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This paper presents a new low phase noise quadrature voltage-controlled oscillator (QVCO), which consists of two differential complementary Colpitts voltage-controlled oscillators (VCOs) with a tail inductor. The output of the tail inductor in one differential VCO is injected to the bodies of the nMOSFETs in the other differential VCO and vice versa. The proposed CMOS QVCO has been implemented with the TSMC 0.18 mum CMOS technology and the die area is 0.725 times 0.839 mm2. At the supply voltage of 1.1 V, the total power consumption is 9.9 mW. The free-running frequency of the QVCO is tunable from 5.26 GHz to 5.477 GHz as the tuning voltage is varied from 0.0 V to 1.1 V. The measured phase noise at 1 MHz frequency offset is -124.36 dBc/Hz at the oscillation frequency of 5.44 GHz and the figure of merit (FOM) of the proposed QVCO is -189.1 dBc/Hz.