Dynamic Thermal Coupling in GaN MMIC Power Amplifiers
Journal article, 2024

The influence of dynamic thermal coupling on gallium nitride (GaN) monolithically microwave integrated circuit (MMIC) power amplifiers (PAs) is investigated through transient measurements, numerical simulations, and equivalent circuit modeling. The measured thermal coupling exhibits a low-pass-filtered response, where the magnitude and cutoff frequency decrease with increasing separation from the heat source. The coupling between two neighboring transistor channels shows a fractional order transient response and a pronounced temperature increase after ≈1 μs in the measurements. The coupling between transistors on the same MMIC is close to a first-order transient response and shows a pronounced temperature increase after 100 μs to 2.6 ms for the measured structure. It is shown that the thermal coupling causes the transistors in the PA to operate at different temperatures, where the transient response of the PA exhibits five distinct time regions. An equivalent linear network is extracted to model the effect efficiently in a circuit simulator. Here, it is shown that the thermal coupling between neighboring transistors can change the thermal response of the PA considerably below 10 kHz. The outlined results give guidelines for predicting the dynamic self-heating in GaN PAs.

power amplifiers (PAs)

Dispersive effects

gallium nitride (GaN)

time-varying systems

electrothermal device modeling

Author

Tobias Kristensen

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Torbjörn M.J. Nilsson

Saab

Andreas Divinyi

Saab

Johan Bremer

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Mattias Thorsell

Saab

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

IEEE Transactions on Microwave Theory and Techniques

0018-9480 (ISSN) 15579670 (eISSN)

Vol. In Press

Subject Categories

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1109/TMTT.2024.3458189

More information

Latest update

10/24/2024