Capacitance detector circuit, capacitance detector method and fingerprint sensor using the same

摘要

A capacitance detecting circuit (1) of a capacitive sensor having a plurality of column lines (2) and a row line (3) intersecting the column lines detects a change in capacitance at an intersection of a column line and a row line. The circuit includes a PN code generating unit for generating a code having orthogonality in time sequence to output the generated code as a column drive signal, a column line drive unit (5) for driving a predetermined one of the column lines which are selected in response to the code, a capacitance detecting unit (100), connected to the row line, for detecting a voltage by converting a total sum of changes in capacitance at intersections of the selected column lines into the voltage to output the detected voltage, and a decode processing unit (10) for performing a predetermined calculation on the detected voltage output from the capacitance detecting unit and the code to determine a voltage value responsive to the capacitance change at the intersection.