A 69.2–85.6-GHz LO Generator Achieving 192.2-dBc/Hz FoM and 201.4-dBc/Hz FoMA with Current-Reused Coupled Frequency Tripler and Implicit Ninth Harmonic Extraction in 65nm CMOS

This paper presents an E-band local oscillator (LO) generator with a current-reused coupled frequency tripler and 9th harmonic extraction. By stacking and coupling two class-F oscillators in a single current branch operating at f₀ and 3f₀, respectively, the proposed coupled frequency tripler optimizes both phase noise and power consumption. Furthermore, by extracting the implicit 9f₀ harmonic through the frequency tripler, a wideband, low-phase-noise E-band LO generator is realized. Fabricated in a 65-nm CMOS process, the proposed prototype achieves a frequency tuning range of 21.1% from 69.2 to 85.6 GHz, with phase noise ranging from -121.2 to -126 dBc/Hz at a 10-MHz offset. The power consumption varies from 10.1 to 11.4 mW, thus yielding a peak figure-of-merit (FoM) of 192.2 dBc/Hz and a FoMT of 198.7 dBc/Hz at the 10-MHz offset. The proposed LO generator occupies a compact core area of 0.12 mm², corresponding to a peak FoMA of 201.4 dBc/Hz.