A 0.1 – 1.8 GHz, 100 W GaN
HEMT Power Amplifier Module
Karthik Krishnamurthy, Don Lieu, Rama Vetury, Jay Martin.
Outline
• Motivation
• RFMD GaN Technology overview
• Multi-decade band PA topologies
• 25 W Unit Amplifier design and performance
• 100 W Module design and performance
• Thermal Evaluation
• Summary
Motivation
• Emerging Software Defined Radio Architectures
• Public Mobile Radio
• Joint Tactical Radio Systems (JTRS)
• Jamming Applications
Handheld Manpack Smallform (HMS) / Airborne Maritime Fixed (AMF) band
30 MHz
1
10
100
Frequency (MHz)
• Requirements
• Multi-decade10W and higher)
• High efficiency & compact size PAs
(critical for handheld / mobile units)
• Multi-band / multi-standard operation
• Cost Savings and Inventory reduction
2000 MHz
1000
10000
GaN HEMT on SiC for HPAs
Wide Bandwidth
High
Impedance
Multi-band
Operation
Configurable
Radios
GaN-on-SiC
S
G
GaN
SiC
Benefits
High Efficiency
D
Low
Capacitance
Enables High
Efficiency Circuit
Techniques
Smaller
Heatsink
High Power
High Breakdown
Voltage
High Power
Density
High Thermal
Conductivity
Compact
HPAs
Reduced:
(1) size/complexity
(2) cooling
(3) weight and
(4) cost
RFMD GaN HEMT Technology
0.5um
2.2 mm device
Parameter
Value
Units
Id-max
900
mA/mm
Peak gm
250
mS/mm
Vp
-5
V
Vbr(GD)
>175
V
ft
11
GHz
fmax
17
GHz
frequency
0.9 / 2.14
GHz
20
Peak Power
20.4 / 18.2
W
10
Peak Drain Eff
74 / 69.7
%
Optimum load
31.4+j46.1

S
D
G
• 0.5 mm Gate length
• Source coupled field plate
40
GMax (dB)
Gain (dB)
30
|H(2,1)| (dB)
0
-10
ft
.1
1
10
Frequency (GHz)
fmax
[1] Class AB Bias: Ids = 44mA ; Vd = 48V
100
Broadband PA topologies
Topology
Resistive FBRf
Zo
Zo
Vin
Vgen
Zo
Vout
Zo
Q
RLC Lossy Match
Zo
Zo
L1
Zo
Vgen
C1
L2
Vout
Zo
Q, W
Ri
matching Zo
network
Cgs
( )
Distributed Amp
Cd
reverse
termination
L
Zo
RF
IN
Cdiv
RF
OUT
L/2
Zo
L/2
L
Cin
Advantages
- lumped implementation
- good S22
- Simple / lumped design
- output optimized for Zopt
- Input optimized for gain
flatness
- All-pass network at input
implies excellent S11
- best bandwidth and gain
- dissipation spread out
Disadvantages
- O/P not designed for Zopt
- Tuning Zload affects
gain flatness and S11
- Rf Pdiss / leakage issues
- Rf Layout issues
- Lumped circuit, so
thermal design is critical
- Complex circuitry
- Zload optimization for each
cell is complicated
- poor efficiency
- implementation feasibility
issues
25W Unit Amplifier Specifications
Specification
Parameter
Min. Typ. Max. Unit
Recommended Operating Conditions
48
V
Drain Voltage (Vdsq)
Drain Bias Current
88
mA
RF Input Power (Pin)
32
dBm
Input Source VSWR
10:1
RF Performance Characteristics
Frequency Range
50
2000 MHz
Linear Gain
12
13
dB
Power Gain
9
10
dB
Gain flatness
-1.5
1.5
dB
S11
-10
dB
Output Power (P3dB)
43
44
dBm
Power Added Efficiency (PAE)
