Circuit and method for sensing a differential capacitance

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.