Fn. Toth et al., A VERY ACCURATE MEASUREMENT SYSTEM FOR MULTIELECTRODE CAPACITIVE SENSORS, IEEE transactions on instrumentation and measurement, 45(2), 1996, pp. 531-535
A very accurate capacitance-measurement system consisting of a discret
e capacitance-dependent oscillator and a microcontroller has been deve
loped, It can measure multielectrode capacitors with capacitances up t
o 2 pF, with an accuracy of 100 ppm with respect to a reference capaci
tor. The resolution amounts to 50 aF with a total measurement time of
300 ms.