gan transistors for efficient power conversion · 2016-01-10 · ©2012 efficient power conversion...

EPC - The Leader in eGaN ® FETs |

Efficient Power Conversion Corporation

The eGaN® FET Journey Continues

GaN Transistors for Efficient Power Conversion Alex Lidow

CEO

©2012 Efficient Power Conversion Corporation EPC - The Leader in eGaN ® FETs |

Agenda

• The GaN Journey Begins

• Enhancement Mode GaN FETs

• Improving Power Conversion Efficiency

• What is in the future?

2


The Ideal Power Switch

• Block Infinite Voltage

• Carry Infinite Current

• Switch In Zero Time

• Zero Drive Power

• Normally Off

3


Material Comparison

4


Material Comparison

5


GaN vs SiC Comparison

Pro GaN • GaN mobility almost 3 times SiC • GaN on silicon can be manufactured in a standard silicon

foundry on large diameter wafers • GaN-on-silicon starting material can be much lower cost

than SiC • Monolithic integration of multiple power and analog

devices is straightforward Pro SiC • SiC thermal conductivity is 3 times GaN • SiC vertical devices may be more straightforward to

manufacture than GaN-on-silicon 6


GaN Market Projection

Total = $350M for GaN in 2015

Source: Yole Development

7


How Does a GaN HEMT Work?

8


GaN + AlGaN

AlGaN

GaN

Spontaneous Polarization

9


Device Construction Concept

GaN

Substrate

Drain

Protection Dielectric

Source

Gate AlGaN

10

AlN Buffer


Normally ON Devices

S D G

11

In a normally ON device the 2DEG can only be removed under the gate electrode when a negative gate voltage is applied

relative to the source


Normally Off Devices – eGaN®FETs

S D G

12

At zero volts on the gate the 2DEG is depleted under the enhancement mode gate electrode and is restored by a

positive voltage on the gate relative to the source


SEM of an eGaN® FET

eGaN® Is A Registered Trademark Of The Efficient Power Conversion Corporation 13


On Resistance vs Temperature

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

2.1

2.2

-50 -25 0 25 50 75 100 125 150

Nor

mal

ized

On

Resi

stan

ce

Junction Temperature (°C)

GaN

MOSFET B

About 20%

Difference At 125 °C

14


Threshold vs Temperature

0.6

0.7

0.8

0.9

1

1.1

1.2

-50 -25 0 25 50 75 100 125 150

Nor

mal

ized

The

rsho

ld V

olta

ge

Junction Temperature (°C)

GaN

MOSFET A

15


eGaN®FET Reverse Conduction

16


Total Gate Charge

0

2

4

6

8

10

12

14

16

0 5 10 15 20 25 30 35

Gat

e-To

-Sou

rce

Volta

ge (

V)

Total Gate Charge (nC)

MOSFET A

MOSFET B

GaN

17


Figure of Merit

0

100

200

300

400

500

EPC2001 BSC109N10NS3 IRFH5030 SiR870DP FDMS86101

FOM = Rdson x Qg (100V)

18


Package Wish List

• Low parasitic resistance

• Low parasitic inductance

• Low thermal resistance

• Small size

• Low cost

19

©2012 Efficient Power Conversion Corporation EPC - The Leader in eGaN ® FETs | 20

Flip Chip LGA Assembly

HEATSINK


LGA Construction

Gate

Substrate

Source Contacts

Drain Contacts

21


Size Comparison

D-PAK

eGaN FET

Drawn To Scale

5.76 mm²

65.3 mm²

22


Package Inductance

23


Package Resistance

24


The Opportunity to Improve DC-DC Efficiency

25


Integrated Gate Driver Solution

LM5113 from Texas Instruments

26


Buck Converter

Advantage: • High power density

and high efficiency

27


Efficiency vs Frequency

62%

64%

66%

68%

70%

72%

74%

76%

78%

80%

82%

84%

86%

88%

90%

92%

300 400 500 600 700 800

Effi

cien

cy (%

)

Switching Frequency (kHz)

MOSFET @ 12Vin

MOSFET @ 24Vin

MOSFET @ 48Vin

eGaN FET @ 12Vin

eGaN FET @ 24Vin

eGaN FET @ 48Vin

1.2 Vout / 5A

28


Parallel FET Buck Converter Efficiency at 1 MHz

12 VIN – 1.2 VOUT

29


Buck Size Comparison

A 24V-1.2V Buck converter was built with both with eGaN FETs and state-of-the-art silicon power MOSFETs

30



184 mm2

31

The MOSFET-based circuit measures 184 mm2



121 mm2

A 24V-1.2V Buck converter with eGaN FETs is 50% smaller and has 30% less power losses at 800 kHz.

