improving system performance with egan fets in dc-dc … · 2016-01-10 · egan fet packaging...
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www.epc-co.com EPC - The Leader in eGaN® FETs 1
The eGaN® FET
Journey Continues
David Reusch, Johan Strydom, Alex Lidow
Efficient Power Conversion Corporation
Improving System Performance with
eGaN® FETs in DC-DC Applications
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Why Gallium Nitride?
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Where Gallium Nitride?
Bus
Converter
AC input: 90~265 V
AC/DC
Front End
Bus
Converter
AC/DC
Front End
48 V
12 V
1.2 V 5 V 3. 3V
POL POL POL
2MHz GaN Based
12 V 3D POL Ref: ece.vt.edu
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TCF TVR
4
Ideal Hard Switching
VDS
IDS
VGS
VIN
IOFF
𝐏𝐓𝐕𝐑 ≈𝐕𝐈𝐍 ∗ 𝐈𝐎𝐅𝐅 ∗ 𝐐𝐆𝐃
𝟐 ∗ 𝐈𝐆 𝐏𝐓𝐂𝐅 ≈
𝐕𝐈𝐍 ∗ 𝐈𝐎𝐅𝐅 ∗ 𝐐𝐆𝐒𝟐𝟐 ∗ 𝐈𝐆
t
VPL
VTH
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40V Device Comparison
0
5
10
15
20
25
30
eGaN® FET Si MOSFET 1 Si MOSFET 2 Si MOSFET 3 Si MOSFET 4
FO
M=
(QG
D+
QG
S2)*
RD
SO
N (p
C*Ω
)
QGD
QGD
QGD QGD QGD
QGS2
QGS2
QGS2 QGS2
QGS2
VDS=20 V, IDS= 20 A
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3
3.25
3.5
3.75
4
4.25
4.5
4.75
5
5.25
5.5
0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3P
ow
er
Lo
ss(W
)
Parasitic Inductance (nH)
Power Loss vs Parasitic Inductance
Ls
3
3.25
3.5
3.75
4
4.25
4.5
4.75
5
5.25
5.5
0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3P
ow
er
Lo
ss(W
)
Parasitic Inductance (nH)
Power Loss vs Parasitic Inductance
Ls LLoop
Cin
T
SR
6
LS: Common Source
Inductance VIN=12 V, VOUT=1.2 V,
FS=1 MHz, IOUT= 20 A
Buck Converter Parasitics
LLoop: High Frequency
Power Loop Inductance
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eGaN FET
Packaging Evolution
SO-8 LFPAK DirectFET LGA
65
70
75
80
85
90
0.5 1 1.5 2 2.5 3 3.5
Eff
icie
ncy (
%)
Switching Frequency (MHz)
SO-8
LFPAK
DirectFET
LGA
0
0.5
1
1.5
2
2.5
SO-8 LFPAK DirectFET LGA
Po
we
r L
os
s (
W)
Device Loss Breakdown
Package
Die
18%
82%
0
0.5
1
1.5
2
2.5
SO-8 LFPAK DirectFET LGA
Po
we
r L
os
s (
W)
Device Loss Breakdown
Package
Die
18%
82%
27%
73%
0
0.5
1
1.5
2
2.5
SO-8 LFPAK DirectFET LGA
Po
we
r L
os
s (
W)
Device Loss Breakdown
Package
Die
18%
82%
27%
73%
53%
47%
0
0.5
1
1.5
2
2.5
SO-8 LFPAK DirectFET LGA
Po
we
r L
os
s (
W)
Device Loss Breakdown
Package
Die
18%
82%
27%
73%
53%
47%
82%
18%
VIN =12V
VOUT =1.2V
IOUT =20A
FS =1MHz
Drain
Source
Gate
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83
84
85
86
87
88
89
90
91
2 4 6 8 10 12 14 16 18 20 22 24
Eff
icie
nc
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
Eff
icie
nc
y (
%)
Output Current (IOUT)
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
Eff
icie
nc
y (
%)
Output Current (IOUT)
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
Eff
icie
nc
y (
%)
Output Current (IOUT)
LLoop≈
1.0nH
LLoop≈
1.6nH
LLoop≈
0.4nH
LLoop≈
2.9nH
40V MOSFET
8
Layout Impact on Efficiency
VIN=12 V, VOUT=1.2 V,
FS=1 MHz, L=150 nH
