Digital fast acquisition method for phase-lock loops

摘要

A method for enhancing the frequency-acquisition performance of phase-lock loops (PLLs) is presented, which can be used in all PLLs that employ sequential phase detectors. The proposed method always forces the PLL into the phase-acquisition mode by realising a phase detector transfer characteristic with a pseudolinear infinite phase range. Especially in the case of charge-pump PLLs the proposed method is very useful. Practical results show that the acquisition performance can increase by nearly two orders of magnitude.