Design of a Low-Phase-Noise Ka-Band GaAs HBT VCO

In this paper, the study of a Ka-band GaAs HBT VCO is reported with particular emphasis on achieving low-phase noise while using direct coupled varactor. A push–push cross-coupled VCO configuration is employed to achieve high oscillation frequency and low-phase noise. The measured oscillation bandwidth spans from 30.2 to 28.6[Formula: see text]GHz with a tuning range of 1.6[Formula: see text]GHz, while the phase noise at 1[Formula: see text]MHz of frequency offset from the carrier at 29.3[Formula: see text]GHz is [Formula: see text][Formula: see text]dBc/Hz. The VCO consumes 28.2[Formula: see text]mW from 3[Formula: see text]V supply and occupies an area of [Formula: see text][Formula: see text]mm. The FOM of the VCO achieves [Formula: see text][Formula: see text]dBc/Hz.