Patent attributes
A capacitive sensing device includes a switch circuitry, a counter circuit, a comparator circuit, an amplifier circuit including first and second input terminals and an output terminal, and a feedback capacitor coupled between the output terminal and the first input terminal. The switch circuitry transmits a reference voltage to the second input terminal and couples the first input terminal to the output terminal during a first phase, transmits another reference voltage to the second input terminal during a second phase, and adjusts a voltage of the output terminal during a third phase. The counter circuit starts counting and the comparator circuit generates the control signal according to the output voltage and the second reference voltage during the third phase. The counter circuit stops counting according to the control signal to generate a count value indicating a capacitance value change of a capacitor under-test coupled to the first input terminal.
