CAPACITANCE MEASUREMENT CIRCUIT
Abstract:
A capacitance measurement circuit includes a charge to voltage converter (CVC) that includes at least one first variable capacitor, an excitation signal generation circuit, a differential amplifier, a first switch circuit, and at least one second variable capacitor, wherein a parasitic capacitance from a sensing capacitance sensed by a capacitance sensor is reduced by the at least one first variable capacitor. The excitation signal generation circuit is arranged to generate and connect a first excitation signal to the capacitance sensor, and generate and connect a second excitation signal to the at least one first variable capacitor, wherein the first excitation signal and the second excitation signal are out-of-phase, and a voltage amplitude of the first excitation signal is different from a voltage amplitude of the second excitation signal. The inverting input terminal of the differential amplifier is arranged to receive the sensing capacitance from the capacitance sensor.
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