QPHY-56G-PAM4 Operator’s Manualcdn.teledynelecroy.com/files/manuals/qphy-56g-pam4-manual.pdfSome of the images in this manual may show QualiPHY products other than QPHY-56G-PAM4,

QPHY-56G-PAM4 Operator’s Manual

Revision B – November, 2017 Relating to:

XStreamDSO™ Version 8.5.x.x QualiPHY Version 8.5.x.x

700 Chestnut Ridge Road Chestnut Ridge, NY, 10977-6499 Tel: (845) 425-2000, Fax: (845) 578 5985 teledynelecroy.com

© 2017 Teledyne LeCroy, Inc. All rights reserved.

Customers are permitted to duplicate and distribute Teledyne LeCroy documentation for internal training purposes. Unauthorized duplication is strictly prohibited.

Teledyne LeCroy and other product or brand names are trademarks or requested trademarks of their respective holders. Information in this publication supersedes all earlier versions. Specifications are subject to change without notice.

927389 Rev B November, 2017


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Table of Contents Introduction .................................................................................................................................................. 1 About QualiPHY ............................................................................................................................................. 1 About QPHY-56G-PAM4 ................................................................................................................................ 1 Required Equipment ...................................................................................................................................... 1 Required Host Computer System .................................................................................................................. 2 Installation and Setup ................................................................................................................................. 3 Install Base Application .................................................................................................................................. 3 Activate Components..................................................................................................................................... 3 Set Up Dual Monitor Display ......................................................................................................................... 3 Set Up Remote Control ................................................................................................................................. 4

Configure Oscilloscope for Remote Control ........................................................................................... 4 Add Connection to QualiPHY ................................................................................................................. 4 Select Connection .................................................................................................................................. 4

Using QualiPHY ........................................................................................................................................... 5 Accessing the Software ................................................................................................................................. 5 General Setup ................................................................................................................................................ 6

Connection tab ....................................................................................................................................... 6 Session Info tab ...................................................................................................................................... 6 Report tab ............................................................................................................................................... 6 Advanced tab ......................................................................................................................................... 6 About tab ................................................................................................................................................ 6

QualiPHY Test Process ................................................................................................................................. 7 Set Up Test Session ............................................................................................................................... 7 Run Tests ............................................................................................................................................... 8 Generate Reports ................................................................................................................................... 9

Customizing QualiPHY ................................................................................................................................ 10 Copy Configuration ............................................................................................................................... 10 Select Tests .......................................................................................................................................... 10 Edit Variables ....................................................................................................................................... 11 Edit Test Limits ..................................................................................................................................... 12

X-Replay Mode ............................................................................................................................................ 13 QPHY-56G-PAM4 Testing ......................................................................................................................... 14 Test Preparation ........................................................................................................................................... 14

Required Test Modes ........................................................................................................................... 14 Physical Setup ...................................................................................................................................... 14

QPHY-56G-PAM4 Test Configurations ........................................................................................................ 14 CEI56G-LR-PAM4 ................................................................................................................................ 14 CEI56G-MR-PAM4 ............................................................................................................................... 14 CEI56G-VSR-PAM4 CTLE Optimizer .................................................................................................. 15 CEI56G-VSR-PAM4 Host Output Emulated HCB ................................................................................ 15 CEI56G-VSR-PAM4 Host Output No HCB .......................................................................................... 16 CEI56G-VSR-PAM4 Module Output Emulated MCB ........................................................................... 16 CEI56G-VSR-PAM4 Module Output No MCB ...................................................................................... 17 CEI56G-VSR-PAM4 TP0a ................................................................................................................... 17 Demo - Simulated CEI56G-VSR-PAM4 Host Output ........................................................................... 17 Demo - Simulated CEI56G-VSR-PAM4 TP0a ..................................................................................... 17

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QPHY-56G-PAM4 Test Descriptions ............................................................................................................ 18 Baud Rate Test .................................................................................................................................... 18 Tx Output Voltage Tests ....................................................................................................................... 19 CTLE Optimize Test ............................................................................................................................. 20 Transition Time Tests ........................................................................................................................... 21 Linear Fit Tests ..................................................................................................................................... 22 Tx Output Jitter Tests ........................................................................................................................... 24 Eye Tests.............................................................................................................................................. 26 Eye Far End Tests ................................................................................................................................ 30

QPHY-56G-PAM4 Variables ........................................................................................................................ 31 Main Settings ........................................................................................................................................ 31

QPHY-56G-PAM4 Limit Sets ....................................................................................................................... 34 Appendix A: Manual Deskewing Procedures ......................................................................................... 35 Cable Deskewing Using the Fast Edge Output ........................................................................................... 35 Cable Deskewing Without Using the Fast Edge Output .............................................................................. 38

About This Manual This manual assumes that you are familiar with using an oscilloscope−in particular the Teledyne LeCroy oscilloscope that will be used with QualiPHY−and that you have purchased the QPHY-56G-PAM4 software option. Some of the images in this manual may show QualiPHY products other than QPHY-56G-PAM4, or were captured using different model oscilloscopes, as they are meant to illustrate general concepts only. Rest assured that while the user interface may look different from yours, the functionality is identical.


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Introduction About QualiPHY QualiPHY is highly automated compliance test software meant to help you develop and validate the PHY (physical-electrical) layer of a device, in accordance with the official documents published by the applicable standards organizations and special interest groups (SIGs). You can additionally set custom variables and limits to test compliance to internal standards. QualiPHY is composed of a “framework” application that enables the configuration and control of separate tests for each standard through a common user interface. Features include:

• Multiple Data Source Capability.

• User-Defined Test Limits: Tighten limits to ensure devices are well within the passing region, even if subsequently measured with different equipment.

• Flexible Test Results Reporting that includes XML Test Record Generation. Understand a device performance distribution, or obtain process related information from the devices under test.

