Accurate Differential Device
Characterization using VectorStar
EuMW 2013 Anritsu Workshop
EuMW Seminars 2013
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Agenda
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Basic concepts and measurement overview
Dual source architecture and True Mode Stimulus measurements
Differential component testing
Signal Integrity testing
Differential PCB and on-wafer fixture de-embedding
DifferentialView user interface
VectorStar performance
mmWave True Mode Stimulus capabilities
System configuration summary
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Differential devices and Measurements
Differential Mode
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Common Mode
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• Differential devices gaining popularity due to advantages in
suppressing noise and EMI effects.
• Preferred driver in SI applications
• VNA needs to accurately modify stimulus conditions for complete
analysis.
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Differential Applications
For reasons of immunity, efficiency and raw performance,
the number of balanced devices (both RF and high speed
digital ) increasing.
balanced
filter
balanced
RF
IF
LO
PCI Express Test Card
Transmission Line
Measurement Needs
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Insertion Loss
Return Loss
Gain
Time domain
Line Impedance
Rejection
Balance
Cross talk
All these measurements can be performed with the 4
port VectorStar
Measurements of Differential Devices
Stimulus
Response
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Response
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Response
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Response
• Derived from single ended S-parameters
– Signal is applied to one port and response is measured at all ports
– Incident signal is applied to each port
– DUT is assumed to be linear
• Excellent for passive devices and linear active devices
– Does not require an expensive second source or complex software corrections.
– Fastest measurement speed
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True Differential Measurements
• Both input ports are excited at once
– Either balanced (in-phase) or differentially (180 degrees out of phase)
– Response is measured at both input and output ports balanced or
differentially
• Technique used for non-linear active devices
• Must not use baluns (e.g. wafer probes)
– Baluns transform phase releationship at DUT plane and not valid
• Generally not valid for on-wafer measurements
– On-wafer measurements are non-50 ohm. Even if you were to ignore the
balun error the DUT performance will change when a different impedance
load is presented to the device after measurement.
DifferentialViewTM for Signal Integrity
Measurements
• Broadest frequency span: 70 kHz to 70/110 GHz
• Best time domain analysis capability
• 4-port test set upgrades 2 port VectorStar to 4port performance. 12-port configurations
available
• Widest range of calibration & de-embedding
methods
• Choice of TMS or Superposition
Poor S-parameter Data
Good S-parameter Data
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VectorStar Dual Source Option
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a1
b1
a2
b2
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Dual Source VectorStar
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Option 031 Dual Source eliminates the need for a transfer switch
Provides up to 7 dB of additional power at 70 GHz
MS4640B series improves noise floor specification as much as 9 dB
Combined, results in improved dynamic range performance up to 16 dB at 70 GHz!
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VectorStar 4-Port Solutions
• External test set offers easy upgrade
capabilities – buy what you need when you
need it
• Broadest frequency balanced/differential
measurements in the market
• MN4694B
– 70 kHz* to 20/40 GHz
– K (2.92 mm)
• MN4697B
– 70 kHz* to 50/70 GHz
– V (1.85 mm)
• Requires MS464xA VectorStar with Option 051,
061, or 062
* Operational down to 40 kHz
Connecting a 4-port Test Set
• Add a 4-port test set (MN4694B or
MS4697B) for multiport
measurements
• Without True Mode Stimulus Option
(Opt 043) this configuration can be
used to measure single ended
multiport components (couplers,
mixers, etc.)
• For passive or linear active devices use
this configuration with standard superposition technique for differential
analysis
• Control of the two sources without
Opt 043 is via Multiple Source Control.
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Performing True Mode Stimulus Differential Measurements
Option 043
• DifferentialView Option 043
Software provides the phase
synchronization needed for True
Mode Stimulus control.
• For independent amplitude and
phase control driving ports are
configured in a 1:3 or 1:4 and
2:4 or 2:3 arrangement.
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DifferentialViewTM and Dual Source
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Differential, common and mixed mode S-parameters
True Mode Stimulus capability
Adjust differential phase & amplitude
Instant view of results during parameter change
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Differential Mode
Common Mode
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Mixed Mode
VectorStar TMS Setup
• DifferentialView menu
provides easy access
to all key parameters
• No need to activate
numerous
configuration panels
to edit setup
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DifferentialView provides easy access to
TMS parameter modification
• DifferentialView software
provides easy to configure
menus and stimulus controls for
accurate TMS measurements
• DifferentialView quickly sets up
VectorStar for specific
differential stimulus needs of the
DUT while continuously
displaying the setup parameters
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Differential View provides TMS mode
measurements of non-linear device
• Performance differences of a
compressed device can clearly
be seen between single ended
and TMS mode.
