Weak signal and wide dynamic range acquisition circuit for high-precision instrument

Abstract

The invention discloses a weak signal and wide dynamic range acquisition circuit for a high-precision instrument. The weak signal and wide dynamic range acquisition circuit comprises a composite transimpedance amplifier, an RC low-pass filter circuit, a voltage offset fine tuning circuit, a multiplying power amplification circuit and a double analog-to-digital conversion acquisition circuit, the output burden of the preceding-stage operational amplifier can be effectively reduced, so that the voltage thermal drift caused by power consumption of the preceding-stage operational amplifier is reduced; the high-frequency noise of the voltage signal is suppressed; interference caused by system noise is adjusted; particularly, the multiplying power amplification circuit and the double analog-to-digital conversion circuits are matched to expand the signal acquisition range of the system, and the signal dynamic range is 6.5 orders of magnitude.

Description

Technical Field

[0001] The invention belongs to the technical field of dynamic weak signal acquisition, and in particular relates to a weak signal and wide dynamic range acquisition circuit for high-precision instruments. Background Art

[0002] Weak current acquisition technology is of great significance in production practice and scientific research. Accurate measurement of weak current signals is crucial for high-precision instruments. Because the measurement of weak current signals is easily interfered with, it has always been the focus of research and attention.

[0003] The key technical indicators of weak current signal detection systems include signal-to-noise ratio, measurement accuracy, and temperature stability. With the development of electronic technology, high-performance integrated operational amplifiers and current-to-voltage converters have been widely used in weak current signal detection. The development of these technologies has greatly improved the sensitivity and accuracy of the detection system and promoted the advancement of related technologies.

[0004] There are many public technical solutions for detecting weak current signals in the prior art, such as the Chinese invention patent with publication number CN117155305A, which involves a weak signal wide-range IV amplification conversion circuit, including a coupled logarithmic amplification conversion circuit, a logarithmic temperature compensation circuit and a secondary amplification circuit; the logarithmic temperature compensation circuit is used to compensate for the temperature drift effect of the logarithmic amplification conversion circuit, and the secondary amplification circuit is used to perform secondary amplification on the output of the logarithmic amplification conversion circuit and then output it; a transistor with high stability and extremely low temperature drift coefficient is used to achieve a large dynamic range I / V conversion.

[0005] Another example is the Chinese invention patent with publication number CN117353741A, which discloses a high-precision acquisition system that achieves an ultra-large dynamic range. It adopts a dual ADC system architecture, and simultaneously inputs one input signal into a 24-bit analog-to-digital converter through an amplification circuit or an attenuation circuit, thereby achieving the acquisition of weak signals and the expansion of the dynamic range; then the two inputs are restored and spliced ​​in the post-stage FPGA to obtain a digital signal with an ultra-large dynamic range; research is also conducted from the perspective of working temperature and compensation calibration, and a temperature compensation table and user self-calibration are produced, which minimizes the impact of temperature changes on the acquisition system and achieves high-precision restoration of the acquisition system signal.

[0006] However, the current weak current signal detection still has some shortcomings, such as the inability to perform program-controlled amplification according to the signal amplitude, low signal resolution, low sampling rate, single signal type support, and poor real-time performance. These shortcomings put forward higher requirements on the weak signal acquisition processor, such as higher sampling rate, support for more signal types, and stronger real-time performance.

[0007] The above requirements cannot be met by existing weak signal collectors. Summary of the invention

[0008] Aiming at the higher technical requirements in the existing weak current signal acquisition, a weak signal and wide dynamic range acquisition circuit for high-precision instruments is proposed.

[0009] In order to solve the above technical problems, the present invention proposes a weak signal and wide dynamic range acquisition circuit for high-precision instruments, including a composite transimpedance amplifier, an RC low-pass filter circuit, a voltage offset fine-tuning circuit, a magnification amplifier circuit, and a dual analog-to-digital conversion acquisition circuit; wherein:

[0010] The composite transimpedance amplifier converts the current signal into a voltage signal that meets the acquisition range of the analog-to-digital conversion module;

[0011] The RC low-pass filter circuit implements frequency-limited passing of the voltage signal;

[0012] The voltage offset fine-tuning circuit can adjust the interference caused by system noise;

[0013] The magnification amplification circuit realizes amplification of the voltage signal at different magnifications;

[0014] The dual analog-to-digital conversion acquisition circuit is responsible for performing analog-to-digital conversion on the voltage signal amplified by the multiplication amplifier circuit.

