The document summarizes techniques and challenges in designing wideband power amplifiers using GaN and LDMOS transistors. It discusses how GaN has advantages over LDMOS like higher bandwidth, efficiency and power density. It provides comparisons of typical parameters for LDMOS and GaN technologies. The document also discusses wideband PA design techniques, challenges involving thermal management, linearity and ruggedness, and provides examples of wideband GaN and LDMOS PA applications with simulation and measurement results.

1. PUBLIC
JEFFREY HO
RF APPLICATIONS ENGINEER
RF POWER GROUP, NXP SEMICONDUCTORS
SEPTEMBER, 20, 2016
ELECTRONIC DESIGN INNOVATION CONFERENCE (EDI CON)
TECHNIQUES AND CHALLENGES IN DESIGNING WIDEBAND
POWER AMPLIFIERS USING GAN AND LDMOS

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Agenda
GaN and LDMOS Parametric Comparison
• Device Technology Benefits
• System Level Tradeoffs
GaN Advantages
• Bandwidth, Efficiency, Power Density
Wideband PA Design and Challenges
• Wideband Techniques
• Thermal, Linearity, Ruggedness
GaN and LDMOS Wideband PA Applications
• Nonlinear Model Simulation
• CW and Pulsed Performance
NXP Power Product Portfolio
Conclusion

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GaN and LDMOS Technology
• GaN-on-SiC 50V technology provides higher
efficiency, power density and more gain in a
small package.
• GaN devices are capable of best in-class
solutions for broadband applications.
• GaN’s high output impedance and low Cds
capacitance enables broadband design.
Bandwidth limitation on the input match.
• For identical power level, GaN transistors
have smaller parasitic capacitance, which
makes the wideband matching easier than
LDMOS transistors.
GaN LDMOS
• LDMOS is still demonstrating high power and
efficiency in cellular and broadcast narrow-
band applications.
• 50V LDMOS are primarily used for
frequencies < 1.5 GHz. 28V LDMOS can
provide compelling performance up to 4 GHz.
• LDMOS transistor’s large peripheries imply
large Cgs/Cds capacitances which limit the
bandwidth.

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GaN and LDMOS: Parametric Comparisons
Typical Parameters
LDMOS (28V)
LDMOS
(50V)
GaN
(50V)
GaN
Advantage
Fmax (GHz) 22 15 30
High frequency operation 
2.5GHz and above
Power Density (W/mm) 0.8 2 5-10
Higher Power density 
smaller device footprint
Efficiency @ P1dB (%) 60 < 55 70
Higher efficiency 
2.5 GHz and above
Bandwidth (MHz) 100-400 100-500 500-2500 One device covers multi-bands
Cds (pf/W)
Output Capacitance
0.23 ½ smaller ¼ smaller
Smaller device capacitance 
broadband operationCgs (pf/W)
Input Capacitance
0.94 ½ smaller ½ smaller

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Leveraging the Benefits of GaN and LDMOS
• Differentiating performance exceeding
LDMOS above 2.5 GHz
• Enables 5G at higher frequencies
• Broadband design
• High efficiency at high frequencies
• Comparable thermal package as LDMOS
• Compact PA design (more power in smaller
package, smaller matching circuitry)
• Wideband CW and Pulse PA applications:
− 200-2600 MHz at 100 W
− S-band 2.7-3.5 GHz at 700 W
GaN Benefits LDMOS Benefits
• Competitive performance to 2.7 GHz
• Cost effective PA solutions
• Mature process technology
• High ruggedness up to 65:1 VSWR
• Consistent thermal behavior
• Broadband VHF/UHF below 1 GHz
• Highest power up to 1.5 GHz
• Narrow-band PA applications:
− Cellular bands up to 2.7 GHz
− Avionics and L-band 1.2-1.4 GHz up to 1.5 kW
− S-band 2.7-3.1 GHz at 300 W

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Material Characteristics Drive System Level Tradeoffs
Material Properties Device Operates Improved Device FOM System Advantage
Increased BW
Smaller # of Die
Per System
Lower Total
Energy Usage
Higher System
Frequency
Smaller Package
Cheaper Package
Relaxed System
Cooling
Power Density
Power Gain
Efficiency
Output Impedance
High ft
High fmax
Smaller Die Size
More Power/Die
High
Breakdown
Field
High Electron
Velocity
High Thermal
Conductivity
High Voltage
High Current
High Temperature
High Frequency

