Another_load_pull_model

Report
The need for an alternative data-based LP
simulation technique
Problem statement
- Need a simulatable component with performance based on
measured LP data
- The LP data files are in some non-Maury format.
- Need a true output signal (voltage and current) for use in lineup simulations including other non-linear devices (e.g. an
electronically controlled matching network)
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1
Power amplifier design and load-pull
measurements in practice
MGA-31189
Datasheet only provides
numbers for P1dB, Gain and
OIP3 when terminated with
50 Ohm.
Device is characterized at
different loads with a custom
(non-Maury) LP set-up
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2
Power amplifier design and load-pull
measurements in practice
Solution: build our own component based on two
special ADS components: FDD and DAC.
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Power amplifier design and load-pull
measurements in practice
How does it work?
The FDD ("Frequency Defined Device") senses the load
impedance seen at its output terminal.
The power associated with this load impedance is looked-up
(using the sensed load values) from the MDIF formatted loadpull data DAC (Data Access Component).
The FDD's output voltage is then set to deliver the looked-up
power to the load.
© Copyright Agilent Technologies and bsw 2013/2014
4
Power amplifier design and load-pull
measurements in practice
Under the hood
Z_sensed
V/I
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Power amplifier design and load-pull
measurements in practice
Under the hood
Z_sensed
V
I
© Copyright Agilent Technologies and bsw 2013/2014
6
Power amplifier design and load-pull
measurements in practice
Under the hood
Z_sensed
V
I
© Copyright Agilent Technologies and bsw 2013/2014
7
Power amplifier design and load-pull
measurements in practice
Under the hood
Z_sensed
V
I
© Copyright Agilent Technologies and bsw 2013/2014
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Power amplifier design and load-pull
measurements in practice
Requirements for the load-pull data to be usable by
this model
The load-pull data should be structured as a generic MDIF file.
The independent variables in the load-pull data (typically the
VSWR and phase of the load) should be monotonic and
constant for a range of inner (faster changing) independent
variables. (a.k.a. "rectangular" data. i.e., not "scattered" data.)
Additional independent variables e.g. Frequency, Temperature,
Vbias, Pin, etc. are supported as long as they are monotonic
and constant for a range of inner independent variables.
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Power amplifier design and load-pull
measurements in practice
Generic MDIF format
Generic MDIF consists of blocks with formatted data.
var1Name, var2Name, VarNName are the independents as well as
bVar1Name (the most inner -fastest changing- independent)
bVar2Name, bVar3Name are the dependents.
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Power amplifier design and load-pull
measurements in practice
Section of Generic MDIF file
mga31189_LP_data.mdf
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Power amplifier design and load-pull
measurements in practice
Example mga31189.lpd LP data files that needs reformatting and merging.
Join files taken at different frequencies
and make Frequency a VAR
Not monotonous, needs re-ordering
Break into blocks of equal Gamma values and variable Phase
© Copyright Agilent Technologies and bsw 2013/2014
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Power amplifier design and load-pull
measurements in practice
File reformatted to generic MDIF
(use a script or Excel and ascii text editor)
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Power amplifier design and load-pull
measurements in practice
Use new LP_data_model to create contour plots
Load tuner represents
(harmonic) impedance
on Smith chart.
FDD requires HB
simulator
Sweeps arranged to
create VSWR circles
with load tuner.
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Power amplifier design and load-pull
measurements in practice
Pout and OIP3 contours at 1900 MHz
Pout optimum is
quite different from
OIP3 optimum.
Discontinuity caused by
extrapolation on sparse data
around -180 degrees in LP file.
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Power amplifier design and load-pull
measurements in practice
Long extrapolation required near -180 degrees due
to limited number of data points.
>
>
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Power amplifier design and load-pull
measurements in practice
Copy data from +180 degrees area to -180 area
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Power amplifier design and load-pull
measurements in practice
Discontinuity removed by augmenting data in -180
degrees area.
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Power amplifier design and load-pull
measurements in practice

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