| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high frequency synthesizing circuit which reduces a circuit scale in order to contribute to cost reduction for a transmitting device. <P>SOLUTION: The high frequency synthesizing circuit synthesizes a plurality of frequency signals of different frequencies for output. The circuit employs a configuration in which the output signal of each prestage amplifier is synthesized by a synthesizer and a signal after synthesis is amplified by a poststage amplifier. In addition, the circuit employs a configuration in which electric power of each frequency signal outputted from the poststage amplifier is measured respectively with an output wave detector. Moreover, a gain of the poststage amplifier is computed from a difference between electric power measured with an input wave detector and electric power measured with the output wave detector, and normality/abnormality of the poststage amplifier are determined from the amount of variation for the gain. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
