Analysis and implementation of behavioral models for the development of advanced GaAs HBT/HEMT RFIC Power Amplifiers
RFIC PA (RF Integrated Circuit Power Amplifier) designers often face the difficult challenge of bridging the gap between simulation data and experimental results, which negatively impacts the design convergence and time-to-market considerations during the development of complex amplifier structures. This is particularly severe when dealing with nonlinear circuit techniques during the practical development phase. Design oriented behavioral models (e.g. [1], [2]) that allow bridging this gap in a time efficient way are valuable to RFIC PA designers. This project aims at developing a design oriented behavioral model that is suited for the development of standalone RFIC PAs employing complex architectures, in GaAs HBT and other technologies.
The project integrates the framework of on-going investigations on complex GaAs/InGaP HBT/BiHEMT RFIC PA structures for wireless communications, in collaboration with a worldwide leading supplier of RFIC PAs. A behavioral model that suits the task of correlating experimental data and simulation results during the practical phase of RFIC PA development will be analyzed, improved and implemented within design platforms (Agilent – ADS Simulation software and other experimental development tools). A methodology that accompanies the behavioral model will be proposed and validated in a way that demonstrates the impact on the design convergence during RFIC PA development.
Starting from a well-defined RFIC PA architecture, RF electrical performance objectives (e.g. gain flatness, power added efficiency, linearity and stability), a preliminary feasibility study, an existing basic behavioral model (e.g. [1], [2]) and mathematical formulations, new formulations (or adapted from formulations proposed in other work) that describe the nonlinear behavior of RFIC PAs will be derived and an improved behavioral model will be developed. On the one hand, the model will aim at enhancing the simulation capabilities with ADS by incorporating experimental RF transistor device and circuit blocks characterization data, as well as PA system experimental results obtained from actual PA implementations. On the other hand, the same model will be adapted to allow efficient diagnosis and troubleshooting of PA performances by the designer during the development phase, with the aim of speeding the design convergence.
[1] S. Sharma, N.G. Constantin, “Formulations for the Estimation of IMD Levels in an Envelope Feedback RFIC Amplifier : An Extension to Dynamic AM and PM Behavior,” IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, Nov. 2013.
[2] N. G. Constantin, K. H. Kwok, H. Shao, C. Cismaru, and P. J. Zampardi, Formulations and a Computer-Aided Test Method for the Estimation of IMD Levels in an Envelope Feedback RFIC Power Amplifier, IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, Dec. 2012.
