Microwave Nonlinear Modeling and Active Frequency Multiplier Design for High Power Silicon-Carbide and Gallium-Nitride Field-Effect Transistors

Wide bandgap silicon-carbide (SiC) and gallium-nitride (GaN) FETs are the premier microwave solid-state power technology and are presently being deployed in a variety of commercial applications. However, performance-degrading self-heating and charge-trapping effects create new challenges for characterization and modeling of these devices. Accurate nonlinear models capable of predicting these effects are necessary to maximally exploit the benefits of this emerging, high power density technology.;An empirical modeling methodology for the SiC MESFET and GaN HEMT using high power dynamic IV measurements to exploit and characterize self-heating and charge-trapping is applied over a vast range of electrothermal operating conditions. Nonlinear diode modeling and multibias, small-signal techniques are performed to create complete nonlinear models for SiC and GaN FETs, which are capable of predicting DC, pulsed, small- and large-signal RF behavior over a wide range of bias and frequency. The presented models are valid for drain currents beyond 2A, drain voltages greater than 50V and up to 10W at RF.;These harmonically-accurate models permit the new application of CAD-based active frequency multiplier design for wide bandgap devices. Frequency doublers and triplers are demonstrated in SiC MESFET and GaN HEMT technology, producing some of the highest power, single-transistor microwave frequency multipliers to date. This work reports SiC- and GaN-based C-band frequency doublers with >5W output power and a GaN-based X-band frequency tripler with 1W output power.