Record 35% Power-Added Efficiency at 170 GHz in 300-nm InP/GaAsSb DHBTs

We report the 170-GHz power performance of multifinger common-emitter (CE) 300-nm indium phosphide (InP)/GaAsSb double heterojunction bipolar transistors (DHBTs). Devices with one-, two-, and four-finger(s) with 7.5-, 10-, or 12.5- <tex-math notation="LaTeX">μ </tex-math> m-long emitter fingers were simultaneously fabricated. A record power-added efficiency PAE =35% is measured for single-finger 7.5- <tex-math notation="LaTeX">μ </tex-math> m-long DHBTs with a saturated matched output power <tex-math notation="LaTeX">POUT,SAT =9.5 </tex-math> dBm. A <tex-math notation="LaTeX">POUT,SAT > 12 </tex-math> and >14.5 dBm with peak PAE =25% and 22% is delivered from two- and four-finger 10- <tex-math notation="LaTeX">μ </tex-math> m-long DHBTs, respectively. To the best of our knowledge, 35% is the highest PAE reported for any PA/PA cell in any transistor technology over the entire G-band range. We attribute the high efficiency achieved in this study to the exceptionally high gain transistors in the (sub)-millimeter-wave (mm-wave) range, as well as the advantageous combination of high breakdown and low knee voltages. This work details the first G-band power characterization of single- and multi-finger GaAsSb-based DHBTs—it is also the first such study in any InP DHBT. An all-technology record Class-A G-band PAE is achieved with a minimal reduction with respect to W-band peak PAE levels. An HICUM-based large-signal model verifies the mm-wave RF measurements.