Strategies for addressing linearity issues in active device modeling

Microwave active-circuit design at the semiconductor level has been proposed as a real alternative for addressing the linearity versus efficiency trade-off in wireless applications, mainly when the use of traditional system-level architectures may be prohibitive due to cost or complexity. A wide set of techniques - valid either for power amplifiers and mixers - are available from the control of the transistor physics to device-based implementations of system concepts. This presentation will firstly discuss on what are the necessary measurements and model strategies to build a semiconductor model able to predict intermodulation distortion behavior. Furthermore, attention will be focused on the selection of optimum operating conditions, the adaptation of bias and load to the input signal envelope, and the use of auxiliary devices for creating an approximated compound linear transistor. Finally, the integration of these semiconductor-based approaches in printed radiators and arrays will also be considered as a way to produce polarization or spatially selective linearization.