copec integration of gan supply modulators and rf power...
TRANSCRIPT
![Page 1: CoPEC Integration of GaN Supply Modulators and RF Power ...pwrsocevents.com/wp-content/uploads/2014-presentations/ts...Dragan Maksimovic maksimov@colorado.edu Colorado Power Electronics](https://reader031.vdocuments.us/reader031/viewer/2022013100/61246c0b79a98329dc17fde4/html5/thumbnails/1.jpg)
1University of Colorado Boulder
CoPEC
Integration of GaN Supply Modulators and RF Power Amplifiers
Dragan [email protected]
Colorado Power Electronics Center (CoPEC), ECEE DepartmentUniversity of Colorado - Boulder
Yuanzhe Zhang1, Dr. Miguel Rodriguez1*, Andrew Zai2, Dr. David Sardin2, Prof. Zoya Popovic2
1CU-Boulder Colorado Power Electronics Center (CoPEC): drain supply modulators2CU-Boulder microwaves research group: RFPAs and transmitter systems1*now with AMD
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2University of Colorado Boulder
CoPEC System: RF Transmitters
100W
-30%
143W
9%AC
3kW
Each site has between 3 and 12 transmitters!
RFPA
4G base station example
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3University of Colorado Boulder
CoPEC System Efficiency Improvement Objectives
100W50%
200W
• Higher reliability• Lower system cost• +In mobile platforms: battery life
Requires systems approach, co-design of architecture, baseband, RF, and power electronics
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4University of Colorado Boulder
CoPEC Supply Modulation Approach
Supply modulator performs a form of “envelope tracking” (ET) to achieve linearity and
efficiency improvements
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5University of Colorado Boulder
CoPEC System Operation[1]
0 10 20 30 40-100
-50
0
Freq [MHz]
PS
D [d
B/H
z]
EnvelopeVddIdd
-20 -10 0 10 20-80
-60
-40
-20
0
Freq [MHz]
PS
D [d
B/H
z]
IQin
20MHz 40W BTS ET Transmitter
0
20
40
60
Vdd
0
50
100
150
Env
elop
e
0
2
4
6
Idd
5
10
15
20
Gai
n [d
B]
Time [usec]0 0.1 0.2 0.3 0.4 0.5
0
20
40
60
80
Sav
ed [
W]
|V|
VA
Note: envelope BW can be substantially larger than baseband signal BW
[1] J. Hoversten, S. Schafer, M. Roberg, M. Norris, D. Maksimovic, and Z. Popovic, “Codesign of PA, Supply, and Signal Processing for Linear Supply-Modulated RF transmitters,” IEEE Trans. Microw. Theory Tech. 2012
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6University of Colorado Boulder
CoPEC PwrSOC: ET Transmitter on a Chip
Cascode ET amp, 500 MHz BW
[5, 6]
10W, X-Band RFPA [2, 3, 4]
100MHz switching ET amp, 20MHz BW [8, 9]
5.4 x 3.8 mm in GaN-on-SiC RF process
Saturated, harmonically terminated, high-efficiency RFPA
High-frequency (100MHz), wide-
bandwidth (20MHz) switcher assisted by
500MHz cascodeamplifier
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7University of Colorado Boulder
CoPEC D-mode GaN-on-SiC 0.15 m RF process• Intended for RF applications, e.g. RFPA’s, MMIC’s• Depletion-mode, n-type only, threshold voltage VT ≈ − 3.5 V• Device size (gate periphery) W = N·Wg N = number of gate fingers Wg = gate width
GaN-on-SiC HEMT basic unit cellSimplified device layout with
4 parallel cells
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8University of Colorado Boulder
CoPEC RF PA MMIC Design Example[3]
3.8 x 3.2 mm
• Two-stage X-band (10 GHz) power amplifier MMIC• Class-E output stage: four 0.9 mm devices• Gain: 20 dB, bandwidth: 1.6 GHz
Power-added efficiency as a function of output RF output power at different drain supply voltages
[3] S. Schafer, M. Litchfield, A. Zai, C. Campbell, Z. Popovic, “X-Band MMIC GaN Power Amplifiers Designed for High-Efficiency Supply-Modulated Transmitters,” IEEE MTT IMS 2013, Seattle, WA, June 2013.
