Logitech, Inc.

Bernhard Joss

Bernard Kasser

Stephen J Bisset

Method and apparatus for determining small variations in capacitance, typically in a capacitive touch sensing device, includes a reference signal of a first frequency and a sample signal of a second frequency. The reference and sample signals are mixed and filtered to isolate the beat frequency therebetween, which is then measured to provide an indication of the variation in the sample frequency. The measurement can then be manipulated by a microprocessor or microcontroller to provide desired control signals. The apparatus is susceptible of digital implementation and single chip implementation.

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Palo Alto, CA, United States of America

Bernhard Joss