About QPHY-56G-PAM4 QPHY-56G-PAM4 is an automated test package performing transmitter testing for 56 Gb/s (28 Gbaud) PAM4 interfaces as specified in:

• OIF CEI-56G-XSR-PAM4 • OIF CEI-56G-VSR-PAM4 • OIF CEI-56G-MR-PAM4 • OIF CEI-56G-LR-PAM4 • IEEE 802.3bs • IEEE 802.3cd

The software can be run on any Teledyne LeCroy oscilloscope with at least 30 GHz Bandwidth and 80 GS/s Sample Rate.

Required Equipment • Teledyne LeCroy real-time oscilloscope, ≥ 30 GHz BW, installed with:

o XStreamDSO v.8.4.x.x minimum* with an activated QPHY-56G-PAM4 option key o QualiPHY v.8.4.x.x minimum with an activated QPHY-56G-PAM4 component o SDAIII Serial Data Analysis software option o PAM4 Signal Analysis software option o VirtualProbe software option

*Note: The versions of XStreamDSO and QualiPHY software must match, so upgrade your version of QualilPHY if you have upgraded your oscilloscope firmware. The versions listed above are the minimum versions required for this product. The QualiPHY software may be installed on a remote PC, but all other software must be run on the oscilloscope.

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Required Host Computer System Usually, the oscilloscope is the host computer for the QualiPHY software, and all models that meet the acquisition requirements will also meet the host system requirements. However, if you wish to run the QualiPHY software from a remote computer, these minimum requirements apply:

• Operating System: o Windows 7 Professional o Windows 10 Professional

• 1 GHz or faster processor

• 1 GB (32-bit) or 2 GB (64-bit) of RAM

• Ethernet (LAN) network capability

• Hard Drive: o At least 100 MB free to install the framework application o Up to 1GB per standard installed to store the log database (each database grows from a few

MB to a maximum of 1 GB) See Set Up Remote Control for configuration instructions.


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Installation and Setup QualiPHY is a Windows-based application that can be configured with one or more serial data compliance components. Each compliance component is purchased as a software option.

Install Base Application Download the latest version of the QualiPHY software from: teledynelecroy.com/support/softwaredownload The link is under Oscilloscope Downloads > Software Utilities. If the oscilloscope is not connected to the Internet, copy the installer onto a USB memory stick then transfer it to the oscilloscope desktop or a folder on a D:\ drive to execute it. Run QualiPHYInstaller.exe and follow the installer prompts. Choose all the components you plan to activate. If you omit any components now, you will need to update the installation to activate them later. By default, the oscilloscope appears as local host when QualiPHY is executed on the oscilloscope. Follow the steps under Add Connection to QualiPHY to check that the IP address is 127.0.0.1.

Activate Components The serial data compliance components are factory installed as part of the main application in your oscilloscope and are individually activated through the use of an alphanumeric code uniquely matched to the oscilloscope’s serial number. This option key code is what is delivered when purchasing a software option. To activate a component on the oscilloscope:

1. From the menu bar, choose Utilities > Utilities Setup. 2. On the Options tab, click Add Key. 3. Use the Virtual Keyboard to Enter Option Key, then click OK.

If activation is successful, the key code now appears in the list of Installed Option Keys. 4. Restart the oscilloscope application by choosing File > Exit, then double-clicking the Start DSO

icon on the desktop.

Set Up Dual Monitor Display Teledyne LeCroy recommends running QualiPHY on an oscilloscope equipped with Dual Monitor Display capability. This allows the waveform and measurements to be shown on the oscilloscope LCD display while the QualiPHY application and test results are displayed on a second monitor. See the oscilloscope Operator’s Manual for instructions on setting up dual monitor display.

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Set Up Remote Control QualiPHY software can be executed from a remote host computer, controlling the oscilloscope through a LAN Connection. To set up remote control:

• The oscilloscope must be connected to a LAN and assigned an IP address (fixed or dynamic).

• The host computer must be on the same LAN as the oscilloscope.

Configure Oscilloscope for Remote Control Note: This component contains script generation files for specific equipment used with the oscilloscope to perform the compliance test. QualiPHY software should be installed on the oscilloscope even if it’s run from a remote computer.

1. From the menu bar, choose Utilities Utilities Setup... 2. Open the Remote tab and set Remote Control to TCP/IP. 3. Verify that the oscilloscope shows an IP address.

Add Connection to QualiPHY 1. On the host PC, download and run QualiPHYInstaller.exe. 2. Start QualiPHY and click the General Setup button. 3. On the Connection tab, click Scope Selector. 4. Click Add and choose the connection type. Enter the oscilloscope IP address from Step 3

above. Click OK. 5. When the oscilloscope is properly detected, it appears on the Scope Selector dialog. Select the

connection, and click OK. QualiPHY is now ready to control the oscilloscope.

Select Connection Multiple oscilloscopes may be accessible to a single remote host. In that case, go to General Setup and use the Scope Selector at the start of the QPHY session to choose the correct connection. QualiPHY tests the oscilloscope connection when starting a test. The system warns you if there is a connection problem.


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Using QualiPHY This section provides an overview of the QualiPHY user interface and general procedures. For detailed information about the QPHY-56G-PAM4 software option, see QPHY-56G-PAM4 Testing.

Accessing the Software Once QualiPHY is installed and activated, it can be accessed from the oscilloscope menu bar by choosing Analysis > QualiPHY, or by double-clicking the QualiPHY desktop icon on a remote computer. The QualiPHY framework dialog illustrates the overall software flow, from general set up through running individual compliance tests. Work from left to right, making all desired settings on each sub-dialog.

Figure 1 - QualiPHY framework dialog and Standard selection menu.

The sub-dialogs are organized into tabs each containing configuration controls related to that part of the process. These are described in more detail in the following sections. If Pause on Failure is checked, QauliPHY prompts to retry a measure whenever a test fails. Report Generator launches the manual report generator dialog. The Exit button at the bottom of the framework dialog closes the QualiPHY application.

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General Setup The first sub-dialog contains general system settings. These remain in effect for each session, regardless of Standard, until changed.

