Patent ID: 9310924
Filing Date: 2016-04-12
CPC Classification: G01R,G06F,H03K

Claim Text:
1. A method of detecting a change in capacitance, comprising: adjusting a variable reference voltage input of an integrator of a mutual-capacitive measurement circuit to a first reference voltage, wherein the first reference voltage is selected to increase a range of voltages that can be output by the mutual-capacitive measurement circuit during a first half of a differential measurement cycle; configuring the mutual-capacitive measurement circuit for obtaining a first reference measurement during the first half of the differential measurement cycle; obtaining the first reference measurement from an analog-digital-converter coupled to an output of the mutual-capacitance measurement circuit; configuring the mutual-capacitive measurement circuit for obtaining a first output measurement during the first half of the differential measurement cycle; obtaining the first output measurement from the analog-digital-converter; adjusting the variable reference voltage input to a second reference voltage, wherein the second reference voltage is selected to increase the range of voltages that can be output by the mutual-capacitive measurement circuit during a second half of the differential measurement cycle; configuring the mutual-capacitive measurement circuit for obtaining a second reference measurement during the second half of the differential measurement cycle; obtaining the second reference measurement from the analog-digital-converter; configuring the mutual-capacitive measurement circuit for obtaining a second output measurement during the second half of the differential measurement cycle; obtaining the second output measurement from the analog-digital-converter; and determining whether a touch or proximity event relative to a touch sensitive device has occurred based on calculating a differential measurement using a difference between the first reference measurement and the first output measurement and a difference between the second reference measurement and the second output measurement.