The PCB signal layers should follow typical good practice guidelines including:
- Layer changes should be minimized for single-ended signals.
- Individual differential pairs can be routed on different layers, but the signals of a given pair should not change layers.
- Stubs should be avoided.
- Low-frequency signals should be routed on the outer layers.
- Differential pair signals should be routed first.
- Pin swapping on components is not allowed.
- Polarized capacitors should have the same orientation.
The PCB should have a solder mask on the top and bottom layers.
- The mask should not cover the vias.
- Except for fine pitch devices (pitch ≤ 0.032 inches). The copper pads and the solder mask cutout should be of the same size.
- Solder mask between pads of fine pitch devices should be removed.
- In the BGA package, the copper pads and the solder mask cutout should be of the same size.
High-speed connectors that meet the following requirements should be used:
- Differential crosstalk: < 5%
- Differential impedance: 90 to 110 Ω for all LVDS signal pairs
Routing requirements for right-angle connectors:
- When using right-angle connectors, LVDS signal P-N pairs should be routed in the same row to minimize delay mismatch.
- When using right-angle connectors, propagation delay difference for each row should be accounted for on associated PCB etch lengths.