A scalable active THz frequency multiplier chain in silicon with multi-phase sub-harmonic injection locking for bandwidth extension

This paper presents a multi-phase sub-harmonic injection locking technique for terahertz (THz) signal generation with bandwidth extension. Utilizing this multi-phase technique, a scalable and cascadable "active frequency multiplier" chain architecture is proposed to generate a THz signal from a lower-frequency reference source. A multi-ring system topology is also proposed to facilitate the implementation. As a proof-of-concept design, a cascaded three-stage three-phase second-order sub-harmonic injection locking oscillator chain is implemented in the IBM9HP SiGe BiCMOS process with ft/fmax of 300/350GHz. It achieves a maximum output power of -16.6dBm at 498GHz, a phase noise of -87dBc/ Hz at 1MHz offset, and a total 5.1% frequency tuning range, which is the largest frequency tuning range among all the reported 0.5THz silicon oscillator sources.