![Page 9: CoPEC Integration of GaN Supply Modulators and RF Power ...pwrsocevents.com/wp-content/uploads/2014-presentations/ts...Dragan Maksimovic maksimov@colorado.edu Colorado Power Electronics](https://reader031.vdocuments.us/reader031/viewer/2022013100/61246c0b79a98329dc17fde4/html5/thumbnails/9.jpg)
9University of Colorado Boulder
CoPEC Very high frequency switching supply modulator• Dynamic capabilities suitable for envelope tracking application High bandwidth (20 MHz LTE envelope) and high efficiency (>80%) must be
met simultaneously• Possibilities for SOC integration in the same GaN-on-SiC RF process
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10University of Colorado Boulder
CoPEC Device switch characteristics
Ron,s Coss,s Ciss,s Qg,s
Simulated 2.1 Ω∙mm 0.4 pF/mm 1.5 pF/mm 8.8 pC/mm
Comparison of 40V devices FOM = Ron,sQg,s [pVs]Silicon MOSFET (e.g. Si 2318) 148GaN-on-Si (e.g. EPC 8008) 58RF GaN-on-SiC process 19
Low device FOM Zero-voltage-switching (ZVS) Gate-drive integration
High-efficiency at very high switching frequency
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11University of Colorado Boulder
CoPEC 100 MHz Integrated GaN PWM Buck Converter20 V
5-17 V, 10 W peak100 MHz
PWMcontrol signals
20 MHz tracking bandwidth
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12University of Colorado Boulder
CoPEC 100 MHz Integrated GaN PWM Buck Converter
Key challenge: level-shifting high-side gate driver to support very high frequency (100 MHz) PWM control
20 V
5-17 V, 10 W peak100 MHz
PWMcontrol signals
20 MHz tracking bandwidth
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13University of Colorado Boulder
CoPEC Standard active pull-up driver
Chip layout: 2.4 × 2.3 mm
QHS, QLS DHS, DLS Q1, Q3 Q2, Q4 R1 R2
10x125μm 10x120μm 2x25μm 4x50μm 300 Ω 125 Ω
Half-bridgepower stage
Half-bridge power stageQHS/DHS, QLS/DLS
High-side gate driverQ1, R1, Q2
Low-side gate driverQ3, R2, Q4
Low-sidegate driver
High-sidegate driver Vdd = Vin
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14University of Colorado Boulder
CoPEC Active pull-up driver operationQHS on, QLS off
IQ3=13.2 mA
QHS off, QLS on
IQ1= 8.5 mA
D=0.5, Io=0.25 APd,conduction = DVssLS IQ3+(1D)(VinVssHS)IQ1
0 V 5 V+
+
HIGH
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15University of Colorado Boulder
CoPEC Modified active pull-up driver[8,9]
Chip micro-photograph: 2.4 × 2.3 mm
Half-bridgePower stage
Half-bridge power stageQHS/DHS, QLS/DLS
Half-side gate driverQ1, R1, Q2
Low-side gate driverQ3, R2, Q4
Low-sidegate driver
High-sidegate driver
QHS, QLS DHS, DLS Q1, Q3 Q2, Q4 R1 R2
20x200μm 20x100μm 4x25μm 4x50μm 100 Ω 75 Ω
Vdd
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16University of Colorado Boulder
CoPEC Modified active pull-up driver operationQHS on, QLS off
IQ3=25.6 mA
QHS off, QLS on
IQ1= 23.3 mA
D=0.5, Io=0.25 APd,conduction = DVssLS IQ3+(1D)(VssHS)IQ1
0 V 5 V+
+
LOW
Low driver power loss, and no bootstrap capacitor required
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17University of Colorado Boulder
CoPEC Experimental prototype• 10-200 MHz PWM switching, ZVS operation (QSW) • Control: Altera Stratix IV FPGA, 125 ps resolution• Chip package: 20-pin 4x4mm QFN package• Filter components Low-ESR capacitors High-Q air-core inductor (47 nH)
20 V
5-17 V, 10 W peak10-200 MHzPWM
control signals
2.4 × 2.3mm integrated buck
switching converter chip
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18University of Colorado Boulder
CoPEC
82
84
86
88
90
92
94
96
98
0 50 100 150 200
Eff
icie
ncy
[%]
Switching frequency [MHz]
Efficiency as a function of switching frequency
Peak efficiency
2.4 × 2.3mm integrated buck
switching converter chip
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19University of Colorado Boulder
CoPEC Experimental results at 100 MHz switching frequency
• Pout up to 7 W static• ~ 0.2 W driver loss• 91% peak power-stage efficiency
D = 0.75
Vout = 14 V, Pout = 4.5 W, η = 91.0 %
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20University of Colorado Boulder
