CAPACITANCE DETECTION CIRCUIT, PRESSURE DETECTOR, ACCELERATION DETECTOR AND TRANSDUCER FOR MICROPHONE

摘要

PROBLEM TO BE SOLVED: To provide a capacitance detection circuit which detects capacitance changes of a capacitance type sensor element, with the capacitance detection circuit being capable of accurately detecting even continuous and minimal changes and is also configured to be small-sized and inexpensive. SOLUTION: The capacitance detection circuit is configured to apply a drive voltage to the capacitance type sensor element 10 by using a sensor drive circuit 120; to convert the capacitance change of the sensor element into a voltage signal using a continuous-time type C-V converting circuit 110; to detect a signal component from the voltage signal obtained through conversion by using a synchronous detection circuit 130; and further smoothes an output signal of the synchronous detection circuit 130 by a smoothing circuit 140. COPYRIGHT: (C)2011,JPO&INPIT