A 5.4-7.4 GHz Ultra-Low Jitter Injection-Locked Frequency Tripler With 3rd Harmonic Current Boosting Input Buffer

We present a 5.4-to-7.4 GHz injection-locked frequency tripler (ILFT) with enhanced $3^{rd}$ harmonic injection using collector-to-base transformer-coupled input buffer. Regenerative feedback in the input buffer using a collector-to-base coupled transformer provides up to 2x improvement in the locking range of the ILFT compared to a conventional ILFT. Fabricated in $0.13~\mu $ m BiCMOS technology, the tripler exhibits a jitter tracking bandwidth, $\omega _{JTB}$ of 20 MHz. Due to its optimal jitter tracking bandwidth, the tripler filters the input noise beyond the $\omega _{JTB}$ and effectively suppresses the free-running oscillator’s phase noise below $\omega _{JTB}$ . We achieve an output rms jitter of 33.6 fs for an input rms jitter of 68 fs over a bandwidth of [1k-100MHz]. The ILFT demonstrates a good sub-harmonic rejection ratio, SHRR of 51 dB and 48 dB for fundamental and second harmonic, respectively.