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CN-121984478-A - Signal processing circuit based on fourth-order band-pass filter

CN121984478ACN 121984478 ACN121984478 ACN 121984478ACN-121984478-A

Abstract

The invention relates to the technical field of electronics, in particular to a signal processing circuit based on a fourth-order band-pass filter, which comprises a signal preprocessing and differential-to-single-ended amplifying module, a conditioning filtering module and a program-controlled gain amplifying module which are sequentially connected, wherein the signal preprocessing and differential-to-single-ended amplifying module is used for receiving differential input signals and converting the differential input signals into single-ended signals for preliminary amplification, the conditioning filtering module is used for carrying out filtering processing on the single-ended signals so as to extract target frequency signals, and the program-controlled gain amplifying module is used for receiving the filtered signals and adjusting the gain of output signals according to external digital control signals.

Inventors

  • YANG HAO
  • Ma Aiben
  • QI ZEYU

Assignees

  • 中船海洋探测技术研究院有限公司

Dates

Publication Date
20260505
Application Date
20260126

Claims (9)

  1. 1. A signal processing circuit based on a fourth-order band-pass filter is characterized by comprising a signal preprocessing and differential-to-single-ended amplifying module, a conditioning filtering module and a program-controlled gain amplifying module which are sequentially connected, wherein the signal preprocessing and differential-to-single-ended amplifying module is used for receiving differential input signals, converting the differential input signals into single-ended signals and carrying out preliminary amplification, the conditioning filtering module is used for carrying out filtering processing on the single-ended signals to extract target frequency signals, and the program-controlled gain amplifying module is used for receiving the filtered signals and adjusting the gain of output signals according to external digital control signals.
  2. 2. The four-order bandpass filter-based signal processing circuit according to claim 1, wherein the signal preprocessing and differential-to-single-ended amplifying module comprises an instrument amplifier chip U12 with a model of AD623ARZ, wherein differential input signals CH1_P and CH1_N are respectively connected to a 3 rd pin and a 2 nd pin of U12, a gain setting resistor R40 is connected between a 1 st pin and an 8 th pin of U12, a 7 th pin and a 4 th pin of a power supply pin are respectively connected to ground through decoupling capacitors C43 and C47 and respectively connected to a positive power supply VCC+5V and a negative power supply VCC-5V, a 5 th pin of a reference pin is grounded, and a 6 th pin of an output pin outputs a preliminarily amplified single-ended signal PRE_SIG.
  3. 3. The signal processing circuit based on the fourth-order band-pass filter according to claim 1, wherein the conditioning filter module comprises at least one dual-channel operational amplifier chip U11, the model ADA4084-2ARMZ, and two channels of each chip are cascaded to form a first-order fourth-order band-pass filter, wherein U11A forms a first-order second-order band-pass filter, an inverting input terminal (2 nd pin) of the first-order second-order band-pass filter is grounded through a resistor R49 and a capacitor C44, an in-phase input terminal (3 rd pin) of the first-order second-order band-pass filter is connected to a signal input PRE_SIG through a resistor R53 and is grounded through a capacitor C46, an output terminal (1 st pin) of the first-order second-pass filter is connected to an in-phase input terminal (6 th pin) of the first-order second-pass filter through a resistor R50 and is grounded through a capacitor C42, an in-phase input terminal of the first-order second-pass filter is connected to an output terminal of U11A through a capacitor C45 and an output terminal of the second-order second-pass filter is connected to an output terminal of the second-order second-pass filter through a capacitor C45.
  4. 4. The signal processing circuit based on a fourth order bandpass filter according to claim 3, wherein the conditioning filter module further comprises a second dual-channel operational amplifier chip U13, model ADA4084-2ARMZ, which is cascaded with U11 to form an optional eighth order bandpass filter configuration; the U13A forms a third-stage second-order band-pass filter, the inverting input end of the third-stage second-order band-pass filter is connected to the output end of the U13A through a resistor R64 and is grounded through a capacitor C51, the non-inverting input end of the third-stage second-order band-pass filter is connected to the output end of the U11B through a resistor R66 and is grounded through a capacitor C51, the non-inverting input end of the third-stage second-order band-pass filter is connected to the output end of the U11B through a resistor R61 and is connected to the non-inverting input end of the U13B through a capacitor C53, the non-inverting input end of the U13A is connected to the output end of the U13A through a resistor R63 and is grounded through a capacitor C50, the output end of the non-inverting input end of the U13A is connected to the output end of the U13A through a resistor R62 and is grounded through a capacitor C52, the output end of the output signal PRE_SIG is selected through a welding resistor R41 or R43, when the welding resistor R41 or R43 is used, the U13 is not connected to the circuit in a fourth-order band-pass filter mode, the U11B outputs the signal SIG1 as an output signal PRE_2_ORDER of a filter module, and is connected to an A channel of a program-controlled gain module when the U11B is connected to the output in a program-controlled gain module.
  5. 5. The signal processing circuit based on the fourth-order band-pass filter of claim 4, wherein the programmable gain amplification module comprises a programmable gain amplifier chip U15 and a level conversion driving chip U14, wherein the model of U15 is LTC6911IMS-2, the model of A channel input pin INA (1 st pin) is used for receiving a signal PRE_SIG_2_ORDER in the fourth-order filtering mode, the model of B channel input pin INB (3 rd pin) is used for receiving a signal PRE_SIG in the eighth-order filtering mode, gain control pins G0, G1 and G2 (4 th, 5 th and 6 th pins) are respectively connected to output pins A1, A2 and A3 (4 th, 5 th and 6 th pins) of U14, the model of A channel output pin OUTA or B channel output pin OUTB is SN74LVC4245A, the model of B1, B2, B3 (21 rd, 20 th and 19 th pins) are respectively connected to output gain control pins A1, A2, G2 (21 rd, 20 th and 19 th pins VCC_PG, VCV_3, and VCV_3) are respectively connected to the gain control pins VCV_3, and the gain control pins are respectively connected to the FPGA and the power supply voltage control pins.
  6. 6. The signal processing circuit based on a fourth order bandpass filter according to claim 5, wherein the program-controlled gain amplification module further comprises pull-up resistors R68 and R69 connected between the output pins A1 and A2 of the U14 and a VCCA (5V) power supply, respectively.
  7. 7. The signal processing circuit based on a fourth order bandpass filter according to claim 1, wherein the conditioning filter module has a center frequency of 70kHz and a 3dB bandwidth of 12kHz.
  8. 8. The signal processing circuit based on a fourth order bandpass filter according to claim 5, wherein the signals AD_CH1 and/or AD_CH1_2_ORDER outputted by the program controlled gain amplification module are connected to the input pin ADC_CH1_PRE of the analog-to-digital converter ADC through resistors R71, R72.
  9. 9. The signal processing circuit based on the fourth-order band-pass filter of claim 1, wherein the input differential signal of the circuit is accessed through a connector P5, and the output signal and the control signal are connected with an external FPGA and an ADC module through connectors P6 and P7.

