Method To Control Amplitude And Phase Of A Signal

A system for generating an offset signal for a capacitive sensor, the system comprising:

• a waveform generator configured to generate a waveform;
• an R-2R ladder circuit having a constant output resistance, wherein the R-2R ladder circuit is coupled to an output of the waveform generator and configured to generate the offset signal based on the waveform;
• and
• an adjustable capacitor that is connected between an output of the R-2R ladder circuit and a reference voltage,
• wherein the capacitive sensor includes one or more sensing electrodes coupled to the waveform generator through a capacitance and is configured to generate a sensed signal by sensing either of proximity of an object and contact with the object, and
• wherein the R-2R ladder circuit and the adjustable capacitor are configured to adjust amplitude and phase of the offset signal such that the amplitude and the phase of the offset signal respectively coincide with an amplitude and a phase of the sensed signal when the sensing electrodes do not sense either of proximity of the object and contact with the object.