| 摘要 |
PROBLEM TO BE SOLVED: To provide transmitter-receiver with an amplitude modulator reducing the number of parts and being capable of cutting down a circuit scale. SOLUTION: The transmitter-receiver has a passive mixer 104 converting a modulation signal into an intermediate frequency in the case of a transmission and up-converting the signal to a transmission frequency band while down-converting a high-frequency signal to the intermediate frequency in the case of a reception and a base-band band variable gain amplifier 110 optimizing and amplifying gains respectively in the case of the transmission and the case of the reception. The transmitter-receiver further has SPDT switches 105, 106 and 107 changing over the modulation signal to a signal path transmitted through the mixer 104 from the variable gain converter 110 in the case of the transmission and the high-frequency signal to the signal path detecting the high-frequency signal through the variable gain amplifier 110 from the mixer 104 in the case of the reception. The transmitter-receiver further has a control section 112 controlling the SPDT switches 105, 106 and 107 and the variable gain amplifier 110. The mixer 104 and the variable gain amplifier 110 in the base-band band are used in common in a transmission-reception band. COPYRIGHT: (C)2006,JPO&NCIPI
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