Patent ID: 7847614
Filing Date: 2010-12-07
Classification: G11C,H03K

Abstract:
1. A switch noise reduction device comprising: a counter configured to count, at a constant rate, a plurality of samples of a switch output by incrementing a counter value by a count value for each sample representing a first switch state and decrementing the counter value by the count value for each sample representing a second switch state; a controller configured to determine the switch is in the first switch state when the counter value exceeds a first state threshold and to determine the switch is in the second switch state when the counter value is below a second state threshold; and a sampler configured to sample, at a sampling frequency different than a noise frequency of noise, the output of the switch to generate the plurality of samples, the sampler comprising a timer configured to determine a voltage decay period for each sample of the plurality of samples, the voltage decay period corresponding to a time required for a switch voltage of a capacitive touch switch to discharge from an initial voltage to a reference voltage.