A 20-28 GHz AlGaAs/GaAs HBT monolithic oscillator

The authors report the design, fabrication, and performance of a monolithic oscillator implemented using a heterojunction bipolar transistor (HBT) for microwave and millimetre-wave applications. A large-signal time-domain-based design approach is developed which applies a SPICE-F simulator to optimize the oscillator circuit parameters for maximum output power over a 20-28-GHz frequency range. The monolithic oscillator employs a 2*10 mu m/sup 2/-emitter-size self-aligned AlGaAs/GaAs HBT fabricated using a pattern-inversion technology. Successful operation of the fabricated monolithic circuit over the 20-28-GHz frequency band indicates the applicability of the HBTs to low-phase-noise oscillators at microwave/millimetre-wave frequencies for which both Si bipolar transistors and GaAs FETs do not exist. The authors note that this is first monolithic microwave oscillator developed using an AlGaAs/GaAs HBT operating at frequencies up to 28 GHz.<>