BROADBAND FM DEMODULATOR, LIGHT RECEIVER USING THE SAME AND OPTICAL TRANSMISSION SYSTEM

摘要

PROBLEM TO BE SOLVED: To solve a problem that a demodulated signal is distorted when a skirt shape and an under-chute exist in an output pulse from an AND gate which outputs a logical product in a delay detection type FM demodulator. SOLUTION: The FM demodulator is provided with a limiter circuit 1 for responding to an inputted FM signal, a delay circuit 2 for delaying one of the two outputs, an AND gate 3 for inputting the other output of the limiter circuit and the output of the delay circuit and a low-pass filter 4 for inputting the output of the AND gate. In the demodulator, a frequency characteristic inclined to the group delay of the delay circuit is provided and non-linearity is given to an fV characteristic by the group delay frequency characteristic. Thus, the fV characteristic is reversely corrected and linearity is improved.