Large-signal modeling of GaN HEMTs for linear power amplifier design

The spectral efficient modulation techniques used in mobile communication systems result in signals having a high peak-to-average power ratio. Consequently, a thorough analysis of the linearity of the power amplifiers designed for these applications is required using computer-aided design (CAD) techniques. This is a convenient and cost effective procedure to meet the stringent linearity requirements of the communication system but at the same time operating the amplifiers at their highest possible efficiency. The recent advances in developing new power transistors using wide bandgap materials, such as SiC MESFETs and AlGaN/GaN HEMTs, demonstrated high output power, power density, efficiency, and linearity at high frequencies. This thesis describes the large-signal modeling procedure for high power AlGaN/GaN HEMTs. The developed electrothermal large-signal model accounts for both trap and thermal related dispersion effects. The complete large-signal modeling process, including detailed procedures for the extrinsic parameters extraction, pulsed I(V) characterization, transient drain current measurements, dispersive drain current modeling, and table-based model implementation have been addressed. The validity of the developed dispersive models were tested through different model verification steps, which also include the intermodulation distortion prediction capability of the large-signal model.