Keysight Technologies Adding a Calibration ...

Keysight Technologies Adding a Calibration Definition File to the 86100D DCA-X to Support TDR/TDT Calibration Using Probes

Application Brief

Introduction This Application Brief applies to the 86100D DCA-X with firmware version A.04.21 or newer. For the highest accuracy TDR/TDT measurements, a TDR Calibration should be performed. The 86100D DCA-X comes from the factory pre-loaded with Calibration Definition Files for the most popular 3.5 mm, 2.92 mm, 2.4 mm and 1.85 mm Calibration Kits. For applications where probes are used, the 86100D DCA-X also supports calibration at the probe tip using a calibration substrate. Due to the wide range of probes and probe substrates available on the market, Calibration Definition Files for probes are NOT included with the 86100D DCA-X but can be added by the user. In addition to useful background information, this Application Brief provides step-by-step instructions for adding a Calibration Definition File for a probe + calibration substrate pair to the 86100D DCA-X. Note that some Calibration Definition Files provided by probe manufacturers are in an older format, typically a .ckt file, that is not compatible with the 86100D DCA-X which uses the newer .xkt file format for Calibration Definition Files. This Application Brief contains background information on what a Calibration Definition File is, the steps needed to convert a .ckt file to a properly formatted .xkt file, and steps needed to validate a .xkt file is formatted properly to work with the 86100D DCA-X.

Figure 1. Probing Arm with TDR Remote Heads

03 | Keysight | Adding a Calibration Definition File to the 86100D DCA-X to Support TDR/TDT Calibration Using Probes - Application Brief

What is a Calibration Definition File? The Calibration Definition File for each Calibration Kit contains the physical characteristics and mathematical definitions for each standard in the kit in the format required by the 86100D DCA-X. A Calibration Kit is a set of physical devices called standards. Each standard has a standard definition: a precisely known or predictable magnitude and phase response as a function of frequency. In order to use the physical standards of a Calibration Kit, the response of each standard must be mathematically defined and then organized into standard classes which correspond to the error models used by the 86100D DCA-X. The Standard Definition is the mathematical model of the electrical characteristics (delay, attenuation and impedance) of each calibration standard. These electrical characteristics can be mathematically derived from the physical dimensions and material of each calibration standard or from its actual measured response. A Standard Definition table lists the parameters that are used to specify the mathematical model. The Standard Definitions for Keysight’s calibration kits can be found at: http://na.support.keysight.com/pna/caldefs/stddefs.html Class Assignment is the process of organizing calibration standards into a format which is compatible with the error models used in measurement calibration. A class or group of classes corresponds to the different calibration types used for the 86100D DCA-X.


What in the Calibration Definition File Is Important to the 86100D DCA-X/TDR? If one were to read through a converted .xkt Calibration Definition File they would encounter four main sections comprised of a general information section, connector list, standard list, and a kit classes section. Each one of these sections is important to the 86100D DCA-X and contains vital information for performing an accurate calibration.

General information –– Cal Kit Label Specifies the name of the Calibration Kit (this is then displayed in FlexDCA, the software that runs the 86100D DCA-X). –– Cal Kit Version Specifies the version of the Calibration Kit. –– Cal Kit Description Gives more information about the Calibration Kit (usually an broader definition of the Cal Kit Label, displayed in FlexDCA in parenthesis following the Label).

Connector list The Connector List describes the electrical characteristics of the connectors and the frequencies that will be used. The Connector List includes: –– Family Specifies what family the connector belongs to (Probe, 1.85 mm, 2.92 mm etc.). –– Gender Specifies the gender of the connector. Usually the Connector List will contain both Male & Female options. Although Probe Gender is often classified as “Genderless”, the 86100D DCA-X does not currently support Genderless, and thus this must be modified in order to be compatible. –– Maximum Frequency Specifies the maximum frequency the connector is used for in calibration. –– Minimum Frequency Specifies the minimum frequency the connector is used for in calibration. –– Z0 Specifies the system characteristic impedance (usually 50 Ω).