Connection tab Shows IP Address of the test oscilloscope (local host 127.0.0.1 if QualiPHY is run from the oscilloscope). The Scope Selector allows you to choose the oscilloscope used for testing when several are connected to the QualiPHY installation. See Set Up Remote Control for details.

Session Info tab Optional information about the test session that may be added to reports, such as: Operator Name, Device Under Test (DUT), Temperature (in °C) of the test location, and any additional Comments. There is also an option to Append Results or Replace Results when continuing a previous session.

To optimize report generation, enter at least a DUT name at the beginning of each session.

Report tab Settings related to automatic report generation. Choose:

• Reporting behavior of: o “Ask to generate a report after tests,” where you’ll be prompted to create a new file for

each set of test results. o “Never generate a report after tests,” where you’ll need to manually execute the Report

Generator to create a report. o “Always generate a report after tests,” to autogenerate a report of the latest test results.

• Default report output type of XML, HTML, or PDF.

• A generic Output file name, including the full path to the report output folder. Optionally, check Allow style sheet selection in Report Generator to enable the use of a custom .xslt when generating reports (XML and HTML output only). The path to the .xslt is entered on the Report Generator dialog. Report Generator launches the Report Generator dialog, which contains the same settings as the Report tab, only applied to individual reports.

Advanced tab This tab launches the X-Replay Mode dialog. See X-Replay Mode.

About tab Information about your QualiPHY installation.


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QualiPHY Test Process Once general system settings are in place, these are the steps for running test sessions.

Set Up Test Session 1. Connect the oscilloscope to the DUT. See QPHY-56G-PAM4 Testing Physical Setup. 2. Access the QualiPHY software to display the framework dialog.

3. If running QualiPHY remotely, click General Setup and open the Scope Selector to select the correct oscilloscope connection.

4. If you have more than one component activated, click Standard and select the desired standard to test against. Otherwise, your one activated component will appear as the default selection. Note: Although all the QualiPHY components appear on this dialog, only those selected when installing QualiPHY are enabled for selection.

5. Click the Configuration button and select the test configuration to run. These pre-loaded configurations are set up to run all the tests required for compliance and provide a quick, easy way to begin compliance testing. See QPHY-56G-PAM4 Test Configurations for a description of your configurations. You can also create custom configurations for internal compliance tests by copying and modifying the pre-loaded configurations. See Customizing QualiPHY for details.

6. Close the Edit/View Configuration dialog to return to the framework dialog.

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Run Tests 1. On the framework dialog, click Start to begin testing.

When tests are in progress, this button changes to Stop. Click it at any time to stop the test in process. You’ll be able to resume from the point of termination or from the beginning of the test.

2. Follow the pop-up window prompts. QualiPHY guides you step-by-step through each of the tests described in the standard specification, including diagrams of the connection to the DUT for each required test mode.

3. When all tests are successfully completed, both progress bars on the framework dialog are completely green and the message “All tests completed successfully” appears. If problems are encountered, you’ll be offered options to:

• Retry the test from the latest established point defined in the script

• Ignore and Continue with the next test

• Abort Session


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Generate Reports The QualiPHY software automates report generation. On the framework dialog, go to General Setup > Report to pre-configure reporting behavior. You can also manually launch the Report Generator from the framework dialog once a test is run. The Report Generator offers the same selections as the Report tab, only applied to each report individually, rather than as a system setting. This enables you to save reports for each test session, rather than overwrite the generic report file. There are also options to link a custom style sheet (.xslt) to the report, or to Exclude Informative Results. The Test Report includes a summary table with links to the detailed test result pages.

Figure 2 - The Test Report Summary and Details pages.

Reports are output to the folder D:\QPHY\Reports, or C:\LeCroy\QPHY\Reports if QualiPHY is installed on a remote PC. You can add your own logo to the report by replacing the file *\QPHY\StyleSheets\CustomerLogo.jpg. The recommended maximum size is 250x100 pixels at 72 ppi, 16.7 million colors, 24 bits. Use the same file name and format.

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Customizing QualiPHY Create custom test configurations by copying one of the standard configurations and modifying it. The pre-loaded configurations cannot be modified.

Copy Configuration 1. Access the QualiPHY framework dialog and select a Standard. 2. Click Edit/View Configuration and select the configuration upon which to base the new

configuration. This can be a pre-loaded configuration or another copy. 3. Click Copy and enter a name and description. Once a custom configuration is defined, it

appears on the Configuration tab with the defined name.

4. Select the new, custom configuration and follow the procedures below to continue making changes. Note: If any part of a configuration is changed, the Save As button becomes active on the bottom of the dialog. If a custom configuration is changed, the Save button will also become active to apply the changes to the existing configuration.

Select Tests On the Test Selector tab, check the tests that make up the configuration. Each test is defined by the PAM4CEI56G standard. A description of each test is displayed when it is selected. To loop an individual test or group of tests, select it from the list, then choose to loop indefinitely until stopped or enter the number of repetitions. When defining a number of repetitions, enter the number of repetitions before enabling the checkbox.


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Edit Variables The Variable Setup tab contains a list of test variables. See QPHY-56G-PAM4 Variables for a description of each. To modify a variable:

1. Select the variable on the Variable Setup tab, then click Edit Variable. (You can also choose to Reset to Default at any time.)

2. The conditions of this variable appear on a pop-up. Choose the new condition to apply.

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Edit Test Limits The Limits tab shows the Limit Set currently associated with the configuration. Any limit set can be associated with a custom configuration by selecting it in this field. The Limits Manager shows the settings for every test limit in a limit set. Those in the default set are the limits defined by the standard. To create a custom limit set:

1. On the Limits tab, click Limits Manager. 2. With the default set selected, click Copy Set and enter a name.

Note: You can also choose to copy and/or modify another custom set that has been associated with this configuration.

3. Double click the limit to be modified, and in the pop-up enter the new values.

You can also Import Limits from a .csv file. Tip: Likewise, Export Limits creates a .csv file from the current limit set. You may wish to do this and copy it to format the input .csv file.


