Capacitance-voltage conversion circuit, an input device using the same, electronic devices and capacitance-voltage conversion method,

摘要

PROBLEM TO BE SOLVED: To provide a capacitance voltage conversion circuit capable of a detecting minute change in electrostatic capacity.;SOLUTION: In the capacitance voltage conversion circuit 100a for converting a difference in electrostatic capacity between a first capacitor 30a and a second capacitor 30b into a voltage, a first voltage applying section 10 applies a power source voltage Vdd to the first capacitor 30a in a first state and applies a ground voltage 0 V thereto in a second state. A second voltage applying section 12 applies a ground voltage 0 V to the second capacitor 30b in a first state and applies a power source voltage Vdd thereto in a second state. A first sample and hold circuit 14 turns on first and second switches SW1, SW2, and holds an average voltage of the first and second capacitors 30a, 30b as a first detection voltage Vdet1 in the first state. Similarly, a second sample and hold circuit 16 holds an average voltage of the first and second capacitors 30a, 30b as a second detection voltage Vdet2 in the second state. An amplification section 20 applies differential amplification to the first and second detection voltages Vdet1, Vdet2.;COPYRIGHT: (C)2006,JPO&NCIPI