Multiple frequency generator for quadrature amplitude...

Details Multiple frequency generator for quadrature amplitude... Multiple frequency generator for quadrature amplitude...

2007-10-03

2009-10-06

Mis, David (Department: 2817)

Oscillators

Automatic frequency stabilization using a phase or frequency...

Tuning compensation

C331S008000, C331S037000, C331S041000, C331S043000, C455S260000

Reexamination Certificate

active

07598815

ABSTRACT:
Multiple carrier frequencies are provided from a phase locked loop, especially closely adjacent quadrature amplitude modulated subcarriers for multiplexed data communications. A quadrature voltage controlled oscillator (VCO) and cascaded frequency dividers provide feedback to a phase comparator to lock the VCO to a reference signal. In addition to frequency divider outputs for use as subcarriers, e.g., binary division factors of the VCO frequency, a quadrature mixer multiplies and adds corresponding quadrature components at two of the frequencies, to generate a differential signal at a difference frequency. The mixer may be outside of the feedback signal path but preferably is in the feedback path to suppress noise. A polyphase filter converts the mixer output to a quadrature signal useful as a subcarrier. The technique efficiently generates sequential integer multiples of a basic frequency, such as sixteen adjacent integer multiples of a frequency reference.

REFERENCES:
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patent: 4581749 (1986-04-01), Carney et al.
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patent: 6850121 (2005-02-01), Detering et al.
patent: 6960962 (2005-11-01), Peterzell et al.
patent: 7323945 (2008-01-01), Cyr et al.
patent: 2007/0026816 (2007-02-01), Heidari et al.
“A 40 Gb/s SMC Optical Communication System based on an Integrated CMOS Transceiver,” ECOC-IOOC 2003 Proceedings, vol. 4, pp. 918-919.

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