Oscillators – Automatic frequency stabilization using a phase or frequency... – Tuning compensation
Reexamination Certificate
2005-06-30
2008-07-29
Pascal, Robert J. (Department: 2817)
Oscillators
Automatic frequency stabilization using a phase or frequency...
Tuning compensation
C327S157000, C341S143000
Reexamination Certificate
active
07405629
ABSTRACT:
A frequency synthesizer is provided having a fractional-N control circuit and method. The control circuit can operate as having a modulator that selectively applies any fractional ratio to a frequency divider within, for example, a feedback loop of a PLL. The modulator can be a delta-sigma modulator or any sequential state machine that can be implemented as the control circuit, and can select amongst a plurality of vector values. The vector values can be spaced relatively close to each other, and the incoming present vector values can each be added to a value chosen from the immediately preceding set of potential values. The selector circuit chooses from among the present set of vector values depending on whether the sum is nearest a target value. The sum nearest the target value is, therefore, selected as the present vector value, and the process is repeated in time for each vector value having a corresponding P value to form a pattern of P values sent to the divider of the PLL. The incoming frequency can therefore be synthesized based on the modulated P values used by the feedback divider to produce the appropriate fractional-N divide ratio for the synthesized frequency.
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International Search Report, PCT/US2006/024746, mailed Oct. 12, 2006.
Cypress Semiconductor Corp.
Daffer Kevin L.
Daffer McDaniel LLP
Goodley James E
Pascal Robert J.
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