Measured Efficiency
Experimental Prototype
LLOOP≈0.4 nH
3x3mm LFPAK
LLoop≈3nH
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LLoop≈1.0 nH
9
LLoop ≈ 0.4 nH
Layout Impact on Peak Voltage
VIN=12 V VOUT=1.2 V IOUT=20 A
FS=1 MHz L=150 nH
Switching Node Voltage
70% Overshoot 30% Overshoot
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Top View
Conventional Lateral Layout
Side View
Shield Layer
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Top View Side View
Conventional Vertical Layout
Bottom View
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Side View
Top View
EPC Optimal Layout
Top View
Inner Layer 1
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Efficiency Comparison
VIN=12 V VOUT=1.2 V FS=1 MHz L=300 nH
GaN T/SR: EPC2015 Driver LM5113
83
84
85
86
87
88
89
90
91
2 4 6 8 10 12 14 16 18 20 22 24 26
Eff
icie
ncy (
%)
Output Current (IOUT)
40 V MOSFETVertical Design 1
Vertical Design 1
Lateral Design 1
Optimal Design 1
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Si MOSFET
eGaN FET
Optimal
Layout
3 V/Div
VIN=12 V VOUT=1.2 V IOUT=20 A FS=1 MHz L=300 nH eGaN FET
T/SR: EPC2015 MOSFET T:BSZ097N04 SR:BSZ040N04
20 ns/ div
40 V eGaN FET vs. 40 V Si MOSFET
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80
81
82
83
84
85
86
87
88
89
90
91
2 4 6 8 10 12 14 16 18 20 22
Eff
icie
ncy (
%)
Output Current (IOUT)
40 V Discrete eGaN FET
40 V Discrete MOSFET
40 V eGaN FET
80
81
82
83
84
85
86
87
88
89
90
91
2 4 6 8 10 12 14 16 18 20 22
Eff
icie
ncy (
%)
Output Current (IOUT)
40 V Discrete eGaN FET
40 V Discrete MOSFET
25 V Discrete MOSFET
40 V eGaN FET
80
81
82
83
84
85
86
87
88
89
90
91
2 4 6 8 10 12 14 16 18 20 22
Eff
icie
ncy (
%)
Output Current (IOUT)
40 V Discrete eGaN FET
40 V Discrete MOSFET
25 V Discrete MOSFET
30 V Module MOSFET
40 V eGaN FET
VIN=12 V VOUT=1.2 V FS=1 MHz L=300 nH
eGaN FET vs. MOSFET Efficiency
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VIN=12 V VOUT=1.2 V L=300 nH
76777879808182838485868788899091
2 4 6 8 10 12 14 16 18 20 22
Eff
icie
nc
y (
%)
Output Current (IOUT)
1 MHz
2 MHz
40 V Optimal
Layout eGaN FET
30 V Integrated
MOSFET Module
Pushing Frequency with eGaN FETs
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30 V Si MOSFET
Module
eGaN FET
Optimal
Layout
eGaN FET vs. Si MOSFET Module
3 V/Div
VIN=12 V VOUT=1.2 V IOUT=20 A FS=1 MHz L=300 nH eGaN FET
T/SR: EPC2015 MOSFET Module: CSD97370Q5M
20 ns/ div
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VIN=12-28 V VOUT=3.3 V
IOUT=15 A FS=1 MHz
2 x EPC2015
5 V/ div
Switching Node
Voltage VIN=28 V IOUT=15 A
VIN=28 V
EPC9107 Demonstration Board
20 ns/ div
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Summary
eGaN FETs improve performance in high
switching frequency converters:
• Lower FOM (QGD+QGS2)*RDSON
• Lower Package Parasitics
• PCB Layout Limits Performance
• Optimizing Layout Enhances Performance
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Thank you for
your time!
Questions?