Oversampled capacitance-to-voltage converter IC with application to SiC MEMS resonator

This paper reports the first electronic circuit used to measure MEMS resonator motion in the time domain. The measurement of shuttle position is made using a capacitance-to-voltage converter IC that has been developed by combining correlated double sampling with delta modulation in a fully differential circuit topology. This oversampling circuit may be adjusted to trade bandwidth (sample rate) for resolution, while reference level may be adjusted to set the desired sensitivity to accommodate a large range of capacitive sensor interface applications. For example, test results demonstrate a resolution of 170 aF for a signal bandwidth of 3 kHz, a 68-dB dynamic range, and nonlinearity less than 0.16%.