A high resolution capacitance deviation-to-digital converter utilizing time stretching

We present a capacitance deviation-to-digital converter (CDC) for the thin membrane transducers (TMT) used for bio-molecular detection. Our CDC consists of a capacitance deviation-to-time converter (CTC), time-stretchers, and a time-to-digital converter (TDC). The time-stretchers are innovatively adopted to achieve higher resolution of the CDC with expanse of moderate power consumption. Designed and simulated in 0.35 um CMOS bulk technology, the CDC has a resolution of 370aF with a maximum error of 0.027⁰/₀₀, at a rate of 700 samples per second.