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ADS for radars
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This document is owned by Agilent Technologies, but is no longer kept current and may contain obsolete or
inaccurate references. We regret any inconvenience this may cause. For the latest information on Agilent’s
line of EEsof electronic design automation (EDA) products and services, please go to:
www.agilent.com/fi nd/eesof
Agilent EEsof EDA
Presented by: HeeSoo LEE
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADS for Radar Applications
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 2
Objectives
• Overview of a systematic medium power amplifier design flow in ADS
• Overview of available tools and utilities in ADS for amplifier design
• Demonstrate ADS co-simulation capability • Demonstrate ADS layout for amplifier design
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 3
Typical Block Diagram of a Radar System
Local Oscillator
TIMING SYNC
PulseGenerator
ToDisplay
LNA
PA
SYNCHRONOUSI/Q DETECTOR
RECEIVERPROTECTOR
Transmitter
Receiver
ADC and Signal
Processor
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 4
Power Amplifier in Radar System
• In this presentation, design3 Watts medium output power two stage power amplifier20+dB gain at 1.95GHz frequencyOverall, good input and output matchTwo separate amplifiers without inter-stage matching
12 dB 8 dB14.8 dBm 26.8 dBm 34.8 dBm
NE6510179ANE651R479A
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 5
Power Stage Amplifier
Deliver 3 Watts
12 dB 8 dB14.8 dBm 26.8 dBm 34.8 dBm
NE6510179ANE651R479A
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 6
3 Watts HJ-FET NE6510179A
• NEC L&S band medium power HJ-FET• Good for power stage transistor because of
– Typical 35dBm output power @5V– Typical 10dB Gain at 1.9GHz
• Also ADS design kit is available with nonlinear models– http://www.cel.com/prod/prod_ads_update.asp
Source: NEC
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 7
Graphical Method of Determining Ropt*
• Ropt, the load impedance at drain terminal that gives the maximum output power for devices* in Class A operation
• Easy to calculate• Reasonably accurate
• 2.67Ω Ropt with NE6510179A at 5V, 1.2A bias point
Ropt = (VBias-VKnee)2
2 x POut
* : Steve C. Cripps, RF Power Amplifier for Wireless communications Artech House Publishers
Vds
Ids
VKnee
Imax
VmaxVBias
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 8
Modeling of FET Ground Pad Inductance
• Substrate on RT Duroid 5870, 31mil thick and ½ oz• Model ground pad in preparation for determining the
optimal load impedance from a load-pull simulation– Momentum EM Simulation to get S-parameters– Calculation of Leff from Z-parameters: 0.163nH at 2GHz
ADS Layout for ground
Recommended PCB Layout
Substrate
31 mil
AIR
GND
RT Duroid 5870
½ oz
Leff = Imaginary (Z11)
ω
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 9
DesignGuides in ADS – Bridging the Gap
FilterBluetooth
Linearization
Mixer OscillatorPLL
RF SystemAmplifierPassive
DesignGuides
Simulation Technology
Applications
Linear, NonlinearCircuit EnvelopeTime DomainAgilent PtolemyElectromagneticOthers
Amplifier, FiltersMixers, OscillatorPassives, SystemMod/DemodsPackagingOthers
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 10
What and Where to use DesignGuides
UWB
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 11
Determine Optimum Load Impedance -Load-Pull*
Simply replace it with your own device!
Complex Load Impedance
• Use Amplifier DesignGuides Load-Pull– Pre-configured simulation setup– Pre-configured data post-processing
Ground pad is attached to the device!
1-Tone Nonlinear Simulations / Load-Pull – PAE, Output Power Contours
Menu
*Also available in load-pull application guides
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 12
Load-Pull Simulation Result
• Simulation maps complex load impedances to power and PAE contours
• Pre-configured data display for gain compression, PAE, harmonics and more
• Load reflection coefficient that gives maximum power is at 0.924/-169.396
Load impedances is mapped to Power and PAE contours36dBm
35.5dBm
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 13
A: 2.67 Ω B: 2.0 + j4.65 Ω
Comparison of Graphical and Load-Pull Methods• Graphical Method
DC only calculation
2.67 Ω• Load-Pull Method
Complete non-linear AC/RF simulationΓRopt = 0.924/-169.396
ZRopt = 2.0 + j*4.65 Ω• Reasonable agreement but slightly different due to
– Where to look into the impedance• Graphical method, at A plane: Drain terminal of intrinsic transistor• Load-Pull method, at B plane: Drain terminal of extrinsic or packaged
transistor– Package parasitic
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 14
Determine Optimum Source Impedance –Linear method
• No information on output power but small signal gain
• Choice 1 : Conjugate match– Good for maximum gain– Good for Input match– Output match is question
• Choice 2: Mismatched input for optimum output match– Better output match with a little
loss of gain– As an example, 0.936/-156.351
gives 1.4dB mismatch loss but better match for output
Mapped input gain circle for transistor’s output impedance
Optimum transistor output match for maximum power
Max Gain = 9.978dB at 1.95GHz
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 15
Determine Optimum Source Impedance –Source-Pull
• Use Amplifier DesignGuides Source-Pull– Pre-configured simulation setup– Pre-configured data post-processing – Brute-force solution for finding optimum source impedance– Full understanding on output power with varying source
impedance
0.778/-159.090
1-Tone Nonlinear Simulations / Source-Pull – PAE, Output Power Contours
Menu
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 16
Stability
• NE6510179A is stable at 1.95GHz design frequency with the addition of pad ground inductance
• Mu factor is over 1
Input Stability Circle
Output Stability Circle
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 17
Matching Network Design
? ?
