A high-performance AlInAs/InGaAs/InP DHBT K-band power cell

In this work the device design and power performance of several AlInAs/InGaAs/InP double heterojunction bipolar transistors (DHBTs) are reported for 18 GHz. The power cells utilize a wet chemical etching technique to create a micro-airbridge base connection and to remove extrinsic collector material from beneath the base which both contribute to a reduced base-collector capacitance and improved f/sub max/ and power gain. For class B operation, the eight-finger 2 /spl mu/m/spl times/30 /spl mu/m power cells achieved 1.17-W output power, which indicates 4.88-W/mm emitter length, with 54% power-added efficiency (PAE) and 7.3-dB gain, This is believed to be the best combination of PAE and output power reported for this power density at K-band frequencies.