Capacitance sensor capacitance change detection method and circuit

Abstract

The invention provides a capacitance change detection method and circuit of a capacitive sensor. The method includes: initialization stage: charging the measured capacitance and the reference capacitance at the same time to generate a voltage bias, and at the same time make the bias on the measured capacitance and the reference capacitance The voltage is a numerical relationship; the bias voltage on the reference capacitor is reduced or increased by a reference voltage value related to the change ratio of the reference capacitor; detection stage: the voltage change on the measured capacitor reaches or is higher than or lower than the reference If the voltage value at both ends of the capacitor is changed, the output OUT will be reversed to realize the detection of the capacitance change. The invention has the advantages of simple circuit, low power consumption, no clock, low noise, high detection precision and wide detection range.

Description

technical field [0001] The invention relates to the field of integrated circuits, in particular to a capacitance change detection method and circuit of a capacitive sensor. Background technique [0002] In the era of intelligence, there are more and more types and quantities of sensors required. Among them, the capacitive sensor is a simple and very effective type of sensor. It can be used as displacement and position sensing, liquid level sensing, humidity sensing, acceleration, and a cavity-type membrane capacitance sensor for measuring negative air pressure. [0003] In capacitive sensing, one type needs to detect the capacitance value, and the other type only needs to detect the relative change of capacitance, so as to know the relative change of the object under test, thus triggering the system to make various needs. Such as switching, driving, protection and other actions. [0004] The current capacitive sensor mainly adopts to actively apply a natural frequency to ...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problems of complex circuits, high benchmark requirements, and large noise and power consumption in the prior art. According to the principle that the charge stored in the capacitor remains unchanged, the present invention proposes a relatively static capacitive sensor capacitance change detection Method and circuit

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