3.2-GHz Digital Phase-Locked Loop With Autocorrelation-Based Direct Jitter Correction

Abstract

This brief solves the challenge of loop latency in the digital filter of conventional digital phase-locked loops (DPLLs), which hinders timely updates of phase frequency detector error information. To address this latency problem, we introduce a direct path for jitter correction, utilizing a pulse generator with an adaptive pulse width controller (PWC). The impact of PWC-based phase correction is analyzed to optimize the proportional gain in DPLLs. The DPLL, designed with adaptive gain control and realized in 40-nm CMOS technology, significantly enhances its performance metrics. Operating from a 100-MHz reference clock to produce a 3.2-GHz output, the prototype achieves a power consumption of 6.36 mW. Remarkably, the measurements indicate a 25% improvement in integrated jitter, reduced from 1231 to 942 fs, while maintaining comparable reference spur performance relative to conventional DPLL designs.