A high-resolution, linear resistance-to-frequency converter

A resistance-to-frequency converter consisting of a Wheatstone bridge followed by an integrator and a comparator is described. In concept the circuit represents a relaxation oscillator whose frequency changes linearly with a resistance change detected by the bridge. Analyses show that a resolution better than 0.05% is possible with the simple configuration, and an excellent linearity is maintained over the wide resistance change by using a simple compensation method. The converter is therefore suited as a signal conditioner of a resistive sensor. Experimental results are included to demonstrate its performance.