| 摘要 |
<P>PROBLEM TO BE SOLVED: To accelerate an AGC operation in a radio wave reception device or the like for receiving an amplitude modulation signal. <P>SOLUTION: A long standard radio wave that is a received amplitude modulation signal is converted into an intermediate frequency signal (a) and inputted to a detector circuit 620. In the detector circuit 620, a signal (b) of a fixed amplitude having the same frequency and the same phase as the signal (a) is generated, and a signal (c) resulting from subtracting a signal b1 for which the signal (b) is amplified, from the signal (a) is outputted from a subtractor 622b. In an AGC circuit 618, the signal b1 and the signal (c) are detected respectively and after their higher harmonic wave components are removed by LPF 618b, 618d, both signal levels are compared by a comparator 618e. In accordance with the compared result, an AGC voltage generating circuit 618f generates and outputs an RF control signal g1 and an IF control signal g2 for controlling the amplification of an RF amplifier circuit 611 and an IF amplifier circuit 616. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
