The following figures describe the formation of an eye diagram. Figures 1 through 5 show some of the transitions that can occur during a time interval. The four patterns in Figures 1 through 4 are superimposed to create the eye diagram shown in Figure 5.
| Figure 1. Transition Pattern 011 | Figure 2. Transition Pattern 001 |
 |
 |
| Figure 3. Transition Pattern 100 | Figure 4. Transition Pattern 110 |
 |
 |
The following information can be obtained from an eye diagram:
Jitter: Jitter is a measure of signal quality and is defined as the measure of variance in signal characteristics. A zero jitter measurement indicates that the signal transition occurs at exactly the same point in time for each transition. The wide superimposed transitions in the eye pattern diagram is the result of high jitter associated with the signals, implying that the signals are not consistently transitioning at the required time. Small eye width implies a large variance in signal transition time.
Voltage Swing: The voltage swing has to be above the required LVDS voltage specification. The minimum specified voltage swing for LVDS is 250 mV, and the maximum is 450 mV. The signals in the eye diagram have to "swing" between these levels for the transitions to be valid.
Transition Time: Transition time is the rise and fall time that is associated with the signals. Transition times can be measured using the slope of the transitioning signals in the eye diagram. A 90 degree slope implies a rise and fall time of 0 ns. In reality, however, there is a certain transition time associated with rising and falling signals. The closer the slope is to 90 degrees, the smaller the transition time. A smaller transition time indicates that the signal is valid for a longer time at the next time period.
