1. What is PCB Trace Propagation Delay?

PCB trace propagation delay (t_pd) is the time it takes for a signal to travel from one point to another through a PCB trace. It depends on the trace length and the distributed inductance and capacitance of the trace.

2. How Does the Calculator Work?

The calculator uses the propagation delay equation:

Where:

• \( t_{pd} \) — Propagation delay (seconds)
• \( length \) — Trace length (meters)
• \( L_c \) — Inductance per unit area (H·F/m²)

Explanation: The equation shows that propagation delay increases linearly with trace length and with the square root of the inductance-capacitance product.

3. Importance of Propagation Delay Calculation

Details: Accurate propagation delay calculation is crucial for high-speed PCB design, signal integrity analysis, and timing synchronization in digital circuits.

4. Using the Calculator

Tips: Enter trace length in meters and inductance per unit area in H·F/m². All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical propagation delay for PCB traces?
A: Typical values range from 50-180 ps/inch (1.97-7.09 ns/m) depending on the dielectric material.

Q2: How does dielectric constant affect propagation delay?
A: Higher dielectric constants increase capacitance, which increases propagation delay.

Q3: Why is propagation delay important in PCB design?
A: It affects signal timing, especially in high-speed designs where synchronization is critical.

Q4: Can propagation delay be reduced?
A: Yes, by using shorter traces, materials with lower dielectric constants, or controlled impedance designs.

Q5: How does this relate to signal speed?
A: The reciprocal of propagation delay gives the signal speed through the trace.