Capacitance detection circuit

By constructing a capacitance detection circuit with a frequency feedback loop, the problems of anti-interference and accuracy in capacitance detection under complex structures and strong interference environments in the prior art are solved, and high-precision capacitance value measurement is achieved.

CN121784382BActive Publication Date: 2026-06-09SUZHOU HUAXIN MICROELECTRONICS
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2026-03-06
Publication Date
2026-06-09

AI Technical Summary

Technical Problem

Existing capacitance detection methods have shortcomings in terms of anti-interference capability and measurement accuracy, especially in complex structures and environments with strong interference, where it is difficult to accurately measure capacitance values.

Method used

The capacitance detection circuit employing a frequency feedback loop consists of a switched capacitor module, an integrator, a first amplifier, and a voltage-controlled oscillator forming the feedback loop. It uses the feedback frequency and a reference frequency to control the charging and discharging process of the capacitor, thereby achieving stable detection of the capacitance value.

Benefits of technology

It significantly improves the anti-interference capability and measurement accuracy of capacitance detection, reduces hardware and software overhead, and enables accurate measurement of capacitance values ​​in complex environments.

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Abstract

This invention discloses a capacitance detection circuit, comprising: a switched capacitor module for controlling the charging and discharging of a reference capacitor Cr based on a periodic first control signal, and controlling the charging and discharging of a capacitor under test Ct based on a periodic second control signal, wherein the frequency of the first control signal is the feedback frequency Fb, and the frequency of the second control signal is the reference frequency Fr; an integrator connected to the switched capacitor module for outputting a first output voltage corresponding to the capacitance values ​​of the reference capacitor Cr and the capacitor under test Ct; a first amplifier, wherein the inverting input terminal of the first amplifier is connected to the first output voltage, the non-inverting input terminal is connected to ground potential, and the output terminal is used to generate a second output voltage; and a voltage-controlled oscillator connected to the output terminal of the first amplifier for generating the first control signal and adjusting the feedback frequency Fb based on the second output voltage. This invention improves the anti-interference level of the capacitance detection circuit by setting up a feedback loop to filter out some interference.
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Citation Information

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