Capacitance change detection method and circuit for capacitance type sensor

Abstract

The invention provides a capacitance change detection method and circuit for a capacitance type sensor. The method comprises the following stages: an initialization stage, wherein a capacitor to be detected and a reference capacitor are simultaneously charged to generate a voltage bias, a numerical relationship between bias voltages on the capacitor to be detected and the reference capacitor is achieved, and the bias voltage on the reference capacitor is reduced or increased by a reference voltage value which is related to a reference capacitance change ratio; and a detection stage, wherein when voltage changes on the capacitor to be detected are equal to, higher than or lower than voltage values at the two ends of the reference capacitor, an OUPUT is reversed to achieve capacitance changedetection. The method and circuit provided by the invention has the advantages of high simplicity of the circuit, low power consumption, avoidance of a clock, low noise, high detection precision, andwide 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

Images