Low Phase Noise sub-1 V Supply 12 and 18 GHz VCOs in 90 nm CMOS

Two low phase noise, sub-1 V supply VCO topologies have been explored at 12 and 18 GHz in a 90 nm CMOS technology for direct LO generation in microwave link applications. At 12 GHz, a cross-coupled differential NMOS pair VCO achieves a phase noise of -117 dBc/Hz at 1 MHz offset while consuming only 1.6 mW from a 0.47 V supply. At 18 GHz a Hartley VCO with a novel tuning scheme reached -119 dBc/Hz at 1 MHz offset, consuming 4.2 mW from a 0.8 V supply. The well established VCO FOM is 196 and 199 for the 12 and 18 GHz VCOs, respectively