A Phase-Locked Loop-based frequency synthesizer switches between channels as the feedback division ratio is changed. For a given spectral purity, the acquisition time is often the bottleneck in the design of integer-N synthesizers. This paper presents a review of the three major phases of the total acquisition time from control systems theory and PLL literature. These are the pull-in time, the settling-time and the lock-time. An implementation example in a 0.25μm CMOS process illustrates the process of reduction of the acquisition time by a factor of 3.5 for an integer-N synthesizer.

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Conference 2004 IEEE International Symposium on Cirquits and Systems - Proceedings
Citation
Ahmed, S.I., & Mason, R. (2004). Improving the acquisition time of a PLL-based, integer-N frequency synthesizer. Presented at the 2004 IEEE International Symposium on Cirquits and Systems - Proceedings.