Patent ID: 9182432
Filing Date: 2015-11-10
Classification: G01D,G01R,G06F

Abstract:
1. A method of capacitance measurement with a differential amplifier having an output and differential first and second inputs, said method comprising: opening a switch disposed between a sensor electrode and said second input of said differential amplifier to initiate a reset phase where said sensor electrode and said differential amplifier are decoupled; resetting a feedback capacitance to a first level of charge, said feedback capacitance disposed between said second input and said output; closing said switch to initiate a measurement phase where said second input and said sensor electrode are coupled, said measurement phase comprising; opening said switch after said measurement phase to initiate a second occurrence of said reset phase; and resetting said feedback capacitance to a second level of charge during said second occurrence of said reset phase, wherein said first and second levels of charge are different.