National Taiwan University · 2016. 1. 10. · EPC -The Leader in eGaN® FETs National Taiwan University 2012F0049, not a controlled doc.; RT001b 2/13/09 30 Summary • eGaN FETs

www.epc-co.comEPC - The Leader in eGaN® FETs National Taiwan University 2012 1

The eGaN® FET Journey Continues

Alex LidowEfficient Power Conversion CorporationNovember 2012

National Taiwan UniversityEmerging Applications for GaN Transistors


Agenda

• Why Gallium Nitride?• Hard Switched Converters

• Envelope Tracking• High Frequency Resonant Converters

• Wireless Power• Summary


Why Gallium Nitride?

• Enhancement-Mode devices available (eGaN® FETs)

• RDS(ON) per unit area much smaller than silicon power MOSFET

• Much faster switching• Very low capacitance (CG, CISS, COSS)• No parasitic PN junction body (QRR=0)


Dielectric

GaN- - - - - - - - - - - - - - -

Si

AlGaN Electron Generating Layer

Aluminum NitrideIsolation Layer

DGS- - - -

eGaN® FET Structure

Two DimensionalElectron Gas (2DEG)


Flip Chip Assembly

HEATSINK


Hard Switched Converters


Example: Buck Converter


33.253.5

3.754

4.254.5

4.755

5.255.5

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3Po

wer

Los

s(W

)Parasitic Inductance (nH)

Power Loss vs Parasitic Inductance

Ls

33.253.5

3.754

4.254.5

4.755

5.255.5

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3Po

wer

Los

s(W

)Parasitic Inductance (nH)

Power Loss vs Parasitic Inductance

LsLLoop

Cin

T

SR

LLoop: High Frequency Power Loop Inductance

LS: Common Source Inductance

VIN=12 V, VOUT=1.2 V, FS=1 MHz, IOUT= 20 A

Buck Converter Parasitics


0

0.5

1

1.5

2

2.5

So-8 LFPAK DirectFET LGA

Pow

er L

oss

(W)

Device Loss BreakdownPackageDie

18%

82%

VIN =12V VOUT =1.2V IOUT =20A FS =1MHz

0

0.5

1

1.5

2

2.5


Pow

er L

oss

(W)


18%

82%

27%

73%


0

0.5

1

1.5

2

2.5


Pow

er L

oss

(W)


18%

82%

27%

73%

53%47%


0

0.5

1

1.5

2

2.5


Pow

er L

oss

(W)


18%

82%

27%

73%

53%47%

82%18%


LFPAK

Packaging Evolution

DirectFET LGA eGaNSo-8

65

70

75

80

85

90

0.5 1 1.5 2 2.5 3 3.5

Effic

ienc

y (%

)

Switching Frequency (MHz)

So-8LFPAKDirectFETeGaN


83

84

85

86

87

88

89

90

91

2 4 6 8 10 12 14 16 18 20 22 24

Effic

ienc

y (%

)

Output Current (IOUT)

LLoop≈2.9nH

40V MOSFET

83

84

85

86

87

88

89

90

91

2 4 6 8 10 12 14 16 18 20 22 24

Effic

ienc

y (%

)


LLoop≈1.6nH

LLoop≈2.9nH

40V MOSFET

83

84

85

86

87

88

89

90

91

2 4 6 8 10 12 14 16 18 20 22 24

Effic

ienc

y (%

)


LLoop≈1.0nH

LLoop≈1.6nH

LLoop≈2.9nH

40V MOSFET

83

84

85

86

87

88

89

90

91

2 4 6 8 10 12 14 16 18 20 22 24

Effic

ienc

y (%

)


LLoop≈1.0nH

LLoop≈1.6nH

LLoop≈0.4nH

LLoop≈2.9nH

40V MOSFET

Layout Impact on Efficiency

VIN=12 V, VOUT=1.2 V, FS=1 MHz, L=150 nH

Experimental Efficiency


0

20

40

60

80

100

120

140

160

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Volta

ge O

vers

hoot

(%)

High Frequency Loop Inductance (LLOOP)

0

20

40

60

80

100

120

140

160

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Volta

ge O

vers

hoot

(%)


0

20

40

60

80

100

120

140

160

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Volta

ge O

vers

hoot

(%)


Peak Voltage Comparison

VIN=12 V, VOUT=1.2 V, FS=1 MHz, L=150 nH


Envelope Tracking


RF Transmission

Fixed supply

Peak PowerAverage Power

Output Power (dBm)

Output Probability

Average efficiency only 25%

Peak efficiency up to 65%


Effect of ET

Envelope Tracking

Output Power (dBm)

Output Probability

Average Power

Average efficiency ~50% (incl. ET)

www.epc-co.comEPC - The Leader in eGaN® FETs National Taiwan University 2012 15F0049, not a controlled doc.; RT001b 2/13/09 www.epc-co.com 15EPC - The Leader in eGaN® FETs National Taiwan University 2012

Linear-Assisted Buck ET


Efficiency45 VIN 22 VOUT


4MHz Loss Breakdown

Top eGaN FET


Resonant Converters


Ref: Y. Ren, M. Xu, J. Sun, and F. C. Lee, “A family of high power density unregulated bus converters,” IEEE Trans. Power Electron., vol. 20, no. 5, pp. 1045–1054, Sep. 2005.

VGS(S1,S3) VGS(SR1)

VGS(S2,S4) VGS(SR2)

ILK1

ILK2

4:1

48V 12V

SR1

SR2

Resonant Converter


eGaN® FET vs MOSFET


MOSFET VGS

MOSFET VDS

eGaN FETVDS

eGaN FET VGS

Duty Cycle Comparison

DMOSFET = 34%DeGaN = 42%

FS = 1.2 MHz, VIN = 48 V, and VOUT = 12 V

21


Efficiency Comparison

90

91

92

93

94

95

96

97

98

0 5 10 15 20 25 30 35 40

Effic

ienc

y (%

)


1.2 MHz MOSFET

1.2 MHz eGaN FET

10 W 12 W

14 W



0

2

4

6

8

10

12

Power Loss (W)

Gate Drive

Transfomrer CoreConduction + Turn Off

eGaN FETIOUT = 20 A

MOSFETIOUT = 20 A

eGaN FET IOUT = 2.5 A

MOSFETIOUT = 2.5 A


Loss Breakdown

Transformer Core


Wireless Power


Wireless Power

25


Wireless Power


Wireless Power


Efficiency Comparison


Loss Breakdown


Summary• eGaN FETs operate efficiently in multi-

megahertz envelope tracking systems which can reduce transmit power by 50%.

• eGaN FETs reduce power losses by 25% or more in 1.2 MHz resonant DC-DC converters.

• eGaN FETs reduce power losses by 25% in 6.78 MHz wireless power transmission systems.

• You can always improve efficiency with eGaN FETs!


The end of the road for silicon…..

is the beginning of the eGaN FET

journey!

Documents

National Taiwan University · 2016. 1. 10. · EPC -The Leader in eGaN® FETs National Taiwan University 2012F0049, not a controlled doc.; RT001b 2/13/09 30 Summary • eGaN FETs