high efficiency microwave amplifiers and sic varactors optimized for dynamic load modulation c...
TRANSCRIPT
![Page 1: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/1.jpg)
High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load
Modulation
CHRISTER ANDERSSON
Microwave Electronics LaboratoryDepartment of Microtechnology and Nanoscience – MC2
May 23, 2013
![Page 2: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/2.jpg)
2
Thesis contributions
Theory and technology for energy efficient and high capacity wireless systems
Power amplifier analysis Transistor technology and modeling Wideband design [A]
Transmitter efficiency enhancement Dynamic load modulation [B, C] Active load modulation [D]
Varactors for microwave power applications SiC varactors for DLM [E, F] Nonlinear characterization [G]
![Page 3: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/3.jpg)
POWER AMPLIFIER ANALYSIS
![Page 4: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/4.jpg)
4
Transistor technology
GaN HEMT High Ropt and high XCds/Ropt ratio Ideal choice for wideband high power amplifiers
Fano limit:
Baredie 15-W GaN HEMT (Cree, Inc.)
Simplified model:
![Page 5: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/5.jpg)
5
Resistive harmonic loading [A]
ZL(f) = Ropt
Pout = class-Bη = 58%
Dimensions: 122 mm x 82 mm.
![Page 6: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/6.jpg)
6
Measurements [A]
Decade bandwidth performance (0.4 – 4.1 GHz) Pout > 10 W η = 40 – 60%
DPD linearized to standard ACRL < –45 dBc
Envelope tracking candidate
![Page 7: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/7.jpg)
TRANSMITTER EFFICIENCY ENHANCEMENT
Dynamic and active load modulation
![Page 8: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/8.jpg)
8
Dynamic load modulation (DLM) [B,C]
Load modulation Restore voltage swing and efficiency
Varactor-based DLM Reconfigure load network at signal rate
![Page 9: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/9.jpg)
9
Class-J DLM theory [B]
DLM by load reactance modulation Ideal for varactor implementation
Theory enables analysis Technology requirements Power scaling [B] → [C] Frequency
reconfigurability
![Page 10: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/10.jpg)
10
10-W demonstrator @ 2.14 GHz [B]
3-mm GaN HEMT + 2x SiC varactors Efficiency enhancement: 20% → 45% @ 8 dB OPBO
CuW-carrier dimensions: 35 mm x 20 mm.
![Page 11: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/11.jpg)
11
100-W demonstrator @ 2.14 GHz [C]
Fully packaged 24-mm GaN HEMT + 4x SiC varactors Record DLM output power (1 order of mag.) Efficiency enhancement: 10-15% units @ 6 dB
DPD by vector switched GMP model 17-W WCDMA signal, η = 34%, ACLR < –46 dBc
Package internal dimensions: 40 mm x 10 mm.
40V30V20V
![Page 12: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/12.jpg)
12
Active load modulation [D]
Mutual load modulation using transistors Both transistors must operate efficiently Co-design of MN1, MN2, and current control functions
• Successful examples: Doherty and Chireix Modulate current amplitudes and phase at signal rate
β1 β2, φ
![Page 13: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/13.jpg)
13
Dual-RF input topology [D]
Complex design space – many parameters Linear multi-harmonic calculations (MATLAB)
Include transistor parasitics No assumption of short-circuited higher harmonics Optimize for wideband high average efficiency
• Output: circuit values + optimum current control(s)
β1 β2, φ
![Page 14: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/14.jpg)
14
Verification of calculations [D] 2 x 15-W GaN HEMT design
Straightforward ADS implementation – plug in MATLAB circuit values Parasitics and higher harmonics catered for already
Good agreement with complete nonlinear PA simulation
WCDMA 6.7 dB PAPR
(MATLAB)(ADS)
![Page 15: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/15.jpg)
15
Measurements [D]
Performance over 100% fractional bandwidth (1.0 – 3.1 GHz) Pmax = 44 ± 0.9 dBm PAE @ 6 dB OPBO > 45%
Record efficiency bandwidth for load modulated PA
Dimensions: 166 mm x 81 mm.
![Page 16: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/16.jpg)
VARACTORS FOR MICROWAVE POWER APPLICATIONS
14-finger SiC varactor (Cmin = 3 pF).
Chalmers MC2 cleanroom.
Varactor-based DLM architecture.
