Injection-locked clock multipliers (ILCMs) achieve superior phase noise compared to conventional PLLs [1, 2]. In its simplest form, an ILCM is an oscillator into which a train of narrow pulses is injected at reference frequency FREF as shown in Fig. 10.6.1. If the free-running frequency, FFR, of the oscillator is tuned close to NFREF (N=4, in Fig. 10.6.1), injected pulses phase lock the oscillator and greatly suppress its close-in phase noise. However, any deviation of FFR from NFREF degrades spurious/jitter performance, making ILCM performance sensitive to PVT variations. A frequency-tracking loop (FTL) was used to continuously tune FFR to be close to NFREF and achieve excellent jitter performance (4psrms) due to mismatch between delay stages. In this work, we seek to overcome this fundamental limitation of conventional ILCMs and extend their benefits to fractional-N ILCMs.