Capacitance detecting circuit, touch detecting device and terminal device

Abstract

The present application provides a capacitance detecting circuit and a touch detecting device, which can improve the sensitivity of capacitance detection. The capacitance detecting circuit includes afront end circuit and a processing circuit, wherein the front end circuit includes a first driving circuit, a first canceling circuit, and a PGA circuit, and the first driving circuit, the first canceling circuit, and the PGA circuit are all connected to the first end of the capacitor to be tested, the second end of the capacitor to be tested is grounded, the first driving circuit is used for charging and discharging the capacitor to be tested, and the first canceling circuit is used for canceling a base capacitor of the capacitor to be tested, the PGA circuit is configured to convert a capacitance signal of the capacitor to be tested after canceling the base capacitor into a voltage signal; and the processing circuit is connected to an output end of the front end circuit, and is used fordetermining a capacitance change amount of the capacitance of the capacitor to be tested relative to the base capacitor according to a voltage signal output by the front end circuit.

Description

technical field [0001] The present application relates to the field of electronic technology, and in particular to a capacitance detection circuit, a touch detection device and a terminal device. Background technique [0002] Capacitive sensors are widely used in the field of human-computer interaction of electronic products. Specifically, a capacitance (or called basic capacitance or initial capacitance) will be formed between the detection electrode and the ground. When a conductor (such as a finger) approaches or touches the detection electrode , the capacitance between the detection electrode and the ground will change, and the information of the conductor approaching or touching the detection electrode can be obtained by detecting the change in capacitance, so as to judge the user's operation. However, since the basic capacitance is often relatively large, the capacitance change caused when the conductor approaches or touches the detection electrode is small, so the exi...

AI Technical Summary

Problems solved by technology

However, since the basic capacitance is often relatively large, the capacitance change caused by the conductor approaching or touching the detection electrode is small, so the existing capacitance detection method has low sensitivity and cannot accurately detect capacitance

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