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Dual Source Multiple Source Control
• Multiple source
control provides
advanced
independent
controls of the two
internal sources
• Also controls up to
4 external sources
for a total of 6
sources.
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Measuring Linear Differential Devices
Single ended, super-positioning measurements
often preferred over TMS method due to faster
measurement speed and less error correction
processing
• Comparing single-ended and TMS mode
measurements of linear differential
amplifier reveals minimal differences.
• Mode-converting match measurements of
the linear amplifier in SE and TMS modes
also shows minimal difference.
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Comparing Superposition and TMS mode
measurements of non-linear device
• SD2D1 values of a compressed
amplifier (for single-ended and
true-mode stimulus drive) are
shown here.
• In this case, performance
differences can clearly be seen
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Measurements of Nonlinear Differential Devices
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a1
b1
a2
b2
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Dual Source VectorStar
1800 Phase Offset at Test Port
No TMS correction
applied.
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Non-1800 Phase Offset
at DUT Input
Measuring nonlinear differential devices with a 1800 offset is preferable for more realistic characterization.
Nonlinear devices are sensitive to source mismatch
Source mismatch will shift stimulus signals to non-ideal offset
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Measurements of Nonlinear Differential Devices
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a1
b1
a3
b3
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Dual Source VectorStar
1800 Phase Offset at Test Port
Opt 043 TMS: Measure mismatch
and apply correction during
measurement
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1800 Phase Offset at
DUT Input
Applying TMS correction within DifferentialView corrects offset shift
Monitoring the applied signals (a3/a1) will provide an indication on the success of correction
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TMS Differential Phase Stability
• Sweep to sweep phase variations from 1800 differential while driving
nonlinear DUT at -12 dBm
• Accurate DDS architecture combined with optimized algorithms offer up to
5 times improvement in true mode accuracy
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Nonlinear DUT Measurement at Non-1800 Offset
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Measuring nonlinear differential devices with a 1800 offset is preferable for more realistic characterization.
Without proper offset correction performance of device will vary
Example demonstrates variance in DUT performance when stimulated by 1800 and 1350 offset
SD2D1 performance of example device changes by as much as 2 dB at 3 GHz
Anritsu white paper discusses this issue in more detail
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VNA measurement uncertainty when
operating in TMS mode
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All VNAs operating in the TMS mode must add an additional layer of corrections for proper analysis
Example comparisons of uncertainties for single-ended vs. true-mode stimulus mode when
performing linear S-parameter measurements
Not included are differences in stability due to drift from thermal changes or cable flexing
Additionally, the increase in sensitivities to source match interactions when operating in a
compressed state will add yet another layer of corrections
Consequently, the common approach is to use single ended (super-positioning) when measuring
passive devices or linear active devices and use TMS when measurement of a compressed device
demands
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Measuring Differential Devices
Through Baluns and Fixtures
DUT test
port plane
Port 1 path
to DUT
Port 3 path
to DUT
Calibrated
test port
plane
VNA test
port cables
• Fixtures often used to transition from single ended VNA test ports to the input of differential
devices
• Challenging to extract directly from measurement. If not de-embedded properly, will contribute to
overall error of predictive model.
• VectorStar’s extensive de-embedding capabilities help reduce the complexity of fixture and
transition removal
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Embedding/De-embedding
Useful to add and remove networks to/from a given result.
DUT
fixture
DUT
Embed
fixture
Match
netwk
Deembed
DUT
Match
Netwk
DUT
• VectorStar provides the most advanced E/DE functions
available on a VNA
• Multiple network E/DE also available
• Applies to 2, 3 and 4 port DUTs
VectorStar Fixture De-embedding
• VectorStar provides an extensive array of network extraction tools
for enhanced de-embedding capabilities.
• Calibration menus generate characterization files (SnP) for fixture
and probe de-embedding.
