Fast acquisition PLL frequency synthesizer with improved N-stage cycle swallower

A new type of fast acquisition frequency synthesizer which improves the operation of the NSCS (N-stage cycle swallower) is proposed. By varying the output frequency of the NSCS and by adopting a programmable divider, the proposed synthesizer has an output frequency of deviation within 0.0003 ppm. By introducing an extra switching operation of the last stage division ratio in the NSCS, the proposed synthesizer can have an extremely fast acquisition time.<>