State-preserving intermittently locked loop (SPILL) frequency synthesizer for portable radio

A phase-locked-loop (PLL) concept called state-preserving intermittently locked loops (SPILL), which is suitable for the intermittent operation of frequency synthesizers used in UHF portable radio sets, is proposed. SPILL uses a digital circuit technique which preserves frequency and phase during power-off periods, in order to perform fast acquisition at the beginning of power-on periods. Both a theoretical analysis and experiments confirm acceptable acquisition performance. A 1.6-GHz SPILL frequency synthesizer achieves an improvement in acquisition time by two orders of magnitude. Applications of SPILL to high-frequency synthesizers in portable radio communication sets are shown to be especially effective for reducing power consumption