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.