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Abstract-In this paper, physical modeling of a GaN HEMT with a field plate structure is proposed, with the objective of providing the connection between the physical design parameters of the device (geometry, Al mole fraction, type of the field plate, etc) and on-resistance together with parasitic capacitances of the device. In this way, it is possible to optimize the design of a switching device for a particular application, which in our case is a high frequency DC DC converter for Envelope Tracking and Envelope Elimination and Restoration techniques. In this work, extrinsic models for output characteristics together with input, output and reverse capacitance of a depletion mode GaN HEMT with a field plate structure were obtained. The obtained physical model was implemented in a Simplorer simulation model of a high frequency buck converter and verified by the prototype that employed modeled GaN HEMT, operating at 7, 15 and 20MHz of switching frequency. Comparing to the measured efficiency curves, simulation results showed good agreement, especially in the low power range at high switching frequency, which are the operating conditions in our application.

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In this paper, implementation and testing of non-commercial GaN FET in a simple buck converter for envelope amplifier in ET and EER transmission techniques has been done. Comparing to the prototypes with commercially available EPC1014 and 1015 GaN FETs, experimentally demonstrated power supply provided significantly better thermal management and increased the switching frequency up to 25MHz. 64QAM signal with 1MHz of large signal bandwidth and 10.5dB of Peak to Average Power Ratio was generated, using the switching frequency of 20MHz. The obtained efficiency was 38% including the driving circuit and the total losses breakdown showed that switching power losses in the FET are the dominant ones. This implies that minimization of the gate charge is the key issue in the optimization of the device for this kind of application

Verification of the power loss model of a high-frequency buck converter together with the precision of the proposed physics-based model 109 5. Verification of the power loss model for a high-frequency buck converter together with the precision of the proposed physics-based model .