Differential circuit, capacitance detecting circuit, touch detecting device and terminal equipment

Abstract

The application provides a differential circuit, a capacitance detecting circuit and a touch detecting device, which can reduce the noise of the differential circuit and improve the signal-to-noise ratio of an output signal. When the differential circuit is applied to the capacitance detecting circuit, the accuracy of the capacitance detection can be improved. The differential circuit comprises afront end circuit and a processing circuit, wherein the front end circuit comprises a control circuit and a PGA circuit, the control circuit is connected to a power supply, two capacitors, and a PGA circuit for controlling the power supply to charge the two capacitors and controlling the two capacitors to discharge to the PGA circuit in a first stage, and for controlling the PGA circuit to chargetwo capacitors in the second stage; the PGA circuit is used for converting the capacitance signals of the two capacitors into voltage signals and obtain the difference in the first and second stages,in order to obtain a differential signal corresponding to the voltage of two capacitors in the first and second stages; the processing circuit is connected to the front end circuit for determining a target differential signal of the voltage corresponding to the two capacitors according to the differential signal output by the front end circuit in the first and second stages.

Description

technical field [0001] The present application relates to the field of electronic technology, and in particular to a differential circuit, a capacitance detection circuit, a touch detection device and a terminal device. Background technique [0002] Capacitors are widely used in many terminal electronic devices, for example, touch sensors for touch control on terminal device display screens. During the use of capacitors, it is essential to measure and analyze their capacitance value. Nowadays, self-capacitance detection has become a very important measurement and analysis method. [0003] However, since the self-capacitance is often relatively large, the existing self-capacitance detection method has low sensitivity when the self-capacitance is large; and the cancel capacitor used to improve the sensitivity is large, so that the cancel capacitor cannot be integrated, and the cost of the cancel capacitor Furthermore, the increase of the self-capacitance reduces the sensitivi...

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Problems solved by technology

[0003] However, since the self-capacitance is often relatively large, the existing self-capacitance detection method has low sensitivity when the self-capacitance is large; and the cancel capacitor used to improve the sensitivity is large, so that the cancel capacitor cannot be integrated, and the cost of the cancel capacitor It is also too high; further, the increase of self-capacitance reduces the sensitivity of the existing self-capacitance detection method, and it is no longer possible to correctly detect the capacitance value

[0004] Using a differential circuit can improve the sensitivity of capacitance detection to a certain extent, but there are often noise signals such as 1 / noise and low-frequency noise, which affect the signal-to-noise ratio of the output signal. Therefore, a low-noise differential circuit is urgently needed

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