VARIABLE CAPACITANCE DETECTING CIRCUIT AND DRIVING TECHNIQUE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a variable capacitance detecting circuit attempting to enhance S/N ratio for signals read from capacitative elements and to enhance sensitivity. SOLUTION: The variable capacitor detecting circuit is equipped with a variable capacitor 101 varying capacity value depending on physical phenomena, an integration circuit 109 including an integral capacity 102 and an operating amplifier 103, and a plurality of switches connected with the variable capacitor 101 or the integration circuit 109. Reducing the noise is attempted from multiple alternative repetition between the steps of storing the charge in the variable capacitor 101 and the steps of transferring the charge accumulated in the variable capacitor 101 to the integral capacity 102 by turning a plurality of switches on and off suitably. COPYRIGHT: (C)2008,JPO&INPIT