K-band 76% PAE InP double heterojunction bipolar power transistors and a 23 GHz compact linear power amplifier MMIC

In this paper, we report a DHBT power cell with 76% PAE at 21 GHz, and the first DHBT MMIC PA operating at 22-24 GHz. The MMIC amplifier combines four power cells where each power cell is made up of two 1.5/spl times/30 /spl mu/m/sup 2/ emitter fingers, yielding a total emitter area of 360 /spl mu/m/sup 2/. A practical design approach is employed to yield a single-ended, single stage power amplifier which achieved a record high output power density per chip area of 0.36-0.38 W/mm/sup 2/ at 23 GHz.