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Gain Compression Comparison – P1dB, P3dB
LDMOS: Hard Gain Compression
1.2dB delta between P-1dB and P-3dB
LDMOS 32V @ 1.96 GHz
GaN: Soft Gain Compression
1.8dB delta between P-1dB and P3-dB
GaN 50V @ 2.50 GHz
36
38
40
42
44
46
48
50
52
54
56
58
20 22 24 26 28 30 32 34 36 38
Pout(dBm)
Pin (dBm)
MMRF5014HR5 - Max Pout Load - 2.5 GHz - 50 V
Actual
Ideal
P-1dB = 50.2 dBm = 105 W
P-3dB = 52 dBm = 160.9 W

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GaN Advantage: Wider Bandwidth in S-Band
MMRF5300N - 50V GaN
60 W Pulsed Power
Wideband over 2.7 – 3.5 GHz
Flat Gain 14.6-14.9 dB
Efficiency > 50%
MRF7S35120H - 32V LDMOS
120 W Pulsed Power
Broadband over 3.1 – 3.5 GHz
Gain 12-13 dB
Efficiency > 40%
-20
-10
0
10
20
30
40
50
60
13
13.5
14
14.5
15
15.5
16
16.5
17
2700 2800 2900 3000 3100 3200 3300 3400 3500
IRL(dB)DrainEfficiency(%)
PowerGain(dB)
Frequency (MHz)
PMRF5300N Performance at 60W Pulsed
Vdd=50V, Idq=60mA, Vgs=-3V, 300us Pulse Width, 20% Duty Cycle
Power Gain
Drain Efficency
IRL

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GaN Advantage: Higher Efficiency
GaN provides high efficiency at peak power, and 6dB power back-off
efficiency across wide bandwidth
Power drive-up gain response is less sensitive to bias current variation.
Flat gain response can achieve over a wide power dynamic range
GaN is well suited for high efficiency amplifiers, such as classes D/E
modes and switch-mode PA’s, where transistor operates like a switch
GaN on SiC technology is continuously improving linearized efficiency for
Doherty PA operation at 7-8 dB peak power back-off

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GaN Advantage: High Efficiency and Output Power
PAE and Output Power vs. Frequency for NXP GaN and LDMOS devices
High Efficiency Beyond 2.5 GHz High Power Beyond 3.5 GHz

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Wideband PA Design Techniques
1. Multi-sections LC matching networks
2. Multi-sections quarter-wave line transformers
Consider Factors:
1. Power level
2. Package
3. PCB size
4. Phase shift
5. Broadband matching
Lower Q Matching

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Wideband PA Design Techniques
• Broadband impedance transformer < 1 GHz
− Coaxial 4:1 transformer with ferrite beads can extend frequency range from 50 to 1000 MHz
Zcoax= Z1 * Z2 = 12.5 * 50 = 25 ohm

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Wideband PA Design Techniques
• Multi-sections transmission lines – broadband matching over 400-3000 MHz

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Wideband PA Design Techniques
1 2 3
Reactive Matching
makes gain adjustment
across wideband by
mismatching at the input,
but results in higher input
VSWR.
L-R Lossy Matching
absorbs gain to achieve
flat gain across wide band.
Reduce low frequency
gain.
R-C Feedback
improves the input and
output match to achieve
broadband matching.
Improve circuit stability by
reducing gain at low
frequency.
Bandwidth Enhancement Techniques:

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Wideband PA Design Challenges
• At high power density, GaN is in the high end
of its operating junction temperature
• GaN on SiC can reduce thermal resistance in
air cavity ceramic and plastic-molded
packages
• GaN die design to spread heat sources evenly
and use highly conductive copper flange
packages
GaN Thermal Challenges GaN Linearity Challenges
• GaN drain lags result in poor linearity, which
results in a slow drain current response to fast
change in drain amplitude swing
• GaN is being optimized for better DPD
correction for switching signals in TDD based
systems

