Fast frequency acquisition phase-frequency detectors for GSamples/s phase-locked loops

This paper describes two techniques for designing phase-frequency detectors (PFDs) with higher operating frequencies [periods of less than 8x the delay of a fan-out-4 inverter (FO-4)] and faster frequency acquisition. Prototypes designed in 0.25-mum CMOS process exhibit operating frequencies of 1.25 GHz [= 1/(8 (.) FO-4)] and 1.5 G14z [= 1/(6.7 - FO-4)] for two techniques, respectively, whereas a conventional PFD operates at <1 GHz 1/(10 (.) FO-4)]. The two proposed PFDs achieve a capture range of 1.7x and 1.4x the conventional design, respectively.