SENSOR CIRCUIT AND METHOD FOR MEASURING A PHYSICAL OR CHEMICAL QUANTITY

摘要

A sensor circuit for measuring a physical or chemical quantity comprises a capacitive sensor (S). A sense and a base electrode (SE, BE) of the sensor (S) form a capacitive element (Cs) with a capacity depending on the quantity. A common electrode (GE) of the sensor (S) forms a first and a second parasitic capacitance (Csg, Cbg) together with the sense and the base electrode (SE, BE), respectively. The sensor circuit is adapted to store a charge on the capacitive element (Cs) and to read out the stored charge via the sense electrode (SE). A buffer element (B) is connected between the sense electrode (SE) and the common electrode (GE) and adapted to drive the common electrode (GE) at a voltage applied to the sense electrode (SE).