Intermodulation distortion in pseudomorphic HEMT's and an extension of the classical theory

Pseudomorphic high electron-mobility transistors (pHEMT's) offer superior RF and microwave performance and, in particular, exhibit exceptional intermodulation distortion characteristics that are not adequately modeled by the classical theory. Intermodulation products are typically 8-10 dB below classical expectations, and can be as much as 12 dB lower. An extension of the classical theory is presented, which allows for a better understanding of this phenomenon in terms of the device transconductance characteristic. Experimental data is included to provide quantitative verification based on both device and amplifier results. pHEMT-based devices have the potential to satisfy the spectral performance requirements of today's wireless systems with improved dc-to-RF efficiencies.