Patent Document ID: 8093914
Application ID: 12332980
Patent Flag: 1

Claim One:
1. An apparatus, comprising: a capacitive sensor including a transmit electrode and a receive electrode, wherein the receive electrode is capacitively coupled with the transmit electrode; a signal generator coupled with the transmit electrode and configured to generate an induced current waveform at the receive electrode by applying a transmit signal to the transmit electrode; a demodulation circuit coupled with the receive electrode, wherein the demodulation circuit is configured to output a rectified current based on the induced current waveform; and a compensation circuit, coupled with the demodulation circuit, to add a compensation current to the rectified current to generate a compensated current waveform, wherein the compensation current is calibrated to cancel a portion of the rectified current attributable to a baseline capacitance of the transmit electrode and the receive electrode, the baseline capacitance comprising a capacitance of the transmit electrode and the received electrode when no input is present.