A CMOS 300-GHz Injection-Locked Frequency Tripler with a Tri-Layer Dual Coupled Line for Improved Locking Range

A triple-push sub-harmonic injection-locked ring tripler is presented in this paper. The circuit converts a 100-GHz injection signal to an output signal of around 300 GHz. The circuit employs a tri-layer dual coupled line, which is composed of three layers of metal stack. The signal injection through the tri-layer dual coupled line structure disturbs the symmetry in the injection-locked ring tripler, leading to a locking range enhancement. The circuit, fabricated in a 65-nm CMOS process, achieved a locking range of up to 24 GHz with a 3-dBm injection power. A measured output power larger than -18 dBm was obtained at the free-running frequency of 302 GHz. The measured phase noise was -105 dBc/Hz at 1-MHz offset.