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SDA II
User Manual
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Teledyne SDA II User Manual

Operator's Manual
SDAII Software
Serial Data Analysis II Software Operator's Manual
© 2013 Teledyne LeCroy, Inc. All rights reserved.
Unauthorized duplication of Teledyne LeCroy documentation materials other than for internal sales and distribution pur­poses is strictly prohibited. However, clients are encouraged to distribute and duplicate Teledyne LeCroy documentation for their own internal educational purposes.
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TABLE OF CONTENTS
SDAII Overview 2
Key Features 2 Serial Data Analysis II Dialog 2 Setting Up SDAII 3
Quick View 4
Setting Up Quick View 5
Signal Inputs 6
Set Up Signal 6 Serial Data Inputs 7 Signal Types 7 Crossing Levels 7
Reference Clock 9
Set Up Reference Clock 9 Reference Clock Inputs 10 Crossing Level 10 Clock Timing 10
Clock Recovery 11
Set Up Clock Recovery 11 Bit Rate 11 Reference Clock 11 PLL Setup 12 Clock Recovery Theory 14
Eye Measurements 17
Eye Measure Dialog 17 Set Up Eye Diagram 17 Eye Modes 18 Mask Testing 19 Eye Diagram Configuration Dialog 19 Eye Parameters Dialog 21 Eye Measurement Parameters 21 Eye Analysis Theory 24
Jitter Measurements 26
Set Up Jitter Measurements 26 Jitter Filter 28 Pattern Analysis 29 Jitter Track 30 Jitter Spectrum 31 Jitter Histogram Analysis 34 Jitter Parameters 35
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SDAII Overview

The new Serial Data Analyzer (SDAII) provides comprehensive measurement capabilities for evaluating serial digital signals. SDAII operates by processing a long signal acquisition. All jitter measurements and displays are based on times of successive edges for the signal only - nothing is relative to the trigger. As a result, they are not affected by trigger jitter. Acquisitions should be long enough to include at least 100, 000 UI of the signal under test (500,000 UI or more is optimal). It may be desirable to acquire longer rec­ords to see low frequency jitter.
Note: Acquisitions can be up to the full available memory depth of the instrument and may take con­siderable time to process.
The SDAII processes include clock recovery, eye pattern measurement, and jitter measurement. These operations are performed on the same data record.

Key Features

l SDAII provides two types of measurements: eye pattern testing and comprehensive jitter anal-
ysis (including random and deterministic jitter separation, and direct measurement of periodic
jitter, DDj, and DCD).
l Many plot types for jitter and eye diagram analysis, including eye diagram, IsoBER, DDj Plot, dig-
ital pattern, DDj Histogram, jitter track, PLL track, jitter spectrum (with peak annotation), spec­trum threshold, Pj Inverse FFT, jitter histogram, CDF, bathtub and Normalized Q-scale fit.
l Filtered jitter processes the time interval error trend versus time with a user-selectable band-pass
filter. This feature allows applying filters in addition to the high-pass filtering effect of the clock recovery PLL, which is required for some serial data specifications.
l IsoBER displays the extrapolated lines of constant Bit Error Ratio down to the BER of interest on an
eye diagram.
l Quick View provides a shortcut displaying the eye diagram, TIE track, bathtub curve, jitter his-
togram, NQ-scale cursors, and jitter spectrum all on the screen at the same time.

Serial Data Analysis II Dialog

Access the SDAII dialog by choosing Analysis → Serial Data.
The Serial Data Analysis II dialog shows the overall flow for viewing and analyzing serial data. Each block in the flow diagram is a button that, when touched, displays its corresponding dialog.
The multiplexer switch button (on the Setup Clock Recovery button's respective dialog) allows you to select clock recovery from the input data signal or, in the down position, a separate explicit clock signal. Touch the multiplexer switch button to change the state.
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Setting Up SDAII

