Patent ID: 8446158
Filing Date: 2013-05-21
Classification: G06F,H03K

Abstract:
1. An apparatus, comprising: a sensor capacitor; a modulation capacitor coupled with the sensor capacitor and configured to receive charge from the sensor capacitor; compensation circuitry coupled with the sensor capacitor and the modulation capacitor, wherein the compensation circuitry is configured to divert a portion of the charge from the modulation capacitor, and wherein the portion of the charge diverted is based on an amount of a parasitic capacitance of the sensor capacitor measured during a calibration of the compensation circuitry; and a comparator circuit coupled with the modulation capacitor, wherein the comparator circuit is configured to discharge the modulation capacitor in response to detecting that the charge on the modulation capacitor exceeds a predetermined threshold; wherein the comparator circuit produces a digital code based on a frequency of the discharge of the modulation capacitor.