Dual-band ultra-wide tuning range CMOS voltage-controlled oscillator

A dual-band wide-tuning range LC CMOS voltage controlled oscillator (VCO) topology is proposed. Dual-band operation is realised by employing a double-tuned double-driven transformer as a resonator. The proposed approach eliminates MOS switches, which are typically used in multi-standard oscillators, and thus improves phase noise and tuning range characteristics. The concept is demonstrated through the design of an LC VCO in a standard 0.18 mum CMOS process. Two frequency bands are realised (2.4 and 6 GHz) with 740 MHz tuning range in the first band and 1.56 GHz tuning range in the second band. Operating from a 1.8 V supply, the VCO has a simulated phase noise of -119 dBc/Hz in the 2.4 GHz band and -110 dBc/Hz in the 6 GHz band at 600 KHz offset from the carrier