Demodulators – Frequency shift keying or minimum shift keying demodulator – Including discrete semiconductor device
Patent
1995-02-28
1995-09-26
Mis, David
Demodulators
Frequency shift keying or minimum shift keying demodulator
Including discrete semiconductor device
329302, 329303, 329337, 375328, 375334, H03D 302, H04L 27148
Patent
active
054537142
ABSTRACT:
A demodulator for demodulating a binary frequency-modulated signal includes a demodulator with a quadrature tank circuit and a duty cycle monitor circuit. The quadrature tank circuit has a voltage-controllable resonant frequency for compensating for shifts in the carrier frequency of the incoming signal and shifts in the tank circuit component values so as to allow the use of a high-Q tank circuit and thereby maximize use of the incoming signal energy. The quadrature tank circuit is a reactive circuit (with both inductive and capacitive elements) which includes a varactor diode having a voltage-controllable capacitance. The duty cycle monitor circuit measures the duty cycle of the demodulated binary output from the demodulator, and provides a control voltage to the quadrature tank circuit for adjusting its center frequency of operation.
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Supplemental Information Disclosure Statement including four declarations and exhibits A-D which were previously filed on Sep. 19, 1994, in U.S. patent application Ser. No. 08/029,134.
Mis David
National Semiconductor Corporation
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