A 0.22 V Quadrature VCO in 90 nm CMOS Process

This letter presents an ultra-low voltage quadrature voltage-controlled oscillator (QVCO). The LC-tank QVCO consists of two low-voltage voltage-controlled oscillators (VCOs) with the body dc biased at the drain bias through a resistor. The superharmonic and back-gate coupling techniques are used to couple two differential VCOs to run in quadrature. The proposed CMOS QVCO has been implemented with the UMC 90 nm CMOS technology and the die area is 0.827 ?? 0.913 mm². At the supply voltage of 0.22 V, the total power consumption is 0.33 mW. The free-running frequency of the QVCO is tunable from 3.42 to 3.60 GHz as the tuning voltage is varied from 0.0 to 0.3 V. The measured phase noise at 1 MHz offset is -112.97 dBc/Hz at the oscillation frequency of 3.55 GHz and the figure of merit (FOM) of the proposed QVCO is about -188.79 dBc/Hz.