A scalable low-voltage extended swing CMOS LC quadrature VCO for RF transceivers

This paper describes a novel scalable low voltage CMOS folded-cascode QVCO (quadrature voltage controlled oscillator) design using the TSMC 0.18 μm 5 MIP CMOS process technology. The startup behavior of the proposed QVCO topology indicate that, the QVCO is free of bi-modal oscillation (frequency ambiguity). The VCO provided extended voltage swing with voltage supply scalable in the range 1.8 V to 0.75 V. The VCO operates in the range of 4 GHz to 3 GHz (corresponding to supply voltage scaling in the range 1.8 V to 0.75 V) with around 7% tuning range. The QVCO consumed under 5 mW within the supply voltage scaling range. Phase noise simulations indicate a phase noise of around -165 dBc/Hz at an offset of 600 KHz from the carrier (@3.7 GHz) for operation using the 1.8 V supply voltage, which is quite favorable compared to other recent low-voltage QVCO designs.