Patent ID: 8803534

Claim:
A method for sensing a differential capacitance, comprising steps of: A.) switching switches to make two terminals of the differential capacitance get connected to a high-voltage source or a low-voltage source or perform charge transfer; B.) storing charges transferred from the differential capacitance to generate a first output voltage and a second output voltage related to capacitances at the two terminals of the differential capacitance; C.) simultaneously resetting a first sampling capacitor and storing a non-ideal error value at a negative input terminal of an operational amplifier into a second sampling capacitor; D.) sampling the first output voltage with the first sampling capacitor; E.) sampling the second output voltage with the first sampling capacitor; and F.) connecting the second sampling capacitor between the negative input terminal and an output terminal of the operational amplifier to generate a sensing value related to a difference between the first and second output voltages.