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X-Replay Mode The X-Replay mode window is an advanced (“developer”) view of QualiPHY. The tree in the upper-left frame enables you to navigate to processes in the PAM4CEI56G test script, in case you need to review the code, which appears in the upper-right frame. Two other particularly useful features are:

• A list of recent test sessions in the lower-left frame. While you can only generate a report of the current test session in the QualiPHY wizard, in X-Replay Mode you can generate a report for any of these recent sessions. Select the session and choose Report > Create Report from the menu bar.

• The QualiPHY log in the bottom-right frame. The frame can be split by dragging up the lower edge. The bottom half of this split frame now shows the raw Python output, which can be useful if ever the script needs debugging.

Figure 3 – X-Replay Mode window.

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QPHY-56G-PAM4 Testing Test Preparation Before beginning any test or data acquisition, warm the oscilloscope for at least 20 minutes. Calibration is performed automatically by the oscilloscope software; no manual calibration is required. The calibration procedure is run again if the temperature of the oscilloscope changes by more than a few degrees.

Required Test Modes The QPHY-56G-PAM4 script requires that the DUT (Device Under Test) outputs specific test patterns. The script will prompt you to do so before each specific test, but it is recommended that you ensure the DUT is capable of generating these patterns before beginning testing.

Physical Setup See the description of each test configuration for specific set up information.

QPHY-56G-PAM4 Test Configurations Test configurations include variable settings, limit sets, and test selections. See QPHY-56G-PAM4 Variables for a description of each variable and its default value.

CEI56G-LR-PAM4 Normative tests for CEI56G-LR-PAM4.

Physical Setup CEI56G-LR-PAM4 transmitter measurements are specified to be made directly at the transmitter output (“compliance point T”). To de-embed fixtures and cables between the transmitter output and the oscilloscope input, Virtual Probe technology is integrated directly into QPHY-56G-PAM4. Create a Virtual Probe setup (see Virtual Probe Software Instruction Manual, also in your oscilloscope online Support under Options), and use the “Using Virtual Probe” and “Path to Virtual Probe Setup” variables to utilize this feature.

CEI56G-MR-PAM4 Normative tests for CEI56G-MR-PAM4.

Physical Setup See description above for CEI56G-LR-PAM4.

http://teledynelecroy.com/doc/docview.aspx?id=7842


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CEI56G-VSR-PAM4 CTLE Optimizer Simple (non-normative) utility test to find the optimal peaking value for the software-implemented reference CTLE used in VSR tests for Host Output and Module Output. Take the value returned by this test and use it in the "CTLE Peaking in dB" variable of your VSR test configuration to ensure compliance testing with the optimum CTLE value for your specific device.

Physical Setup The reference CTLE is typically used in CEI56G-VSR-PAM4 Host Output and CEI56G-VSR-PAM4 Module Output tests. See their descriptions below for details on the physical measurement setup.

CEI56G-VSR-PAM4 Host Output Emulated HCB Normative tests for CEI56G-VSR-PAM4 at the Host Output. Host Compliance Board (HCB) is emulated via S-parameters in this configuration—that is, it is assumed the signal is acquired at TP0a.

Physical Setup CEI56G-VSR-PAM4 Host Output measurements are specified to be made at Test Point 1a, which includes a Host Compliance Board (HCB) between the transmitter output and the measurement equipment. This setup assumes that the signal is being acquired directly at the transmitter output, and uses Virtual Probe technology to embed an S-parameter model of the nominal HCB (located at D:\PAM4\VP\ hcb_s2p.s2p). It does this by enabling Virtual Probe and recalling the setup file D:\PAM4\VP\ CEI56G_VSR_TP1a.lss.

If you need to embed or de-embed other parts of the test setup, you can utilize the file D:\PAM4\VP\CEI56G_VSR_TP1a.lss as a template and use the three empty “blocks” A3, A4 and A5 for your own purposes. CAUTION: Do not overwrite CEI56G_VSR_TP1a.lss or hcb_s2p.s2p. These files are recreated every time QualiPHY starts up. Instead, save your own Virtual Probe setup file and reference it in the “Path to Virtual Probe setup” variable.

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CEI56G-VSR-PAM4 Host Output No HCB Normative tests for CEI56G-VSR-PAM4 at the Host Output. Host Compliance Board (HCB) is NOT emulated in this configuration, it is assumed that a hardware HCB is used—that is, the signal is being acquired at TP1a.

Physical Setup CEI56G-VSR-PAM4 Host Output measurements are specified to be made at Test Point 1a, which includes a Host Compliance Board (HCB) between the transmitter output and the measurement equipment. This setup assumes that the signal is being acquired through a physical HCB.

CEI56G-VSR-PAM4 Module Output Emulated MCB Normative tests for CEI56G-VSR-PAM4 at the Module Output. Module Compliance Board (MCB) is emulated via S-parameters in this configuration—that is, it is assumed the signal is acquired at the Tx pins of the module.

Physical Setup CEI56G-VSR-PAM4 Module Output measurements are specified to be made at Test Point 4, which includes a Module Compliance Board (MCB) between the transmitter output and the measurement equipment. This setup assumes that the signal is being acquired directly at the transmitter output, and uses Virtual Probe technology to embed an S-parameter model of the nominal MCB (located at D:\PAM4\VP\ mcb_s2p.s2p). It does this by enabling Virtual Probe and recalling the setup file D:\PAM4\VP\ CEI56G_VSR_TP4.lss:

If you need to embed or de-embed other parts of the test setup, you can utilize D:\PAM4\VP\ CEI56G_VSR_TP4.lss as a template and use the three empty “blocks” A3, A4 and A5 for your own purposes. CAUTION: Do not overwrite CEI56G_VSR_TP4.lss or mcb_s2p.s2p. These files are recreated every time QualiPHY starts up. Instead, save your own Virtual Probe setup file and reference it in the “Path to Virtual Probe Setup” variable.


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CEI56G-VSR-PAM4 Module Output No MCB Normative tests for CEI56G-VSR-PAM4 at the Module Output. Module Compliance Board (MCB) is NOT emulated in this configuration, it is assumed that a hardware MCB is used—that is, the signal is being acquired at TP4.

