Low phase noise GaAs HBT VCO in Ka-band

Design and fabrication of a Ka-band voltage-controlled oscillator(VCO) using commercially available 1-μm GaAs heterojunction bipolar transistor technology is presented.A fully differential common-emitter configuration with a symmetric capacitance with a symmetric inductance tank structure is employed to reduce the phase noise of the VCO,and a novel π-feedback network is applied to compensate for the 180° phase shift.The on-wafer test shows that the VCO exhibits a phase noise of-96.47 dBc/Hz at a 1 MHz offset and presents a tuning range from 28.312 to 28.695 GHz.The overall dc current consumption of the VCO is 18 mA with a supply voltage of-6 V.The chip area of the VCO is 0.7×0.7 mm~2.