| 摘要 |
PROBLEM TO BE SOLVED: To provide a modem for power line communication which selectively reduces a signal gain of a receiving circuit unit 2 by a transmission switching signal output from a transceiving control unit 3, and reduces consumption power of the receiving circuit unit 2 at a time of transmission. SOLUTION: The modem performs double-way communication using a power line, and is provided with a transmission circuit unit 1 powered on at a time of transmission, and powered off except transmission time; the receiving circuit unit 2 which is always powered on; and the transceiving control unit 3 which outputs a transmission control signal at a time of transmission. The receiving circuit unit 2 consists of a differential amplifier 8, an input side, and an output side buffer amplifiers of the differential amplifier 9, 11; and the differential amplifier 8 and the buffer amplifiers 9, 11 can perform gain control. If a transmission switching signal is supplied from the transceiving control unit 3 at transmission time, their signal gains are controlled to be reduced by the transmission switching signal. COPYRIGHT: (C)2007,JPO&INPIT
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