Linear capacitance-to-voltage converter using a single amplifier for transducer front ends with cancellation of spurious forces contributed by sensor circuitry

Abstract

Capacitive transducer systems are disclosed that reduce nonlinearities due to feedthrough capacitances or residual electrostatic forces. The systems can include a core with a first input coupled to a first variable capacitor, a second input coupled to a second variable capacitor, and a core output coupled to a common node; an amplifier with input switchably coupled to common node and an output; a feedback path switchably coupling amplifier output to common node; and a main clock with first and second phases, that controls switches coupling system components. When clock is in first phase, first core input is coupled to reference voltage, second core input is coupled to negative reference voltage, and common node is coupled to amplifier output. When clock is in second phase, core inputs are grounded, and common node is coupled to amplifier input. The system can have single amplifier. Neutralization capacitor can cancel feedthrough and parasitic capacitances.