Demodulators – Frequency modulation demodulator
Patent
1994-08-08
1995-09-12
Mis, David
Demodulators
Frequency modulation demodulator
329319, 329337, 455214, 455337, 327 39, 327 47, H03D 306
Patent
active
054500338
ABSTRACT:
A frequency demodulation circuit having an improved detection sensitivity is provided by forming an all-pass equalizer in a Quadrature-type demodulator capable of allowing a band covering at least a carrier frequency deviation to pass therethrough. The equalizer comprises a band-pass filter for detecting the frequency deviation of an inputted FM carrier signal, a gain-doubling amplifier and a substractor for performing subtraction between the signal inputted to the band-pass filter and the output of the amplifier. The operation of the circuit is such that a FM carrier signal is supplied to the band-pass filter through a phase shifter and to a phase comparator and the output of the substractor and the FM carrier signal are compared to each other by the phase comparator to thereby obtain a FM demodulated signal.
REFERENCES:
patent: 4079330 (1978-03-01), Ishigaki et al.
patent: 4198609 (1980-04-01), Ishigaki et al.
patent: 4388595 (1983-06-01), Brooks
patent: 4451792 (1984-05-01), Gay
patent: 5161004 (1992-03-01), Egger
patent: 5307380 (1994-04-01), Kume
patent: 5341107 (1994-08-01), Bijker et al.
International Journal of Electronics, vol. 34, No. 2, Feb. 1973, London GB pp. 241-246 S. K. Das et al. `Active RC all-pass networks using a summation or a differential amplifier` p. 244, line 1-line 3; figures 3A, 3B.
Frommer William S.
Mis David
Sinderbrand Alvin
Sony Corporation
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