Differential circuits, capacitance detection circuits, touch detection devices, and terminal equipment

Abstract

The present application provides a differential circuit, a capacitance detection circuit and a touch detection device, which can reduce the noise of the differential circuit and improve the signal-to-noise ratio of the output signal. When the differential circuit is applied in the capacitance detection circuit, the accuracy of capacitance detection can be improved. The differential circuit includes a front-end circuit and a processing circuit. The front-end circuit includes a control circuit and a PGA circuit. The control circuit is connected to the power supply, two capacitors and the PGA circuit, and is used to control the power supply to charge the two capacitors and control the two capacitors to charge the two capacitors in the first stage. The PGA circuit discharges, and controls the PGA circuit to charge the two capacitors in the second stage; the PGA circuit is used to convert the capacitance signals of the two capacitors into voltage signals and calculate the difference in the first and second stages, and obtain the two capacitors at The differential signal of the voltage corresponding to the first and second stages; the processing circuit is connected to the front-end circuit, and is used to determine the 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...

AI Technical Summary

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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