Use the following steps to start your SDAII setup.
1. If you haven't done so already, touch Analysis → Serial Data on the menu bar.
2. On the Serial Data Analysis II dialog, place a checkmark in the Enable SDA box.
3. Touch the Setup Signal Inputs button to configure your signal input sources, crossing levels, and sig­nal type.
Note: Touch the Quick View button to quickly set up and view your serial data.
4. If you are recovering clock data from the data signal (the default selection), make sure the clock recovery input multiplexer switch is in the up position (clock recovery via the red path).
When the switch is in the up position, the Setup Ref. Clock button is disabled (grayed out).
5. Touch the Setup Clock Recovery button and define clock recovery settings, such as Bit Rate and PLL settings.
OR
If you are using an explicit reference clock, click the clock recovery multiplexer switch button so that the switch is in the down position.
6. The Setup Reference Clock Inputs button is then enabled. Click this button and set up your reference clock inputs.
7. On the far right of the Serial Data Analysis II dialog, place a checkmark in the Enable Eye Meas. box and click the Setup Eye Measurements button (showing its respective dialog) to define eye meas­urement settings.
8. On the far right of the Serial Data Analysis II dialog, place a checkmark in the Enable Jitter Meas. box and click the Setup Jitter Measurements button (showing its respective dialog) to define jitter measurement settings. The Jitter Measure dialog opens displaying another flow diagram.
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Quick View

The SDAIIQuick View shows the eye diagram, TIE track, bathtub curve, jitter histogram, NQ-scale, and jitter spectrum (with peaks annotated) in a single, summarized view.
SDAII Quick View
You must specify only the input signal for analysis. You can also specify the crossing level.
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Setting Up Quick View

Follow these steps to set up Quick View.
1. If you haven't done so already, touch Analysis → Serial Data on the menu bar or touch the Serial Data Analyzer button on the Quick Access toolbar.
2. On the Serial Data Analysis II dialog, touch the Quick View button. The Signal Input(s) to be Analyzed pop-up window opens.
3. On the Serial Data Input(s) section, if you are using a differential probe, touch the 1 Input (or Diff. Probe) button. Now, touch inside the Data field below the 1 Input (or Diff. Probe) button and select an input source from the Select Source pop-up window.
OR
If you are using two single-ended probes to calculate the differential signal, touch the Input1-Input2 button. Input2 is subtracted from Input1. Touch inside each Data field and select a source for each Select Source pop-up window.
4. Increase the sampling rate of the signal by touching inside the Upsample by data entry field and entering the upsample factor . at the bottom of the screen.
5. In the Crossing Level section, if you want to set an absolute crossing level, touch inside the Level is field and choose Absolute from the pop-up menu. Then, touch inside the Abs Level data entry field and enter the voltage level at which the signal timing is measured at the bottom of the window.
OR
If you want to use a relative level set to the selected percentage on each acquisition, touch inside the Level is field and choose Percent from the pop-up menu. Then, touch inside the Percent Level data entry field and enter the percentage . at the bottom of the window.
Note: You can touch the Find Level button to automatically find the level. The level is found by locat­ing the midpoint between the highest and lowest signal levels in the current acquisition.
6. Click OK to view the summary all on one screen.
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Signal Inputs

Set Up Signal

On the Serial Data Analysis II dialog, touch the Setup Signal Input button to access the Signal Input dialog.
Serial Data Input(s) section (1) lets you define the serial data input(s). If you are using a differential probe or if your signal is connected by one coaxial cable, you can select 1 Input (or Diff. Probe) and specify the input source in the Input1 box. If you are using two single-ended probes or two coaxial cables, you can select Input1-Input2 and specify the input sources to use when calculating the differential signal. For more information, see Serial Data Inputs.
Crossing Level section (2) lets you to set the voltage level at which the signal timing is measured. The crossing level is set separately for the data and clock signals (if an external clock is selected) and can either be an absolute voltage or a percentage of the signal amplitude via the relative selection. You can also con­figure a hysteresis level, and between positive, negative and both edge types for when the "Clock" Signal Type is selected. The Crossing Level section on this dialog is for the data signal. For more information, see
Crossing Levels.
Signal Type section (3) lets you choose a standard signal type. The signal type you choose automatically sets the nominal bit rate for the selected standard, and populates the Mask Type selector in the Eye dialog. For more information, see Signal Types.
Noise Settings includes settings that are used by the vertical noise measurements toolkit. Settings include the Sample Phase, which determines where in the unit interval the sample is taken for the noise measurement. Also, see How to Order SDAIII-CompleteLinQ Capabilities for information on which prod- ucts include the vertical noise analysis capabilities.
NOTE:
l Many of the measurements in SDAIIrequire both a high sampling rate and long memory to com-
pute jitter and vertical noise accurately.
l Lower sampling rates can result in less accurate jitter measurements, and short record lengths can
give incomplete eye patterns or jitter and noise displays that diverge.
l For best results, acquire waveforms with at least 100,000 unit intervals, and of >100 iterations of
the pattern. See Jitter Pattern Analysis.
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Serial Data Inputs

