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US 2002/0163390 A1Published application
Analog/digital carrier recovery loop circuit
OwnerDonald C. Richardsoninventor
Life of this patent
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Abstract
A circuit for carrier signal recovery in a communications system having a phase detector output that switches between digital high and low levels and a voltage-controlled oscillator and circuits for deriving the phase detector output, the voltage-controlled oscillator being implemented as analog circuits and the processing of the phase detector output in order to derive a control signal for the voltage-controlled oscillator being implemented as digital circuits
Claims32
A circuit comprising:
- a phase detector for comparing the frequency of an input signal to the frequency of a reference signal whereby the phase detector generates a digital error signal;
- an digital averaging circuit coupled to the phase detector and including an input to receive the digital error signal;
- a digital-to-analog converter with an input coupled to a digital output of the averaging circuit, the digital-to-analog converter generating an analog signal relating to the digital signal output of the averaging circuit;
- and
- a voltage-controlled oscillator coupled between the phase detector and the digital-to-analog converter, the voltage-controlled oscillator receiving the analog signal as a control signal and generating the reference signal.
2 more elements
A circuit comprising:
- a quadrature amplitude modulation circuit whereby an input signal is represented in the complex plane, the quadrature amplitude modulation circuit producing encoded signals;
- a phase detector for receiving the encoded signals and comparing the phase of the encoded signals to the phase of a reference signal whereby the phase detector generates a digital error signal;
- a digital loop filter coupled to the phase detector and including an input to receive the digital error signal;
- a digital-to-analog converter with an input coupled to a digital output of the digital loop filter, the digital-to-analog converter generating an analog signal relating to the digital signal output of the digital loop filter;
- and
- a voltage-controlled oscillator coupled between the phase detector and the digital-to-analog converter, the voltage-controlled oscillator receiving the analog signal as a control signal and generating the reference signal.
3 more elements
A method of processing a signal, the method comprising:
- receiving an analog input signal and an analog reference signal;
- generating a digital error signal representing the difference in the frequencies or phases of the analog input signal and the analog reference signal;
- converting the digital error signal into an analog error signal;
- and
- varying the frequency or phase of the analog reference signal based upon the analog error signal.
2 more elements
A method of processing a signal, the method comprising:
- receiving an analog signal and a reference signal to which the analog signal is compared;
- modulating the analog signal into an in-phase component and a quadrature component;
- generating a digital error signal representing the difference in the frequencies or phases of the analog signal and the reference signal components;
- converting the digital error signal into an analog error signal;
- and
- varying the frequency or phase of the reference signal based upon the analog error signal.
3 more elements
A circuit comprising:
- means for generating a digital error signal representing the difference in the frequencies or phases of an input signal and a reference signal;
- means for averaging the digital error signal;
- means for converting the digital error signal into an analog error signal;
- and
- means for varying the frequency and/or phase of the analog reference signal based upon the analog error signal until the analog reference signal and the input signal have a desired phase difference.
2 more elements
Dependencies are inferred from the claim text.