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Wideband PA Design Challenges
• 50V LDMOS is designed for high breakdown
voltage and can survive 65:1 VSWR and >3
dB input overdrive
• 50V GaN is designed for high ruggedness
20:1 VSWR
Device Ruggedness Device Reliability
• Use Mean-Time-To-Failure (MTTF) product
calculators to determine device
electromigration failure rate for a given set of
operating conditions, junction-case
temperature (Tj-c) and thermal resistance
• MTTF vs. Tj-c is calculated for CW conditions
and pulse applications

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GAN AND LDMOS
WIDEBAND PA APPLICATIONS
SINGLE-ENDED VS. PUSH-PULL AMPLIFIERS

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MMRF5014H GaN Wideband PA Application
• 50 V GaN on SiC Wideband Transistor
• 100 W CW, 12 dB min Gain, 40% min
Efficiency covers 450-2500 MHz
• Single-ended Compact
Wideband Amplifier
• Full CW & Pulse Operation
• Housed in NI-360 air-cavity
ceramic package
• Thermal Resistance = 0.86 °C/W *
* Refer to App Note AN1955

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MMRF5014H GaN 450-2500 MHz Wideband Design
• Broadband design using multi-section
transmission lines methodology with
MMRF5014H non-linear device model
• Load and source impedances generated from
load pull techniques to develop broadband
matching networks
• ADS harmonic balance simulation to optimize
power gain and efficiency
• Design Goals:
− 100 W across 450-2500 MHz
− CW Gain >12 dB
− Efficiency >40 %
MMRF5014H Source and Load
Impedance
Freq (MHz)
Zsource
(ohm)
Zload (ohm)
500 1.3+j3.9 5.9+j3.5
1000 1.0+j0.3 5.5+j2.9
1500 0.8-j0.5 3.4+j2.0
2000 1.2-j2.0 4.7+j0.3
2500 2.7-j3.8 3.7+j1.4

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MMRF5014H GaN Wideband Circuit Simulation – 450-2500 MHz
Input Matching Circuit
Output Matching Circuit
NXP can provide ADS device model to enable nonlinear circuit simulation

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MMRF5014H GaN Wideband Circuit Simulation Results
800 MHz 800 MHz 800 MHz

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MMRF5014H GaN 450 – 2500 MHz CW Measurement
20
30
40
50
60
70
80
4
6
8
10
12
14
16
20 30 40 50 60 70 80 90 100 110
Efficiency(%)
Gain(dB)
Output Power (W)
MMRF5014H CW Power Drive-up
500 MHz Gain 1000 MHz Gain 1500 MHz Gain 2000 MHz Gain 2500 MHz Gain
500 MHz Eff 1000 MHz Eff 1500 MHz Eff 2000 MHz Eff 2500 MHz Eff
VDD = 50 V
IDQ = 300 mA
Device shows no gain expansion at selected bias current

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MMRF5014H GaN 450 – 2500 MHz CW Measurement
0
10
20
30
40
50
60
70
80
8
10
12
14
16
18
20
22
24
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
Efficiency(%)
Gain(dB)
Frequency (MHz)
MMRF5014H 450-2500 MHz CW at 100 W
100 W Gain 10 W Gain 100 W Eff
VDD = 50 V
IDQ = 300 mA

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MMRF5014H GaN 450 – 2500 MHz Pulse Measurement
0
10
20
30
40
50
60
70
80
8
10
12
14
16
18
20
22
24
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
PulseEfficiency(%)
Gain(dB)
Frequency (MHz)
MMRF5014H 500-2500MHz Pulse at 100 W
200usec pulse width, 20% duty cycle
100 W Gain 100 W Pulse Eff
VDD = 50 V
IDQ = 300 mA
Higher gain due to non-thermal heating effects in pulse operation

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MMRF1305HR5 LDMOS Broadband PA
• 50 V Wideband LDMOS Transistor
• 100 W PEP, 14 dB min Gain, 30%
min Efficiency
• Push-pull Amplifier covers 400-1000
MHz
• Broadband Coaxial transformer
design
• Housed in a NI-780H air-cavity
ceramic package
• Low Thermal Resistance = 0.38
°C/W *
* Refer to App Note AN1955

