A NOVEL SELF-OSCILLATING HEMT-HBT CASCODE VCO-MIXER USING AN ACTIVE TUNABLE INDUCTOR

Here we describe a unique Ka-band self-oscillating HEMT-HBT cascode mi xer design which integrates an active tunable resonator circuit. The V CO-mixer MMIC integrates GaAs HEMT's and HBT's using selective molecul ar beam epitaxy (MBE) technology. The HEMT-HBT cascode active mixer op erates similarly to a dual-gate mixer. The HBT of the cascode is used to construct a VCO by presenting the base with an HEMT tunable active inductor. The VCO can be tuned from 28.5 to 29.3 GHz while providing a pproximate to 0 dBm of output power. Operated as an upconverter, the M MIC achieves 6-9-dB conversion loss over a 31-39-GHz output frequency band. Using these active approaches, both VCO and mixer functions were integrated into a compact 1.44 x 0.76 mm(2) chip area. The active RF integrated circuit (IC) techniques presented here have direct implicat ions to future high complexity millimeter-wave monolithic microwave in tegrated circuits (MMIC's) for ultrahigh-speed clock recovery and digi tal radio applications.