Patent ID: 8890544
Filing Date: 2014-11-18
Classification: G06F

Abstract:
1. A circuit for measuring a capacitive charge, said circuit comprising: a drive module configured for coupling with a sensor electrode of a capacitive input device, said drive module configured to drive said sensor electrode with a plurality of positive and negative measurement cycles, wherein a positive measurement cycle drives said sensor electrode between a first voltage level and a second voltage level, and wherein a negative measurement cycle drives said sensor electrode between a third voltage level and a fourth voltage level; a latched comparator, wherein said latched comparator comprises: a first counter wherein said first counter is set based on a first output signal produced by a first voltage captured by said input during a positive measurement cycle; a second counter, wherein said second counter is set based on a second output signal produced by a second voltage captured by said input during a negative measurement cycle, wherein a capacitance charge on said electrode is related to counter values of said first and second counters; and a determination module configured to produce a demodulated output signal based on said first counter value and said second counter value.