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EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
The eGaN® FET Journey Continues
Alex Lidow
Efficient Power Conversion Corporation
GaN Transistors – Successes and
Challenges Ahead
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Agenda
• GaN Device Structure
• Envelope Tracking
• Wireless Power
• What is in the future?
2
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com 3
Dielectric
GaN
- - - - - - - - - - - - - - -
Si
AlGaN Electron Generating Layer
Aluminum Nitride Isolation Layer
D G S - - - -
eGaN® FET Structure
Two Dimensional Electron Gas (2DEG)
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Printed Circuit Board Copper Traces
Silicon Substrate
Active GaN Device Region
Solder Bars
4
LGA Construction
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Key Applications • RF DC-DC “Envelope Tracking”
• Wireless Power Transmission
• RadHard
• Power Over Ethernet
• RF Transmission
• Network and Server Power Supplies
• Point of Load Modules
• Solar Micro-inverters
• Energy Efficient Lighting
• Class D Audio
5
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Envelope Tracking (ET)
6
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Peak to Average Power Ratio
Reference: Nujira.com website
Same average
Normalized
to same peak
7
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Effect of PAPR
Peak Power Average Power
Output Power (dBm)
Output Probability
Fixed supply
Average efficiency only 25 %
PAPR = 0dB Peak efficiency
up to 65%
Increasing PAPR
8
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Effect of Envelope Tracking
Output Power (dBm)
Average Power
Output Probability
Only 1/3 the losses Average efficiency > 50 % (incl. ET)
Envelope Tracking
9
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Envelope Tracking Supply
Buck ~ 10% Bandwidth ~ 90% Power
Linear AMP ~ 10% Power Highest 90% of Bandwidth
*Reference: V. Yousefzadeh, et al, Efficiency optimization in linear-assisted switching power converters for envelope tracking in RF power amplifiers, ISCAS 2005
10
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Efficiency Results
0
2
4
6
8
10
12
14
16
90%
91%
92%
93%
94%
95%
96%
97%
98%
0 50 100 150 200 250 300 350
Pow
er lo
ss (W
)
Effic
ienc
y (%
)
Output Power (W)
4 MHz Efficiency
1 MHz Efficiency
4 MHz Losses
1 MHz Losses
11
45 VIN – 22VOUT
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Wireless Power
12
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Wireless Power
13
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
⁺ Resonant design is in the coil set ⁺ Switch voltage rating = to supply value
Class D Wireless Power
+
VDD
Crp Crs Lrp
Cmrp
Cmp
Lp Ls Cms
⁻ COSS plays an important role in losses
QRF2
QRF1 V / I
VDS_QRF ID_QRF
time
VDD
50%
14
Load
Co
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
System Setup
Device Board
Source Coil Source Board
Coil Feedback
Device Coil
25m
m
25m
m
eGaN FETs RF connection
RF connection
50mm 50mm
15
MOSFETs RF connection
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Efficiency
54
56
58
60
62
64
66
68
70
72
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Efficiency [%]
Output Power [W]
6.639 MHz, 23.6 Ω load
Vin =8V
Vout=6.8V
Vin =22V
Vout=18.3V
16
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
What’s in the Future?
17
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
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?
18
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
• Does it enable significant new capabilities?
• Is it easy to use?
• Is it VERY cost effective to the user?
• Is it reliable?
19
Breaking Down the Barriers
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
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
20
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
• Does it enable significant new capabilities?
• Is it easy to use?
• Is it VERY cost effective to the user?
• Is it reliable?
21
Breaking Down the Barriers
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
It’s just like a MOSFET
Is an eGaN FET 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
22
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
What Other Advances are Needed?
• High speed digital controller ICs and integrated controller/driver ICs.
– Application specific controllers to reduce time-to-market
– Dynamic deadtime control with ~1 ns resolution
– Envelope Tracking Controllers
• Improved measurement systems
23
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
• Does it enable significant new capabilities?
• Is it easy to use?
• Is it VERY cost effective to the user?
• Is it reliable?
24
Breaking Down the Barriers
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Silicon vs. eGaN Wafer Costs
Starting Material
Epi Growth
Wafer Fab
Test
Assembly
OVERALL
2012 2015
same same
higher
same
same
lower
lower
same
lower
~same?
lower! higher
25
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
• Does it enable significant new capabilities?
• Is it easy to use?
• Is it VERY cost effective to the user?
• Is it reliable?
26
Breaking Down the Barriers
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
eGaN FETs are Reliable
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 200 400 600 800 1000
No
rma
lize
d R
dso
n
Stress Hours
EPC2001 RDS(ON) after 100VDS HTRB at 125oC
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
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
No
rmal
ized
Eff
icie
ncy
Stress Hours
EPC9001 Efficiency after Op Life Test at 85oC TJ
board a
board b
board c
board d
board e
27
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Driver On Board
Beyond Discrete Devices
Full-Bridge with Driver and Level Shift
Discrete FET with Driver
28
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com
Summary
• GaN transistors improve efficiency compared with power MOSFETs in power conversion.
• eGaN FETs are straightforward to use, but you can’t just drop them into a MOSFET socket.
• GaN transistors enable exciting new applications such as RF Envelope Tracking and Wireless Power Transmission.
29
EPC - The Leader in eGaN® FETs | April, 2013 | www.epc-co.com 30
The end of the road
for silicon…..
is the beginning of
the eGaN FET
journey!