Digital stereo recovery circuitry and method for radio receivers
AssigneeCirrus Logic, Inc.
InventorBrian D. Green
Life of this patent
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Abstract
Stereo recovery circuitry for a digital receiver is disclosed that provides increased accuracy and efficiency in recovering stereo signal information from transmitted stereo signals. The stereo decoder includes a digitally controlled oscillator that recovers a pilot tone signal from transmitted stereo signal information. By processing demodulated stereo signals on the digital side and digitally controlling the oscillator, the stereo decoder has increased efficiency and accuracy. In one embodiment, the oscillator may be a phase-locked-loop having a loop filter and an amplitude stabilized tunable resonator. Additional circuitry is disclosed for utilizing the pilot tone signal to recover left and right channel signal information from the demodulated stereo signals.
Claims15
A digital phase-locked loop circuit, comprising:
- a tunable resonator;
- and
- a loop filter coupled to the tunable resonator;
- and
- wherein the tunable resonator has a pilot tone signal as an output signal.
A digitally controlled oscillator, comprising:
- a digital phase-locked loop having:
- a tunable resonator;
- and
- a loop filter coupled to the tunable resonator;
- and
- wherein the tunable resonator has a pilot tone signal as an output signal.
A method of implementing a digital phase-locked loop circuit, comprising:
- coupling a loop filter to a tunable resonator;
- and
- outputting, by the tunable resonator, a pilot tone signal as an output signal.
Dependencies are inferred from the claim text.