A PVT-Robust and Low-Jitter Ring-VCO-Based Injection-Locked Clock Multiplier With a Continuous Frequency-Tracking Loop Using a Replica-Delay Cell and a Dual-Edge Phase Detector

Abstract

A low-jitter, ring-type voltage-controlled oscillator (VCO)-based injection-locked clock multiplier (ILCM) with a continuous frequency-tracking loop (FTL) for process-voltage-temperature (PVT)-calibration is presented. 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. Therefore, the proposed ILCM can calibrate real-time frequency drifts due to voltage or temperature variations as well as static frequency deviations due to process variations. Since the FTL provided an additional filtering of in-band VCO noise, the ILCM was able to achieve excellent jitter performance over the PVT variations, while it was based on a ring-VCO. The proposed ILCM was fabricated in a 65 nm CMOS process. When injection locked, the RMS-jitter integrated from 10 kHz to 40 MHz of the 1.20 GHz output signal was 185 fs. The proposed PVT-calibrator regulated the degradations of jitter to less than 5% and 7% over temperatures and supply voltages, respectively. The active area was $\text {0.06 mm}^{2}$ and total power consumption was 9.5 mW.