Single-chip 30 W CW AlGaAs/GaAs heterojunction bipolar transistor at 3 GHz

We have fabricated heterojunction bipolar transistors that, to our knowledge, exhibit record operating voltage and single-chip output power for GaAs microwave power devices. A device with 720 /spl mu/m total emitter length achieved an output power of 4 W with 62% power-added efficiency at 3 GHz at a collector bias of 20 V. A device monolithically combining 16 unit cells, for a total emitter length of 7.68 mm, achieved a CW output power of 30 W with 55% power-added efficiency at 3 GHz.