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Aerospace and Defense Symposium 2005
Graphical Method of Determining Ropt*
Ropt, the load impedance at drain terminal that gives the maximum output power for devices* in Ids Class A operation Imax (VBias-VKnee)2 Ropt = 2 x POut Easy to calculate Reasonably accurate
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Aerospace and Defense Symposium 2005
DesignGuides in ADS – Bridging the Gap
DesignGuides
Passive RF System Filter Linearization Bluetooth Mixer Amplifier Oscillator PLL
Aerospace and Defense Symposium 2005
Amplifier Design in ADS for Radar Applications
Presented by: HeeSoo LEE
Aerospace and Defense Symposium 2005
Objectives
Deliver 3 Watts
14.8 dBm
12 dB
26.8 dBm
34.8 dBm
8 dB
NE651R479A
NE6510179A
Amplifier Design in ADS for Radar Applications
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Aerospace and Defense Symposium 2005
*
VKnee
VBias
Vmax
Vds
2.67Ω Ropt with NE6510179A at 5V, 1.2A bias point
: Steve C. Cripps, RF Power Amplifier for Wireless communications Artech House Publishers
– Package parasitic
Amplifier Design in ADS for Radar Applications
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Aerospace and Defense Symposium 2005
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
Simulation Technology
Applications
Amplifier, Filters Mixers, Oscillator Passives, System Mod/Demods Packaging Others
Linear, Nonlinear Circuit Envelope Time Domain Agilent Ptolemy Electromagnetic Others
Comparison of Graphical and Load-Pull Methods
Graphical Method DC only calculation 2.67 Ω Load-Pull Method Complete non-linear AC/RF simulation ΓRopt = 0.924/-169.396
A: 2.67 Ω B: 2.0 + j4.65 Ω
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
36dBm 35.5dBm
Load impedances is mapped to Power and PAE contours
Amplifier Design in ADS for Radar Applications
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Aerospace and Defense Symposium 2005
Simply replace it with your own device!
Menu
1-Tone Nonlinear Simulations / Load-Pull – PAE, Output Power Contours
Complex Load Impedance
Ground pad is attached to the device!
– 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
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
Substrate
oz 31 mil AIR RT Duroid 5870 GND
Recommended PCB Layout
Leff =
ADS Layout for ground
Imaginary (Z11) ω
Amplifier Design in ADS for Radar Applications
Amplifier Design in ADS for Radar Applications
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Aerospace and Defense Symposium 2005
What and Where to use DesignGuides
UWB
Amplifier Design in ADS for Radar Applications
Also ADS design kit is available with nonlinear models
– /prod/prod_ads_update.asp
Source: NEC
Amplifier Design in ADS for Radar Applications
TIMING SYNC
PA
Local Oscillator
RECEIVER PROTECTOR
To Display
ADC and Signal Processor
SYNCHRONOUS I/Q DEห้องสมุดไป่ตู้ECTOR
LNA
Receiver
Amplifier Design in ADS for Radar Applications
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Aerospace and Defense Symposium 2005
Determine Optimum Load Impedance Load-Pull*
Use Amplifier DesignGuides Load-Pull
– Pre-configured simulation setup – Pre-configured data post-processing
*Also available in load-pull application guides Amplifier Design in ADS for Radar Applications Page 11
Aerospace and Defense Symposium 2005
Load-Pull Simulation Result
Optimum transistor output match for maximum power Mapped input gain circle for transistor's output impedance
Choice 2: Mismatched input for optimum output match
Amplifier Design in ADS for Radar Applications
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Aerospace and Defense Symposium 2005
Modeling of FET Ground Pad Inductance
Substrate on RT Duroid 5870, 31mil thick and 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