Use the product documents for more information on the application functions, understand the theory of operation, how to remotely program or operate the application, and do other tasks.

This application help uses the following conventions:

• The term "Application," and "Software" refers to the TekExpress 400G-TXE application.
• The term “DUT” is an abbreviation for Device Under Test.
• The term “select” is a generic term that applies to the two methods of choosing a screen item (button control, list item): using a mouse or using the touch screen.
• A Note identifies important information.

Table 1. Icons used in the help

Icon	Description
	This icon identifies important information
	This icon identifies conditions or practices that could result in loss of data.
	This icon identifies additional information that will help you use the application more efficiently.

Tektronix values your feedback on our products. To help us serve you better, please send us your suggestions, ideas, or comments on your application or oscilloscope. Contact Tektronix through mail, telephones, or the Web site. See Contacting Tektronix at the front of this document for contact information.

When you contact Tektronix Technical Support, please include the following information (be as specific as possible):

If skew is present between positive and negative channels, then the channels need to be deskewed before being used for waveform measurements.

Apply the appropriate input attenuator such that the signal on the screen for each channel can be adjusted (using the oscilloscope's Vertical > Scale settings) to less than 10 division Pk-Pk but greater than 8 division Pk-Pk.

Use maximum instrument bandwidth so narrow noise peaks that might reach out-of-range are visible in their full amplitude, rather than limited by the post-digitizer bandwidth processing. Set the record length to 50 MSa or longer; Measure both channel 1 and channel 2 with a Measure > Amplitude > Peak - Peak to monitor that the trace is without clopping, that is the measurements don't display a warning indicating over-driven input.

TekExpress 400G-TXE provides support for channel deskew and attenuation using the following method:

1. Determine what the skew is for each channel.

   Please use method recommended by Tektronix. DPO70k SX oscilloscope to find the skew, for example, minimum common mode. Tektronix recommends using channel 1 as a reference with 0 skew, and entering a measured skew value in channel 2.

2. From the TekScope menu, select Vertical > Deskew.
3. In the Deskew/Attenuation window, click the channel 1, and set the skew to 0. Then select channel 2 button for the first channel to be deskewed.
4. Click in the Ch(x) Deskew Time entry field and enter the skew. The skew can be +ve or –ve.
5. Click the channel button for the next channel and repeat step 4.
6. After entering the skew for all the channels that require it, from the Options menu in TekExpress 400G-TXE, select Deskew.

   

7. Click Read from Scope to read the deskew and attenuation values from the oscilloscope.
8. Click View values to view the deskew, attenuation, and bandwidth values.
9. When the status in the dialog box indicates the deskew is finished, click Close.

Each input channel has its own deskew settings. Deskew compensates individual channels for probes or cables of different lengths. The instrument applies the delay values after each completed acquisition. The deskew values are saved as part of the instrument setup. The deskew values for the selected channel are retained until you change the probe, you restore a saved setup, or you recall the factory setup.

Note:If you perform the de-embed settings of all oscilloscope input connected components, then the Attenuation settings should be left at default (0 dB).

Select tests, set acquisition parameters, set configuration parameters, set preferences parameters, and click Start to run the tests. While tests are running, you cannot access the Setup or Reports panels. To monitor the test progress, switch between the Status panel and the Results panel.

While the tests are running, other applications may display windows in the background. The TekScope application takes precedence over other applications, but you can switch to other applications by using Alt + Tab key combination. To keep the TekExpress 400G-TXE application on top, select Keep On Top from the TekExpress Options menu.

The application displays report when the tests execution is complete.

Click Setup > Test Selection > Schematic to view the equipment setup diagram(s).

To access the Options menu, click in the upper-right corner of the application. It has the following selections:

Use the Email Settings utility to get notified by email when a measurement completes or produces any error condition. Follow the steps to configure email settings:

1. Select Options > Email Settings to open the Email Settings dialog box.
2. (Required) For Recipient email Address(es), enter one or more recipient email addresses. To include multiple addresses, separate the addresses with commas.
3. (Required) For Sender’s Address, enter the email address used by the instrument. This address consists of the instrument name, followed by an underscore, followed by the instrument serial number, then the @ symbol, and the email server ID. For example: [email protected].
4. (Required) In the Server Configuration section, type the SMTP Server address of the Mail server configured at the client locations, and the SMTP Port number, in the corresponding fields.

   If this server requires password authentication, enter a valid login name, password, and host name in the corresponding fields.

   Note:If any of the above required fields are left blank, the settings will not be saved, and email notifications will not be sent.

5. In the Email Attachments section, select from the following options:
   • Reports: Select to receive the test report with the notification email.
   • Status Log: Select to receive the test status log with the notification email. If you select this option, then also select whether you want to receive the full log or just the last 20 lines.
6. In the Email Configuration section:
   • Enter a maximum file size for the email message. Messages with attachments larger than this limit will not be sent. The default is 0 MB.
   • Enter the number in the Number of Attempts to Send field, to limit the number of attempts that the system makes to send a notification. The default is 1. You can also specify a timeout period.
7. Select the Email Test Results When complete or on error check box. Use this check box to quickly enable or disable email notifications.
8. To test your email settings, click Test Email.
9. To apply your settings, click Apply.
10. Click Close when finished.

