V-band low phase noise QVCO in 90nm CMOS technology using a gate-connected tank

A quadrature voltage controlled oscillator (QVCO) with -111 dBc/Hz average phase noise at 1MHz offset across an output frequency range of 48.9-50.3-GHz is presented. The design employs a modification of the Armstrong technique of using a transformer in the LC tank to improve the phase noise by reducing the single-ended component of the tank capacitance in a differential cross-coupled design and by separating the gate and drain transistor bias. Tuning is achieved by an accumulation MOS varactor and a thermometer-coded bank of 14 switched capacitors. The design consumes 23-mA from a 1.3 V supply and occupies an area of 0.25-mm² in 90 nm CMOS technology.