Prepositioned frequency synthesizer and method therefor

摘要

A PLL-type frequency synthesizer (10) in which a loop filter (24) state is recorded during an earlier hop to a given frequency then assigned back to the loop filter (24) during a subsequent hop to the same frequency is disclosed. The state is recorded through an A/D converter (48) and assigned through a D/A converter (60). Offset and linearity error is compensated in a compensation circuit (54) so that the state subsequently assigned to the loop filter (24) accurately matches the state that was previously measured for recording. Reference frequency and output signal dividers (16, 40) are both immediately initialized at a hop boundary (82) so that the signals compared by a phase comparator (20) are forced into a phase-matched condition.