Designer’s Notebook

Non-planar designs and side-mounted components are next up for 3-D printing.

Read more: Next-Generation Additive Manufacturing

Lance WangHow to calculate trace length from time delay value for high-speed signals.

To keep a good high-speed signal quality from driver to receiver on a PCB is not an easy task for designers. One of the most challenging issues is managing the propagation delay and relative time delay mismatches. To manage the time delays, we need to know how to calculate trace length from time delay value in order to implement the PCB trace routing accordingly. Let me take you through the process.

Calculating signal speed. According to physics, electromagnetic signals travel in a vacuum or through the air at the same speed as light, which is:

Vc = 3 x 108M/sec = 186,000 miles/sec = 11.8 in/ns

Read more: Managing Time Delays

What to do when the trace doesn’t act as an “ideal” connection.

Read more: The Physics of Transmission Lines

A mismatch in trace symmetry can cause noise coupling or timing issues.

Read more: Signal Integrity Design Fundamentals

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