[0015] Furthermore, the composite impedance amplifier circuit includes an operational amplifier 1 whose negative input terminal is connected to an input signal J7, whose output terminal is connected to a positive input terminal of an operational amplifier 2, whose negative input terminal is grounded and then connected to the output terminal, and whose input signal J7 is connected in series with R13, R15, R17 and a capacitor C35 and then connected in parallel to the output terminal of the operational amplifier 2;

[0016] Furthermore, the RC low-pass filter circuit is connected to the output end of the composite transimpedance amplifier, and includes two 5.1K resistors R22 and R23 connected in series to output a signal, wherein the front ends of the resistors R22 and R23 are grounded through 4.7nF capacitors C68 and C69 respectively;

[0017] Furthermore, the voltage offset fine-tuning circuit is connected to the RC low-pass filter circuit, and is used to receive the output signal of the RC low-pass filter circuit, and includes an operational amplifier three, the output signal is connected to the positive input terminal of the operational amplifier three, and the negative input terminal is connected in series with a resistor R18 and then connected to the output terminal of the operational amplifier;

[0018] Furthermore, the multiplication factor amplification circuit is connected to the output end of the voltage offset fine-tuning circuit, and includes an operational amplifier 4, the output end of the voltage offset fine-tuning circuit is connected to the positive input end of the operational amplifier 4, the negative input end is connected to the resistor R10 and then grounded, and the negative input end is also connected in series with the resistor R7 and the capacitor C16 and then connected in parallel to the output end of the operational amplifier;

[0019] Furthermore, the dual analog-to-digital conversion acquisition circuit is connected to the output end of the multiplication amplifier circuit. The dual analog-to-digital conversion acquisition circuit includes an analog-to-digital converter AD7663ASTZ, and its 41, 42, and 43 pins are all connected to the output end of the multiplication amplifier circuit. The system signal acquisition range can be expanded through the cooperation of the multiplication amplifier circuit and the dual analog-to-digital conversion circuit, and the signal dynamic range is 6.5 orders of magnitude.

[0020] The beneficial effects of the present invention are as follows: the output burden of the front-stage operational amplifier can be effectively reduced, so that the front-stage operational amplifier can reduce the voltage thermal drift caused by power consumption; the high-frequency noise of the voltage signal can be suppressed; the interference caused by the system noise can be adjusted; in particular, the combination of the multiplier amplification circuit and the dual analog-to-digital conversion circuit can expand the system signal acquisition range, and the signal dynamic range is 6.5 orders of magnitude. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The signal flow chart of the present invention is

[0022] Figure 2 This is a circuit diagram of a composite impedance amplifier of the present invention;

[0023] Figure 3 This is the RC low-pass filter circuit diagram of the present invention;

[0024] Figure 4 The voltage offset fine-tuning circuit diagram of the present invention;

[0025] Figure 5 This is a magnification circuit diagram of the present invention;

[0026] Figure 6 This is the analog-to-digital conversion circuit diagram of the present invention; DETAILED DESCRIPTION

[0027] The present invention provides a weak signal and wide dynamic range acquisition circuit for high-precision instruments. The specific implementation of the present invention is further explained below in conjunction with the accompanying drawings.

[0028] It should be noted that the embodiments described in the present invention are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention.

[0029] A weak signal and wide dynamic range acquisition circuit for high-precision instruments, comprising a composite transimpedance amplifier, an RC low-pass filter circuit, a voltage offset fine-tuning circuit, a magnification amplification circuit, and a dual analog-to-digital conversion acquisition circuit; wherein:

[0030] The composite transimpedance amplifier realizes the conversion of current signals into voltage signals that meet the acquisition range of the analog-to-digital conversion module; at the same time, the ultra-low input bias current reduces the DC bias error at output. The current feedback amplifier has a strong ability to drive the load, which reduces the output burden of the previous stage amplifier and reduces the voltage thermal drift caused by power consumption of the previous stage amplifier.

[0031] The above-mentioned composite transimpedance amplifier inherits the dual advantages of ultra-low input bias current operational amplifier and ultra-strong driving capability of current feedback operational amplifier;

[0032] The RC low-pass filter circuit can effectively suppress the high-frequency noise of the voltage signal by limiting the frequency of the voltage signal.

[0033] The voltage offset fine-tuning circuit can adjust the interference caused by system noise;

[0034] The magnification amplification circuit realizes amplification of the voltage signal at different magnifications;

[0035] The dual analog-to-digital conversion acquisition circuit is responsible for performing analog-to-digital conversion on the voltage signal amplified by the multiplication amplifier circuit.

[0036] The system signal acquisition range can be expanded by cooperating with the multiplier amplification circuit and the dual analog-to-digital conversion circuit, and the signal dynamic range is 6.5 orders of magnitude.

[0037] The following is combined with Figure 2-6 The circuit structure of each module is introduced in detail.

