| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce a chip area in an integrated circuit, that is, the area of capacity (feedback capacitor ) forming part, and resolve the rise of manufacturing cost and the gain control of detection voltage. <P>SOLUTION: The capacity detection circuit of this invention forms a plurality of column wiring and facing row wiring, detects capacitance variation at a part where the column wiring and the row wiring cross, and converts the capacitance variation to electric signal. The detection circuit has a column wiring drive means for driving the column wiring, a comparator connected to the row wiring, converting the charge of the crossing part with the driven column wiring to a measuring voltage, comparing the measuring voltage with a set value and outputting charging/discharging signals, a constant current source for charging and discharging charge accordingly to the charging/discharging signals, and a capacitor for accumulating the charge by the current of filling and discharging, and outputs the voltage of two ends of the capacitor as electric signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