40
50
%
[1] Test Conditions: CW Operation, Vdsq=48V, Idq=88mA, T=25ºC
• Features:
•
•
•
•
•
•
•
48V Operation
Input Internally Matched to 50Ω
50–2000 MHz Instantaneous Bandwidth
Gain > 16 dB over the band
Output Power 25 W
Power Added Efficiency > 50%
Small Form Factor Copper Package
Package and evalution board
• 2 x 2 inch size evaluation board
• AlN SO8 package
5mm x 6mm
• Broadband DC Bias chokes for
gate and drain
• 50Ω match at the package input
• Two element low pass match at the
output
• 50Ω feed at the input and output of
the evaluation board
• PCB mounted on Aluminum heat
sink with fins
20
0
16
-5
12
-10
8
-15
-20
0
0.0
0.5
1.0
1.5
• Frequency : 1000 MHz
• Gain : 12 dB
• P3dB : 28.2 W
• PAE : 49 %
-25
2.0
45
• Bandwidth: 50 – 2000 MHz
• Gain: 12 dB
• Input return loss: < 9 dB
Output Power (dBm)
Frequency (GHz)
60
Output Power
PAE
Gain
40
35
50
40
30
30
25
20
20
10
15
0
5
10
15
20
Pin (dBm )
25
30
35
PAE (%), Gain (dB)
S21
S11
S22
4
• Vdq = 48V, Idq = 88mA
S11 (dB), S22 (dB)
S21 (dB)
Unit Amplifier Performance
46
80
45
70
44
60
43
50
P2dB
42
40
PAE
41
0.0
0.5
PAE (%)
P2dB (dBm)
Unit Amplifier Performance
30
1.0
1.5
2.0
Frequency (GHz)
• Vdq = 48V, Idq = 88mA
15
• Bandwidth: 50 – 2000 MHz
• Gain over band: 11 – 12 dB
• Output power: 23.6 – 30.9 W
• PAE: 39.4 – 57.0%
Gain (dB)
12
9
6
0.25 W
2.5 W
25 W
3
0
0.0
0.5
1.0
Frequency (GHz)
1.5
2.0
PA Module Topology
Vg
• Pairs of devices combined through
25Ω traces and further combined
together using the balun.
Vd
• Ferrite loaded broadband 1:1 Balun at
input and output.
RF
IN
25
25
• 50Ω coax with 0.2dB/m loss,
RF that can handle 162 W at 1 GHz
OUT
25
25
• Dual aperture core high frequency
ferrite from Fair-Rite corp minimizes
board space and provides broad
bandwidth
• Gate bias feeds isolated through a
470Ω resistor, and jumpered together.
Vd
• 82nH high-Q bias inductors at drain of
each device, and the bias feed
jumpered together.
• 115Ω ferrite (at 100 MHz) at the drain
bias feed to extend low frequency
performance.
PA Module
• 2 x 2 inch size
• Dual aperture core high frequency
ferrite from Fair-Rite corp minimizes
board space and provides broad
bandwidth
• 50Ω feed at the input and output of
the PA module
• Gate and Drain bias feeds for
individual devices jumpered
together
• PCB soldered down to a copper
block, and mounted on Aluminum
heat sink with fins
Balun performance
0
S21
S21 (dB)
-0.2
-5
S11
S22
-0.4
-10
-0.6
-15
-0.8
-20
-1.0
-25
-1.2
-30
0.0
0.5
1.0
1.5
Frequency (GHz)
2.0
• Insertion loss (back to back) :
0.5 – 0.9 dB
• Insertion loss per balun :
0.45 dB
• Return loss:
18 – 28 dB
S11 (dB), S22 (dB)
0.0
5
12
0
9
-5
6
-10
3
-15
0
-20
S21 (dB)
15
0.0
0.5
1.0
1.5
S11 (dB) , S22 (dB)
100 W Module Small Signal performance
2.0
Frequency (GHz)
• Bandwidth: 50 – 1800 MHz
