Propagation Delay & Length Matching
Compare routing delay on two layers and convert a skew budget to allowable trace mismatch.
Live results
| Measurement | Result |
|---|
Formula and worked example
Method. Path delay = sum of length × propagation delay per unit length. For a supplied effective dielectric constant, delay = 1000 × √εeff / 299.792458 ps/mm. Allowable mismatch on a layer = skew budget ÷ that layer’s delay rate.
Assumptions. Use effective permittivity for the routed cross section, or measured layer delay. Each mismatch result allocates the full budget to one layer. Add via, package and connector delay separately.
Example. At 6 ps/mm, 100 mm and 102 mm produce 600 ps and 612 ps. A 30 ps budget allows 5 mm (196.85 mil) on that layer.