New high-precision circuits for on-chip capacitor ratio testing and sensor readout

This paper presents novel CMOS switched-capacitor circuits for high-accuracy on-chip capacitor ratio testing and sensor readout. Using sigma-delta and correlated-double-sampling (CDS) techniques, these circuits provide accurate digitized capacitive ratio readout. Simulation results show that the resolution can be as fine as 100 aF for 10 pF tested capacitors. One of the circuits was realized in fully integrated form. It provided readings with a standard deviation of less than 20 aF (2 ppm) for 10 pF capacitors.

[1]  Kenzo Watanabe,et al.  A switched-capacitor interface for intelligent capacitive transducers , 1986, IEEE Transactions on Instrumentation and Measurement.

[2]  Andrea Baschirotto,et al.  Finite gain compensation techniques for high-Q bandpass SC filters , 1990, IEEE International Symposium on Circuits and Systems.

[3]  Henry Baltes,et al.  CMOS absolute value precision capacitance measurement system , 1992, [Proceedings] 1992 IEEE International Symposium on Circuits and Systems.

[4]  M. L. Nagy,et al.  A capacitive sensing integrated circuit for detection of micromotor critical angles , 1997, IEEE J. Solid State Circuits.

[5]  R. Howe,et al.  A digital readout technique for capacitive sensor applications , 1988 .

[6]  Gabor C. Temes,et al.  High-accuracy circuits for on-chip capacitance ratio testing or sensor readout , 1994 .