Current reuse cross-coupling CMOS VCO using the center-tapped transformer in LC tank for digitally controlled oscillator

A current reuse cross-coupling transformer-based VCO with low phase noise and low power consumption was implemented in 0.13 mum CMOS. The oscillation frequency was tuned from 4.6 GHz to 6 GHz (26% tuning range) using two different-sized varactor that adjusted fine and coarse tuning. The measured phase noise at 5.0 GHz was -124 dBc/Hz (1 MHz offset) and maximum output power level was -5.5 dBm. The 0.4times0.3 mm² core consumes very low power of 1.8 mW for 1.2 V and FOM has -196.2 dB.