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 18
Smith Chart Utility
• User interactive matching network design• View frequency response• View matching network topology• Define Q of the circuit• Build ADS schematic• Easy to use
Source and Load TerminationsSeries ComponentsShunt ComponentsTransmission Line and Transformers
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 19
Matching Utility
• Available network topologies– Lowpass– Highpass– Bandpass
• Source/Load impedance can be defined over wide frequency range
• Matching element transformation utility
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 20
Output Matching Network Design
• Design with Smith Chart Utility
• Design for reflection coefficient from load-pull, ΓRopt 0.924/-169.396
• Ideal lumped passive and transmission line elements
ΓRopt 0.924/-169.396
Display of Smith Chart Utility
Enter conjugate of ΓRoptfor load termination5.6 pF
59.85 deg
50 Ohm
0.627 pF Reflection Trajectory
Q circle
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 21
Input Matching Network Design
• Design with Smith Chart Utility
• Design for reflection coefficient from source-pull, ΓIN opt 0.778/-159.090
• Ideal lumped passive and transmission line elements
ΓIN opt 0.778/-159.090
Input Match
3.3 pF
46 deg
50 Ohm
1.37 pF
Conjugate of ΓINoptfor load termination
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 22
Impedance Loci with Different Width and Length of Transmission Line
• Discrete SMT capacitance value limits flexibility of design
• Parameter sweep simulation capability allows designers to understand– Impedance loci of network
with varying physical dimension
• Consider bandwidth of network with each combination
Output matching with different capacitance Blue: 0.5pF, Red: 1.0pF
Output matching
Input matching
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 23
Realization of Input and Output Networks
• Replace ideal capacitors with discrete vendor SMT capacitors • SMT capacitors from Taiyo-Yuden • ADS model library is available (Download from Web)
– http://66.40.41.39//simtools/index.cfm
1.2pF 1 pF
Physical Realization
5.6 pF
59.85 deg
50 Ohm
0.627 pF
3.3 pF
46 deg
50 Ohm
1.37 pF
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 24
Linear Simulation With ADS Models
• Transmission lines in input and output matching networks were chosen to be close to 50 Ω lines
• 7.81 dB small signal gain at 1.95GHz• Excellent match for input and reasonable match for output
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 25
Non-Linear Simulation with ADS Models
• Use Amplifier DesignGuides’ pre-configured power simulation setup
• Gain compression at 37.07dBm • 38.24% PAE• 7.81 dB small signal gain
1-Tone Nonlinear Simulations / Spectrum,Gain,Harmonic Distortion vs Power (w/PAE)
Menu
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 26
Linear Simulation with Momentum Component
• Layout look alike Momentum Component for physical layout– Nested EM simulation for physical layout– Accurate simulation for layout parasitics– Overcome limitation of valid model range for circuit models
• Frequency response is shifted
Shifted
Comparison with ADS model simulation
Solid = Layout Simulation
Faint Solid = ADS Models
Momentum Component
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 27
Detuned Matching Network
• Input and output impedances are detuned from desired impedances due to physical layout parasitics
• Very convenient SProbe simulation component
0.778/-159.090
ΓIN optΓRopt
0.924/-169.396
Sprobe Component
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 28
Advanced Model Composer (AMC)
W12
W3
freq
W12
W3
freq
W12
W3
freq
W12
W3
freq
W12
W3
freq
W12
W3
ADS Model Composer builds parameterized models for passive componentscontinuous frequency range & discrete and/or continuously varying layout parameters
component : tee_s : symmetrical teemodel is function of :
substratefrequency rangelayout parameters W12 & W3
continuous frequencydiscrete W12 discrete W3
continuous frequencydiscrete W12 continuous W3
continuous frequencycontinuous W12 continuous W3
single frequencysingle W12, W3
continuous frequencysingle W12, W3
Momentum calculates S-data•
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 29
AMC Model for In/Output Matching Network
• Two perturbed parameters – Line width and length
• Once the model is developed, AMC provides very fast simulation speed without a loss of accuracy
Line Width
Line Length
Parameter Sweep Simulation with AMC Input Matching Network Model
Parameter Sweep Simulation with AMC Output
Matching Network Model
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 30
Tuned Matching Network
• Input and output matching networks are tuned for desired impedances
• Linear and Non-linear simulations are performed– Swept input power –20 to 30dBm
Gain Compression 36dBm, 4W
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 31
Bias Circuit Design
