A fast-acquisition PLL using split half-duty sampled feedforward loop filter

Abstract

We reduce the pattern jitter and acquisition time of a phase-locked loop (PLL) by adopting the split half-duty sampled feedforward loop filter. A prototype designed and fabricated in a 0.18μm standard CMOS technology has a 40% lower acquisition time than a PLL without operating in fast acquisition mode. Its peak-to-peak jitter is 26% less than that of a PLL with a conventional 2nd-order RC loop filter.