Switched capacitor triple slope capacitance to digital converter
Boby George, V. Jagadeesh Kumar · IEE Proceedings - Circuits Devices and Systems · 2006
A high accuracy switched capacitor, triple slope digital converter suitable for differential capacitive sensors is presented. The proposed technique accepts differential capacitive sensors possessing either linear or inverse characteristics and provides a linear capacitance to digital conversion. The output is dependent only on a pair of d.c. reference voltages and the clock frequency. Detailed analysis of the proposed scheme establishes that the sensitivity of the scheme to parameter variations is minimal. A prototype implemented and tested for a typical differential capacitive transducer of full-scale ±250 pF gave a worst-case error less than 0.05%.