APPLICATION NOTE
2
Figure 2: Standard Noise output.
To observe this standard noise output waveform perform Transient analysis to the same design.
Figure 2 shows the standard display of the EFREQ output versus time. It is very difficult to use this display to
determine the voltage and timing margins for data recovery from the system. The eye display, on the other hand,
superimposes the results for all three hundred data periods on a shortened time axis, enabling both margins to be
gauged easily. To include all of the simulation data in one eye, we need to use a single data period for the sweep
period. We also need to offset the display slightly to make sure that the eye is centered in the smaller display.
Following are the results:
Figure 3: Output showing all simulation data in one eye.
Apart from the simulation data we can also create Eye displays from external data source, if available. For
example, an eye display shown below is plotted using external data that is available at the location:
%HOME%\< Version number>\Eye_Display-PSpiceFiles\Eye_Diagram\Tran\Waveform.dat For
example:
%HOME%\cdssetup\OrCAD_Capture\16.6.0\tclscripts\caplearningresources\work\supportfiles\Eye_Display\Misc\
Designfiles\Eye_Display-PSpiceFiles\Eye_Diagram\Tran\Waveform.dat. and using macros the eye display is
plotted.