Description

Signal processing circuit based on fourth-order band-pass filter Technical Field The invention relates to the technical field of electronics, in particular to a signal processing circuit based on a fourth-order band-pass filter. Background In the field of analog signal processing, especially in application scenarios (such as sensor signal conditioning, communication receiving front end, etc.) where weak signals with specific frequencies need to be extracted from a strong noise background, a discrete and staged design method is generally adopted in a traditional signal conditioning scheme. The basic constitution is as follows: (1) And the whole signal link is formed by connecting a plurality of independent functional sub-circuit modules in series. Typically comprising a separate instrumentation or differential amplifier chip for signal reception and preliminary amplification, a multi-stage active filter consisting of a plurality of operational amplifiers and passive elements (e.g. resistors, capacitors) for bandpass filtering, and a separate variable gain amplifier chip, or gain control circuit consisting of an operational amplifier and analog switches, for adjusting the amplitude of the output signal. (2) In the traditional scheme, the gain adjustment is manually adjusted by a mechanical potentiometer or a feedback resistor is switched by a digital potentiometer or an analog switch in a more advanced system, so that limited stepping gain control is realized. However, the above conventional scheme has the following obvious drawbacks in practical application: (1) The system has low complexity and integration level, and each functional module is realized separately, so that the circuit board has large area, more elements and higher overall power consumption, and is not beneficial to the miniaturization and integration design of equipment. (2) The design and debugging difficulties are great, and impedance matching and signal level among modules need to be carefully designed, otherwise, signal distortion or attenuation is easy to cause. The design and debugging process of the multi-order active filter is complex, the requirements on the precision and the layout and wiring of components are severe, and the final center frequency and the filter characteristic can be influenced by the minor deviation of any parameter. (3) Overall performance is limited in that the connections between the separate modules introduce additional noise and interference. In addition, the mechanical potentiometer or the digital potentiometer is adopted for gain control, so that the problems of low adjustment resolution, poor precision, sliding noise, easiness in abrasion, low speed and the like exist, and the automatic gain control with high precision and quick response is difficult to realize. (4) The flexibility and the intelligent degree are low, namely, once parameters (especially gains) of the whole system are determined on hardware, the later modification is very inconvenient, the flexible and remote real-time configuration cannot be carried out through software, and the requirements of a modern intelligent measurement and control system on the reconfigurability are difficult to adapt. Therefore, how to overcome the inherent defects of the conventional discrete circuit structure and provide a highly integrated signal processing scheme has become a technical problem to be solved in the art. Disclosure of Invention The invention aims to solve the problems of high system complexity, high debugging difficulty, low gain control precision, poor flexibility and the like of the traditional discrete signal conditioning scheme by integrating three functions of differential signal receiving, high-order bandpass filtering and digital program-controlled gain amplification into a whole, thereby realizing high-precision extraction and intelligent amplitude adjustment of weak signals with specific frequencies. Aiming at the defects of the prior art, the signal processing circuit based on the fourth-order band-pass filter comprises a signal preprocessing and differential-to-single-ended amplifying module, a conditioning filtering module and a program-controlled gain amplifying module which are sequentially connected, wherein the signal preprocessing and differential-to-single-ended amplifying module is used for receiving differential input signals and converting the differential input signals into single-ended signals and carrying out preliminary amplification, the conditioning filtering module is used for carrying out filtering processing on the single-ended signals so as to extract target frequency signals, and the program-controlled gain amplifying module is used for receiving the filtered signals and adjusting the gain of output signals according to external digital control signals. Preferably, the signal preprocessing and differential-to-single-ended amplifying module comprises an instrument amplifier chip U12, the model of which is AD623ARZ, w