CEI56G-VSR-PAM4 TP0a Informative tests for CEI56G-VSR-PAM4 at TP0a (test connection nearest the Tx pins).

Physical Setup CEI56G-VSR-PAM4 specifies informative measurements to be made directly at the transmitter output (Test Point 0a). To de-embed fixtures and cables between the transmitter output and the oscilloscope input, Virtual Probe technology is integrated directly into QPHY-56G-PAM4. Create a Virtual Probe setup (see Virtual Probe Software Instruction Manual, also in your oscilloscope online Support under Options), and use the “Using Virtual Probe” and “Path to Virtual Probe Setup” variables to utilize this feature.

Demo - Simulated CEI56G-VSR-PAM4 Host Output Demo using simulated waveforms of normative tests for CEI56G-VSR-PAM4 at the Host Output. Host Compliance Board (HCB) is emulated via S-parameters in this configuration—that is, it is assumed the signal is acquired at TP0a.

Demo - Simulated CEI56G-VSR-PAM4 TP0a Demo using simulated waveforms of informative tests for CEI56G-VSR-PAM4 at TP0a (test connection nearest the Tx pins).


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QPHY-56G-PAM4 Test Descriptions Baud Rate Test This test measures the baud rate of the signal. OIF specifications typically allow between 18 and 29 Gbaud, with most devices transmitting at 28 Gbaud. IEEE specifications allow a narrower range around 26.5625 Gbaud. The measurement can be made on any PAM4 signal with sufficient transition density.


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Tx Output Voltage Tests These tests measure output differential mode voltage, common mode voltage, and common mode noise. Shown on this screen:

• Vpp: Peak-to-peak differential mode voltage

• VcmMax: Maximum common-mode voltage

• VcmMin: Minimum common-mode voltage

• VcmRMS: RMS common-mode voltage

Figure 4 – Tx Output Voltage Test Results

Output Differential Voltage pp Vdiff = Max(V+ - V-) = Min(V+ - V-)

Common Mode Voltage VCM_max = Max((V+ + V-)/2)VCM_min = Min((V+ + V-)/2)

Common Mode Noise VCM = RMS((V+ + V-)/2)

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CTLE Optimize Test CEI-56G-VSR-PAM4 testing requires the oscilloscope to implement a reference receiver with a variable level of CTLE peaking. Selecting the optimal CTLE peaking value for the specific signal under test is crucial to obtaining the best results. QPHY-PAM4-56G includes a fast, simple utility test to determine the optimal CTLE peaking value for use in subsequent tests. This test performs that optimization and returns the optimal peaking value in dB. This value can then be entered into the “CTLE Peaking Near-End” variable in a test configuration.

Figure 5 – CTLE Optimize Test Results


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Transition Time Tests These tests measure the 20-80 rise and fall times of the signal. As per the specifications, rise times are measured only on edges which occur when a sequence of three “0” symbols is followed by a sequence of three “3” symbols. Fall times are measured only on edges which occur when a sequence of three “3” symbols is followed by a sequence of three “0” symbols. If these sequences do not appear in the acquired pattern, rise and fall times will not be measured. Shown on this screen:

• Math function: Eye Diagram

• Math function: Histogram of rising edge 20-80 rise times

• Math function: Histogram of falling edge 20-80 fall times

• Math function: Histogram of slew rates

• Parameter Trise min: Minimum rise time

• Parameter Tfall min: Minimum fall time

• Parameter Tslew max: Maximum slew rate

Figure 6 – Transition Time Test Results

Fall Time Minimum 20-80 fall time as described above

Rise Time Minimum 20-80 rise time as described above.

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Linear Fit Tests These tests all perform measurements related to the PAM4 signal shape – see individual test descriptions below for detailed descriptions.

• Math function: Linear Fit waveform

• Parameter EstRLM: Level Separation Mismatch Ratio

• Parameter SNDR: Signal-to-Noise-and-Distortion-Ratio

• Parameter PkPulse: Peak value of linear fit waveform

• Parameter VSS: Steady-state voltage

Figure 7 – Linear Fit Test Results

RLM Estimation

Level Separation Mismatch Ratio, often abbreviated RLM, is a measure of how equally spaced the four levels in the PAM4 signal are. It is defined as:

RLM = min((3ES1), (3ES2), (2 - 3ES1), (2 - 3ES2))

where

Vmid = (V-1 + V+1) / 2

ES1 = (V-1/3 - Vmid) / (V-1 - Vmid)

ES2 = (V+1/3 - Vmid) / (V+1 - Vmid)

The values for V-1, V-1/3, V+1/3, and V+1 are defined as the mean value of the center of each unit interval of the corresponding level in the acquired waveform.


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Linear Fit Pulse Peak This test utilizes the “linear fit to the measured waveform” process as defined in OIF-CEI-03.1. The signal is resampled to an integer number of samples per UI, then mathematically analyzed to determine its response to a single-UI full-amplitude pulse – called the “Linear fit pulse response”. Some specifications require that the peak value of this linear fit waveform be greater than a defined multiple of the steady state voltage (see below).

Steady State Voltage The steady-state voltage is defined to be the sum of the linear fit pulse waveform (see above) divided by M (the number of samples per UI when resampled as described above).

Signal to Noise & Distortion Ratio Signal to Noise & Distortion Ratio (SNDR) is defined as the ratio between a noiseless signal with the pulse response derived in the Linear Fit process (above) and the actual acquired signal.

