Capacitor detection method and capacitor detection circuit

Abstract

The invention relates to the field of electronics, and discloses a capacitor detection method and a capacitor detection circuit. According to the method, the voltage of a negative input end of an operational amplifier is adjusted to the required reference value, and the voltage of the upper end of a capacitor Cs to be detected can be limited to Vset in the charge transfer phase, i.e. the charge on a sampling capacitor Cs is not completely transferred onto an integrating capacitor Ci. Consequently, the charge conservation principle can also be utilized, and according to the voltage variation of the output end of the operational amplifier, the capacitance of the capacitor to be detected is calculated. Because the voltage of the negative input end of the operational amplifier is adjustable, even if the capacitor with the capacitance varies from a small miicromicro farad to hundreds of miicromicro farads is detected, the voltage of the output end of the operational amplifier can still be controlled within a reasonable scope through adjusting the voltage of the negative input end of the operational amplifier, and accordingly, the capacitor detection method is enabled to detect the capacitor with the capacitance which varies from a small miicromicro farad to hundreds of miicromicro farads.

Description

Technical field

[0001] The present invention relates to the field of electronics, in particular to capacitance detection in capacitive touch or capacitive buttons. Background technique

[0002] At present, capacitive touch technology has developed rapidly and brought great convenience to people’s lives. The technology first divides the touch detection area into a number of grid points that intersect horizontally and vertically, and then detects the change in the capacitance value of the grid point to obtain the touch point Location information.

[0003] If the capacitive touch technology is classified according to the specific implementation, it includes capacitive buttons, self-sensing capacitive screens, and mutual-sensing capacitive screens. Among them, capacitive buttons and self-sensing capacitive screens have a large range of capacitance to be measured, and some small touch circuit boards Among them, the self-inductance capacitance value is only a few picofarads, while in so...

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