High-Frequency PWM Buck Converters Using GaN-on-SiC HEMTs

GaN high electron mobility transistors (HEMTs) are well suited for high-frequency operation due to their lower on resistance and device capacitance compared with traditional silicon devices. When grown on silicon carbide, GaN HEMTs can also achieve very high power density due to the enhanced power handling capabilities of the substrate. As a result, GaN-on-SiC HEMTs are increasingly popular in radio-frequency power amplifiers, and applications as switches in high-frequency power electronics are of high interest. This paper explores the use of GaN-on-SiC HEMTs in conventional pulse-width modulated switched-mode power converters targeting switching frequencies in the tens of megahertz range. Device sizing and efficiency limits of this technology are analyzed, and design principles and guidelines are given to exploit the capabilities of the devices. The results are presented for discrete-device and integrated implementations of a synchronous Buck converter, providing more than 10-W output power supplied from up to 40 V with efficiencies greater than 95% when operated at 10 MHz, and greater than 90% at switching frequencies up to 40 MHz. As a practical application of this technology, the converter is used to accurately track a 3-MHz bandwidth communication envelope signal with 92% efficiency.

[1]  R. Saleh.  FastCap : A Multipole Accelerated 3-D Capacitance Extraction Program , 1991 .

[2]  D. Maksimović.  Design of the zero-voltage-switching quasi-square-wave resonant switch , 1993, Proceedings of IEEE Power Electronics Specialist Conference - PESC '93.

[3]  U. Mishra,et al.  AlGaN/GaN HEMTs-an overview of device operation and applications , 2002, Proc. IEEE.

[4]  Eduard Alarcón,et al.  Efficiency optimization in linear-assisted switching power converters for envelope tracking in RF power amplifiers , 2005, 2005 IEEE International Symposium on Circuits and Systems.

[5]  Feipeng Wang,et al.  An Improved Power-Added Efficiency 19-dBm Hybrid Envelope Elimination and Restoration Power Amplifier for 802.11g WLAN Applications , 2006, IEEE Transactions on Microwave Theory and Techniques.

[6]  F.C. Lee,et al.  Analytical loss model of power MOSFET , 2006, IEEE Transactions on Power Electronics.

[7]  D. Perreault,et al.  Design Considerations for Very High Frequency dc-dc Converters , 2006 .

[8]  L. Eastman,et al.  Comparison of GaN HEMTs on Diamond and SiC Substrates , 2007, IEEE Electron Device Letters.

[9]  D.J. Perreault,et al.  Very High Frequency Resonant Boost Converters , 2007, 2007 IEEE Power Electronics Specialists Conference.

[10]  E. McCune.  Process- and technology-independent power switching transistor figures of merit , 2008, 2008 IEEE Radio and Wireless Symposium.

[11]  D. G. Lamar,et al.  An Insight into the Switching Process of Power MOSFETs: An Improved Analytical Losses Model , 2010, IEEE Transactions on Power Electronics.

[12]  Zoya Popovic,et al.  GaN HEMT PA with over 84% power added efficiency , 2010 .

[13]  O. Garcia,et al.  Optimum design of an envelope tracking buck converter for RFPA using GaN HEMTs , 2011, 2011 IEEE Energy Conversion Congress and Exposition.

[14]  Karim S. Boutros,et al.  A 95% Efficient Normally-Off GaN-on-Si HEMT Hybrid-IC Boost-Converter with 425-W Output Power at 1 MHz , 2011, 2011 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS).

[15]  Dragan Maksimovic,et al.  GaN-FET based dual active bridge DC-DC converter , 2011, 2011 Twenty-Sixth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[16]  Michel Campovecchio,et al.  Over 10MHz bandwidth envelope-tracking DC/DC converter for flexible high power GaN amplifiers , 2011, 2011 IEEE MTT-S International Microwave Symposium.

[17]  R. S. Pengelly,et al.  A Review of GaN on SiC High Electron-Mobility Power Transistors and MMICs , 2012, IEEE Transactions on Microwave Theory and Techniques.

[18]  D. Maksimovic,et al.  10 MHz large signal bandwidth, 95% efficient power supply for 3G-4G cell phone base stations , 2012, 2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[19]  Youhao Xi,et al.  Optimization of the drive circuit for enhancement mode power GaN FETs in DC-DC converters , 2012, 2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[20]  Rongming Chu,et al.  GaN power electronics for automotive application , 2012, 2012 IEEE Energytech.

[21]  F. Lee,et al.  Gallium Nitride based 3D integrated non-isolated point of load module , 2012, 2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[22]  F. C. Lee,et al.  High frequency high power density 3D integrated Gallium Nitride based point of load module , 2012, 2012 IEEE Energy Conversion Congress and Exposition (ECCE).

[23]  Alberto Rodriguez,et al.  Analysis and Design of the Output Filter for Buck Envelope Amplifiers , 2014, IEEE Transactions on Power Electronics.