Use the TekExpress Instrument Control Settings dialog box to search the instruments (resources) connected to the application. You can use the Search Criteria options to search the connected instruments depending on the connection type. The details of the connected instrument is displayed in the Retrieved Instruments window.

To access, click Options > Instrument Control Settings. Select GPIB as search criteria for TekExpress application and click Refresh. The connected instruments displayed in the Retrieved Instruments window and can be selected for use under Global Settings in the test configuration section.

Use the DUT tab to select parameters for the device under test. These settings are global and apply to all tests of current session. DUT settings also affect the list of available tests in the Test Selection tab.

Click Setup > DUT to access the DUT parameters:

Table 1. DUT tab configuration

Setting	Description
DUT ID	Adds an optional text label for the DUT to reports. The default value is DUT001. The maximum number of characters is 32. You cannot use the following characters in an ID name: (.,..,...,\,/:?”<>|*)
Comments icon (to the right of the DUT ID field)	Opens Comments dialog box to enter text to add to the report. Maximum size is 256 characters. To enable or disable comments appearing on the test report, see Select report options.
Acquire live waveforms	Acquire active signals from the DUT for measurement and analysis.
Use pre-recorded waveform files	Run tests on a saved waveform. Select Options > Open Test Setup to recall a saved test setup.
Mode	Compliance User Defined
Standard	OIF-PAM4 IEEE-802.3cd/bs IEEE 802.3ckTM
Specification	For OIF-PAM4 standard CEI-VSR CEI-MR CEI-LR For IEEE-802.3cd/bs standard AUI CR4 KR4 For IEEE 802.3ckTM standard Version: IEEE 802.3ckTM Interface: AUI-C2C AUI-C2M Host AUI-C2M Module CR
Test Points	For OIF-PAM4 standard TP0a TP1a TP4 For IEEE-802.3cd/bs standard TP0a TP1a TP4 For IEEE 802.3ck standard Version: IEEE 802.3ckTM Interface: AUI-C2C AUI-C2M Host AUI-C2M Module CR
Specification Version	Displays the specification version for the selected Specification and Test Points.
Device Profile
DUT Type	Select the DUT type 56G 112G
Symbol Rate	Set the symbol rate to be tested.
Crosstalk Source	Select crosstalk source when a cross talk generator is connected. This is applicable for eye measurements only.

Use the Test Selection tab to select the tests. The test measurements available depends on the settings selected in the DUT tab.

Use Acquisitions tab to view the test acquisition parameters. The contents displayed on this tab depends on the DUT type and the tests selected.

Note:400G-TXE application acquires all waveforms needed by each test before performing the analysis.

TekExpress 400G-TXE application saves all acquisition waveforms to files by default. Waveforms are saved in a unique folder for each session (a session is started when you click the Start button). The folder path is X:\TekExpress 400G-TXE\Untitled Session\<dutid>\<date>_<time>. Images created for each analysis, XML files with result values, reports, and other information specific to that particular execution are also saved in this folder.

Saving a session moves the session file contents from the Untitled Session folder to the specified folder name and changes the session name to the specified name.

Use Configuration tab to view and configure the Global Settings and the measurement configurations. The measurement specific configurations available in this tab depends on the selections made in the DUT panel and Test Selection panel.

