High-speed signal routing basics in PCB Design - Cell-by-Cell Formula Trace

Sample Data

This data shows trace lengths in millimeters and signal speed in meters per nanosecond for high-speed PCB signal routing. The goal is to calculate the propagation delay in nanoseconds.

Cell	Value
A1	Trace Length (mm)
B1	Signal Speed (m/ns)
C1	Propagation Delay (ns)
A2	100
B2	0.15
A3	150
B3	0.15
A4	200
B4	0.15

Formula Trace

=A2/1000/B2

Step 1: A2 = 100

Step 2: Convert 100 mm to meters: 100 / 1000

Step 3: Signal speed B2 = 0.15 m/ns

Step 4: Calculate propagation delay: 0.1 / 0.15

Cell Reference Map

    A       B       C
1 |Trace Length|Signal Speed|Propagation Delay
2 |   100     |   0.15    |  =A2/1000/B2
3 |   150     |   0.15    |
4 |   200     |   0.15    |

The formula in C2 uses A2 for trace length and B2 for signal speed to calculate propagation delay.

Result

    A       B       C
1 |Trace Length|Signal Speed|Propagation Delay
2 |   100     |   0.15    |  0.6667
3 |   150     |   0.15    |  1.0000
4 |   200     |   0.15    |  1.3333

Propagation delay is shown in column C, calculated by dividing trace length (converted to meters) by signal speed.

Sheet Trace Quiz - 3 Questions

What does the formula =A2/1000/B2 calculate?

A Trace length in meters

B Signal speed in meters per nanosecond

C Propagation delay in nanoseconds

D Trace length in millimeters

Key Result

Propagation delay = (Trace length in meters) / (Signal speed in meters per nanosecond)