The top five buttons on the DOMAIN menu form a button selection group where the selection of one button de-selects the other four buttons. Descriptions, prerequisites, and variations of each menu item are described later in this section.
The presence and availability of some DOMAIN menu selections depend on installed options, the domain mode selected on the DOMAIN menu, as well as on the SWEEP TYPES and FREQUENCY menus.
Domain Menu Variations:
1. Frequency, with No Time Gate selected
2. Frequency, with Time Gate selected
3. Time, Low Pass selected
4. Time, Band Pass selected
5. Time, Eye Diagram (TED) selected
Note
Since the presence and availability of some DOMAIN menu selections depend on the selections made on the SWEEP TYPES and FREQUENCY menus, refer to:
• Impulse Width [3dB] Display Button: Appears when the Time, Low Pass button has been selected. The units in the Impulse Width display change to match the setting on the Display Unit button.
• Display Unit (Time/Distance): Select toggles the display units between time and distance.
• Time Definition: Select displays the TIME DEFINITION menu. (See TIME DEFINITION Menu).
• Impulse Width [3dB] Display Button: Appears when the Time, Band Pass button has been selected. The units in the Impulse Width display change to match the setting on the Display Unit button.
• Display Unit (Time/Distance): Select toggles the display units between time and distance.
• Time Definition: Select displays the TIME DEFINITION menu. (See TIME DEFINITION Menu).
Option 47 (Eye Diagram) and Option 2 (Time Domain Measurements) must be installed.
The Time Eye Diagram (TED) selection is only available when a harmonic sweep condition is established. Sweep must be set to a frequency‑based sweep:
• SWEEP TYPES Menu = Freq Sweep (Linear), Freq Sweep (Log), or Segmented Sweep (Freq-based)
For example, at the FREQUENCY menu, set the following values:
• Start point of 1 GHz
• Stop point of 10 GHz
• # of Points set to 10
The Time, Eye Diagram button then becomes available.
Eye Diagram Statistics
With a trace set up for TED, selecting MAIN | Marker opens the EYE STATISTICS Menu, which provides options for toggling various eye diagram measurements on or off.
Selection and Other Function Availabilities
• The Time, Eye Diagram button is unavailable if:
• A power-based sweep of Power Sweep (CW Frequency) or Power Sweep (Swept Frequency) is set.
• A Segmented Sweep (Index-Based) is set.
• When a trace is set to TED the following additional restrictions apply:
• Data Mem Math is not available for eye diagram trace and is disabled if the trace is set to Time Eye Diagram.
• Group Delay graph type and Circular graph types is not supported for eye diagram. If group delay or any circular graph type is selected for the current trace before TED is selected, the graph type is changed to Log Mag.
• Inter-trace Math is not available for eye diagram trace and cannot be turned on. Inter-trace Math cannot be turned ON for TED.
• Conversions are not available on eye diagram traces. Conversion cannot be turned ON for TED.
• Trace Smoothing on the Averaging menu is not available on eye diagram traces. Trace smoothing cannot be turned on for TED.
• Impulse Width [3dB] Display Button: Appears when the Time, Low Pass button has been selected. The units in the Impulse Width display change to match the setting on the Display Unit button.
• Display Unit (Time/Distance): Select toggles the display units between time and distance.
• Time Definition: Select displays the TIME DEFINITION menu. See TIME DEFINITION Menu.
• Eye Diagram Setup: Select opens the EYE DIAGRAM CALCULATIONS dialog box where eye diagram parameters can be set up. See EYE DIAGRAM CALCULATIONS Dialog.
Time, Eye Diagram Display Example – Note that when in Time, Eye Diagram mode, the display trace annotation displays “TED”.
EYE DIAGRAM CALCULATIONS Dialog
Prerequisites
The Eye Diagram Setup selection, which opens the EYE DIAGRAM CALCULATIONS dialog, is available only when Time, Eye Diagram mode is selected in the DOMAIN menu.
MAIN | Display | DISPLAY | Domain | DOMAIN | Time, Eye Diagram (selected)|
Eye Diagram Setup | EYE DIAGRAM CALCULATIONS
The EYE DIAGRAM CALCULATIONS dialog box (Figure: EYE DIAGRAM CALCULATIONS Dialog Box) provides an area to set parameters for data stream and signaling format selection, data rate, rise/fall time, high level/low level, pattern length, horizontal shift, jitter, noise (AWGN), and persistence.
EYE DIAGRAM CALCULATIONS Dialog Box
EYE DIAGRAM CALCULATIONS Dialog Parameters
Data Stream Settings
• Select the signaling format:
• NRZ
• PAM-4
• Select one type:
• PRBS
• K28.5 (available for NRZ signaling format only)
• User Fixed Pattern:If the user chooses the data stream to be User fixed pattern, the text box becomes available for entering the desired pattern (a string with 1s and 0s only, e.g.,00111110101100000101). The maximum length allowed is 64 bit).
• Data rate:units in GBPS
• Rise Time:units in ps
• Fall time: units in ps
• Horizontal Shift: While the eye centering scheme correctly places the eye for analysis most of the time, sometimes there are cases where it cannot such as with heavy skew on a differential pair. For this reason, a manual horizontal shift (expressed in fraction of a bit period) is provided. Internally, the data steam would be advanced by a number of samples= samplesPerSymb* (user entered fractional shift).
• Pattern Length: Can be selected from the combo (drop-down box)
• High Level: units in SE mV (NRZ signaling format only)
• Low Level:units in SE mV (NRZ signaling format only)
• Level 3: units in SE mV, where Level 0 < Level 1 < Level 2 < Level 3 (PAM-4 signaling format only)
• Level 2:units in SE mV (PAM-4 signaling format only)
• Level 1: units in SE mV (PAM-4 signaling format only)
• Level 0:units in SE mV (PAM-4 signaling format only)
Jitter Settings
• Random RMS: units in ps
• Sinusoidal1 Amplitude: units in ps
• Sinusoidal1 Frequency: units in Hz
• Sinusoidal2 Amplitude: units in ps
• Sinusoidal2 Frequency: units in Hz
• Dirac1 Offset: units in ps
• Dirac1 Probability
• Dirac2 Offset: units in ps
• Dirac2 Probability
Noise (AWGN) Setting
• RMS Amplitude: units in mV
Persistence Setting
• Persistence: Number of cycles
Click Done on the dialog after entering the required parameters.
• In case of valid values, the time domain mode switches to eye diagram and eye diagram data corresponding to the user-entered parameters will start plotting (dot display) for the current active trace.
• If the validation is not successful, an error message is displayed to the user.
Cancel button: Cancels the eye diagram computation.
Note
While selecting the Time, Eye Diagram from the DOMAIN menu, the eye diagram calculations are done using the default values and the corresponding eye diagram is plotted for the current trace. Then the user will be able to invoke the EYE DIAGRAM CALCULATION dialog and modify the parameter values, which will update the eye diagram plot.