CoPEC Application: envelope tracking supply for RFPAs
L1 C2 L3 C4 RL Vin Pout,pk
28 nH 820 pF 307 nH 270 pF 30 Ω 20 V 10 W
vin
L1C2
RLL3
C4vLS
FPGA Look-up
TablevHS
vdd
+
-vsw
+
-
vtarget
• Target signal: 20 MHz bandwidth LTE envelope• 4th order filter, 25 MHz cut-off frequency• 100 MHz switching frequency
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21University of Colorado Boulder
CoPEC Envelope tracking experimental results
• 20 MHz LTE envelope, 100 MHz switching frequency
• Power stage efficiency: 83.7%
• Total efficiency: 80.1% (including on-chip driver loss)
• Normalized RMS error: 5.4%
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22University of Colorado Boulder
CoPEC Path to very high bandwidth (500MHz) tracking
RFPA
Drain modulator vdd(t)
Vin
Drain modulator
Drain modulator
-+
vdd,ref(t)
ilin(t)
Multi-phase switcher [10]
AC-coupled wide-bandwidth linear amplifier [5, 6]
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23University of Colorado Boulder
CoPEC Two-phase buck converter chip
2.6 x 2.7 mm
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24University of Colorado Boulder
CoPEC Two-phase switching ET amplifier
• 50MHz per-phase switching frequency
• 25MHz tracking bandwidth
• 3.4% RMSE tracking 20MHz LTE envelope
• 93.2% peak, 85% total efficiency
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25University of Colorado Boulder
CoPEC ET Transmitter System Test Results
18MHz LTE
PAR=7.1dB
VeSP = signal split + DPD
Composite power-added efficiency: 53.6%
ACPR: -28 dB
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26University of Colorado Boulder
CoPEC Conclusions
• Integrated switching converters in GaN-on-SiC process
• 20 V, 10 W peak, >90% peak efficiency, 100 MHz switching
• Accurate tracking of 20 MHz LTE envelope, 85% overall efficiency
• Path to ET RF transmitter SOC integration with up to 500 MHz envelope bandwidth capability in GaN-on-SiC process
Acknowledgments Dr. Chuck Campbell, John Hitt and Maureen Kalinski, TriQuint (now Qorvo) DARPA MPC program
CascodeET amp,
500 MHz BW [5, 6]
10W, X-Band RFPA [2, 3, 4]
100MHz switching ET amp, 20MHz BW [8, 9]
ET Transmitter on a Chip5.4 x 3.8 mm in GaN-on-SiC RF process
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27University of Colorado Boulder
CoPEC Selected References[1] J. Hoversten, S. Schafer, M. Roberg, M. Norris, D. Maksimovic, Z. Popovic, “Co-design of PA, Supply and
Signal Processing for Linear Supply-Modulated RF Transmitters,” IEEE Trans. Microwave Theory and Techniques, Special Issue on PAs, pp. 210-220, April 2012.
[2] M. Litchfield, M. Roberg, Z. Popovic, “A MMIC/hybrid high-efficiency X-band power amplifier, Power Amplifiers for Wireless and Radio Appl. (PAWR), 2013 IEEE Topical Conf., pp.10,12, Jan. 2013.
[3] S. Schafer, M. Litchfield, A. Zai, C. Campbell, Z. Popovic, “X-Band MMIC GaN Power Amplifiers Designed for High-Efficiency Supply-Modulated Transmitters,” IEEE MTT IMS 2013, Seattle, WA, June 2013.
[4] A. Zai, S. Schafer, D. Sardin, Y. Zhang, D. Maksimovic, Z. Popovic, “High-Efficiency X-Band MMIC GaNPower Amplifiers with Supply Modulation,” IEEE IMS 2014
[5] D. Sardin, Z. Popovic, “Decade Bandwidth High-Efficiency GaN VHF/UHF Power Amplifier,” IEEE MTT IMS 2013, Seattle, WA, June 2013
[6] D. Sardin, Z. Popovic, “High Efficiency 15-500MHz Wideband Cascode GaN HEMT MMIC Amplifiers,” IEEE IMS 2014.
[7] M. Rodriguez, Y. Zhang, and D. Maksimovic, “High-frequency PWM buck converters using GaN-on-SiCHEMTs,” IEEE Trans. Power Electron., vol. 29, no. 5, pp. 2462–2473, 2014.
[8] Y. Zhang, M. Rodriguez, and D. Maksimovic, “High-frequency integrated gate drivers for half-bridge GaNpower stage,” in Control and Modeling for Power Electron. (COMPEL), 2014 IEEE 15th Workshop on, 2014.
[9] Y. Zhang, M. Rodriguez, and D. Maksimovic, “100 MHz, 20 V, 90% efficient synchronous Buck converter with integrated gate driver,” in Proc. IEEE Energy Convers. Congr. Expo., 2014.
[10] M. Norris, D. Maksimovic, “10 MHz large signal bandwidth, 95% efficient power supply for 3G-4G cell phone base stations,” IEEE APEC 2012.