A Low-Jitter and Low-Reference-Spur Ring-VCO- Based Injection-Locked Clock Multiplier Using a Triple-Point Background Calibrator

Abstract

This work presents a low-jitter, low-reference-spur ring voltage-controlled oscillator (ring VCO)-based injection-locked clock multiplier (ILCM). Since the proposed triple-point frequency/phase/slope calibrator (TP-FPSC) can accurately remove the three root causes of the frequency errors of ILCMs (i.e., frequency drift, phase offset, and slope modulation), the ILCM of this work is able to achieve a low-level-reference spur. In addition, the calibrating loop for the frequency drift of the TP-FPSC offers an additional suppression to the in-band phase noise of the output signal. This capability of the TP-FPSC and the naturally wide bandwidth of the injection-locking mechanism allows the ILCM to achieve a very low-RMS jitter. The ILCM was fabricated in a 65-nm CMOS technology. The measured reference spur and RMS jitter of the 2.4-GHz output signal were -72 dBc and 140 fs, respectively, both of which are the best among the state-of-the-art ILCMs. The active silicon area was 0.055 mm², and the power consumption was 11.0 mW.