Oscillators – Automatic frequency stabilization using a phase or frequency... – Afc with logic elements
Reexamination Certificate
2006-04-04
2006-04-04
Mis, David (Department: 2817)
Oscillators
Automatic frequency stabilization using a phase or frequency...
Afc with logic elements
C331S010000, C331S016000, C331S017000, C331S03600C, C331S17700V, C331S179000
Reexamination Certificate
active
07023282
ABSTRACT:
An improved coarse tuning process for fractional-N frequency synthesizers is provided. In general, a coarse tuning circuit controls a phase lock loop (PLL) of a frequency synthesizer. During coarse tuning, a reference signal used to control an output frequency of the PLL is provided to the coarse tuning circuitry and is divided by a factor M to provide a divided reference signal. A controllable oscillator (CO) output signal from a CO in the PLL is divided by an N divider in the PLL to provide a divided CO signal. The periods or, equivalently, frequencies of the divided CO signal and the divided reference signal are compared, and the result is used to select an appropriate tuning curve for the CO. In order to reduce a period comparison error, synchronization circuitry operates to synchronize the N divider of the PLL and an M divider of the coarse tuning circuit.
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Bunch Ryan
Humpreys Scott
Mis David
RF Micro Devices, Inc.
Withrow & Terranova , PLLC
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