| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a radio wave receiving circuit which enables improvement in productivity and inhibition of incorrect judgment of tuning. <P>SOLUTION: The receiving circuit comprises: an antenna 101 which needs tuning for receiving standard radio waves ; a gain control amplifier 106 for amplifying an output signal of the antenna 101; a filter circuit 108 for transmitting a signal of prescribed frequency in an output signal of a gain control amplifier 106; a rectifying circuit 110 for rectifying an output signal of the filter circuit 108; a peak hold circuit 112 for holding the voltage of an output signal of the rectifying circuit 110; and a detection circuit 114 for outputting a pulse signal by demodulating an output signal of the rectifying circuit 110. The amplification factor of the gain control amplifier 106 is controlled by the voltage kept by the peak hold circuit 112, and the time constant of the peak hold circuit 112 is controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
