Resistance Deviation-to-Frequency Converter for Resistive Bridge Sensors

Abstract

A resistance deviation-to-frequency converter using second generation current conveyor (CCIIs) is designed for connecting resistive bridge sensors with a digital system. It consists of a integrator and a voltage comparator. The integrator is composed of positive second generation current conveyor(CCII+), negative second generation current conveyor(CCII-), capacitor, half bridge sensor, and two analog switches. The prototype converter was measured using commercially available discrete components. The result shows that the converter has a conversion sensitivity amounting to 125Hz/Ω and a linearity error less than ±0.03%. The temperature stability of the converter measured in the temperature range of －25-85℃ is less than 250ppm/℃. This results indicate that the proposed converter with simple structure than conventional converters have high linearity and is less affected by temperature change.