Readout interface circuits for MOS C-V sensors

The present work reports the design, implementation and testing of readout interface electronic circuits using switched-capacitor and ring oscillator techniques in 2/spl mu/m n-well CMOS technology. For MOS C-V type sensors, the switched capacitor technique is more appropriate for relatively small capacitance change compared to the ring oscillator technique which suits mostly for large capacitance variation. It is shown that the switched-capacitor readout interface circuit can be used to measure sensor capacitance change with high resolution and is insensitive to parasitic capacitances.