Two-wire system built-in charge amplifying circuit based on field-effect tube

Abstract

The invention relates to a two-wire system built-in charge amplifying circuit based on a field-effect tube and belongs to the technical field of low-noise two-wire system charge-voltage conversion amplifying circuit and structure design. According to the invention, at an input stage, the change in a small-signal voltage-controlled current of a field-effect tube is adopted for realizing the impedance conversion from a high internal resistance alternating charge signal to a low internal voltage signal; a biasing circuit is formed by resistance differential pressure; a signal passes by a common base current follower formed by a PNP bipolar transistor and a common emitter output circuit formed by a NPN bipolar transistor and then is compounded with a power supply, so that the two-wire system signal transmission can be formed; an input end filtering capacitor can realize the reduction of noise interference; and a signal voltage is compounded and overlapped with a direct current bias voltage. The field-effect tube is low in noise and the field-effect tube and the bipolar transistor are high in characteristic frequency, so that the circuit frequency response range is wide, and the output driving capacity is higher; few electron components are used, and the resistance elements are subjected to resistance slurry sintering and laser resistor trimming and are easy to integrate and control precision; and a circuit base plate is made from aluminum oxide ceramics, so that the structure strength is high.

Description

technical field [0001] The two-wire built-in charge amplifier circuit based on the field effect tube of the present invention is used to convert and amplify the high-impedance charge input signal into a low-impedance output signal voltage and a DC bias voltage composite output electrical signal, which belongs to the low-noise two-wire charge-voltage Conversion amplifier circuit structure and design field. Background technique [0002] At present, domestic piezoelectric vibration sensors or airborne vibration amplifiers with integrated charge-voltage conversion functions have been applied and promoted in the structural health monitoring of aircraft and new or newly developed aero-engines. The existing charge-voltage signal conversion technology generally consists of an integrated op amp plus a feedback capacitor to form the main circuit, plus a secondary signal gain adjustment to reach the signal voltage range required by the user. But there is following defective in prior a...

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Problems solved by technology

[0004] 2) Operational amplifier plus feedback capacitor structure circuit, there are many stages of conversion amplification and adjustment, which reduces the signal-to-noise ratio of signal conversion;

[0005] 3) The existence of the feedback capacitor has a certain limit on the signal bandwidth or the upper limit of the signal processing frequency response;

[0006] 4) The existing technology requires integrated circuits such as operational amplifiers, the internal and external structures are complex, and there are many signal and noise sources;

[0007] 5) The circuit structure of operational amplifier and feedback capacitance is relatively large, and it is difficult to realize miniaturized packaging;

[0008] 6) The traditional circuit structure requires single-ended or double-ended power supply, and the power supply line, signal line and ground line need to be routed separately, and there are many requirements for the number, wiring and cost of signal lines;

[0009] 7) The traditional structure has no DC monitoring voltage and cannot monitor whether the device is working normally;

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