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Tx Output Jitter Tests These tests measure PAM4-specific jitter. They are usually specified for a QPRBS13 pattern, but this software will make them on arbitrary patterns except where specifically noted. Shown on screen below:

• Math functions UJ(low), UJ(mid), UJ(high): Histogram of Uncorrelated Jitter for lower, middle and upper eyes

• Math functions Q(low), Q(mid), Q(high): Q-scale plot of UJ histograms, to illustrate UUGJ and UBHPJ derivation

• Parameters UUGJ(low), UUGJ(mid), UUGJ(high): Uncorrelated Unbounded Gaussian Jitter for lower, middle and upper eyes

• Parameters UBHPJ(low), UBHPJ(mid), UBHPJ(high): Uncorrelated Bounded High-Probability Jitter for lower, middle and upper eyes

• Parameters UJ4(low), UJ4(mid), UJ4(high): Uncorrelated Jitter at the 10-4 probability for lower, middle and upper eyes – used in UUGJ and UBHPJ calculations

• Parameters UJ6(low), UJ6(mid), UJ6(high): Uncorrelated Jitter at the 10-6 probability for lower, middle and upper eyes – used in UUGJ and UBHPJ calculations

Figure 8 – Output Jitter Test Results


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UUGJ Uncorrelated Unbounded Gaussian Jitter is analogous to Random Jitter as seen in many NRZ-based serial data standards, but UUGJ is derived directly from measured data rather than through extrapolation after fitting to a model.UUGJ and UBHPJ (below) are calculated from the values UJ4 (Uncorrelated Jitter at the 10-4 probability) and UJ6 (Uncorrelated Jitter at the 10-6 probability). By definition, any direct measurement of UJ6 requires the acquisition of 106 transitions, and true statistical confidence requires 107 transitions. Building up this level of statistical data takes many acquisitions over some period of time – particularly keeping in mind that for most patterns, the central eye of a PAM4 signal will have a transition density of around 50%, where the upper and lower eyes will have transition densities of around 37.5%. QPHY-56G-PAM4 indicated the progress of this data gathering process by annotating each of the three PAM4 transition histograms onscreen as follows:

• “Insufficient statistics”: <106 transitions acquired, no measurements available

• “Insufficient statistics”: <107 transitions acquired, preliminary measurements available

• No annotation: >107 transitions acquired, final measurements available

UBHPJ Uncorrelated Bounded High-Probability Jitter is analogous to Deterministic Jitter as seen in many NRZ-based serial data standards, but UBHPJ is derived directly from measured data rather than through extrapolation after fitting to a model.

EOJ Even-odd jitter is a measure of the jitter between even-numbered and odd-numbered transitions in the pattern, typically caused by duty-cycle effects in the transmitter clock. This parameter is measured by comparing successive repetitions of the pattern, and by definition can only be measured on a repeating pattern containing an odd number of Unit Intervals.

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Eye Tests Eye diagram parameter measurements as defined in the OIF-CEI56G-VSR-PAM4 specification. These measurements require a relatively large number of unit intervals (UIs) to be acquired in order to achieve the statistical depth required by the specification. QPHY-56G-PAM4 will take some time to acquire all the required data, but will then process all measurements on the acquired data relatively quickly.

Eye Linearity Eye Linearity is measured as:

𝐴𝐴𝐴𝐴𝑢𝑢𝑢𝑢𝑢𝑢 = 𝐴𝐴3 − 𝐴𝐴2

𝐴𝐴𝐴𝐴𝑚𝑚𝑚𝑚𝑚𝑚 = 𝐴𝐴2 − 𝐴𝐴1

𝐴𝐴𝐴𝐴𝑙𝑙𝑙𝑙𝑙𝑙 = 𝐴𝐴1 − 𝐴𝐴0

𝐸𝐸𝐸𝐸𝐸𝐸 𝐿𝐿𝑚𝑚𝐿𝐿𝐸𝐸𝐿𝐿𝐿𝐿𝑚𝑚𝐿𝐿𝐸𝐸 =min (𝐴𝐴𝐴𝐴𝑢𝑢𝑢𝑢𝑢𝑢,𝐴𝐴𝐴𝐴𝑚𝑚𝑚𝑚𝑚𝑚 ,𝐴𝐴𝐴𝐴𝑙𝑙𝑙𝑙𝑙𝑙)max (𝐴𝐴𝐴𝐴𝑢𝑢𝑢𝑢𝑢𝑢,𝐴𝐴𝐴𝐴𝑚𝑚𝑚𝑚𝑚𝑚 ,𝐴𝐴𝐴𝐴𝑙𝑙𝑙𝑙𝑙𝑙)


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Eye Width 10^-6 This test measures the width of the upper, middle and lower eyes at a BER probability of 10-6. Shown on screen below:

• Math function: Eye diagram with contours indicating 10-3 opening (red) and 10-6 opening (green)

• Parameters EW(1e-6) low, EW(1e-6) mid, EW(1e-6) high: Upper, middle, and lower eye widths at a probability of 10-6, measured at the voltage levels defined in the CEI56G-VSR-PAM4 standard specification. Indicated by horizontal arrows within eye openings onscreen.

• Parameters TL(1e-6) low, TL(1e-6) mid, TL(1e-6) high: Left point of the 10-6 contour for each eye, used in calculating the respective EW(1e-6).

• Parameters TR(1e-6) low, TR(1e-6) mid, TR(1e-6) high: Right point of the 10-6 contour for each eye, used in calculating the respective EW(1e-6).

Figure 9 – Eye Width Test Results

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Eye Height 10^-6 This test measures the height of the upper, middle and lower eyes at a BER probability of 10-6. Shown on this screen:

• Math function: Eye diagram with contours indicating 10-3 opening (red) and 10-6 opening (green)

• Parameters EH(1e-6) low, EH(1e-6) mid, EH(1e-6) high: Upper, middle, and lower eye heights at a probability of 10-6, measured at the horizontal point in the UI defined in the CEI56G-VSR-PAM4 standard specification. Indicated by vertical arrows in the eye openings onscreen.

• Parameters VL(1e-6) low, VL(1e-6) mid, VL(1e-6) high: Lower point of the 10-6 contour for each eye, used in calculating the respective EH(1e-6).

• Parameters VH(1e-6) low, VH(1e-6) mid, VH(1e-6) high: Upper point of the 10-6 contour for each eye, used in calculating the respective EW(1e-6).

