A 185-fsrms Integrated-Jitter and –245-dB FOM PVT-Robust Ring-VCO-Based Injection-Locked Clock Multiplier
S. Choi, S. Yoo, and J. Choi
IEEE International Solid-State Circuits Conference, Feb. 2016
This work presents a PVT-robust, low-jitter, ring-VCO-based injection-locked clock multiplier (ILCM) with a continuous frequency-tracking loop (FTL). Using a single replica-delay cell of the VCO that provides the intrinsic phase information of the free-running VCO, the proposed FTL can continuously track and correct frequency drifts. In addition, due to an additional noise-filtering by the FTL, the proposed ILCM provides the 2nd order rejection to VCO noise. Thus, whereas it used a ring-type-VCO, the ILCM achieved excellent jitter performance over the PVT-variations. For a 1.2-GHz output signal, the RMS-jitter integrated from 10 kHz to 40 MHz was 185 fs. The variation of jitter was regulated to less than 7% over temperatures and supply voltages.