Table 2. Configuration tab: Global Settings configuration

Setting	Description
Compliance Mode	Select compliance mode. By default, Compliance Mode is selected.
User Defined Mode	Select user defined mode
Global Settings
Instruments Detected	Displays the instruments connected to this application. Click the instrument name to open a list of available (detected) instruments. Select Options > Instrument Control Settings and click Refresh to update the instrument list. Note: Verify that the GPIB search criteria (default) is selected in the Instrument Control Settings.
General Configuration
Bandwidth	Select the bandwidth limit for the oscilloscope.
Scope Noise	Enter the scope noise in mV. Scope noise the standard deviation of the noise of the oscilloscope. Scope noise is important for many of the electrical measurements. To ensure accurate measurement results, measure the scope noise manually and set the compensation value in the TekExpress. For more information on how to measure and apply scope noise, please refer PAM4 Analysis tool help document.
De-embedding Filter	Select to apply the de-embedding filter file for Data Positive and Data Negative.
Phase Inverted Filter for Data- (using SDLA with dual input mode)	Select this option if the filter is created from SDLA using Dual input option. The negative channel filter must be phase inverted when you select this option.
Data+	Click Browse and select the de-embedding filter file (.flt) for data positive signal.
Data-	Click Browse and select the de-embedding filter file (.flt) for data negative signal.
Tx Output Waveform
Samples per Symbol (M)	Select the number of samples per symbol for calculating the Tx out waveform parameters. If the acquired signal has less samples than specified, re-sampling is done to achieve the required samples per symbol. By default it is 32.
Linear Pulse Length (Np)	Select the linear fit pulse curve length in Unit intervals (UI). It is recommended to use higher value for better accuracy. The analysis time is more when you select higher value.
Linear Pulse Delay (Dp) (Dp<Np)	Select the delay of the linear fit pulse.
Eye Configuration
CTLE Filter File	Select the CTLE Filter File. Compliance mode All: Application will run through the CTLE filters. For TP1a: CTLE filters from 1 dB - 9dB in steps of 0.5 dB For TP4: For Near End, 1 dB, 1.5 dB, and 2 dB CTLE filters and for Far End, CTLE filters from 1 dB - 9 dB in steps of 0.5 dB Best CTLE: After the first run, if the eye measurements are passed, best CTLE filter option gets enabled. User can run the measurement with the Best CLTE instead of looping through all CTLE filters in the specification. Note:For 112G, CTLE filters from 1 dB - 13 dB in steps of 1 dB User Defined mode User can run the measurement with any specified CTLE filter. The application provides CTLE filters from 1 dB - 9 dB. Select the CTLE filters from the drop-down list or Custom to browse and select the custom CTLE filter files. Custom CTLE filters (CSV) must contain the following data, delimited by comma: CTLE peaking (dB): 1 to 9 Gain: 0.05 to 2 Poles and Zeros: 0.5 to 80 Example: //dB,gain,pole1,pole2,pole3,zero1,zero2 1,0.8913,18.6,14.1,1.2,8.359,1.2
Target BER (1e-) /Target BER (10^-)	Select the Target BER (1e-). As per the compliance, Target BER should be set to 1e-5 and 1e-6 for IEEE and OIF standards respectively. If the Target BER is set to higher values, more time is required to analyse the data. You can select BER of 1e-5 for quicker analysis. Select the Target BER (10^-). As per the compliance, Target BER values should be set to 4.00 to 6.00 for IEEE802.3ck standards respectively.
Mask Width	Select the mask width in Unit intervals (UI). This configuration is for Eye symmetry mask width measurement only.

Use Preferences tab to set the application action on completion of a measurement. The Preferences tab has the feature to enable or disable certain options related to the measurement execution.

Refer the below table for the options available in the Preferences tab:

The tests are grouped and displayed based on the Clock and Data lane. It displays the tests along with the acquisition type, acquire, and analysis status of the tests. In pre-recorded mode, Acquire Status is not valid.

The Test Status tab presents a collapsible table with information about each test as it is running. Use the symbols to expand () and collapse () the table rows.

The Test Status tab displays the detailed execution status of the tests. Also, displays each and every execution step in detail with its timestamp information. The log details can be used to troubleshoot and resolve any issue/bug which is blocking the test execution process.

The Configuration tab describes the report generation settings to configure the Reports panel. Select report settings before running a test or when creating and saving test setups. Report settings configured are included in saved test setups.

Table 1. Report configuration panel settings

Control	Description
View	Click to view the most current report.
Generate	Generates a new report based on the current analysis results.
Save As	Specify a name for the report.
Report Update Mode Settings
Generate new report	Each time when you click Run and when the test execution is complete, it will create a new report. The report can be in either .mht, .pdf, or .csv file formats.
Append with previous run session	Appends the latest test results to the end of the current test results report. Each time when you click this option and run the tests, it will run the previously failed tests and replace the failed test result with the new pass test result in the same report.
Include header in appended reports	Select to include header in appended reports.
Replace current test results	Replaces the previous test results with the latest test results. Results from newly added tests are appended to the end of the report.
In previous run, current session	Select to replace current test results in the report with the test result(s) of previous run in the current session.
In any run, any session	Select to replace current test results in the report with the test result(s) in the selected run session’s report. Click and select test result of any other run session.
Report Creation Settings
Report name	Displays the name and path of the <Application Name> report. The default locations is at \My Documents>\My TekExpress\<Application Name>\Reports. The report file in this folder gets overwritten each time you run a test unless you specify a unique name or select to auto increment the report name. To change the report name or locations, do one of the following: In the Report Path field, type the current folder path and name. Double-click in the Report Path field and then make selections from the popup keyboard and click Enter. Be sure to include the entire folder path, the file name, and the file extension. For example: C:\Documents and Settings\your user name\My Documents\My TekExpress\<Application Name> \DUT001.mht. Note:You cannot set the file locations using the Browse button. Open an existing report Click Browse, locate and select the report file and then click View at the bottom of the panel.
Save as type	Saves a report in the specified file type, selected from the drop-down list. The report is saved in .csv, .pdf, or .mht. Note: If you select a file type different from the default, be sure to change the report file name extension in the Report Name field to match.
Auto increment report name if duplicate	Sets the application to automatically increment the name of the report file if the application finds a file with the same name as the one being generated. For example: DUT001, DUT002, DUT003. This option is enabled by default.
Create report automatically at the end of the run	Select to create the report with the settings configured, at the end of run.
View report after generating	Automatically opens the report in a Web browser when the test execution is complete. This option is selected by default.

The View Settings tab describes the report view settings to configure the Reports panel. Select report view settings before running a test or when creating and saving test setups. Report settings configured are included in saved test setups.

Sample report and its contents

A report shows detailed results and plots, as set in the Reports panel.

Setup Information

The summary box at the beginning of the report lists setup configuration information. This information includes the oscilloscope model and serial number, optical module model and serial number, and software version numbers of all associated applications.

