2
Outline
• What is load pull and why do it?
• Working with measured load pull data – use to design matching networks
• Simulating load pull on nonlinear device models (including X-Parameters) – use to determine optimal source and load impedances
3
Outline
• What is load pull and why do it?
• Working with measured load pull data – use to design matching networks
• Simulating load pull on nonlinear device models (including X-Parameters) – use to determine optimal source and load impedances
Device performance depends on source and load impedances
5
Input match.network
Output match.network
freqf1 f2 f3
freqf1 f2 f3
Externalload (or next stage)
Externalsource (or previous stage)
Fundamental load pull setup
6
freqf1 f2 f3
freqf1 f2 f3
Load tunerSource
tuner
Available source power constant
Why? Quick “sanity check”; adjust sampled area
Guess reasonablevalues for allvariables.Adjust, if necessary.
Fundamental load pull – with power sweep
7
freqf1 f2 f3
freqf1 f2 f3
Load tunerSource
tuner
Available source power swept freq
Why? See gain compression and constant powerdelivered data
Fundamental source pull setup
8
freqf1 f2 f3
freqf1 f2 f3
Load tuner
Source tuner
Available source power constant
Why? Source impedances affect performances, too
Fundamental load pull with parameter sweep
9
freqf1 f2 f3
freqf1 f2 f3
Load tunerSource
tuner
Available source power constant
…
Sweep any parameter - source frequency, bias, etc.Why? Investigate device performancemore thoroughly
freq
Harmonic load phase sweep
10
freqf1 f2 f3
freqf1 f2 f3
Load tunerSource
tuner
freq
Sweep input power to see constant powerdelivered data
Why? Harmonic impedancesmatter, but usually want highreflection
Source stimulus determines responses we may plot
11
Gain comp.curves from source powersweep
IMD from2-tonesource
ACLR frommodulated source
Constant power delivered load pull with parameter sweep – more precise characterization
12
freqf1 f2 f3
freqf1 f2 f3
Load tuner
Source tuner
Available source power optimized
…
Sweep any parameter - source frequency, bias, etc.
freq
Power deliveredheld constantvia optimization
Check sensitivity of completed design
13
Input match.network
Output match.network
freqf1 f2 f3
freqf1 f2 f3
Loadtuner
Sourcetuner
Could be X-Parametermodel, instead
14
Outline
• What is load pull and why do it?
• Working with measured load pull data – use to design matching networks
• Simulating load pull on nonlinear device models (including X-Parameters) – use to determine optimal source and load impedances
Examine performance contours
17
1) Reads LP data file2) Simulates S-parameters
of network3) Gets corresponding
performance data Tuner generates loads in region you specify
Using measured data containing a power sweep
20
Sweep valueswithin rangeof those in file
Sweep based ongamma_x, gamma_yvalues in file
Why sweep power? See gain compression data.
Contours at specified gain compression
21
Why do contours look strange? Measurements at some loads were not valid.
From contours we decide optimal impedances. What’s next?
23
Design impedance matching network(s) using existing techniques, or…
26
Outline
• What is load pull and why do it?
• Working with measured load pull data – use to design matching networks
• Simulating load pull on nonlinear device models (including X-Parameters) – use to determine optimal source and load impedances
A sequence for running load pull simulations
27
1) 1-tone, 1 input power load pull2) Add power sweep to see gain compression3) Run frequency or bias sweep4) Run harmonic load phase sweep5) Run constant output power with swept var6) Run source pull7) Use 2-tones to see IMD8) Use modulated signal to see ACLR
Based on experience:a) Change orderb) Delete stepsc) Iterate
Use of “instrument” subcircuits simplifies setup
28
Most parameters are passed to tuner inside “instrument” subcircuit
Start with fast, simple load pull
29
Source Power= 5 dBm
Source Power= 12 dBm
Refine sample space
• Available source power held constant• Guess optimal Zsource and harmonic Zs
A sequence for running load pull simulations
30
1) 1-tone, 1 input power load pull2) Add power sweep to see gain compression3) Run frequency or bias sweep4) Run harmonic load phase sweep5) Run constant output power with swept var6) Run source pull7) Use 2-tones to see IMD8) Use modulated signal to see ACLR
Based on experience:a) Change orderb) Delete stepsc) Iterate
Adjusting contour lines to all pass through maximum PAE load
35
Maximum PAE (Perf1 marker) occurs with 28.8 dBm power delivered (Perf3 contour) and 12.3 dB gain(Perf2 contour.)
A sequence for running load pull simulations
36
1) 1-tone, 1 input power load pull2) Add power sweep to see gain compression3) Run frequency or bias sweep4) Run harmonic load phase sweep5) Run constant output power with swept var6) Run source pull7) Use 2-tones to see IMD8) Use modulated signal to see ACLR
Based on experience:a) Change orderb) Delete stepsc) Iterate
A sequence for running load pull simulations
38
1) 1-tone, 1 input power load pull2) Add power sweep to see gain compression3) Run frequency or bias sweep4) Run harmonic load phase sweep5) Run constant output power with swept var6) Run source pull7) Use 2-tones to see IMD8) Use modulated signal to see ACLR
Based on experience:a) Change orderb) Delete stepsc) Iterate
A sequence for running load pull simulations
40
1) 1-tone, 1 input power load pull2) Add power sweep to see gain compression3) Run frequency or bias sweep4) Run harmonic load phase sweep5) Run constant output power with swept var6) Run source pull7) Use 2-tones to see IMD8) Use modulated signal to see ACLR
Based on experience:a) Change orderb) Delete stepsc) Iterate
A sequence for running load pull simulations
45
1) 1-tone, 1 input power load pull2) Add power sweep to see gain compression3) Run frequency or bias sweep4) Run harmonic load phase sweep5) Run constant output power with swept var6) Run source pull7) Use 2-tones to see IMD8) Use modulated signal to see ACLR
Based on experience:a) Change orderb) Delete stepsc) Iterate
A sequence for running load pull simulations
47
1) 1-tone, 1 input power load pull2) Add power sweep to see gain compression3) Run frequency or bias sweep4) Run harmonic load phase sweep5) Run constant output power with swept var6) Run source pull7) Use 2-tones to see IMD8) Use modulated signal to see ACLR
Based on experience:a) Change orderb) Delete stepsc) Iterate
Load pull with WCDMA signal
48
Read modulated data from file. Scale signal amplitude by optimizing “SFexp” variable.
49
Review
• Basic load pull concepts
• Using measured load pull data files to design matching networks
• Fast, simple load pull
• Adding power sweeps to see compression
• Sweeping frequency
• Sweeping harmonic reflection coefficient phase
• Constant power-delivered load pull with sweep
• Using two tones to see intermodulation distortion
• Load pull with a WCDMA source
For more information:
50
http://edocs.soco.agilent.com/display/eesofkc/Load+Pull+DesignGuide+Enhancements+for+post+ADS+2011_05
On the latest release of ADS:
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On the latest release of the ADS Load Pull DesignGuide:
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