What in the Calibration Definition File Is Important to the 86100D DCA-X/TDR? (Continued) Standard list/Definitions The standard list section will contain whatever Standard Definitions the particular Calibration Definition File uses to perform calibration; often it will contain the SOLT (Short-Open-LoadThru) standards. Standard SHORT OPEN LOAD THRU/LINE

Terminal impedance Zero ohms Infinite ohms System impedance, Z0 No terminal impedance

Standard Definitions describe the electrical characteristics of the standards and the frequencies that will be used. Standard Definitions include: –– Label Specifies type of standard (SHORT, OPEN, THRU/LINE, LOAD, ARBITRARY). –– Description Specifies what the standard does (usually this is just the same information that is in the Label). –– Port Connector IDs Specifies which connector Family and Gender (from the Connector List) is to be used. –– Maximum Frequency Specifies the maximum frequency the standard is used for in calibration. –– Minimum Frequency Specifies the minimum frequency the standard is used for in calibration. –– Standard Number Used to match corresponding standards and kit classes. –– Offset Delay Specifies a uniform length of transmission line between the standard being defined and the actual calibration plane. –– Offset Loss Specifies energy loss, due to skin effect, along a one-way length of coaxial cable. –– Offset Z0 Specifies the characteristic impedance of the standard (not the system characteristic impedance or the terminal impedance of the standard). Note: The order of standards is not critical; as long as the kit classes and standards are matched correctly (using the Standard Number) the calibration should have no problem.

If you are looking through the OPEN, and SHORT Standards: After the Standard Number you will see four different values labeled as C0-C3, and L0-L3. These values are used to build capacitive and inductive models for their given standards.

Capacitance model equation C0, C1, C2, C3. Specifies the fringing capacitance for the open standard. –– C = (C0) + (C1 x F) + (C2 x F²) + (C3 x F³) –– F is the measurement frequency. –– The terms in the equation are defined when specifying the open as follows: –– C0 term is the constant term of the third-order polynomial and is expressed in Farads. –– C1 term is expressed in F/Hz (Farads/Hz). –– C2 term is expressed in F/Hz². –– C3 term is expressed in F/Hz³.


What in the Calibration Definition File Is Important to the 86100D DCA-X/TDR? (Continued) Inductance model equation L0, L1, L2, L3. Specifies the residual inductance for the short standard. –– L = (L0) + (L1 x F) + (L2 x F²) + (L3 x F³) –– F is the measurement frequency. –– The terms in the equation are defined when specifying the short as follows: –– L0 term is the constant term of the third-order polynomial and is expressed in Henries. –– L1 term is expressed in H/Hz (Henries/Hz). –– L2 term is expressed in H/Hz². –– L3 term is expressed in H/Hz³.

Kit classes used in the 86100D DCA-X –– SA - OPEN Standards (standards in the SA class are not always Opens) –– SB - SHORT Standards –– SC - LOAD Standards –– FWD/REV Trans and Match - THRU Standards. Most Calibration Kits do NOT include a physical THRU standard, but assume that an Insertable Thru will be used. –– SA, SB, SC - These are the three classes for reflection calibrations. They are required in removing the directivity, source match, and reflection tracking errors. Typically, these classes might consist of an open, a short and a load standard. –– Transmission and Match (forward and reverse) - The transmission class relates primarily to the transmission tracking, while the match class refers to load match. For both of these classes, the typical standard is a thru or delay.

Note: You may see TRL (Thru, Reflect, Line) calibration kit classes in your Calibration Definition File. TRL calibration is not supported by the 86100D DCA-X, and thus these kit classes are ignored.


How do I Modify a .ckt or .xkt Calibration Definition File for the 86100D DCA-X? This section will cover the steps to convert a .ckt file to a .xkt, as well as how to modify a .xkt file to be compatible with the DCA-X. Note: If your file is already in .xkt format then skip to Step 3. 1. In order to perform this conversion you will need the most recent (2013) VNA Calibration Kit Editor from Keysight (Agilent) which can be downloaded using the following link: http://na.support.keysight.com/pna/apps/calkiteditor.msi 2. Once open, do not modify the file, just save it as a .xkt file and exit the VNA Calibration Kit Editor (Figure 2).

