High Efficiency Power Converters Using Gallium Nitride Transistors

High Efficiency Power Converters Using Gallium Nitride Transistors Marl Nakmali Mentors: Dr. Leon Tolbert Yutian Cui

Room for Improvement 5 -2

Material Properties and Limitations 5 -3

Size Minimization 5 -4

Data Sheet Comparison VDS [V] RDS(on) [Ω] ID [A] VGS [V] Size [mm 2] Gallium Nitride Silicon 30 30 0. 001 1. 3 60 42 -4<VGS<6 -20<VGS<20 13. 915 30 5 -5

But what about the price? 5 -6

How it works 5 -7

The Buck Converter 5 -8

The Buck Converter 5 -9

The Buck Converter 5 -10

Loss Analysis These losses are: • Switching Loss • Conduction Loss 5 -11

Results 5 -12

Efficiency Graphs 3 V Input Performance 1 0. 9 0. 8 Efficiency 0. 7 0. 6 0. 5 0. 4 0. 3 0. 2 0. 1 0 11. 995 23. 977 Output Power [W] 200 k. Hz Ga. N: 600 k. Hz 1 MHz 36. 038 200 k. Hz Silicon: 600 k. Hz 1 MHz 5 -13

Efficiency Graphs Efficiency 4 V Input Performance 1 0. 9 0. 8 0. 7 0. 6 0. 5 0. 4 0. 3 0. 2 0. 1 0 11. 996 23. 992 Output Power [W] 200 k. Hz Ga. N: 600 k. Hz 1 MHz 35. 981 200 k. Hz Silicon: 600 k. Hz 1 MHz 5 -14

Efficiency Graphs 5 V Input Performance 1 0. 9 0. 8 Efficiency 0. 7 0. 6 0. 5 0. 4 0. 3 0. 2 0. 1 0 11. 991 24. 006 Output Power [W] 200 k. Hz Ga. N: 600 k. Hz 1 MHz 35. 977 200 k. Hz Silicon: 600 k. Hz 1 MHz 5 -15

Efficiency Graphs 6 V Input Performance 1 0. 9 0. 8 Efficiency 0. 7 0. 6 0. 5 0. 4 0. 3 0. 2 0. 1 0 11. 996 23. 994 Output Power [W] 200 k. Hz Ga. N: 600 k. Hz 1 MHz 35. 988 200 k. Hz Silicon: 600 k. Hz 1 MHz 5 -16

Silicon Switching Period 5 -17

Ga. N Switching Period 5 -18

Ga. N Physical Switching Period 5 -19

Conclusion Gallium Nitride has: • Desirable material properties in a transistor. • High frequency, allowing smaller circuits. • Development into becoming cheaper. Applications: • Smaller, more efficient power converters. • Faster, more reliable data transfer. 5 -20

Acknowledgements This work was supported primarily by the ERC Program of the National Science Foundation and DOE under NSF Award Number EEC-1041877. Other US government and industrial sponsors of CURENT research are also gratefully acknowledged. 21

Questions and Answers 22

5 -23

Power Converters A power converts electrical energy from: • AC to AC • AC to DC • DC to AC • DC to DC Types of DC to DC converters: • Step Down (Buck) Converters • Step Up (Boost) Converters

Result Analysis • Put in efficiency of simulation versus efficiency of measured values • Compare these efficiencies with data from Silicon Opti. MOS direct. FET

What is existing technology? Silicon MOSFETs • Currently the industry is mostly reliant on Silicon MOSFETs • It has a cheap price • Its manufacturing processes are matured • It is already in enhancement mode, which is easier and safer Ga. N MOSFETs • Ga. N MOSFETs are not as cheap • Its manufacturing processes are not yet mature • It is not inherently in enhancement mode and steps must be taken for it to be in that mode

Switching Loss 5 -27

Conduction Loss 5 -28

Gate Loss 5 -29