Patent ID: 8749520

Claim:
A detection method for a capacitive touchpad including a plurality of capacitance sensor traces, the detection method comprising the steps of: applying a first voltage to charge a detected capacitance sensor trace selected from the plurality of capacitance sensor traces; setting a voltage across a gain control capacitor array; connecting the detected capacitance sensor trace to a first terminal of the gain control capacitor array under compensating the self capacitor of the detected capacitance sensor trace; extracting a first sense signal from a second terminal of the gain control capacitor array; applying a second voltage to charge the detected capacitance sensor trace, wherein a voltage difference between the first voltage and a voltage on the first terminal of the gain control capacitor array, and a voltage difference between the second voltage and the voltage on the first terminal of the gain control capacitor array, are equal in magnitude but opposite in polarity; resetting the voltage across the gain control capacitor array; connecting the detected capacitance sensor trace to the first terminal of the gain control capacitor array under compensating the self capacitor of the detected capacitance sensor trace; extracting a second sense signal from the second terminal of the gain control capacitor array; and extracting an average from the first and second sense signals to determine whether the detected capacitance sensor trace has a touch point thereon.