Figure 10 – Eye Height Test Results


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Eye Mask The Eye Mask as defined in OIF CEI56G-VSR-PAM4 consists of a vertical “stripe” of defined width (dependent on test point) which is centered on a calculated timing point Tmid. In order to be compliant, the horizontal points of the 10-6 contour as measured at specified voltage levels must lie outside the mask. This tests for both horizontal eye opening and horizontal symmetry. Shown on this screen:

• Math function: Eye diagram with contours indicating 10-3 opening (red) and 10-6 opening (green), as well as eye mask (lighter vertical stripe)

• Parameters TL(1e-6) low, TL(1e-6) mid, TL(1e-6) high: Left point of the 10-6 contour for each eye – these must all lie to the left of the mask extents for compliance.

• Parameters TR(1e-6) low, TR(1e-6) mid, TR(1e-6) high: Right point of the 10-6 contour for each eye, these must all lie to the right of the mask extents for compliance.

• Patameter Tmid: Mask center position, calculated from maximal vertical extent of middle eye 10-

3 contour as specified in OIF CEI-56G-VSR-PAM4.

Figure 11 – Eye Mask Test Results

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Eye Far End Tests This test measures the height of the upper, middle and lower eyes at a BER probability of 10-6, at the far end of a compliance channel as defined by OIF CEI56G-PAM4-VSR (module output). Math functions and parameters are the same as those described for the Eye Width at 10^-6 and Eye Height at 10^-6 tests above.

Figure 12 – Eye Far-End Test Results


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QPHY-56G-PAM4 Variables Main Settings

Which input to use Selects for using oscilloscope Input A or B. Default selection is the interleaved input B.

Bessel-Thompson filter enable Enables fourth-order Bessel-Thomson reference receiver filter as required by some standards. When enabled, -3dB bandwidth is set by the Bessel-Thomson -3dB point in GHz variable ("BWLimit"). When disabled, the bandwidth limit and optimization mode in the oscilloscope input channel dialog determine the response shape. Default state is Enabled.

Bessel-Thompson 3dB point in GHz Sets the -3dB bandwidth of the Bessel-Thomson reference receiver filter. Only active if "Bessel Thomson filter enable" is set to Enabled. The default value is 40 GHz.

Dp Linear Fit Pulse Delay in UIs.

Dw Equalizer Delay in UIs.

Np Linear Fit Pulse Length (as per IEEE description) in UIs.

Nw Equalizer Length in UIs.

Pause after each test group When selected, the program pauses after each test and prompts the user to continue. Default state is No.

CTLE peaking near-end CTLE Peaking in dB for Near End Eye measurements. The optimum CTLE peaking is a function of the device output and the channel connecting it to the oscilloscope. The “CEI56G-VSR-PAM4 CTLE Optimizer” test configuration can be used to determine the correct value in advance.

CTLE peaking far-end CTLE Peaking in dB for Far End eye measurements. Only used in VSR TP4a testing where a reference channel is automatically embedded.

Symbol rate Expected symbol rate for incoming signal. Default value is 28 GHz.

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Long acquisition time/div (sec) The program uses multiple long acquisitions for some measurements where a lot of statistical data is required. This variable adjusts this acquisition length – it is recommended to leave this at its default value.

Short acquisition time/div (sec) The program uses shorter acquisitions for measurements where less statistical data is required. This variable adjusts this acquisition length – it is recommended to leave this at its default value.

Source of Waveform Data Test can be performed on live acquisition waveforms, saved waveforms (on disk) or simulated waveforms.

• Live: Waveforms will be acquired by the oscilloscope for live testing. Each waveform is saved to a folder (by default: “D:\Waveforms\PAM4\VSR\<DUTname>” where DUTname is the DUT name entered by the user at the start of testing).

• Saved: In this mode, when the user enters the DUT name at the start of testing, the program will recall the previously-saved waveforms from that DUT (if they exist). This can be useful for re-testing old data with new settings.

• Simulated: Uses a built-in software simulator in the oscilloscope software to simulate a PAM4 signal for testing.

Using Virtual Probe Enables/disables use of Virtual Probe software to de-embed fixtures and cables between the transmitter output and the oscilloscope input when simulating transmitter test points.

Path to Virtual Probe setup Path to custom Virtual Probe setup file (.lss) used when additional blocks are needed to embed or de-embed other parts of the test setup. See the Virtual Probe Software Instruction Manual, also in your oscilloscope online Support under Options.

VSRmode Probing and measuring scenario for PAM4 56G: HostOutput or ModuleOutput. Two distinct options use different test criteria and limits.

Waveform filepath Root folder name for where various DUT folders with saved waveforms will appear (see “Source of Waveform Date” above). Default is D:\Waveforms\PAM4.



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Simulator Settings

Deterministic Jitter (Dj) in picoseconds Deterministic jitter value used when testing simulated waveforms This variable has no effect when testing on live or saved data (see “Source of Waveform Date” above).

Deterministic Noise (Dn) in millivolts Deterministic noise value used when testing simulated waveforms. This variable has no effect when testing on live or saved data (see “Source of Waveform Date” above).

Random Jitter (Rj) in picoseconds Random jitter value used when testing simulated waveforms. This variable has no effect when testing on live or saved data (see “Source of Waveform Date” above).

Random Noise (Rn) in millivolts Random vertical noise in millivolts RMS used when testing simulated waveforms. This variable has no effect when testing on live or saved data (see “Source of Waveform Date” above).

Signal bandwidth in Gigahertz Input signal BW used when testing simulated waveforms. This variable has no effect when testing on live or saved data (see “Source of Waveform Date” above).

Simulator amplitude in Volts for single-ended signals Single-ended signal amplitude used when testing simulated waveforms. This variable has no effect when testing on live or saved data (see “Source of Waveform Date” above).

Simulated Even-Odd Jitter (in ps) Peak-Peak Even-Odd Jitter in picoseconds.

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QPHY-56G-PAM4 Limit Sets PAM4_56G_XSR Test limits for OIF CEI-56G-XSR-PAM4, as per table 20-7 in document OIF2017.106.00.

