RTL8366/8369 & RTL8212
Layout Guide
RTL8366/8369 & RTL8212 Layout Guide
6
Track ID: JATR-1076-21 Rev. 1.1
3.
RSGMII PCB Layout Guidelines
As the RSGMII transmits over 2.5GHz differential signal pairs, the PCB layout needs some attention in
order to meet layout guidelines. The following lists some important guidelines for layout of the RSGMII
in a 4-layer PCB.
•
Differential impedance is 100
Ω±
10% and single-ended impedance is 60
Ω±
6%.
•
All micro-strip traces of a differential pair should be 5-mil-wide with 7-mil-wide air-gap spacing
between the traces of the pair.
•
Spacing to all non-Serdes signals should be at least 30-mil in order to avoid harmful coupling
issues.
•
Trace routes over long distances should be routed at an off-angle to the X-Y axis of a PCB layer
to distribute the effects of fiberglass bundle weaves and resin-rich areas of the dielectric. See
Figure 1 for an illustration of diagonal routing.
Resin-rich Areas
of Dielectric
Fiberglass Bundles
of Dielectric
Preferred Differential
Pair Routing for
Long Lengths
Avoid this Type of
Routing for Long
Lengths
Figure 1. Long Trace Layout for RSGMII
