A Scalable Small-Signal and Noise Model for High-Electron-Mobility Transistors Working Down to Cryogenic Temperatures

This article reports on a scalable, temperature-dependent small-signal and noise model of a 50-nm metamorphic high-electron-mobility transistor (HEMT) technology. The model is valid for temperatures ranging from 5 to 297 K. The highest scalability is achieved by using a distributed model topology. The model is able to predict the small-signal and noise performance of 2–8 finger transistors with absolute gate widths ranging from 10 to 480
$\mu \text{m}$
. Short gate width transistor fingers (5
$\mu \text{m}$
) and wide transistor fingers (100
$\mu \text{m}$
) are covered by the model. The model is valid over a very broad bandwidth from 0.1 to at least 150 GHz. Furthermore, the model covers all reasonable bias points of the given transistor technology. To the best of the authors’ knowledge, this is the first scalable HEMT model that is able to predict the small-signal and noise performance at arbitrary cryogenic temperatures. The scaling ratio related to the absolute gate width of the model is the highest among small-signal models reported in the literature.