Test Name Summary Table

The test summary table lists all the tests which are executed with its result status.

Measurement

The measurement table displays the measurement related details with its parameter value.

User comments

If you had selected to include comments in the test report, any comments you added in the DUT tab are shown at the top of the report.

You can save the test setup and recall it later for further analysis. Saved setup includes the selected oscilloscope, general parameters, acquisition parameters, measurement limits, waveforms (if applicable), and other configuration settings. The setup files are saved under the setup name at X:\TekExpress 400G-TXE

Note:Images that are shown in this Saving and recalling test setup chapter are for illustration purpose only and it may vary depending on the TekExpress application.

You can save a test setup before or after running a test. You can create a test setup from already created test setup or using a default test setup. When you save a setup, all the parameters, measurement limits, waveform files (if applicable), test selections, and other configuration settings are saved under the setup name. When you select the default test setup, the parameters are set to the application’s default value.

• Select Options > Save Test Setup to save the opened setup.
  
  
  
  
• Select Options > Save Test Setup As to save the setup with different name.
  
  
  
  

To open (load) a saved test setup, do the following:

• Select Options > Open Test Setup.
  
  
  
  
• From the File Open menu, select the setup file name from the list and click Open.
  
  
  
  

Note:Parameters that are set for the respective test setup will enable after opening the file.

This section verifies that the DC common mode output voltage of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

Maximum input to be provided to the ATI channels is ≤ 300 mV peak-to-peak. The DC common mode voltage of the signal cannot be measured using ATI channels. Measure the voltage using an external digital multimeter and enter the value in the application.

This section verifies that the common mode noise of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Positive and negative signals from the oscilloscope by setting the bandwidth to 40 GHz

Measurement procedure

The common mode voltage is a measure of the deviation of the common mode signal around the mean value. Find the sum of the positive and negative signals to create the common mode signal and create a vertical histogram on this signal. The RMS value of the vertical histogram is the AC common mode output voltage.

To find the effective common mode voltage after removing the instrumentation noise, use the following formula:

This section verifies that the single-ended output voltage of the data positive and data negative signals of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Data positive and data negative signals

Measurement procedure

The single-ended output voltage is the measure of maximum and minimum values of the single-ended signals. Since the voltage levels can go beyond the 300 mV peak-to-peak, this measurement cannot be done using the ATI channels of the oscilloscope. Connect a DC block to eliminate the DC content present in the signal and then measure the maximum and minimum values of the positive and negative signals.

Effective Data Positive Max voltage = DC Common Mode + Data Positive Max

Effective Data Positive Max voltage = DC Common Mode + Data Positive Min

Note:DC Common Mode measurement is pre-requisite for this measurement and you will be prompted to measure DC voltage using external multimeter.

This section verifies that the differential peak-to-peak voltage of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

QPRBS13-CEI or any valid signal filtered through a fourth order Bessel Thomson filter.

Measurement procedure

The differential peak-to-peak voltage is the peak-to-peak value of the signal acquired using a base oscilloscope.

This section verifies that the differential peak-to-peak voltage of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Noise signal captured when the DUT is disabled (without applying filters)

Measurement procedure

1. Capture the differential noise using Math1 as source (without applying filters). Math1 = (Data positive – Data negative)

   Note:For IEEE 802.3ck, Capture the differential noise using Math1 as Source , Math1 = Arnflt1 (Data positive – Data negative), Arbflt1 – Bessel Thomson Filter

2. Select the oscilloscope free run mode option.
3. In oscilloscopes menu, select Measure > Amplitude and select peak-to-peak measurement.
4. Value of Peak-Peak measurement is reported as the differential peak-to-peak output voltage.

This section verifies that the transition time of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

QPRBS13-CEI test pattern or any valid signal filtered through a fourth order Bessel Thomson filter.

Measurement procedure

Transition time (rise and fall) are defined as the time between the 20% and 80% times, or 80% and 20% times, respectively, of isolated -1 to +1 or +1 to -1 PAM4 edges. Using the QPRBS13-CEI test pattern, the transitions within sequences of three -1s followed by three +1s, and three +1s followed by three -1s, respectively, are measured. These are PAM4 symbols 1820 to 1825 and 2086 to 2091, respectively, where symbols 1 to 7 are the run of seven +1’s. In this case, the 0% level and 100% level may be estimated as the average signal within windows from -1.5 UI to -1 UI and from 1.5 UI to 2 UI relative to the edge.

TekExpress 400G-TXE application captures sufficient record length and uses PAM4 utility to perform this measurement.

This section verifies that the Eye width, VEC (Vertical Eye Closure), Eye height, Eye linearity, and Eye symmetry mask width of the DUT are within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through fourth order Bessel Thomson filter (with appropriate bandwidth) in concatenation with a Continuous Time Linear Equalizer (CTLE).

In case of AUI-IEEE802.ck, The Eye-opening parameters Eye height and VEC are measured with the effect of a reference receiver (Butterworth filter) which includes receiver input referred noise, a continuous-time filter and DFE (4^th Order) as per the specification.

