Patent ID: 7724001
Filing Date: 2010-05-25
Classification: G01D

Abstract:
1. A circuit sensing a process variable, comprising: a voltage divider that includes first and second capacitors, at least one of which has a capacitance that is varied by the process variable in a baseband frequency range; the divider having divider ends that receive modulated potentials that have modulation in a carrier frequency range and that have a baseband envelope; the divider having a center tap connection that provides a detector input; a detector with a detector output representative of carrier frequency range components of the detector input; and a control circuit that controls the baseband envelope of the modulated potentials as a function of the detector output, the control circuit providing a process variable output in the baseband frequency range; wherein the first capacitor comprises a process variable sensing capacitance, and the second capacitor comprises a capacitance that is substantially insensitive to the process variable; wherein the control circuit controls at least one of the modulated potentials as a non-linear function of the detector output, compensating the process variable output for a non-linerity with respect to the process variable.