Microwave power heterojunction bipolar transistors fabricated with thermal shunt and bathtub

Heterojunction bipolar transistor devices and circuits were fabricated using thermal shunt and bathtub thermal management techniques. Broadband cascode MMICs exhibited 10-14 dB gain at an output power of 2.5-3.0 Watts across 7-11 GHz. A 200 /spl mu/m/sup 2/ common-emitter unit cell achieved 7-8 dB linear power gain and 40% power-added efficiency at a noise power ratio (NPR) of 18 dBc at 12 GHz. Under single tone measurements at 12 GHz, the unit cell achieved 52% power-added efficiency, with 9.5 dB linear gain, 8 dB power gain and 240 mW output power at 5 V bias.