1EuMW Seminars 2013

Accurate Differential Device Characterization using VectorStar

EuMW 2013 Anritsu Workshop

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Agenda• 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

Differential devices and Measurements

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Differential Mode

Common Mode

• 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.

Differential ApplicationsFor reasons of immunity, efficiency and raw performance, the number of balanced devices (both RF and high speed digital ) increasing.

filterbalanced balanced IF

LO

RF

PCI Express Test Card Transmission Line

Measurement Needs• 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

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Response

Response Response

Response

Stimulus

• 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

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 4-

port performance. 12-port configurations available

• Widest range of calibration & de-embedding methods

• Choice of TMS or Superposition

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Good S-parameter DataPoor S-parameter Data

VectorStar Dual Source Option

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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!

Dual Source VectorStar

a1 b1

a2 b2

xN

xN

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

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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 super-position 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

• 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.

Option 043

DifferentialViewTM and Dual Source

• 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 Mixed Mode

VectorStar TMS Setup

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• 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

• 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.

Single ended, super-positioning measurements often preferred over TMS method due to faster measurement speed and less error correction

processing

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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

Measurements of Nonlinear Differential Devices

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1800 Phase Offset at Test Port Non-1800 Phase Offset at DUT Input

Dual Source VectorStar

a1 b1

a2 b2

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No TMS correction applied.

• 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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1800 Phase Offset at Test Port 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

Opt 043 TMS: Measure mismatch and apply correction during measurement

Dual Source VectorStar

a1 b1

a3 b3

xN

xN

Measurements of Nonlinear Differential Devices

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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

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

• 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

Measuring Differential Devices Through Baluns and Fixtures

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Port 1 path to DUT

Port 3 path to DUT

Calibrated test port plane

DUT 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

Embedding/De-embedding

• 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

Useful to add and remove networks to/from a given result.

DUTEmbed

DUTMatchnetwk

Match Netwk

DUTfixture fixtureDe-embed DUT

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

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• DifferentialView offers easy configuration for differential and mixed mode measurements for thorough analysis

Differential Measurements

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SweptPhase

• 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

VectorStar DifferentialView Phase Sweep

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• 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

DifferentialViewTM for Broadband and mmWave Measurements

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• 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

VectorStar mmWave True Mode Stimulus Measurements

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• 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

Multiport CONFIGURATIONS

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Passive Device Measurements

Recommended:

• MS464xB Vector Network Analyzer 10 MHz to 20, 40, 50, 70 GHz

- Opt 051 Direct Access Loops

- Opt 007 Frequency Offset. Multiple source control software.

• MN469xB 4-port test set

• Add options as desired:

• Option 002 Time Domain

• Opt 070 70 kHz Low-end extension

• Opt 031 Dual Source

Active Device Measurements

Recommended:

• MS464xB Vector Network Analyzer 10 MHz to 20, 40, 50, 70 GHz

- Opt 061 Active Device Measurements Suite

- Opt 007 Frequency Offset. Multiple source control software.

• MN469xB 4-port test set

• Add options as desired:

• Opt 031 Dual Source

• Opt 070 70 kHz Low-End ExtensionSee datasheet for full list

Differential Device CONFIGURATIONS

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Linear Device Measurements

Recommended:

• MS4647B Vector Network Analyzer 10 MHz to 70 GHz

- Opt 002 Time Domain

- Opt 061 Active Device Measurements Suite

• MN4697B 4-port test set

• Add other options as desired.

• Opt 070 70 kHz Low-End ExtensionSee datasheet for full list

Non-linear Device Measurements

Recommended:

• MS4647B Vector Network Analyzer 10 MHz to 70 GHz

- Opt 070 70 kHz Low-End Extension

- Opt 031 Dual Source

- Opt 043 DifferentialViewTM

- Opt 061 Active Device Measurements Suite

• MN4697B 4-port test set

• Add other options as desired. See datasheet for full list

Signal Integrity CONFIGURATIONS

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Backplane/Interconnect Measurements

• MS4647B Vector Network Analyzer 10 MHz to 70 GHz

- Opt 002 Time Domain

- Opt 051 Direct Access Loops

- Opt 070 70 kHz Low-End Extension

• MN4697B 4-port test set

Active Device Measurements

• MS4647B Vector Network Analyzer 10 MHz to 70 GHz

- Opt 070 70 kHz Low-End Extension

- Opt 031 Dual Source

- Opt 043 DifferentialViewTM

- Opt 061 Active Device Measurements Suite

• MN4697B 4-port test set

• Add other options as required. See datasheet for full list

Summary

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• 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.

Thank You!

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VectorStar 70 kHz–20,40,50,70 GHz VectorStar 70 kHz – 70 GHz 4 port

VectorStar 70 kHz – 110 GHz VectorStar 40 MHz – 70 GHz 12 port

VectorStar 4 Port70 kHz – 110 GHz