes operational amplifiers to achieve signal amplification, filtering, and closed-loop control. Through differential input, multi-stage amplification, filtering and shaping, and closed-loop feedback, it achieves precise processing and stable output of complex signals. This effectively improves signal accuracy, anti-interference capability, and adaptability, making it suitable for constant current source feedback, precision instruments, and industrial sensor signal processing, thus contributing to equipment performance upgrades.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, specifically to a high-precision analog signal processing circuit based on a multi-stage operational amplifier. Background Technology

[0002] In the fields of precision electronic measurement and automation control, high-precision analog signal processing circuits are the core foundation for building various types of equipment. Especially in devices such as constant current sources and precision sensors, signal processing accuracy directly determines the upper limit of system performance. With the development of industry and intelligent manufacturing, higher demands are being placed on the accuracy, anti-interference capabilities, and adaptability of signal processing circuits.

[0003] Traditional analog signal processing circuits mostly employ single-stage or two-stage operational amplifier structures. While these structures can amplify basic signals, they have significant limitations:

[0004] Insufficient accuracy: Single-stage amplification is limited by the op-amp'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: Lacking a complete differential processing and multi-stage filtering mechanism, it has limited ability to suppress common-mode noise (such as power fluctuations and electromagnetic interference). The common-mode rejection ratio (CMRR) is usually below 60dB, which cannot meet the requirements of harsh industrial environments.

[0006] Poor adaptability: Fixed-gain designs cannot adapt to input signals with different amplitude ranges. For example, when testing batteries of different capacities, constant current sources require frequent replacement of the amplifier circuit to match the signal strength, which is cumbersome and prone to introducing errors.

[0007] Inadequate feedback mechanisms: Simple feedback structures (such as single-resistor feedback) struggle to achieve precise adjustment of the output signal. In constant current source applications, they cannot respond quickly to load changes, causing output current fluctuations exceeding ±0.1%, impacting the reliability of battery test data.

[0008] To improve performance, some existing technologies employ multi-stage cascaded amplifiers or differential input structures, but problems still exist:

[0009] Unoptimized inter-stage matching in multi-stage amplification can easily lead to phase distortion and bandwidth compression.

[0010] Differential circuits do not consider the balance between common-mode input range and dynamic response, resulting in a sharp drop in performance when large signal inputs are applied.

[0011] Feedback networks lack adjustable mechanisms, making it difficult to balance 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 lag significantly behind in signal processing accuracy (<0.05% error), dynamic response speed (>10kHz), and environmental adaptability, and technological breakthroughs are urgently needed through circuit architecture innovation. Summary of the Invention

[0013] The purpose of this invention is to provide a high-precision analog signal processing circuit based on multi-stage operational amplification to solve the problems mentioned in the background art.

[0014] To achieve the above practical objectives, the present invention adopts the following technical solution:

[0015] A high-precision analog signal processing circuit based on multi-stage operational amplification includes a signal input conditioning module, a main amplification channel, a feedback adjustment channel, and a closed-loop feedback network. These modules work collaboratively to complete signal preprocessing, multi-stage amplification, feedback adjustment, and stable output.

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

[0017] The main amplification channel is composed of a first operational amplifier unit, a second operational amplifier unit, and a third operational amplifier unit cascaded in sequence to realize multi-stage amplification and filtering of the signal; coupling capacitors C3 are set between each stage of the operational amplifier unit in the main amplification channel to isolate DC bias and transmit only AC signal components.

[0018] The first operational amplifier unit includes a first operational amplifier (U1), whose inverting input is connected to the fourth voltage divider resistor R4 and the non-inverting input is connected to the sixth voltage divider resistor R6, providing a stable operating bias for the operational amplifier. The feedback network is composed of a capacitor (C2) and a resistor (R1) connected in parallel, connecting the output of the first operational amplifier (U1) and the inverting input, forming an amplifier circuit with low-pass filtering characteristics. This circuit can filter out high-frequency interference of a specific frequency while amplifying the signal, and preliminarily adjust the signal amplitude and frequency.

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

[0020] The third operational amplifier unit: It adopts the third operational amplifier (U3), and the seventh feedback resistor (R7) is connected to the output terminal and the inverting input terminal to form a voltage follower structure. It utilizes the low output impedance characteristic of the operational amplifier to enhance the circuit's load-driving capability, stabilize the output VOUT, and drive the subsequent load (such as test equipment, actuator).

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

[0022] The fourth operational amplifier unit consists of a fourth operational amplifier (U4), differential input resistors (R10) and (R12), and a balancing resistor (R15). The differential input resistors (R10) and (R12) have equal resistance values, and the balancing resistor (R15) is matched with the differential input resistors to form a differential amplifier circuit. This circuit can effectively suppress common-mode noise (such as power supply fluctuations and environmental interference), achieving a common-mode rejection ratio of ≥80dB. It performs preliminary amplification on the differential input signal and outputs a "cleaner" signal to the subsequent stage.