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MMRF1305HR5 LDMOS 400-1000 MHz Broadband Design
• Broadband design using two-section
impedance transformer with
MMRF1305HR5 nonlinear device model
• ADS load pull and source pull techniques
to obtain maximum power impedances
between 400 MHz to 1 GHz
• ADS harmonic balance simulation to
optimize power gain and efficiency
• Design Goals:
− 100 W across 400-1000 MHz
− CW Gain >14 dB
− Efficiency >30 %
MMRF1305H Source and Load Impedance
(Simulated in balanced configuration)
Freq (MHz) Zsource (ohm) Zload (ohm)
400 4.21-j0.85 6.63+j0.27
500 3.82-j1.05 6.82+j0.18
600 3.44-j0.97 6.98+j0.01
700 3.23-j0.75 7.09-j0.25
800 3.21-j0.55 7.11-j0.55
900 3.31-j0.49 7.00-j0.88
1000 3.50-j0.60 6.80-j1.16

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MMRF1305H LDMOS Broadband Circuit Simulation
400-1000 MHz
Output Matching Circuit
NXP can provide ADS or AWR MWO device models to enable nonlinear circuit simulation
Balun
Balun
Input Matching Circuit
4:1 Impedance
Transformer

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MMRF1305H LDMOS Broadband Circuit Simulation Results

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MMRF1305H LDMOS 400 – 1000 MHz CW Measurement
10
20
30
40
50
60
70
80
4
6
8
10
12
14
16
18
10 20 30 40 50 60 70 80 90 100 110 120 130
Efficiency(%)
Gain(dB)
Output Power (W)
MMRF1305H 400-1000 MHz CW Power Drive-up
400 MHz Gain 700 MHz Gain 1000 MHz Gain
400 MHz Eff 700 MHz Eff 1000 MHz Eff
VDD = 50 V
IDQ = 400 mA
Device exhibits gain expansion at low drive power and specified bias current

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10
15
20
25
30
35
40
45
50
55
60
10
12
14
16
18
20
22
24
26
28
30
400 450 500 550 600 650 700 750 800 850 900 950 1000
DrainEff(%)
Gain(dB)
Frequency (MHz)
MMRF1305H 400-1000MHz CW at 100 W
100 W Gain 10 W Gain 100 W Eff
VDD = 50 V
IDQ = 400 mA
MMRF1305H LDMOS 400 – 1000 MHz CW Measurement

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MMRF1305H LDMOS 400 – 1000 MHz Pulse Measurement
10
15
20
25
30
35
40
45
50
55
60
10
12
14
16
18
20
22
24
26
28
30
400 450 500 550 600 650 700 750 800 850 900 950 1000
DrainEff(%)
Gain(dB)
Frequency (MHz)
MMRF1305H 400-1000MHz Pulse at 100 W
200usec pulse width, 20% duty cycle
100 W Gain 100 W Eff
VDD = 50 V
IDQ = 400 mA
Higher gain due to non-thermal heating effects in pulse operation

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GaN and LDMOS Wideband Application Comparison
Parameters
GaN
MMRF5014H
LDMOS
MMRF1305H
Circuit Topology Single-ended Push-pull
Bandwidth @ 100 W 450-2500 MHz 400-1000 MHz
Gain @ 100 W 12-14 dB 13-17.5 dB
Efficiency @ 100 W
> 39 % > 32 %
P3dB 160 W 140 W

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LDMOS Power Product Portfolio
• 1
1.8 MHz 500 MHz 915 MHz 1400 MHz 2900 MHz 3500 MHz
10W
100W
1kW
1200 MHz
S-BandRadar2700-3100
Industrial
FM/VHF
Broadcast
Aerospace
UHF Broadcast
Industrial
Aerospace
2450 MHz
1.5kW MRF1K50N
To 500MHz, 1500W CW
Cellular ICs
28V class AB
Cellular3400-3600
Cellular1800-2050
Cellular2100-2200
L-BandRadar
IFF
50V LDMOS
28/32V LDMOS
Cellular2300-2700
ISM2500
Aerospace
Industrial500W
Frequency (MHz)
PeakPower(W)

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GaN Power Product Portfolio – Compliments LDMOS to Address
High Frequency, High Power Applications
Frequency (MHz)
1000
400
100
10
2
PeakPower(W)

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Conclusion
• Benefits have been presented for GaN and
LDMOS technologies. Including device
parameters with performance trade-offs, design
challenges, and wideband PA applications.
• GaN devices have great potential for high-power
cellular and defense aerospace markets in
wideband, multi-band PA applications
• NXP provides full product support for
GaN and LDMOS product solutions