[0038] Figure 2 The composite impedance amplifier circuit is shown, which includes an operational amplifier 1 whose negative input terminal is connected to an input signal J7, whose output terminal is connected to a positive input terminal of an operational amplifier 2, whose negative input terminal is connected to the ground and then to the output terminal, and whose input signal J7 is connected in series with R13, R15, R17 and a capacitor C35 and then connected in parallel to the output terminal of the operational amplifier 2;

[0039] Figure 3 The RC low-pass filter circuit is shown, which is connected to the output end of the composite transimpedance amplifier, and includes two 5.1K resistors R22 and R23 connected in series to output signals, wherein the front ends of the resistors R22 and R23 are grounded through 4.7nF capacitors C68 and C69 respectively;

[0040] Figure 4The voltage offset fine-tuning circuit is shown, which is connected to the RC low-pass filter circuit and is used to receive the output signal of the RC low-pass filter circuit. It includes an operational amplifier three, the output signal is connected to the positive input terminal of the operational amplifier three, and the negative input terminal is connected in series with a resistor R18 and then connected to the output terminal of the operational amplifier;

[0041] Figure 5 The figure shows a multiplication amplification circuit, which is connected to the output end of the voltage offset fine-tuning circuit, and includes an operational amplifier 4, the output end of the voltage offset fine-tuning circuit is connected to the positive input end of the operational amplifier 4, the negative input end is connected to the resistor R10 and then grounded, and the negative input end is also connected in series with the resistor R7 and the capacitor C16 and then connected in parallel to the output end of the operational amplifier;

[0042] Figure 6 The figure shows a dual analog-to-digital conversion acquisition circuit, which is connected to the output end of the multiplication amplifier circuit. The dual analog-to-digital conversion acquisition circuit includes an analog-to-digital converter AD7663ASTZ, and its 41, 42, and 43 pins are all connected to the output end of the multiplication amplifier circuit. The system signal acquisition range can be expanded by cooperating with the multiplication amplifier circuit and the dual analog-to-digital conversion circuit, and the signal dynamic range is 6.5 orders of magnitude.

[0043] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A weak signal and wide dynamic range acquisition circuit for high-precision instruments, characterized in that: It includes a composite transimpedance amplifier, an RC low-pass filter circuit, a voltage offset fine-tuning circuit, a magnification amplifier circuit, and a dual analog-to-digital conversion acquisition circuit; wherein: The composite transimpedance amplifier converts the current signal into a voltage signal that meets the acquisition range of the analog-to-digital conversion module; The RC low-pass filter circuit implements frequency-limited passing of the voltage signal; The voltage offset fine-tuning circuit can adjust the interference caused by system noise; The magnification amplification circuit realizes amplification of the voltage signal at different magnifications; The dual analog-to-digital conversion acquisition circuit is responsible for performing analog-to-digital conversion on the voltage signal amplified by the multiplication amplifier circuit.

2. The weak signal and wide dynamic range acquisition circuit for high-precision instruments according to claim 1, characterized in that: The composite impedance amplifier circuit includes an operational amplifier 1 whose negative input terminal is connected to an input signal J7, whose output terminal is connected to a positive input terminal of an operational amplifier 2, whose negative input terminal is grounded and then connected to the output terminal, and whose input signal J7 is connected in series with R13, R15, R17 and a capacitor C35 and then connected in parallel to the output terminal of the operational amplifier 2.

3. The weak signal and wide dynamic range acquisition circuit for high-precision instruments according to claim 2, characterized in that: The RC low-pass filter circuit is connected to the output end of the composite transimpedance amplifier, and includes two 5.1K resistors R22 and R23 connected in series to output signals, wherein the front ends of the resistors R22 and R23 are grounded via 4.7nF capacitors C68 and C69, respectively.

4. The weak signal and wide dynamic range acquisition circuit for high-precision instruments according to claim 3, characterized in that: The voltage offset fine-tuning circuit is connected to the RC low-pass filter circuit and is used to receive the output signal of the RC low-pass filter circuit. It includes an operational amplifier three, the output signal is connected to the positive input terminal of the operational amplifier three, and the negative input terminal is connected in series with a resistor R18 and then connected to the output terminal of the operational amplifier.

5. The weak signal and wide dynamic range acquisition circuit for high-precision instruments according to claim 4, characterized in that: The multiplication factor amplification circuit is connected to the output end of the voltage offset fine-tuning circuit, and includes an operational amplifier 4. The output end of the voltage offset fine-tuning circuit is connected to the positive input end of the operational amplifier 4, and the negative input end is connected to the resistor R10 and then grounded. The negative input end is also connected in series with the resistor R7 and the capacitor C16 and then connected in parallel to the output end of the operational amplifier.

6. The weak signal and wide dynamic range acquisition circuit for high-precision instruments according to claim 5, characterized in that: The dual analog-to-digital conversion acquisition circuit is connected to the output end of the multiplication amplifier circuit. The dual analog-to-digital conversion acquisition circuit includes an analog-to-digital converter AD7663ASTZ, and its 41, 42, and 43 pins are all connected to the output end of the multiplication amplifier circuit. The system signal acquisition range can be expanded through the cooperation of the multiplication amplifier circuit and the dual analog-to-digital conversion circuit, and the signal dynamic range is 6.5 orders of magnitude.

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