Impedance Matching Test Board

My personal goal for this project was to learn how to use Altium EDA to design a Printed Circuit Board (PCB) whose traces are Impedance matched. This project was originally created as part of a class project, but I extended the scope of the project by designing the board using Altium’s Impedance Profile Tool. The purpose of the project was to route two differential pair wires on a 6 Layer PCB. The two differential pair wires would go between two different signal layers. Another goal of the project was to test the PCB differential wires using HyperLynx SI/PI.

The following were the major constraints of the project:
  • Must follow the OSHPark 6 Layer PCB Manufacturing Guidelines
  • Differential Traces must be Impedance Matched to 100 Ω (50 Ω Single Ended)
  • The differential pair wires must have 4 Vias per individual wire
  • The total wire length for each differential pair wire must be 6 inches
  • Maximum undershoot and overshoot of 140 mV

Pictured below in Figure 1 is the PCB. The two differential pairs were intentionally designed to be perpendicular to prevent any electromagnetic interference between the two pairs.
Impedance Board
Figure 1: PCB Layout
Pictured below in Figure 2 is the Altium Impedance Profile. The profile was manually created around the OSHPark guidelines.
Impedance Profile
Figure 2: Altium Impedance Profile
Pictured below in Figure 3 is the Altium Via Profile.
Via Profile
Figure 3: Altium Via Profile
The following design considerations were taken into account.
  • Perpendicular signal wires across layers to minimize crosstalk
  • Curved signal turns instead of 90 degree signal turns
  • Use of ground planes to mitigate EMI.
Figures 4 and 5 show the 2-D Electromagnetic Fields.
Layer 3 Field
Figure 4: Layer 3 Electromagnetic Field
Layer 5 Field
Figure 5: Layer 5 Electromagnetic Field


The following slides were used as the submission for the class project. The slides detail the design choices from the PCB and explain the HyperLynx simulation results.