A 55-63 GHz fundamental Quad-Core VCO with NMOS-only stacked oscillator in 28 nm CMOS

Abstract

This paper presents a 55-63GHz fundamental multicore VCO in a 28nm bulk CMOS process. The single-core VCO is made by stacking and magnetically coupling two NMOS-based resonators for reliability and increasing the tank energy for phase noise reduction. Potential parasitic modes which occur both in single-core and multi-core configuration are suppressed by design. The four in-phase LO outputs can also be used for LO distribution in millimeter-wave systems. The prototype achieves phase noise of -95 and -121.7dBc/Hz at 1MHz and 10MHz offset from the carrier at 55GHz with a 13.4% tuning range. The corresponding peak FOM achieved is 178dBc/Hz and 184.7dBc/Hz at 1MHz and 10MHz offset from the carrier.