Physical modeling and optimization of a GaN HEMT design with a field plate structure for high frequency application

Abstract

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.

Digital controller based on delta operator for high‐frequency DC–DC switching converters

“…2b. Accordingly, (9) indicates that the steady region in the delta-plane is still a circle, but its centre is located at (−1/T s , 0), and its radius is equal to 1/T s , as shown in Fig. 2c.…”

“…The transfer function of the conventional PID controller in the sdomain shown in (1) is still used as an example herein. The zdomain discrete transfer function of the D-PID in (3) is transferred to the δ-domain using the δ-domain definition provided in (9), which can be expressed using (11), the delta operator D-PID can be expressed by (12)…”

“…The increase in the switching frequency of a DC-DC switching converter not only improves its transient response features with load variation, but also significantly reduces the sizes and weights of the passive filtering components, including inductors and capacitors. These power supply module improvements are particularly beneficial for portable and mobile consumer electronics [7][8][9][10][11]. Consequently, high-frequency digitally controlled (HFD) DC-DC switching converters attract considerable attention from both the academia and industry [12][13][14][15].…”

“…The switching frequencies of analogue-control DC-DC switching converters have exceeded several tens of megahertz [7][8][9][10]. However, the switching frequencies of digitally controlled DC-DC switching converters have only increased from hundreds of kilohertz [1,11,12] to several megahertz [13][14][15], because of two special issues that exist at high frequencies: maintaining the stability and the accuracy of the feedback control system and reducing the hardware cost.…”

Analysis of AlGaN/GaN HEMT and Its Operational Improvement Using a Grated Gate Field Plate

“…The capacitance trends are flat up to the threshold voltage as depicted in Region I because the channel is depleted from 2DEG charges. Both C gd and C gs increase and show a step-like change around the threshold voltage as these capacitance values are largely influenced by the change in 2DEG carrier concentration while HEMT is being turned on 34 . This behavior can be attributed to the fact that when gate bias is increased the electric field set by gate and the intrinsic polarization field increases the concentration of 2DEG charges.…”