HIGH-ACCURACY CIRCUITS FOR ON-CHIP CAPACITIVE RATIO TESTING AND SENSOR READOUT

This paper presents novel CMOS switched-capacitor circuits for high-ac curacy, on-chip capacitive-ratio testing and sensor readout, Using sig ma-delta and correlated-double-sampling (CDS) techniques, these circui ts provide accurate digitized capacitive-ratio readout, Both single-en ded and fully differential circuits are presented. Simulation results show that the resolution can be as fine as 100 aF for 10 pF capacitors . Single-ended circuit and fully-differential circuits were implemente d and tested. The measured standard deviation was below 20 aF when 10 pF capacitors were tested.