Cross talk calibration

Calibrate the co-propagating signals (signal on the other lanes) as per the specification, before performing the Eye measurements.

If you want to run with cross talk source, select Crosstalk Source from the DUT panel. By default, this option is unselected and application will provide normal connection diagram procedure.

Eye measurements are done after passing the signal through a reference receiver which includes a fourth order Bessel Thomson filter (in case of IEEE802.3ck Eye measurement, receiver Butterworth filter is used) with appropriate bandwidth cutoff and a selectable continuous time linear equalizer (CTLE filter). It is recommended to use PRBS13Q pattern for this measurement.

Note:For 112G-VSR Eye measurements, signal will be passed through additional five tap FFE equalizer after Bessel Thomson and CTLE filters

CTLE filters are selected as per the below table:

TekExpress uses PAM4/PAMJET utility to perform this measurement. Details about measuring Eye width and Eye height from the equalized signal is explained in OIF-CEI-56G-VSR and IEEE802.3bs specifications.

Near End Eye width, VEC and Eye height are same as Eye width and Eye height measurements. Whereas far end Eye width and Eye height measurements are done with an emulated loss channel.

Rapid approach finds the optimized and faster way to reach to best CTLE. Where exhaustive simply run each CTLE form list of individual and get the Best out of it. User can go the configuration tab and check the Best CTLE to run for next run.

Note:Eye measurement for IEEE802.3ck also use the below configuration as per specification.

Eye symmetry mask width (ESMW)

An Eye mask of width as per the specification is drawn on the top of Eye diagram. All the three Eyes have to open beyond the mask drawn which will make the test pass.

This section verifies that the signal-to-noise and distortion ratio (SNDR) of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through a fourth order Bessel Thomson filter with appropriate bandwidth

Measurement procedure

Signal-to-noise and distortion ratio is measured using the following formula:

Where,

P_max is the linear fit pulse peak

σ_e - RMS error

σ_n – Standard deviation of noise

This section verifies that the pre-cursor and post-cursor equalization ratio of the Device Under Test (DUT) is within conformance limits as given in IEEE802.3 200GAUI-4/400GAUI-8 specification at test point TP0a, Table 120D-1, Section 120D.3.1.5.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

1. Set the DUT in PRESET state and find the Linear fit pulse response.
2. For pre-cursor test, prompt the user to vary the Local_eq_cm1 value from 0 to 3 and each time find the equalizer coefficients C(-1), C(0) and C(1) value using PRESET linear fit curve and linear fit of each state of Local_eq_cm1.
3. Find the pre-cursor equalization ratio using below formula:
   
   
4. Vary the Local_eq_c1 value from 0 to 5 and each time find the equalizer coefficients C(-1), C(0) and C(1) value using PRESET Linear fit curve and Linear fit of each state of Local_eq_c1.
5. Find the Post-cursor equalization ratio using below formula:
   
   

Limits

Pre-cursor equalization ratio for each state of Local_eq_cm1 are the following:

Local_eq_cm1 value
0	0±0.04
1	-0.05±0.04
2	-0.1±0.04
3	-0.15±0.04

Pre-cursor equalization ratio for each state of Local_eq_c1 are the following:

Local_eq_c1 value
0	0±0.04
1	-0.05±0.04
2	-0.1±0.04
3	-0.15±0.04
4	-0.2±0.04
5	-0.25±0.04

This section verifies that the coefficient range of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

1. Acquire the PRESET signal. Export the linear fit impulse response curve from PAM4 utility.
2. Increment a coefficient (C(-2), C(-1), C(0) or C(1)) such that it reaches its maximum value and keep all other coefficients in hold state. Export the Linear fit impulse response from PAM4 utility .
3. Find the equalizer coefficients using PRESET and incremented linear fit pulses.

4. Similarly ask the user to sufficiently decrement the equalizer coefficient (C(-1), C(0) and C(1)) one by one such that it reaches its minimum value. Capture the waveform and find the linear fit pulse from the PAM4 utility .

5. Find the equalizer coefficients using PRESET and decremented linear fit pulses.

6. Verify that each transmitter equalizer coefficient is within the minimum and maximum range of specification.

This section verifies that the coefficient range of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

1. Range for C(1) or value at minimum state for C(1): with C(-2) and C(-1) both set to zero and both C(0) and C(1) having received sufficient “decrement” requests so that they are at their respective minimum values, C(1) shall be less than or equal to -0.25
2. Range for C(-1) or value at minimum state for C(-1): with C(-2) and C(1) set to zero and both C(-1) and C(0) having received sufficient “decrement” requests so that they are at their respective minimum values, C(-1) shall be less than or equal to -0.25
3. Range for C(-2) or value at maximum state for C(-2): with C(-1) and C(1) set to zero, C(0) having received sufficient “decrement” requests so that it is at its minimum value, and C(-2) having received sufficient “increment” requests so that it is at its maximum value, C(-2) shall be greater than or equal to 0.1

Measurement procedure for IEEE 802.3ck

This section verifies that the far end pre-cursor ISI ratio of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