There are several scenarios for the configuration of the SeriaData Input(s) section.
If you are using a differential probe or if your signal is connected by one coaxial cable, use the 1 Input (or Diff. Probe) button and select the input source.
If you have a differential signal transmitted on two two coaxial cables or two single-ended probes., use the Input1-Input2 button and select the input channels used.
NOTE:There is no need to configure a math function to calculate the difference between to inputs. Doing so adds additional computational steps, and unnecessarily uses RAM.
Lastly, any math function, memory trace, etc. can be used as an input, as well as any input channel. When in Input1-Input2 mode, and when using traces that may have been the result of other processing steps, be sure that both traces have the same record length and sample rate.
You can choose to upsample rate in the Serial Data Inputs dialog by a factor of two in order to provide a higher sample density for analysis. In SDAII this was typically done to facilitate formation of eye diagrams without gaps for bit rates integrally related to the sampling rate (for example, 20 GS/s is exactly eight times 2.5 Gb/s), and especially for relatively short acquisitions. This, however, unnecessarily slowed down the analysis process. When needing to upsample to remove gaps in the eye use the upsample con­trol in the Eye Diagram dialog.

Signal Types

The signal type defines the compliance masks and bit rate for the selected standard.
When you touch the Signal Type field, a pop-up table of standard signal types is shown. Touch the desired signal type to populate the Signal Type field. The list of signal types is taken from the SDAMask Database. As new serial data standards are invented, masks are added to the database.
When choosing Custom from the Signal Type pop-up menu, always enter a bit rate in the Nominal Rate entry box. Using an incorrect Nominal Rate can lead to incorrect equalizer results, since this value is used by several of the equalizers that are available the oscilloscope includes Eye Doctor II functionality. The Custom selection does not specify any eye masks, and the Mask Type selector in the Eye dialog will be greyed out.

Crossing Levels

The Crossing level section of the Signal Input dialog determines the voltage level where the arrival time of each edge of the signal is measured. The crossing level is set separately for the data and clock (if an external clock is selected).. The Crossing Level on this dialog is for the data. Setting the crossing level to a value that is not optimal can result in higher than expected deterministic jitter, since the error in the tim­ing of the edges will be different for rising and falling edges.
The Level Type can be either absolute or relative.
The Absolute crossing level can be set directly in volts (or watts for an optical signal) , or you can click the Find Level button to automatically find the level. The level is found by locating the midpoint between the highest and lowest signal levels in the current acquisition. When you select the Absolute crossing level, the crossing time used by both the jitter and eye pattern measurements is determined as the time at which the signal level crosses the specified threshold. When Relative level is selected, the level is auto-
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matically set on each acquisition. The value set is the selected percentage of the signal amplitude (which equals base - top).
The Slope selector determines which edges are measured when "Clock" is selected in the Signal Type selector in the Signal dialog.. The choices for slope are Pos(itive), Neg(ative) or Both Select the choice that corresponds to the edge type that is used for clocking of the data in your device, or that is of inter­est in your analysis. For example, if you only latch data on positive edges, select Pos. If you clock on both edges, you can select Pos or Neg rather than both in order to understand how the edge type affects the jitter measurement.
The Hysteresis entry box sets the hysteresis level to use for edge detection, in units of vertical divisions. The hysteresis is the vertical amount that the signal is required to travel beyond the crossing level to allow detection of a crossing in the opposite direction. Incorporating hysteresis in the edge detection algorithm prevents the software from finding false edges that would otherwise be detected due to noise or other small glitches in the signal. The default value is 500mdiv, or 1/2 a division. When the input sig­nals are properly scaled (i.e. to fill approximately 90% of the grid, vertically, this level of hysteresis should be sufficient. When dealing with signals that result in closed eyes, a smaller value for hystersis may be required.
More information about how the SDAanalysis software determines the edge timing using the crossing level can be found in the Clock Recovery Theory section
NOTE: The Relative setting can potentially remove jitter by tracking slow level shifts between acqui­sitions, if this is not desired, use the Absolute level setting.
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Reference Clock