![Page 17: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/17.jpg)
17
Varactor effective tuning range
Increasing RF swing decreasing Teff Shape of varactor C(V) matters Nonlinear characterization [G]
Engineer C(V) to be less abrupt
![Page 18: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/18.jpg)
18
Schottky diode SiC varactors [E,F]
SiC varactor performance [E,F] Moderate small-signal tuning range High breakdown voltage High Q-factor Highest tuning range when |RF| > 5 V Used in [B,C,d,g,h]
Engineer doping profile Higher doping
• Lower loss• Higher electric fields
Wide bandgap SiC High critical electric field
![Page 19: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/19.jpg)
19
Conclusions Energy efficient wideband power amplifiers
Simplified modeling (XCds/Ropt) Resistive harmonic loading [A] Varactor-based dynamic load modulation [B,C] Active load modulation [D]
Varactors for microwave power applications Nonlinear characterization [G] Novel SiC varactor [E,F]
• Dynamic load modulation one of many applications
Theory and technology for energy efficient high capacity wireless systems
![Page 20: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/20.jpg)
20
Acknowledgment
• ”Microwave Wide Bandgap Technology project”• ”Advanced III-Nitrides-based electronics for future microwave communication and sensing systems”• ”ACC” and ”EMIT” within the GigaHertz Centre
This work has been performed as part of several projects:
![Page 21: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/21.jpg)
21
![Page 22: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/22.jpg)
22
![Page 23: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/23.jpg)
23
Power amplifiers (PA)
Final stage amplifier before antenna High power level → efficiency (η) critical
PA internals FET Input matching network Load matching network Nonlinear circuit
Propose simplifications to allow linear analysis These are used in [A-D]
![Page 24: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/24.jpg)
24
Model simplifications [A-D]
Linear transistor (constant gm) Load line in saturated region
(no compression) Class-B bias
Sinusoidal drive → half-wave rectified current
Bare-die parasitics mainlyshunt-capacitive Effective ”Cds” found by load-pull
15-W GaN HEMT (Cree, Inc.)
![Page 25: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/25.jpg)
25
Power amplifiers (PA)
Final stage amplifier before antenna High power level → efficiency most critical
![Page 26: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/26.jpg)
26
Typical PA
Transistor Microwave frequency FET
Input network Gate bias, stability, source impedances (current wave shaping)
Load network Drain supply, load impedances (voltage wave shaping)
![Page 27: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/27.jpg)
27
Transistor equivalent circuit
Complete model is complicated Nonlinear voltage-controlled current source Nonlinear capactiances Feedback Package parasitics
Propose simplifications to allow linear analysis These are used in [A-D]
![Page 28: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/28.jpg)
28
Comparison [A]
![Page 29: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/29.jpg)
29
PA efficiency and modern signals
PA efficiency drops in output power back-off (OPBO) Modern signals
High probability to operate in OPBO Average efficiency is low
Need an architecture to restore the efficiency in OPBO
![Page 30: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/30.jpg)
30
Dynamic load modulation (DLM)
PA efficiency drops in output power back-off (OPBO) Load modulation
Restore voltage swing and efficiency Varactor-based DLM
Reconfigure load network at signal rate Linearization: RF input + baseband varactor voltage
![Page 31: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/31.jpg)
31
Doherty-outphasing continuum [D]
Dual-RF input PA – optimum current control versus power & frequency Classic Doherty impedances & short-circuited higher harmonics Classic Doherty transmission line lengths not best choice
• Adding 90° includes outphasing operation and gives higher efficiencies
(class-B efficiency)
WCDMA 6.7 dB PAPR
![Page 32: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/32.jpg)
32
Reality check [D]
Realistic circuit Cannot assume short-circuited higher harmonics Must consider transistor parasitics
Complicated design space (not suitable for ADS) Linear multi-harmonic calculations (MATLAB)
Assume simplified transistor model Optimize circuit values
• Relatively cheap calculation• Brute-force evaluation of 14M circuits vs. drive and frequency
![Page 33: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/33.jpg)
33
Nonlinear characterization [G]
Active multi-harmonic source/load-pull system Study of an abrupt SiC varactor
![Page 34: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/34.jpg)
34
Power dependent detuning and loss [G]
Capacitance and loss increase with RF swing Dependent on varactor and circuit topology
![Page 35: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/35.jpg)
35
Effect of 2nd harmonic loading [G]
Q–factor drop due to resonance Relevance in tunable circuit design Varactors inherently nonlinear devices
![Page 36: High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation C HRISTER A NDERSSON Microwave Electronics Laboratory Department](https://reader036.vdocuments.site/reader036/viewer/2022062515/56649c905503460f94949d29/html5/thumbnails/36.jpg)
36
Nonlinear varactor characterization [G]
Active multi-harmonic source/load-pull system Study of an abrupt SiC varactor
Capacitance and lossincrease versus RF swing Harmonic loading dependent
| RF | | RF |