1. Apply the CTLE filter which produces the optimal eye opening and export the linear fit pulse from the PAM4 utility.
2. Using linear fit impulse, measure the far end pre-cursor ratio:

   Far End Pre-cursor ratio = Ppre/Pmax

   Where,

   Ppre is the value of linear fit pulse 1 UI prior to the time of the pulse peak

   Pmax is the peak amplitude of the linear fit pulse

This section verifies that the maximum value of transmitter output residual ISI of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

1. Acquire the signal and export the linear fit pulse using PAM4 utility.
2. Perform single sequence in PAM4 utility and export the linear fit pulse to a file.
3. Using Linear fit pulse, calculate the SNR-ISI value using below equation:
   
   

   ISI cursors are calculated using below equation:

   
   
   

   Where,

   tp is the index of the linear fit pulse where p(tp) = pmax

   M is the oversampling ratio of the measured waveform and linear fit pulse

   Np is the linear fit pulse length

   Nb is given in Table 120D–8

For UAI-4 at TP0a, Equalization has to be performed on signal before running measurement for SNR-ISI. For CR4 and KR4, measurement is done on unequalized signal.

Equalization procedure

gDC	gDC2	G	ZLF	Z1	PLF	P1	P2
-15 to 0	-4 to 0	1			fb/40	fb/2.5	fb*2

1. Equalize the signal with equalization filters given above(varying gDC and gDC2) ad measure the SNR-ISI in each case

2. Maximum value of SNR-ISI is reported out as result.

Note:The observed SNRISI can be significantly influenced by the measurement setup, for example, the reflections in cables and connectors. High-precision measurement and careful calibration of the setup are recommended.

This section verifies that the normalized coefficients step size of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

Normalized coefficient step size is the measure of variation in the equalizer coefficient when the increment or decrement operations were done.

1. Set the DUT in PRESET state. Export the linear fit pulse response from PAM4 utility.
2. Set the DUT in INITIALIZE state. Export the Linear fit pulse response from PAM4 utility.
3. Calculate all the equalizer coefficient C(x) before using these linear fit pulse responses and denote it as C(x)_Before.
4. Increment or decrement the equalizer coefficient in DUT by giving an increment or decrement command.
5. Measure the linear fit pulse response. Calculate the updated equalizer coefficient C(x) in the signal using linear fit pulse response before and after sending increment or decrement request and denote it as C(x)_After.

6. Find the Increment or decrement step size for equalizer coefficient C(x) using below equation.

   Increment or decrement step size = C(x)_After – C(x)_Before

   Normalized coefficient step size for C(x) is calculated using below equation:

   Normalized coefficient step size = Absolute value of ((Increment or Decrement step size) / C(x)_Before)*100

7. Repeat the above method for all the coefficients to find the increment and decrement step sizes.

Limits

Note:C(x) is an equalizer coefficient and the values can be C(-2), C(-1), C(0), and C(1)

IEEE 802.3ck, Step size for co-efficient C(-3), C(-2), C(-1), C(0), and C(1)

This measurement measures the values of equalizer coefficient when the DUT is in OUT_OF_SYNC and NEW_IC states (PRESET1, PRESET2 and PRESET3).

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

1. Configure the DUT in PRESET state, capture the signal and export the linear fit pulse curve using PAM4 utility.

2. Configure the DUT into OUT_OF_SYNC state, capture the signal and export the linear fit pulse using PAM4 utility. Find the values of Equalizer coefficients in OUT_OF sync state using the linear fit curves of Preset state and OUT_OF_SYNC state.

3. Configure DUT into NEW_IC state with PRESET1, PRESET2 and PRESET3. Each time export the linear fit pulse using the PAM4 utility. Measure the Equalizer coefficients for the each state (PRESET1, PRESET2 and PRESET3). All the time equalizer coefficients should be within the specified limit as per the specification.

This section verifies that the signaling speed of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Measurement procedure

1. Perform oscilloscope settings.
2. Capture the BT filtered differential signal using Math1 as source. Math1 = BT_filter(Data positive – Data negative)
3. Configure signal source in PAM4 utility and perform single sequence.
4. Signaling rate is measured using PAM4 utility and the results are queried.

This section verifies that the level separation mismatch ratio of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through a fourth order Bessel Thomson filter with appropriate bandwidth.

Measurement procedure

The level separation mismatch ratio R_LM is defined by the following equation:

R_LM = min ( ( 3.ES₁), (3.ES₂), (2 - 3.ES₁), (2-3.ES₂))

Where,

ES₁ = (V_+1/3 - V_mid / (V₊₁ - V_mid)

ES₂ = (V_-1/3 - V_mid / (V_-1 - V_mid)

V_mid = (V_-1 + V₊₁) / 2

V_-1, V_-1/3, V_+1/3, and V₊₁ are the mean signal levels for each symbol of -1, -1/3, +1/3, and +1 PAM4 symbols, respectively.

This section verifies that the linear fit pulse peak voltage of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through a fourth order Bessel Thomson filter with appropriate bandwidth.

Measurement procedure

The linear fit pulse peak is the peak value of linear fit pulse p(k).

This section verifies that the steady state voltage of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through a fourth order Bessel Thomson filter with appropriate bandwidth.

