The Eye Diagram assistant in Virtuoso® Visualization and Analysis allows you to create eye diagrams, add masks and also calculate some standard measurements. The measurements have recently been enhanced by adding more jitter calculations, maximum eye height and width calculations, level annotations and Bit Error Rate (BER) curves. New Eye Diagram Measurements Let's walk through an example to view the new eye diagram measurements. Plot an eye diagram and choose the Eye Measurements tab. Here you can select the Eye Diagram and define the Threshold . The threshold is the Y-axis voltage level, and is generally half of the signal range. The Level 0 and Level 1 areas can be annotated by checking the Annotate check box. If you tick the Plot BER Curve option, you will get a Bit Error Rate plot showing jitter. Maximum Eye Height and Width These new measurements, highlighted in the image above, provide information about the maximum eye height and the time at which it occurs and also depicts the maximum eye width and the threshold Y value at which it occurs. I've added markers to the image below to illustrate these new measurements. Adding Eye Measurements to ADE Did you know that you can send any eye measurement back into ADE and evaluate it during the current simulation run, without opening the Eye Diagram assistant? You just need to have an ADE session associated with the Virtuoso Visualization and Analysis window. For this, simply right-click the Eye Measurement in the assistant (or multi-select and right click) and choose Send to ADE -> Generic Expression. This will create the outputs in ADE where you can also add specs to see which eye measurements pass or fail. Original Waveform Time Another recent enhancement is the addition of the original waveform time on markers on the eye diagram. It is shown in square brackets after the eye time value. You can see from this image that the X point in the square brackets above is the same as the X value below. Related Resources RAK Eye Diagram Blog Virtuoso Video Diary: Eye Masks Video Using Eye Masks User Guide Virtuoso Visualization & Analysis User Guide More about Eye Diagrams For more information on Cadence circuit design products and services, visit www.cadence.com. About Virtuosity Virtuosity has been our most viewed and admired blog series for a long time that has brought to fore some lesser known, yet very useful software and documentation improvements, and also shed light on some exciting new offerings in Virtuoso. We are now expanding the scope of this series by broadcasting the voice of different bloggers and experts, who would continue to preserve the legacy of Virtuosity , and try to give new dimensions to it by covering topics across the length and breadth of Virtuoso, and a lot more… Click Subscribe to visit the Subscription box at the top of the page in which you can submit your email address to receive notifications about our latest Virtuosity posts. Happy Reading! Arja Hunkin![]()
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