A conditioning circuit for resistive sensors combining frequency and duty-cycle modulation of the same output signal

A signal conditioning circuit based on a relaxation oscillator is presented for use with resistive transducers. Both the frequency and the duty-cycle of the output signal carry independent information coming from a pair of different sensors. Namely, the frequency of the output signal changes linearly with the resistance deviations detected by a Wheatstone bridge, while the duty-cycle is dependent on the resistance of a second sensor.