A 206–220-GHz Compact Fundamental Oscillator With up to 7-dBm Output Power and 7.4% Peak DC-to-RF Efficiency in a 130-nm SiGe Technology

This letter presents a 206.5–220.5-GHz fundamental differential Colpitts oscillator in a cascode topology implemented in a 130-nm SiGe HBT technology with $f_{t}$ / $f {_{\max }}$ of 350/450 GHz. Base inductors at the common-base (CB) stages are used to provide an inductive load at the output of the common-emitter (CE) stage, hence, boosting the output power by 27%. The resonant tank is embedded straight on top of the devices, reducing layout parasitics and resulting in a compact and efficient oscillator core layout. The oscillator provides a peak output power of 7 dBm at 208 GHz, 7.4% peak dc-to-RF efficiency at 220 GHz, and 6.55% tuning range (TR). At peak efficiency, the oscillator delivers an output power of 5.7 dBm with 50-mW dc power consumption and a phase noise (PN) of −90.2/−110 dBc/Hz at 1-/10-MHz offset, respectively. To the best of the authors’ knowledge, the presented oscillator has the best PN figure-of-merit (FoM) of −182.1 dBc/Hz at 1-MHz offset in a SiGe/CMOS technology above 200 GHz. It occupies a total area of 0.086 mm2, including the RF pad, and an ultracompact core size of 0.0049 mm2.