[0023] The fifth operational amplifier unit includes a fifth operational amplifier (U5), a resistor (R9), an adjustable resistor (R11), a resistor (R13), and a resistor (R14). By adjusting the value of the adjustable resistor (R11), the gain can be dynamically adjusted from 0 to 50 times, allowing the circuit to adapt to input signals of different amplitude ranges and 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) to the input of the second operational amplifier unit (U2) in the main amplification channel, with a third voltage divider resistor (R3) included in the path. Its function is to transmit the feedback signal from the fifth operational amplifier (U5) back to the main amplification channel, forming a closed-loop control system with the main channel signal. By monitoring the feedback signal (reflecting the system output state, such as the current signal in a constant current source scenario), the amplification parameters of the main amplification channel are adjusted in real time to ensure stable output VOUT (e.g., achieving output current accuracy ≤ ±0.05% in constant current source applications). The third voltage divider resistor (R3) allows for flexible adjustment of the feedback signal strength, optimizing the closed-loop control effect.

[0025] Preferably, the power supply terminal of the circuit is provided with decoupling capacitors C4 and C5 connected in parallel, wherein C4 is a ceramic capacitor and C5 is a tantalum capacitor, for stabilizing the power supply voltage.

[0026] Preferably, the circuit can be applied to: a feedback control circuit for a constant current source device, which monitors the output current signal and adjusts it to achieve a current accuracy of ≤±0.05% within the range of ±1000A; a precision sensor signal conditioning circuit, which processes differential input signals within the range of 0.1mV-10V; and a signal amplification and filtering circuit in an industrial automation control system.

[0027] Beneficial effects

[0028] High-precision signal processing:

[0029] Employing a differential input and multi-stage operational amplification design, combined with low-pass filtering and differential amplification techniques, it effectively suppresses common-mode noise and high-frequency interference, achieving adjustable signal gain (0-50 times), low signal distortion, and ensuring high output signal accuracy. It is suitable for applications with stringent signal quality requirements, such as precision instruments and constant current sources.

[0030] Strong anti-interference capability:

[0031] The differential input structure works in synergy with the multi-stage filter network to achieve a common-mode rejection ratio of ≥80dB, which can resist environmental noise such as power fluctuations and electromagnetic interference, and improve the stability and reliability of the circuit under complex operating conditions.

[0032] High adaptability:

[0033] The adjustable gain design (0-50 times) adapts to different amplitude input signals (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 enhances the versatility of the circuit.

[0034] Reliable drive and protection:

[0035] The voltage follower structure of the third operational amplifier unit (U3) enhances the load-driving capability and stably drives subsequent devices; optional protection diodes, decoupling capacitors and other designs further improve the circuit's resistance to overvoltage and power supply noise, ensuring long-term stable operation.

[0036] This utility model solves the problems of accuracy, anti-interference and adaptability of traditional analog signal processing circuits by optimizing circuit architecture and module design, providing a reliable signal processing solution for high-precision electronic equipment and promoting the technological upgrading of fields such as constant current sources and precision instruments. Attached Figure Description

[0037] Figure 1 This is the overall schematic diagram of the practical high-precision analog signal processing circuit. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0039] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "comprising" or "including," and similar terms used in this disclosure, mean that an element or object preceding the term encompasses the elements or objects listed following the term and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but may also include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0040] In the fields of precision electronic measurement and automation control, high-precision analog signal processing circuits are the core foundation for building various devices. Especially in devices such as constant current sources and precision sensors, signal processing accuracy directly determines the upper limit of system performance. Although traditional analog signal processing circuits can amplify basic signals, they have significant limitations: insufficient accuracy, weak anti-interference ability, poor adaptability, and imperfect feedback mechanisms.

[0041] To address the aforementioned issues, this invention provides a high-precision analog signal processing circuit based on multi-stage operational amplifiers, comprising a signal input conditioning module, a main amplification channel, and a feedback adjustment channel. The core functionality utilizes operational amplifiers to achieve signal amplification, filtering, and closed-loop control. Through differential input, multi-stage amplification, filtering and shaping, and closed-loop feedback, it achieves precise processing and stable output of complex signals. This effectively improves signal accuracy, anti-interference capability, and adaptability, making it suitable for constant current source feedback, precision instruments, and industrial sensor signal processing, thus contributing to equipment performance upgrades.

[0042] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0043] Figure 1 The diagram shows the overall schematic of a high-precision analog signal processing circuit based on multi-stage operational amplification according to an embodiment of the present invention.

[0044] like Figure 1As 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.

[0045] Specifically, the signal input conditioning module consists of differential input terminals VF+ and VF-, a filter capacitor (C1), differential input resistors (R10) and (R12), and a balancing voltage (R15), and is used to filter and condition the amplitude of the externally input differential signal.

[0046] Specifically, the main amplification channel consists of three cascaded operational amplifier units: the first operational amplifier unit obtains the bias voltage through voltage divider resistors (R4) and (R6), and uses a feedback network formed by capacitor (C2) and resistor (R1) in parallel to achieve low-pass filtering and signal amplification; the second operational amplifier unit performs secondary amplification and frequency shaping of the signal through RC network (R2) and (C3); the third operational amplifier unit forms a voltage follower structure through feedback resistor (R7) to enhance signal driving capability and stabilize output VOUT.

