A noise circulating cross-coupled VCO with a 195.6dBc/Hz FoM and 50kHz 1/f3 noise corner

Abstract

This paper presents a transformer-based cross-coupled voltage-controlled-oscillator (VCO) topology with a noise circulating active core. The proposed noise circulating technique suppresses both the 1/f 2 and 1/f 3 phase noise. Due to its broadband nature, the resulting VCO phase noise in both 1/f 2 and 1/f 3 regions is greatly improved over a wide tuning range. A prototype VCO at 2.35GHz is implemented in a standard 130nm bulk CMOS process with 0.36mm 2 core area. It consumes 2.15mA from a 1.2 V supply. The measured figure-of-merit (FoM) is 193.1/195.0/195.6 dBc/Hz at 100k/1M/10MHz offsets with a 1/f 3 phase noise corner of only 50kHz. The VCO design consistently achieves >192.8dBc FoM at 100k/1M/10MHz offsets and <;60kHz 1/f 3 phase noise corner over its entire 18.6% tuning range (2.05-2.47GHz). It has very low supply pushing of -25MHz/V and -13MHz/V at the highest and lowest frequencies, respectively.