• Transistor Bias Utility for biasing circuit for transistors– Unregulated bias network for BJT and FET– OPAMP based active biasing network up to 4 devices– OPAMP based regulated biasing network up to 4 devices
• LineCalc Utility for synthesizing transmission lines
31 mil RT Duroid 5870
50 Ohm - 91 mil
Resistive bias networkOpamp based active biasOpamp based regulated bias
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 32
Linear Simulation with Bias Lines
• Bias lines for source and drain terminals are attached• 8.179dB small signal gain at 1.95GHz• Very good input and output return loss
Due to λ /4 lines
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 33
Final Non-Linear Simulation
• 8.179dB gain at small signal• 35.48dBm 1dB gain compression• 35% PAE at 35.5dBm Pout
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 34
Driver Stage Amplifier
Deliver 480 mW
12 dB 8 dB14.8 dBm 26.8 dBm 34.8 dBm
NE6510179ANE651R479A
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 35
1 Watt HJ-FET NE651R479A
• NEC L&S band medium power HJ-FET• Good for driver stage transistor because of
– Typical 29.5dBm output power– Typical 12dB Gain at 1.95GHz
• ADS design kit is available with nonlinear models– http://www.cel.com/prod/prod_ads_update.asp
Source: NEC
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 36
Load and Source Matching Network
• HJ-FET NE651R479A is biased at 5V, 250mA• Optimum source and load impedances were
extracted from Load-Pull and Source-Pull Simulation
ΓIN opt 0.846/-153.444 ΓRopt 0.707/-169.644
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 37
Linear Performance of Driver Amplifier
• 13.1dB small signal gain at 1.95GHz• Good input and output return loss characteristic
Due to λ /4 bias lines
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 38
Non-Linear Performance
• 1dB gain compression at 30.57dBm• 41% PAE at 30.56dBm Pout
• 13.1 dB small signal gain
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 39
Final Integration and Layout
Deliver 3 Watts
12 dB 8 dB14.8 dBm 26.8 dBm 34.8 dBm
NE6510179ANE651R479A
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 40
Linear Performance of Two Stage Amplifier
• Total 21.37dB small signal gain• Good match for input and reasonable match for output• Hierarchical design is employed with a sub-network
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 41
Non-Linear Power Simulation Setup
• Use Amplifier DesignGuides’ pre-configured power simulation setup
• Hierarchical design is employed with a sub-network
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 42
Non-Linear Performance (1)
Gain Compression at 35.33 dBm
Pre-configured data presentation from Amplifier DesignGuides
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 43
Non-Linear Performance (2) - PAEPre-configured data presentation
from Amplifier DesignGuides• Overall 39.55% PAE
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 44
Non-Linear Performance (3) - AM-to-PMPre-configured data presentation
from Amplifier DesignGuides
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 45
ADS Layout for Two Stage Amplifier
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 46
Co-Simulation of Power Amplifier in Radar System
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 47
Power of Co-Simulation in ADS
Top Level Radar System Using ADS Ptolemy
Concept – Block Diagram
Transmitter System Using ADS Circuit Envelope
Power Amp Circuit Using ADS EM-Circuit Co-simulation
Baseband Float/Fixed PointHDL(Verilog & VHDL), MatLab®C++.System-C
Behavior RF/Analog Subsystem, Circuit, Transistor Level Models
Physical, EM Models, Circuit Models
Connected Solution
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 48
Transmitter Response with 2-Stage Power AMP
• 70 dB System Gain• Double Conversion• Simulated with Circuit Envelope
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 49
Top Level Radar System Performance with 2-Stage Power AMP
Top Level Radar System Design Using ADS Ptolemy
Target Distance & RCS
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 50
Co-Simulation ResultLFM Chirp Source Spectrum
Transmitter Output Spectrum
Output to Dynamic VSA Software
Click the graph to animate in slide show mode…
Aerospace and Defense Symposium 2005Aerospace and Defense Symposium 2005
Amplifier Design in ADSfor Radar Applications
Page 51
Summary
• ADS provides an integrated and seamless design environment for designing medium power amplifier
• ADS DesignGuides and Application Guides bridge the gap between complex simulation technologies and advanced applications
• ADS Momentum and Momentum Component provide both accuracy and convenience for taking into account physical layout parasitics
• ADS Co-Simulation capability allows “single click” simulation for multiple simulation technologies and various abstract level models
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