Eye Diagram & Jitter Interactive Simulator

Signal Integrity Lab: Eye Diagram & Jitter

Interactive ISI and Timing Analysis for High-Speed Digital Links

Rise Time (ps) 40

Controls the slope of 0-1 transitions.

Channel Loss (ISI) 0.2

Simulates bandwidth limitation/cable length.

Clock Jitter (UI) 0.05

Adds Gaussian random timing noise.

Eye Height: --

Eye Width: --

CH1: 200mV/div
Time: 0.5 UI/div

Mathematical Analysis of Eye Closures

1. Intersymbol Interference (ISI)

ISI occurs when a pulse spreads in time and interferes with adjacent bits. We model the channel as a low-pass filter with an impulse response:

h(t) = (1/τ) * exp(-t/τ)

Where τ is determined by your Channel Loss setting. As loss increases, the signal cannot reach full amplitude within one Bit Period (UI), causing the eye to close vertically.

2. Jitter Components

Total Jitter (TJ) defines the horizontal closure of the eye. In this lab, we focus on Random Jitter (RJ), modeled as a Gaussian distribution:

PDF(t) = [1 / (σ√(2π))] * exp(-(t-μ)² / 2σ²)

The Clock Jitter slider adjusts σ. In real links, we aim for a Bit Error Rate (BER) of 10⁻¹², requiring an eye width of at least 0.5 UI.

Why is the Eye Diagram important?

The "Eye" represents the statistical window where a receiver can safely sample the data. If the eye is closed, the receiver cannot distinguish between a '1' and a '0', leading to data corruption. Engineers use this to optimize Equalization (CTLE/DFE) and Pre-emphasis settings.