Measurement procedure

The steady state voltage v_f is defined as the sum of the linear fit pulse p(k), divided by M, as shown in following equation:

This section verifies that the maximum value of the even odd jitter of the DUT is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through a fourth order Bessel Thomson filter with the bandwidth of 40 GHz.

Measurement procedure

Even odd jitter is the measure of two repetitions of a QPRBS13-CEI test pattern. The deviation of the time of each transition from an ideal clock at the signaling rate is measured.

Even odd jitter is defined as the magnitude of the difference between the average deviation of all even-numbered transitions and the average deviation of all odd-numbered transitions. Determining if a transition is even or odd is based on the possible transitions (only actual transitions are measured and averaged).

This section verifies that the maximum value of the uncorrelated bounded high probability jitter (UBHPJ) and Uncorrelated unbounded gaussian jitter (UUGJ) is within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through a fourth order Bessel Thomson filter with appropriate bandwidth.

Measurement procedure

UBHPJ and UUGJ are measured using a QPRBS13-CEI test pattern. This measurement requires at least 10⁷ symbols.

This measurement finds all the zero crossings in the signal and then finds the average pulse width. The difference of the edge time is the jitter value. The jitter is filtered through a high pass filter. Find the CDF of the filtered jitter. The UBHPJ and UUGJ are calculated by the following equation:

Where,

J5 is the difference between the τHPF at the (1-0.5 × 10^-5) and 0.5 × 10^-5 probabilities.

J6 as the difference between the τHPF at the (1-0.5 × 10^-6) and 0.5 ×10^-6 probabilities.

This section verifies that the maximum value of the uncorrelated J3/J4 jitter (J3u/J4u) and Uncorrelated Jitter RMS (Jrms) are within the conformable limits according to the specification.

Required test equipment

Minimum system requirements

Equipment connection diagram

Input

Differential signal filtered through a fourth order Bessel Thomson filter with appropriate bandwidth.

Measurement procedure

J4u, J3u and Jrms are defined by measurements of 12 specific transitions in a PRBS13Q pattern to exclude correlated jitter. The 12 transitions represent all possible combinations of four identical symbols followed by two different identical symbols as shown in Table 120D–2. The sequences are located by the symbol indices given in the table where symbols 1 to 7 are the run of seven 3s.

J4u is defined as the time interval that includes all but 10–4 of fJ(t), from the 0.005th to the 99.995th percentile of fJ(t). JRMS is defined as the standard deviation of fJ(t).

J4u₀₃is calculated the same way as J4u except that the calculation uses only transitions R03 and F30 as define in IEEE802.3 specification.

J3u is defined as the time interval that includes all but 10–3 of fJ(t), from the 0.05th to the 99.95th percentile of fJ(t).

This measurement requires minimum of 3500 specific transitions. Hence the application will capture 10 waveforms each with 8M. It analyzes the waveforms one by one using PAM4 utility until it accumulates the required number of transitions (3500). Incase of noisy signals, more data is needed to get the required number of transitions which application takes care internally.

Limits

This section verifies the Signal to AC common mode noise ratio (SCMR) within the comfortable limits according to the specification.

Measurement procedure

Signal to AC common-mode noise ratio, SCMR, is defined by the below equation with the exception that the full-band peak-to-peak AC common-mode voltage is defined in 120F.3.1.1.

Signal to AC common-mode noise ratio, SCMR, is calculated using Equation,

Where,

SCMR is the signal to AC common-mode noise ratio in dB

V_peak is defined as a maximum value of p(k).

P(k) is linear fit pulse response

VCM_FB is the full-band peak-to-peak AC common-mode voltage defined by the method specified in “Peak-Peak AC Common mode Voltage” and measured with the transmitter equalization set to “no equalization”

This section verifies Peak-Peak AC common mode voltage within the comfortable limits according to the specification.

This section verifies the Signal to Residual Inter Symbol Interface Ratio (SNR_ISI) within the comfortable limits according to the specification.

Measurement procedure

Signal-to-residual-intersymbol-interference ratio SNR_ISI is defined by the method with the exception that the continuous time filter settings are provided in Table 120F–8

SNR_ISI is computed using below equation. It is computed from p_max and ISI_cursors after these have been recalculated with CTLE described in specification and optimized for maximum SNR_ISI.

ISI_cursors =[p(t_p +M x ( N_b +1)) , p(t_p +M x ( N_b +2)) , ……………., p(t_p +M x ( N_b -D_p-1)) ]

t_p – is the index of the linear fit pulse where p(t_p) equals p_max

M – is the oversampling ratio of the measured waveform and linear fit pulse

N_p – is the linear fit pulse length

N_b - 6

1. The linear fit pulse response p(k) is determined using the linear fit procedure in specification.
2. The continuous time filter parameters are provided in specification. For calculation of SNR_ISI using above equation a value of 6 is used for N_b.
3. A time offset is added to t_p whose value is swept from –0.5 UI to 0.5 UI when calculating ISI_cursors. SNR_ISI is defined as the lowest value found across the time offset sweep.
4. The transmitter equalizer setting is chosen, within the required coefficient ranges to result in the highest SNR_ISI value.

