George H. Corrigan

Three-phase capacitive position sensing

We present a novel sensing scheme for capacitive position sensors based on physical and electrical modifications of traditional sensing arrangements. In addition to improved sensitivity, this “three-phase” sensing scheme enables a purely electrical method for post-process compensation of fabrication tolerances that can be implemented in the signal conditioning circuitry. This same method can be also be used to trim the sensor output for cancelling biases or nulling offsets, allowing the sensor to be operated in its regime of maximum sensitivity and with maximum signal output and linearity regardless of orientation, fabrication errors, or other effects.