Switched-capacitor transducers with digital or duty-cycle output based on pulse-width modulation technique
Andrzej S Cichocki, Rolf Unbehauen · International Journal of Electronics · 1991
New switched-capacitor transducers for capacitive or resistive sensors have been developed based on a pulse-width modulation technique. The output signal is a duty-cycle modulated square-wave voltage or a binary-coded digital signal which can be accurately related to the value of the unknown capacitance or resistance. Several different configurations of transducers have been proposed to meet different requirements and/or to compensate parasitic and non-ideal effects such as the offset voltage and noise of an op.-amp., stray capacitances and the parasitic charge injection due to the clock feedthrough effect of MOS switches. The properties of the proposed transducers and their performance are demonstrated using computer simulation.