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Differential-Pair Skew & Length-Match Planner

Calculate propagation delay and length matching for high-speed differential pairs

Inputs

FR-4 typically 4.0-4.5

Typical: 10% for general use

Results

How it works

Effective εr (microstrip): εeff = 0.64·εr + 0.36

Propagation velocity: v = c / √εeff

Propagation delay: tpd = 1 / v

Unit Interval: UI = 1 / data_rate

Skew budget: Δt = fraction × UI

Length mismatch: ΔL = Δt / tpd

Based on typical FR-4 properties and industry guidelines for high-speed differential signaling.