US Patent 9588626 Capacitive sensing button on chip

A method and apparatus include a plurality of sensor elements arranged within an integrated circuit package and a controller arranged within the integrated circuit package and coupled to the plurality of sensor elements. The controller is configured to apply a transmit signal to a first sensor element of the plurality of sensor elements and receive a receive signal from a second sensor element of the plurality of sensor elements. The receive signal represents a mutual capacitance of the first sensor element and the second sensor element.