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-
$\mu $
m-long emitter fingers were simultaneously fabricated. A record power-added efficiency PAE =35% is measured for single-finger 7.5-
$\mu $
m-long DHBTs with a saturated matched output power
$P_{\mathrm {OUT,SAT}} =9.5$
dBm. A
$P_{\mathrm {OUT,SAT}} \gt 12$
and >14.5 dBm with peak PAE =25% and 22% is delivered from two- and four-finger 10-
$\mu $
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.