Comparison of Millimeter Wave Quadrature-VCOs for 28GHz 5G Applications

Two 28GHz mm-wave quadrature voltage-controlled oscillator designs in a 45nm bulk CMOS process are reported in this work. The first topology uses two VCOs coupled with each other using cascode devices. The second topology uses a single VCO followed by a Lange Coupler to give quadrature phase outputs. This comparative study shows that the latter exhibits better phase noise and tuning range with respect to the former. Post-layout EM simulations of the Lange Coupler QVCO predict an improvement of 4–6 dB in phase noise over the Cascode Injected QVCO, across all bit configurations. The total dc power consumption of this Lange coupled QVCO with two buffers is 20 mW when running at a power supply of 1.1V.