Ultra-compact PLL with wide tuning range and low noise

摘要

A design for an oscillator, and a PLL incorporating such an oscillator, which takes up little physical area but maintains a large tuning range and low phase noise. Two LC-tanks are nested and switched. Through tuning the inactive tank, the range of the active tank may be increased and finer tuning becomes possible.

主权项

1. A method for tuning a digitally controlled dual-oscillator circuit, comprising the steps of:
if an oscillator has a frequency range which includes a desired frequency:
activating the oscillator having said frequency range;tuning a resonance of the active oscillator to the desired frequency; andtuning a resonance of the inactive oscillator to a frequency at the extreme end of its range which is farthest from the desired frequency; and if no oscillator has a range which includes the desired frequency, activating an oscillator which has a range that is closest to the desired frequency and tuning a resonance of the inactive oscillator such that a resonance of the active oscillator extends beyond the range.