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DifferentialViewTM True Mode Stimulus Interface
• DifferentialView offers easy configuration for
differential and mixed mode measurements
for thorough analysis
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Differential Measurements
Swept
Phase
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• Measure device performance in an unbalanced state:
• Set amplitude or phase to an offset relationship
• Sweep phase to find device anomalies
• Use data to:
• Verify operating performance over wide input range
• Analyze non-linear boundaries
• Optimize input matching circuit to maximize performance
• Specify better device performance
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VectorStar DifferentialView Phase Sweep
• DifferentialView menu
provides real time
display of
measurement
parameters
• Immediately observe
DUT performance
changes with changes
in setup
• Example of modifying
phase sweep
parameters while
observing effects
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VectorStar Dual Source
• Using Multiple Source
Control to configure
VectorStar for mixer
measurements
• Up-converters or
Down-converters can
be configured
• Use external loop
options (051, 061, or
062) for direct access
to VNA converters
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DifferentialViewTM for Broadband and
mmWave Measurements
• Compact size
and high
performance
make the
Anritsu
mmWave
modules ideal
for 2 port or 4
port
configuration
• Enables
Broadband
differential
analysis on small
platen
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True Mode Stimulus Broadband Measurements
• Excellent stability due to excellent raw directivity and close
positioning of the mmwave test and reference couplers
• Improve device models due to high-quality low frequency data
• Remove RF/microwave concatenation issues
• Spend more time measuring (& less time calibrating)
• Easy positioning of small
modules on probe station
• Short cables conveniently
connect to probes for
best
performance & stability
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VectorStar mmWave True Mode Stimulus
Measurements
• VectorStar supports
Anritsu mmwave modules
to 125 GHz in coax or
mmwave OML or VDI
modules in waveguide
bands up to 1.1 THz
• mmWave modules used in
single ended or TMS mode
differential measurement
configuration
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Multiport CONFIGURATIONS
Passive Device Measurements
Active Device Measurements
Recommended:
Recommended:
• MS464xB Vector Network Analyzer
10 MHz to 20, 40, 50, 70 GHz
• MS464xB Vector Network Analyzer
10 MHz to 20, 40, 50, 70 GHz
- Opt 051 Direct Access Loops
- Opt 061 Active Device
Measurements Suite
- Opt 007 Frequency Offset.
Multiple source control software.
- Opt 007 Frequency Offset.
Multiple source control software.
• MN469xB 4-port test set
• Add options as desired:
• Option 002 Time Domain
• MN469xB 4-port test set
• Add options as desired:
• Opt 031 Dual Source
• Opt 070 70 kHz Low-end
extension
• Opt 070 70 kHz Low-End
Extension
See datasheet for full list
• Opt 031 Dual Source
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Differential Device CONFIGURATIONS
Linear Device Measurements
Non-linear Device Measurements
Recommended:
Recommended:
• MS4647B Vector Network Analyzer
10 MHz to 70 GHz
• MS4647B Vector Network Analyzer
10 MHz to 70 GHz
- Opt 002 Time Domain
- Opt 070 70 kHz Low-End Extension
- Opt 061 Active Device
Measurements Suite
- Opt 031 Dual Source
- Opt 043 DifferentialViewTM
• MN4697B 4-port test set
- Opt 061 Active Device
Measurements Suite
• Add other options as desired.
• Opt 070 70 kHz
Low-End Extension
See datasheet for full list
• MN4697B 4-port test set
• Add other options as desired.
See datasheet for full list
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Signal Integrity CONFIGURATIONS
Backplane/Interconnect Measurements
Active Device Measurements
• MS4647B Vector Network Analyzer
10 MHz to 70 GHz
• MS4647B Vector Network Analyzer
10 MHz to 70 GHz
- Opt 002 Time Domain
- Opt 070 70 kHz Low-End Extension
- Opt 051 Direct Access Loops
- Opt 031 Dual Source
- Opt 070 70 kHz
Low-End Extension
- Opt 043 DifferentialViewTM
- Opt 061 Active Device
Measurements Suite
• MN4697B 4-port test set
• MN4697B 4-port test set
• Add other options as required.
See datasheet for full list
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Summary
• Option 031 Dual Source offers improved power output for high power
measurement requirements.
• Improved MS4640B noise floor further improves dynamic range
performance
• Use standard 4-port configurations with super-positioning for passive
and linear device customers
• Include Option 043 TMS mode when measuring non-linear differential
devices.
• VNAs using TMS mode double the sweep count for additional stimulus
corrections. Use TMS mode only when a must.
• If must use TMS mode then use a VNA offering the optimum TMS
mode performance.
• VectorStar offers improved TMS mode performance using DDS
architecture and enhanced performance algorithms.
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VectorStar 70 kHz–20,40,50,70 GHz
VectorStar 4 Port
70 kHz – 110 GHz
Thank You!
VectorStar 70 kHz – 110 GHz
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VectorStar 70 kHz – 70 GHz 4 port
VectorStar 40 MHz – 70 GHz
12 port