GAIN ADJUSTMENT METHOD FOR BANDPASS FILTER AND SYNCHRONOUS RECTIFICATION CIRCUIT built in DC circuit ground fault detection device and DC circuit ground fault detection device

摘要

PPROBLEM TO BE SOLVED: To automatically regulate a gain in a regulation method for a band-pass filter/synchronous rectification circuit. PSOLUTION: Mode switching means 8, 9, 72 are switched to calibration modes in a calibration mode, a rectangular wave a for calibration is input into a band-pass filter 3 from a rectangular wave generating circuit 1 for the calibration, and a value X is obtained by a synchronous rectification circuit 4 and an A/D converter 70. A constant W/X expressing an amplification degree (gain) of the band-pass filter 3 is computed by a computing part 71, based on an expected value W of the rectangular wave a for the calibration. In the measuring mode, the mode switching means 8, 9, 72 are switched to measuring modes, a measured value b is input to obtain a value Y by the synchronous rectification circuit 4 and the A/D converter 70. A measured result value A=YW/X is computed by the computing part 71, using the value Y and the W/X, to obtain the measured result value. PCOPYRIGHT: (C)2005,JPO&NCIPI