All-digital detection apparatus of differential capacitor

Abstract

The invention, which belongs to an electronic circuit, more particularly relates to a circuit for detecting a differential capacitor. The invention relates to an all-digital detection apparatus of a differential capacitor. The apparatus comprises a digital controller (1), a digit programmable clock generator (2), a digit programmable waveform generator (3), a charge amplifier (4), a amplificationmultiple programmable instrument amplifier (5), a binary channel synchronization analog-to-digital converter (6). According to the invention, the digital controller is utilized to carry out programming control on clock source provided by the programmable clock generator, so that all output signal frequencies of the programmable waveform generator can be adjusted flexibly according to demands and a frequency adjusting range is large; An amplification factor G of the instrument amplifier is programmablly controlled by the digital controller; when a delta C is small, a delta C detection for a small signal has a high resolution by increasing the G value; when the delta C is large, the delta C detection for a large signal has a large detection range by reducing the G value. The control of the digital controller to all detection links of the differential capacitor is realized by programming, and links of bandpass frequency selection filtering, frequency mixing demodulation, lowpass filtering and the like are completed by software codes; besides, the hardware structure is concise and the flexibility of adjustment is good.

Description

technical field [0001] The invention belongs to an electronic circuit, in particular to a circuit for detecting differential capacitance. Background technique [0002] Differential capacitive sensors have the advantages of simple structure, high sensitivity, good dynamic characteristics, high stability, and non-contact measurement. They are widely used in the measurement of parameters such as displacement, pressure, acceleration, material composition, and level. [0003] The output signal of the differential capacitance sensor is usually very weak, or even completely submerged in various interference signals. It is the key to the application of the differential capacitance sensor to detect the very small change in the differential capacitance by using effective differential capacitance detection technology. Typical differential capacitance detection technology includes high-stable temperature-compensated clock source, excitation signal generator, charge amplifier, phase-shif...

AI Technical Summary

Problems solved by technology

[0004] The various links included in a typical differential capacitance detection technology are usually designed by a mixture of discrete and integrated circuits. The hardware structure is complex, the degree of integration is low, there are many adjustment points, the adjustment flexibility is poor, the detection resolution is fixed, and the small signal detection resolution Difficult to balance with large detection range

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