This section verifies Difference steady-state voltage d_vf within the comfortable limits according to the specification.

Measurement procedure

The difference steady-state voltage, d_vf, is calculated using below Equation

1. User need to brown Test Fixture S4_p file to compute the V_f(ref).
2. Measurement will compute the 'h()' using Reference device and Package model, Test Fixture scattering parameters.
3. Acquire the signal
4. Select the d_vf test in PAMJET, which compute the v_f(mean) from acquire signal and v_f(ref) using above formula.
5. Difference between V_f(mean) and V_f(ref) is reported to compare against the limit.

This section verifies the Difference steady-state voltage d_vf within the comfortable limits according to the specification.

This section describes the steps to configure the TCPIP socket configuration in your script execution device and the steps to configure the TekVISA configuration in the oscilloscope to execute the SCPI commands.

This command sets or queries the device name of the application.

This command sets or queries the suite name of the application.

This command selects or deselects the specified test name of the application.

This command sets or queries the version name of the application.

This command sets or queries the general parameter values of the application.

This command sets or queries the acquire parameter values of the application.

This command sets or queries the analyze parameter values of the application.

This command queries the list of available devices on the DUT panel as comma separated values.

This command queries the list of available suites for the selected device as comma separated values.

This command queries the list of available tests of the application for the selected device as comma separated values.

This command queries the list of available version names of the application for the selected device as comma separated values.

This command queries the list of available instruments based on the specified instrument type.

This command sets or queries the IP address of the instrument based on the specified instrument type.

This command queries the information of the generated report file in the format "<FileSize>","<FileName>".

This command queries the information of the generated waveform files in the format.

<File1Size,"File1Name”>.

If there are more than one waveform, the waveform file names are displayed with the comma separated values in the format

<File1Size,"File1Name">,<File2Size,"File2Name">.

This command queries the information of the generated image files in the format.

<File1Size,"File1Name”>.

If there are more than one image, the image file names are displayed with the comma separated values in the format

<File1Size,"File1Name">,<File2Size,"File2Name">.

This command queries the active TekExpress application name running on the oscilloscope.

This command sets or queries the DUTID of the application.

This command sets or queries the acquire mode status.

This command sets or queries the execution mode status.

This command generates the report for the current session.

This command queries the value of specified report header field in the report.

Command arguments

Argument Name	Argument Type
<Device Field> Device field is the header name of each field in the setup information section of the report.	<String>

This command queries the value of specified result detail available in report summary/details table.

This command restores the setup to default settings.

This command saves the setup.

This command saves the settings to a specified session.

This command opens the setup from a specified session.

This command queries the current setup file name.

This command run/stop/pause/resume the selected measurements execution in the application.

This command queries the current measurement execution status.

This command queries whether the current setup is saved or not saved.

The command exits or close the application

This command queries whether the previous command execution is completed successfully.

This command queries the last error occurred.

This command sets or queries the popup details.

This command sets or queries the limit values in the limits editor window.

This command set or queries the waveform file recalled for the specified test name and acquire type.

If there are more than one waveform, the waveform file names are displayed with the symbol "$" separated values in the format

<WaveformFileName1$ WaveformFileName2>.

This command sets or queries the enable/disable status of Verbose function.

This command queries the enable or disable status of Continuous run function.

This command sets or queries the enable/disable status of Continuous Run function.

This command sets or queries the continuous run duration time value.

This command sets or queries the option for session creation in the continuous run function.

This command sets or queries the enable/disable status of the View report after generating function.

This command returns the report as XML string.

This command copies all the images from current run session to the given destination locations.

This command selects the specified test(s) and deselect all other tests.

This command returns the complete information about the selected test.

The information includes application name, TestID, Device selected, Suite selected, version, Test name, Test description.

Sets the application configurations to default value.

Enter the name to save/config the session.

Load the selected config/run session.

Deletes the selected config/run session.

Run the selected config/run session.

Returns the list of available config/run session.

Returns the selected config/run session.

Overrides the selected config/run session.

This section provides the examples for the SCPI commands.

You can find the application files at C:\Program Files\Tektronix\TekExpress 400G-TXE. The application directory and associated files are organized as follows:

The TekExpress 400G-TXE software uses the following file name extensions:

Files related to tests are stored in My Documents\TekExpress 400G-TXE\Untitled session folder. Each test setup in this folder has both a test setup file and a test setup folder, both with the test setup name. The test setup file is preceded by the TekExpress icon.

Inside the test setup folder is another folder named for the DUT ID used in the test sessions. The default is DUT001.

Inside the DUT001 folder are the session folders and files. Each session also has a folder and file pair, both named for the test session using the naming convention (date)_(time). Each session file is stored outside its matching session folder:

Each session folder contains image files of any plots generated from running the test session. If you selected to save all waveforms or ran tests using prerecorded waveform files, these are included here.

The first time you run a new, unsaved session, the session files are stored in the Untitled Session folder located at X:\TekExpress 400G-TXE. When you name and save the session, the files are placed in a folder with the name that you specify. A copy of the test files stay in the Untitled Session folder until you run a new test or until you close the application.