Set Up Reference Clock

An accurate reference clock is central to the measurements performed by SDAII. When the clock is recov­ered from data, the clock is defined from the locations of the data's crossing points in time. When a ref­erence clock is used, the clock is defined from the locations of the reference clock's crossing points. Starting with zero, the clock edges are computed at specific time intervals relative to each other.
Example: A 2.5 GHz clock has edges separated in time by 400 ps. Making a 2.5 GHz clock from a 100 MHz reference clock requires setting the Multiplier to 25.
Follow these steps to define the crossing points.
1. Touch Analysis → Serial Data on the menu bar.
2. On the Serial Data Analysis IIdialog, make sure the multiplex switch next to Clock Recovery is in the down position to select Reference Clock, then touch the Setup Ref Clock button.
3. Under Reference Clock Inputs, touch the Clock+ Only button, then touch the Clock Ref+ box and select an input source from the Select Source pop-up window.
OR
Touch the Clock+ and Clock- button, then touch the Clock Ref+ and Clock Ref- boxes and select a source for each from the Select Source pop-up window.
4. If you want to increase the sampling rate of the signal, touch inside the Upsample by data entry field and enter the upsample factor.
5. To set an absolute crossing level, touch inside the Level field and choose Absolute from the pop-up menu. Then, touch inside the Abs Level data entry field and enter the voltage level at which the sig­nal timing is measured using either the keypad or the slider bar at the bottom of the screen.
OR
To use a relative level set to the selected percentage on each acquisition, touch inside the Level is field and choose Percent from the pop-up menu. Then, touch inside the Percent Level data entry field and enter the percentage at the bottom of the screen.
NOTE: Alternatively, touch Find Level to automatically find the level. The level is found by locating the midpoint between the highest and lowest signal levels in the current acquisition.
6. Determine clock timing by touching the Clock Slope field and choose Positive, Negative, or Both.
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Reference Clock Inputs

The Reference Clock Input(s) section in the Ref. Clock Input dialog lets you define the clock input(s). You can choose Clock+ Only or Clock+ and Clock- .You can also define the upsample rate (when increasing the sampling rate of the clock signal).

Crossing Level

The Crossing level section of the Reference Clock Inputs dialog lets you set the voltage level where tim- ing is measured for the reference clock. The crossing level is set separately for the data and clock (the con­trols on this dialog are for the clock) and can be either absolute or relative.
You can either set the Absolute crossing level in volts (or watts for an optical signal) directly, or you click the Find Level button to automatically find the level. The level is found by locating the midpoint between the highest and lowest clock levels in the current acquisition. When you select the Absolute crossing level, the crossing time used by both the jitter and eye pattern measurements is determined as the time at which the clock level crosses the specified threshold. The Relative level is automatically set to the selected percentage on each acquisition.

Clock Timing

The Clock Timing section of the Ref. Clock Input dialog lets you define a clock slope setting. A clock signal goes through one complete cycle during each bit interval. The edge timing can be measured relative to the rising slope, falling slope, or both slopes, of the clock by means of the Clock Slope setting.
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