Extracting a compact transistor model requires several weeks of work, and potentially up to several months when starting from scratch. This investment worth the value when a foundry wants to support all its customers for a large variety of operating conditions (T°; bias, matching conditions).
In this case, the model need to be broadband to cover all the needs.
Nevertheless, there are some cases where such a model is not accurate enough for a particular case, especially for space applications where every point of power added efficiency is crucial.
In this case, the RF transistor model must be perfectly accurate to predict the power added efficient, output power, gain, return loss with a set of harmonic load impedances and for some particular carrier frequencies.
Refining the foundry compact model to make it accurate for those particular operating conditions can be a solution.
Nevertheless, there are some cases where the time needed to extract a compact model is not compatible with the project timeline (one or two weeks maximum) or budget. In this latter case, the EPHD is the right candidate because it allows extracting a model on the fly from load-pull measurements, which saves considerable design time. The ability of this model to predict the overall design performances without any convergence issues for harmonic balance simulations has been proved even for extrapolated load conditions, during the simulation, and with the load impedances used during the load pull measurement process. Therefore, this new model is a promising candidate for the design of power amplifiers of future telecommunication systems due to its robustness, flexibility, reliability under ROI constraints.
MT930R1 is a stand-alone module for the extraction of Enhanced Poly Harmonic Distortion (EPHD) transistor behavioral models.
This tool allows a transistor model extraction on the fly and can advantageously replace load pull measurement data file export in circuit simulators. The EPHD model can be used in Harmonic Balance simulations to describe the transistor behavior as a function of the RF power level as well as fundamental and harmonic terminations.
EPHD model is a proven and robust modeling platform. It can be used for PA circuit design with complex parallel or cascaded branch architectures.
Thanks to use of our Harmonic Phase Reference, the model extraction is based on IVCAD MT930GA LSA based load pull measurements and does not require time consuming measurement process.
The EPHD can predict the transistor nonlinear behavior against fundamental and harmonic frequencies, for different carrier frequencies, and enables accelerated PA design flow.
AN : Behavioral Model of High Power GaN HEMTs for RF Doherty Amplifier
When dealing with complex setups to characterize Transistors in pulsed conditions, it is easy to face the issue of instrument synchronization, especially when using different instruments from different vendors and different generations. For example, some RF sources can generate a fixed output synchronization signal with 50nsec width, but most of the triggered instruments like Power Meters; DMMs… have a minimum trigger hold-off timing of 1usec, resulting in a bad synchronization and wrong measurements, as well as software timeouts.
In this case, it is recommended to advantageously use a Trigger Box with the RF Modulator to help build a robust bench for transistors' Pulsed Characterization.