PAM4_56G_VSR_TP1a Test limits for OIF CEI-56G-VSR-PAM4 (Host-to-Module), as per table 16-1 in document OIF2017.261.01.

PAM4_56G_VSR_TP4 Test limits for OIF CEI-56G-VSR-PAM4 (Module-to-Host), as per table 16-4 in document OIF2017.261.01.

PAM4_56G_MR Test limits for OIF CEI-56G-MR-PAM4, as per table 17-2 in document OIF2017.129.01.

PAM4_56G_LR Test limits for OIF CEI-56G-LR-PAM4, as per table 21-2 in document OIF2017.130.01.

PAM4_56G_VSR_TP0a Test limits for OIF CEI-56G-VSR-PAM4 (informative Host-to-Module at TP0a), as per table 16-10 in document OIF2017.261.01.


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Appendix A: Manual Deskewing Procedures Cable Deskewing Using the Fast Edge Output The following procedure demonstrates how to manually deskew two oscilloscope channels and cables using the fast edge output, with no need for any T connector or adapters. Note: This procedure only applies to the oscilloscope and cables connected directly to oscilloscope channels. Fast Edge output is available only on some models. If your oscilloscope does not have Fast Edge output, see Cable Deskewing Without Using the Fast Edge Output. This can be done once the temperature of the oscilloscope is stable. The oscilloscope must be warmed up for at least 20 min. before proceeding. This procedure should be run again if the temperature of the oscilloscope changes by more than a few degrees. For the purpose of this procedure, the two channels being deskewed are referred to as Channel X and Channel Y. The reference channel is Channel X and the channel being deskewed is Channel Y.

1. Begin by recalling the Default Oscilloscope Setup. 2. Configure the oscilloscope as follows:

• Timebase i. Fixed Sample Rate ii. Set the Sample Rate to 40 GS/s iii. Set the Time/Division to 1 ns/div

• Channels i. Turn on Channel X and Channel Y. ii. Set V/div for Channel X and Channel Y to 100mV/div. iii. Set the Averaging of Channel X and Channel Y to 500 sweeps. iv. Set the Interpolation of Channel X and Channel Y to Sinx/x.

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• Trigger i. Configure to Source to be FastEdge. ii. Set the Slope to Positive.

• Parameter Measurements: i. Set the source for P1 to CX and the measure to Delay. ii. Set the source for P2 to CY and the measure to Delay. iii. Set the source for P3 to M1 and the measure to Delay.

3. Set the display to Single Grid.

• Click Display Single Grid. 4. Using the appropriate adapter, connect Channel X to the Fast Edge Output of the oscilloscope. 5. Adjust the Trigger Delay so that the Channel X signal crosses at the center of the screen. 6. Change the Timebase to 50 ps/div.

7. Fine tune the Trigger Delay so that the Channel X signal crosses at the exact center of the screen.

8. Press the Clear Sweeps button on the front panel to reset the averaging. 9. Allow multiple acquisitions to occur until the waveform is stable on the screen.


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10. Save Channel X to M1.

• Click File Save Waveform.

• Set Save To Memory.

• Set the Source to CX.

• Set the Destination to M1.

• Click Save Now.

11. Disconnect Channel X from the Fast Edge Output and connect Channel Y to the Fast Edge Output.

12. Press the Clear Sweeps button on the front panel to reset the averaging.

13. Allow multiple acquisitions to occur until the waveform is stable on the screen. 14. From the Channel Y menu, adjust the Deskew of Channel Y until Channel Y is directly over the

M1 trace. 15. Ensure that P3 and P2 are reasonably close to the same value. (Typically < 5ps difference)

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Cable Deskewing Without Using the Fast Edge Output The following procedure demonstrates how to manually deskew two oscilloscope channels and cables using the differential data signal, with no need for any T connector or adapters. Note: This procedure only applies to the oscilloscope and cables connected directly to oscilloscope channels. Warm the oscilloscope for at least a half-hour before proceeding. This procedure should be run again if the temperature of the oscilloscope changes by more than a few degrees.

1. Connect a differential data signal to C1 and C2 using two approximately matching cables. Set up the oscilloscope to use the maximum sample rate. Set the timebase for a few repetitions of the pattern (at least a few dozen edges).

2. On the C3 menu, check Invert. Now C1 and C2 should look the same. 3. Using the Measure Setup, set P1 to measure the Skew of C1, C2. Turn on Statistics (Measure

menu). Write down the mean skew value after it stabilizes. This mean skew value is the addition of Data skew + cable skew + channel skew.

4. Swap the cable connections on the Data source side (on the test fixture), and then press the Clear Sweeps button on the oscilloscope (to clear the accumulated statistics; since we changed the input).

5. Write down the mean skew value after it stabilizes. This mean skew value is the addition of (-Data skew) + cable skew + channel skew.

6. Add the two mean skew values and divide the sum in half: UU [cable skew + channel skew]

2 7. Set the resulting value as the Deskew value in C1 menu. 8. Restore the cable connections to their Step 1 settings (previous). Press the Clear Sweeps

button on the oscilloscope. The mean skew value should be approximately zero - that is the data skew. Typically, results are <1ps given a test fixture meant to minimize skew on the differential pair.

9. On the C2 menu, clear the Invert checkbox and turn off the parameters.


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In the previous procedure, we used the default setup of the Skew parameter (which is detecting positive edges on both signals at 50%). We also inverted C2 in order to make C1 and C2 both have positive edges at the same time. Alternately, we clearly could have not inverted C2 and instead selected the Skew clock 2 tab in the P1 parameter menu and set the oscilloscope to look for negative edges on the second input (C2). However, we believe that the previous procedure looks much more aesthetically pleasing from the display as it shows C2 and C3 with the same polarity.

Figure 13 - The Skew parameter right side dialog, Skew clock 2 tab, showing default setup.

Documents

QPHY-56G-PAM4 Operator’s Manualcdn.teledynelecroy.com/files/manuals/qphy-56g-pam4-manual.pdfSome of the images in this manual may show QualiPHY products other than QPHY-56G-PAM4,