[0047] Specifically, the feedback adjustment channel includes a fourth operational amplifier unit and a fifth operational amplifier unit: the fourth operational amplifier (U4) forms a differential amplifier circuit through differential input resistors (R10), (R12) and balancing resistor (R15) to suppress common-mode noise; the fifth operational amplifier unit includes a fifth operational amplifier (U5), resistor (R9), adjustable resistor (R11), resistor (R13) and resistor (R14); by adjusting the value of the adjustable resistor (R11), the gain can be dynamically adjusted from 0 to 50 times, and the conditioned signal is fed back to the input terminal of the second operational amplifier (U2) of the main amplification channel through the third voltage divider resistor (R3) to form a closed-loop control system.

[0048] Specifically, in the signal processing flow, the differential signals are input from VF+ and VF-, filtered by capacitor (C1), differentially amplified by the fourth operational amplifier (U4), and then gain-adjusted by the fifth operational amplifier (U5). Finally, the signals are fed back to the main amplification channel through a closed-loop feedback network. Simultaneously, the signal VIN is low-pass filtered and amplified by the first operational amplifier (U1), then superimposed with the feedback signal in the second operational amplifier (U2), and finally output as a stable VOUT signal by the third operational amplifier (U3). This circuit, through multi-stage amplification and closed-loop feedback design, achieves high-precision processing capabilities with a signal distortion rate ≤0.1% and a common-mode rejection ratio ≥80dB, making it suitable for output fluctuation control scenarios within ±0.05% when the constant current source load changes.

[0049] The present utility model has been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms 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 mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.

[0050] Unless otherwise stated, the numerical parameters in this specification and the accompanying embodiments are approximate values ​​and can be changed according to desired characteristics derived from the content of this utility model. Specifically, all figures used in the specification and embodiments to indicate the content of components, reaction conditions, etc., 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 embodiments. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0051] The use of ordinal numbers such as "first," "second," and "third" in the specification and embodiments to modify the corresponding elements does not imply that the element has any ordinal number, nor does it represent the order of one element with another element, or the order of manufacturing methods. The use of these ordinal numbers is only to enable a named element to be clearly distinguished from another element with the same name.

[0052] The above embodiments are merely exemplary embodiments of this utility model and are not intended to limit this utility model. The scope of protection of this utility model is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this utility model within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this utility model.

Claims

1. A high-precision analog signal processing circuit based on multi-stage operational amplification, characterized in that, include: Signal input conditioning module: Composed of differential input terminals (VF+, VF-), filter capacitor (C1), differential input resistors (R10, R12) and balancing resistor (R15), used to receive and preprocess differential input signals; Main amplification channel: The first operational amplifier unit, the second operational amplifier unit, and the third operational amplifier unit are cascaded in sequence for multi-stage amplification and filtering of signals; Feedback adjustment channel: includes a fourth operational amplifier unit and a fifth operational amplifier unit. The fourth operational amplifier unit receives the differential input signal and performs differential amplification. The fifth operational amplifier unit adjusts the gain of the output of the fourth operational amplifier unit. Closed-loop feedback network: The output signal of the fifth operational amplifier unit is fed back to the input of the second operational amplifier unit 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 amplification according to claim 1, characterized in that: The first operational amplifier unit includes: The first operational amplifier (U1) and its fourth voltage divider resistor (R4) connected to its inverting input terminal and the sixth 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 is connected to the output terminal and the inverting input terminal of the first 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 amplification according to claim 1, characterized in that: The fourth operational amplifier unit includes: The fourth 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 resistors, thus forming a differential amplifier circuit.

4. The high-precision analog signal processing circuit based on multi-stage operational amplification according to claim 1, characterized in that: The fifth operational amplifier unit includes: Fifth operational amplifier (U5), resistor (R9), adjustable resistor (R11), resistor (R13), resistor (R14); the gain is adjustable from 0 to 50 times by adjusting the adjustable resistor (R11).

5. A high-precision analog signal processing circuit based on multi-stage operational amplification according to claim 1, characterized in that: The third operational amplifier unit includes: The third operational amplifier (U3) and its seventh feedback resistor (R7) are connected to the output terminal and the inverting input terminal of the third operational amplifier (U3) to form a voltage follower structure to enhance the output drive capability.

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

7. A high-precision analog signal processing circuit based on multi-stage operational amplification according to any one of claims 1-6, characterized in that: The circuit is used in: The feedback control circuit of the constant current source device monitors the output current signal and adjusts it accordingly to achieve a current accuracy of ≤±0.05% within a 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. A high-precision analog signal processing circuit based on multi-stage operational amplification according to claim 1, characterized in that: The main amplification channel is configured with the following between its various operational amplification units: The coupling capacitor (C3) is used to isolate the DC bias and transmit only the AC signal component.

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

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