Figure 2. Save as a .xkt

3. Open and view your .xkt file in a text editor such as Notepad. 4. Now compare the of your .xkt file with that of the “Generic_Probe” Calibration Definition File (copied below) that comes with the 86100D DCA-X (located under Keysight/FlexDCA/Demo/CalibrationKitDefinitions). It is important that the new .xkt Connector List matches that of the Generic Probe file – Typically it works best to simply remove your file’s Connector List and copy/paste in the Connector List from the Generic Probe.


Below is the Connector List section of the “Generic_Probe” Calibration Definition File: Probe Female 999000000000 0 50 Probe Male 999000000000 0 50

5. Also in the converted .xkt file search for the line in each of the “Standards” sections (Figure 3). These lines will need to be changed to “Probe Female”. The Port Connector IDs must be modified for each standard in the cal file (Short, Load, Open, Thru etc.). Note that the Thru standard will contain two , be sure to modify both. Note: The reason for adding the “Female” gender in Step 5 is because the 86100D DCA-X does not support Genderless connectors.

Figure 3. Port Connector IDs.


How do I Open a Converted Calibration Definition File on the 86100D DCA-X? 1. In order to properly view the Calibration Definition File on the 86100D DCA-X, save your converted file (still as a .xkt) under: Keysight/FlexDCA/Demo/CalibrationKitDefinitions (Figure 4).

Figure 4. Calibration Definition File Save Location

2. If FlexDCA is already open on the 86100D DCA-X, you will need to close and restart the firmware for the new Calibration Definition File to be recognized. 3. After opening the FlexDCA firmware, under TDR/TDT Mode go to “New TDR Calibration”. In the “Step 2: Specify Cal Kits and Connectors” section make sure the “Calibration Method” is either SOLT or SLT, and the “DUT Connectors” is set to “Probe”. Your Calibration Definition File should now be visible in the “Calibration Kit” drop-down (Figure 5).

Figure 5. Selecting Converted Calibration Definition File


Note: If you are doing a 2 port calibration (as pictured in Figure 5), or any other connector configuration that is not just probes, you can select “Customize Per Port” in the bottom right of the “Step 2: Specify Cal Kits and Connectors” section (Figure 5). You can then specify which Calibration Definition File goes to which connectors (Figure 6).

Figure 6. Specify Connector Configuration

4. You can now calibrate using your correctly configured Calibration Definition File.

Hint: If you receive errors upon starting the FLexDCA firmware such as “Failed to load TDR/TDT file: … etc.“. It is likely that one or more of the PortConnectorIDs lines were either:

a. Not copied in correctly (beware of extra spaces). b. Missed for a certain standard. The error message will likely tell you what standard the error occurred in (Short, Load, Open, Thru). After finding the error using a text editor, correct and save the file and restart the FlexDCA firmware on the 86100D DCA-X. Only when FlexDCA opens with no errors will the new Calibration Definition File be visible in the “Calibration Kit” drop-down.

References Keysight Calibration Standards: http://na.support.keysight.com/pna/help/latest/S3_Cals/Calibration_Standards.htm Network Analyzer Calibration Kit Info: http://cp.literature.agilent.com/litweb/pdf/5956-4352.pdf Keysight Calibration Kit Definitions: http://na.support.keysight.com/pna/caldefs/stddefs.html


www.axiestandard.org AdvancedTCA® Extensions for Instrumentation and Test (AXIe) is an open standard that extends the AdvancedTCA for general purpose and semiconductor test. Keysight is a founding member of the AXIe consortium. ATCA®, AdvancedTCA®, and the ATCA logo are registered US trademarks of the PCI Industrial Computer Manufacturers Group. www.lxistandard.org LAN eXtensions for Instruments puts the power of Ethernet and the Web inside your test systems. Keysight is a founding member of the LXI consortium. www.pxisa.org PCI eXtensions for Instrumentation (PXI) modular instrumentation delivers a rugged, PC-based high-performance measurement and automation system.


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Keysight Technologies Adding a Calibration ...

Keysight Technologies Adding a Calibration ...

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