| 摘要 |
A start signal output circuit having an RF/DC conversion circuit to which radio frequency power (RF) of specified frequency is inputted and from which a direct current potential (DC) is outputted, comprises a detection/amplification circuit 210 which includes a voltage doubler wave-detector circuit 10 configured including a sensing diode Q 1 (Tr 34 ) for sensing the RF power, a differential amplifier including differential pair transistors Tr 31 and Tr 32 , and a current mirror circuit. A base current of one Tr 31 of the differential pair transistors is brought into substantial agreement with a DC component of a current flowing through the sensing diode Q 1 (Tr 34 ). A total of currents flowing through the differential pair transistors Tr 31 and Tr 32 is regulated to a substantially constant value by the current mirror circuit. Thus, the start signal output circuit which is small in size, high in sensitivity and low in power consumption can be realized.
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