High-precision and high-stability self-capacitance detection circuit

Abstract

The invention provides a high-precision and high-stability self-capacitance detection circuit and relates to the field of self-capacitance detection. The circuit is characterized by obtaining voltage for representing self capacitance to be detected through a capacitive voltage divider method; then, charging a sampling capacitor to the voltage to be detected through a voltage follower, and storing the voltage of the self capacitance to be detected to the sampling capacitor in the form of charges; adjusting an internal capacitance adjustment array to enable voltage of the internal capacitance adjustment array to approximate to the voltage of the sampling capacitor in a successive approximation manner, and after finishing successive approximation, adopting the function of the capacitance of the internal capacitance adjustment array to represent the capacitance of the self capacitance to be detected. The circuit has the advantages of high precision and stability, and good sensitivity and consistency for different magnitudes of self capacitance and the like, and can improve experience of touch products and reduce development cost.

Description

technical field [0001] The present invention relates to the field of capacitance detection, and more specifically, to a method for self-capacitance detection using capacitive voltage division, which is applicable to the field of capacitive touch technology. Background technique [0002] At present, capacitive touch technology is widely used in mobile phones, tablet computers, induction cookers, refrigerators, washing machines and other products. The quality of capacitive detection technology determines the experience of capacitive touch products to a certain extent. [0003] Commonly used self-capacitance detection schemes include a detection scheme based on charge and discharge time and a detection scheme based on charge transfer. [0004] The detection scheme based on the charge and discharge time is commonly used to use the relaxation oscillator to generate a clock related to the self-capacitance to be measured, and use the clock to count the fixed time. Since sufficient...

AI Technical Summary

Problems solved by technology

[0006] In summary, the traditional charge and discharge time detection scheme has the disadvantages of long detection period and different detection sensitivity under different parasitic capacitances; while the charge transfer scheme will increase the chip area or require additional components when the filter capacitance is large and pins, the detection sensitivity will be significantly reduced when the parasitic capacitance is larger

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