32


Isolated Full Bridge Converter

Advantage: • Isolation and high power

density at high power 36~75 V

12 V 15 A 180 W

~48 V ~53V

700 W 2-phase

33



34


84%

86%

88%

90%

92%

94%

96%

0 2 4 6 8 10 12 14 16

Effi

cien

cy

Output Current (A)

36 V eGaN FET

36 V MOSFET

48 V eGaN FET

48 V MOSFET

60 V eGaN FET

60 V MOSFET

eGaN FET @ 333 kHz vs MOSFET @ 250 kHz


35

VOUT = 12 V


PoE-PSE Full Bridge Converter

36


88%

89%

90%

91%

92%

93%

94%

95%

96%

97%

98%

0 2 4 6 8 10 12 14

Effic

ienc

y

Output Current (A)

38 V eGaN FET 38 V MOSFET



140 kHz MOSFET

250 kHz eGaN FET

550 W

700 W

37



88%

89%

90%

91%

92%

93%

94%

95%

96%

97%

98%

0 2 4 6 8 10 12 14

Effic

ienc

y

Output Current (A)

38 V Two phase 38 V Single phase



38



Paralleling eGaN®FETs

39


Half-Bridge Topologies

Q1a

Q2a

Gate Driver

Gate Driver

. . .

Q1b Q1n

Q2b Q2n

40


Introducing the PIF

• Based on minimum switching time that maintains dv/dt and di/dt immunity

• Normalizes evaluations relative to a single FET

• Can be used to predict switching performance

41

Note: dvx/dt and dix/dt are in units of time


Half Bridge Layout Evaluations

D E B C A

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Single Component Sided Double Component Sided

42


PIF for Half Bridge Layouts

2 Devices in Parallel 4 Devices in Parallel

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D E B C A

43


Best Layout Configuration

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44


Four FETs Operating in Parallel


What’s in the Future?

46


Breaking Down the Barriers

• Does it enable significant new capabilities?

• Is it easy to use?

• Is it VERY cost effective to the user?

• Is it reliable?

47






• Is it reliable?

48


• Wireless Power Transmission – GaN Enabled

• RF DC-DC “Envelope Tracking” – GaN Enabled

• RadHard

• Power Over Ethernet

• RF Transmission

• Network and Server Power Supplies

• Power Factor Correction

• Point of Load Modules

• Solar Microinverters

• Energy Efficient Lighting

• UPS Systems

• Class D Audio

49

Applications for eGaN® FETs


0

10

20

30

40

50 500

Gai

n (d

B)

Frequency [MHz]

EPC1012 Maximum Gain Vs Frequency

High Frequency High Voltage and High Power

1000

EPC 2012 Maximum Gain vs Frequency 200 V eGaN FETs

50


Wireless Power

51


RF Envelope Tracking

0

10

20

30

40

50

60

70

PA Ef

ficie

ncy (

%)

Peak PowerAverage Power

Output Power (dBm)

Output Probability

52






• Is it reliable?

53


It’s just like a MOSFET

Is it easy to use?

except

The high frequency capability makes circuits using eGaN FETs sensitive to layout

The lower VG(MAX) of 6 V makes it advisable to have VGS

regulation in your gate drive circuitry

The ultra-small LGA increases the concentration of heat on the PCB

54






• Is it reliable?

55


Silicon vs eGaN® FET Wafer Costs

Starting Material

Epi Growth

Wafer Fab

Test

Assembly

OVERALL

2011 2015

same same

higher

same

same

lower

lower

same

lower

~same?

lower! higher

56






• Is it reliable?

57


eGaN® FETs are Reliable

58

00.20.40.60.8

11.21.41.61.8

2

0 200 400 600 800 1000

Nor

mal

ized

Rds

on

Stress Hours

EPC2001 RDS(ON) after 100VDS HTRB at 125oC

00.20.40.60.8

11.21.41.61.8

2

0 200 400 600 800 1000

Vth

(V)

Stress Hours

EPC2001 VGS(TH) after 100VDS HTRB at 125oC

0.0E+00

1.0E-04

2.0E-04

3.0E-04

4.0E-04

5.0E-04

0 200 400 600 800 1000

Idss

@40

V (A

)

Stress Hours

EPC2015 Idss after 40V H3TRB at 85oC/85%RH

datasheet spec: 500uA max

0.9

0.95

1

1.05

1.1

0 1000 2000 3000

Nor

mal

ized

Effic

ienc

y

Stress Hours

EPC9001 Efficiency after Op Life Test at 85oC TJ

board a

board b

board c

board d

board e


59

47

25

100

250400

1.00

10.00

100.00

1000.00

0 200 400 600 800 1000 1200 1400

Rat

ed R

DS(

ON

)m

Ω

Rated VDSS(MAX)

Beyond 600 Volts

500 mΩ 5x6mm PQFN

150 mΩ 8x8mm PQFN

90 mΩ 8x8mm PQFN

LGA Package

59


Driver On Board

Beyond Discrete Devices

Full-Bridge with Driver and Level Shift

Discrete FET with Driver

60


Summary

• eGaN FETs are straightforward to use, but care must be taken due to the higher switching speeds compared with power MOSFETs

• eGaN FETs will replace silicon power MOSFETs in power conversion applications with a low-cost and higher efficiency solution

• Higher voltage devices and the integration of analog plus power will enhance the performance and cost-effectiveness of eGaN FETs

61


The end of the road for silicon…..

is the beginning of

the eGaN FET journey!

gan transistors for efficient power conversion · 2016-01-10 · ©2012 efficient power conversion...

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