A 1.3–6 GHz triple-mode CMOS VCO using coupled inductors

An integrated VCO with an ultra-wide tuning range is designed and fabricated in a 0.13 mum CMOS technology. The triple-mode VCO uses a 6^th-order resonator based on three coupled inductors with a compact common-centric layout, banks of switched varactors, and continuously-tuned varactors to cover the measured 1.28-6.06 GHz frequency range. Each mode corresponds to a resonant frequency of the 6^th-order resonator. Mode selection is achieved using three independent active cores without using lossy switches in the resonator path. The VCO current consumption is automatically adjusted from 2.9 mA to 6.1 mA to achieve a low phase noise throughout the frequency range. The measured phase noises at 1 MHz offset from carrier frequencies of 1.76, 2.26, 3.3, 4.5, and 5.6 GHz are -120.89, -121.82, -118.46, -117.12, and -114.15 dBc/Hz, respectively. The chip area, including the pads, is 1 mm times 1 mm and the supply voltage is 1.5 V.