1. An improved capacitive sensor comprising: a first electrode; a first driver for providing a first periodic signal to the first electrode; a second electrode; a second driver for providing a second periodic signal to the second electrode, the first and second periodic signals being out of phase with respect to each other; a third electrode between and movable relative to the first and second electrodes, the first, second, and third electrodes forming a differential capacitor; and signal processing circuitry including an amplifier coupled to the third electrode for providing an output signal, wherein the improvement comprises a feedback signal from the amplifier that is modulated, fed through a fix-up capacitor and coupled to the third electrode.