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US 6,445,246 B1Granted
Signal compensator circuit and demodulator circuit
AssigneeOki Electric Industry Co., Ltd.
InventorAkira Yoshida
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Abstract
The demodulator according to the invention comprises a negative feedback loop which slowly compensates for a DC potential of a demodulated signal through an integrator formed of a resistor and a capacitor, and a negative feedback loop which senses a amplitude of a demodulated signal and rapidly charges or discharge the capacitor in response to the result of the sensing, wherein the two negative feedback loop operate independently of each other.
Claims6
A signal compensator circuit comprising:
- variable gain amplifying means for amplifying an input signal with a gain variable with a gain control signal;
- first signal generating means for detecting variations in a DC level of an output signal from said amplifying means to generate a DC level variation signal indicative of a magnitude of the detected variations in the DC level;
- second signal generating means for detecting variations in an amplitude level of the output signal from said amplifying means to generate an amplitude level variation signal indicative of a magnitude of the detected variations in the amplitude level;
- and
- gain control signal generating means for integrating said DC level variation signal with a predetermined time constant, integrating said amplitude level variation signal with a time constant smaller than said predetermined time constant, and generating said gain control signal based on results of the integrations.
2 more elements
A demodulator circuit comprising:
- detecting means for detecting a modulated input signal;
- variable gain amplifying means using an output from said detecting means as an input signal for amplifying said input signal with a gain in variable with a gain control signal;
- first signal generating means for detecting variations in a DC level of an output signal from said amplifying means to generate a DC level variation signal indicative of a magnitude of the detected variations in the DC level;
- second signal generating means for detecting variations in an amplitude level of the output signal from said amplifying means to generate an amplitude level variation signal indicative of a magnitude of the detected variations in the amplitude level;
- gain control signal generating means for integrating said DC level variation signal with a predetermined time constant, integrating said amplitude level variation signal with a time constant smaller than said predetermined time constant, and generating said gain control signal based on results of the integrations;
- and
- comparing means for comparing the output signal from said amplifying means with a predetermined reference level to output a digital signal which has a definite logical level.
4 more elements
Dependencies are inferred from the claim text.