Work out eye diagram margin instantly with clear inputs, formula shown and shareable results.
The unit interval at 25 Gbit/s is 40 ps, so 12 ps of total jitter consumes 30% of the eye horizontally. Vertical margin is amplitude minus twice the noise, since noise closes the eye from both rails. Both margins must remain open at the target bit error rate.
Eye margin
UI = 1 / bit rate; horizontal margin = (UI - total jitter) / UI; vertical = (amplitude - 2 x noise) / amplitude
Because total jitter is the peak-to-peak spread at the target BER, and it closes the eye from both edges within a single unit interval.
Standards typically require 0.3-0.5 UI of horizontal opening and tens of millivolts vertically at the receiver after equalisation.