• Gain: 11 dB
• Input return loss: 9 dB
• Vdq = 50V, Idq = 360mA
100 W Module CW performance
53
15
PAE
Pout (dBm)
9
6
Pin = 20 dBm
3
70
51
60
50
50
49
40
48
30
PAE (%)
52
12
Pin = 40 dBm
0
0.0
0.4
0.8
1.2
1.6
2.0
0.0
0.4
0.8
1.2
1.6
2.0
Frequency (GHz)
Frequency (GHz)
55
• Bandwidth: 100 – 1800 MHz
• Gain over band: 11 – 13.2 dB
• Output power: 94 – 142 W
• Efficiency: 40.6 – 74 %
Output Power (dBm)
Gain (dB)
80
Pout
200 MHz
800 MHz
1200 MHz
1600 MHz
50
45
40
35
30
15
20
25
30
Pin (dBm )
35
40
45
15
• Vdq = 50V, Idq = 360mA
12
• Frequency : 200 MHz
• Pout : 128.4 W
9
• PAE : 68.0 %
6
200 MHz
800 MHz
1200 MHz
1600 MHz
3
• Drain efficiency : 74 %
0
30
35
40
45
50
70
55
Pout (dBm )
200 MHz
800 MHz
1200 MHz
1600 MHz
60
50
• Frequency : 1600 MHz
• Pout : 125.4 W
• PAE : 61.8 %
• Drain efficiency : 67.3 %
PAE (%)
Gain (dB)
100 W Module CW performance
40
30
20
10
0
30
35
40
45
Pout (dBm )
50
55
Two Tone Linearity Performance
• Vdq = 50V
IMD3 vs. Pout
(2‐Tone 1MHz Seperation, Vd = 50V, Idq varied, fc = 1600MHz)
• Idq = Varied
180mA
360mA
540mA
720mA
900mA
‐15
‐20
‐25
• Fc = 1600 MHz
• Tone spacing = 1MHz
Gain vs. Pout
‐30
(2‐Tone 1MHz Seperation, Vd = 50V, Idq varied, fc = 1600MHz)
16
‐35
15
‐40
14
13
‐45
‐50
0.1
1
10
100
Pout, Output Power (W‐PEP)
1000
Gain (dB)
IMD3, Intermodulation Distortion (dBc)
‐10
12
11
180mA
360mA
540mA
10
9
720mA
900mA
8
• Optimum Idq = 720 mA
7
6
0.1
1
10
Pout, Output Power (W‐PEP)
100
1000
Two Tone Linearity Performance
IMD vs. Output Power
(Vd = 50V, Idq = 720mA, f1 = 1599.5MHz, f2 = 1600.5MHz)
0
IMD3
‐IMD5
IMD5
‐IMD7
IMD7
‐20
‐30
Drain Efficiency vs. Pout
(2‐Tone 1MHz Seperation, Vd = 50V, Idq varied, fc = 1600MHz)
60
‐40
‐50
50
‐60
‐70
0.1
1
10
100
Pout, Output Power (W‐ PEP)
• Frequency : 1600 MHz
• Pout : 65 W
• IMD3 < 35 dBc
• Drain efficiency : 41 %
1000
Drain Efficiency (%)
Intermodulation Distortion (IMD ‐ dBc)
‐10
‐IMD3
40
30
180mA
360mA
540mA
20
720mA
900mA
10
0
0.1
1
10
Pout, Output Power (W‐PEP)
100
1000
Infrared thermal measurements
• Vdq = 48V, Idq = 88mA
• Base plate temperature : 85ºC
Peak Junction Temperature vs Power Dissipation
Peak Junction Temperature(oC)
300
250
200
150
100
50
Leaded Cu Package
0
0
5
10
15
20
Power Dissipation (W)
• Junction temperature of 209.3ºC
25
30
35
Summary
• We’ve demonstrated a 100W, 0.1 – 1.8 GHz, 50V GaN HEMT PA module
with >40% drain efficiency over the band
Output
power (W)
Bandwidth
(GHz)
94 – 142 0.1 – 1.8
Gain
(dB)
Supply
Drain
Voltage (V) Efficiency (%)
11 – 13.2
50
41 – 74
• Further work is in process:
• Extending the bandwidth to 50 MHz – 2.5 GHz
• Improving efficiency and thermal performance
• Broadband / High efficiency / compact size serve applications including
PMR (Public Mobile Radio)
and test instrumentation.
20
Do You Have
Any Questions?
Thank you