Design and fabrication of X-band AlGaAs/GaAs power HBTs

We performed systematical thermal design and fabricated X-band 0.5 W class power HBTs. Based on the thermal design, we adopted an HBT with emitter-to-emitter spacing of 30 /spl mu/m as a standard device. The collector-emitter breakdown voltage is 16 V indicating that 8 V operation is possible. f/sub t/, f/sub max/ and output power of the HBT at 10 GHz are 67, 58 GHz and 0.58 W, respectively. Various kinds of HBTs with different structures have been studied for reducing the thermal effects and we will present the dominant effect on thermal problems and the measurement data for thermal design guide.