| 摘要 |
PROBLEM TO BE SOLVED: To easily correct the bias distortion of a demodulated output signal by setting the peak-to-peak amplitude of a demodulated base band signal at the dead band width of a rectifying device and feeding the obtained DC offset component back to a subtracter via an amplifier and a loop filter for its correction. SOLUTION: The demodulated base band signal of a frequency shift keying receiver is added to a subtracter 2 which subtracts the error voltage of a base band having a DC offset component from the based band signal. Then the output of the subtracter 2 is added to a clip circuit 4 where the rectifying device having the dead bands at low voltage parts of the silicone epitaxial diodes, etc., are reversely connected in parallel to each other. The peak-to-peak amplitude of output of an amplitude control circuit 3 is set at the width of the said dead band, so that a DC offset component of the base band signal is obtained at the output side of the circuit 4. This offset component is amplified by an amplifier 9 and smoothed by a loop filter 5. Then the smoothed offset component is fed back to the subtracter 2 and corrected there. |
