Designing SerDes Applications for Intel® GbE Controllers
Designing SERDES Applications--82545/82546, 82571/82572 & 631xESB/632xES
The goal of this document is to enable customers to construct a board layout design using the Serializer-Deserializer (SERDES) interface on Intel Gigabit Ethernet (GbE) controllers. A typical application using the SERDES interface is a GbE fiber design where the electrical interface connects to an optical module. However, another possible application would use the SERDES interface to drive and receive electrical signals over a backplane for board-to-board communication such as in modular servers. The benefit of using the internal SERDES for a backplane is that it reduces the cost, power, and board-size real estate of a design since neither optical module with associated fiber connectors nor copper PHY-related components, such as magnetics and cable connectors, are required. Instead, the electrical signals are sent from the internal SERDES to traces that go to a backplane connection, then over a backplane and another backplane connector to the SERDES-capable link partner for communication.
The use of SERDES is called out in many industry specifications. For example:
• IEEE 802.3z: Gigabit for fiber
• 1000BaseCX: Gigabit over 30 meters of 75 Ω coax cable
• PICMG 3.1: Gigabit over 100 Ω differential backplane
This document was created for use in aiding the design of modular servers or embedded designs that are based on GbE as the protocol for onboard and board-to-board communications. Additionally, it is anticipated that many designs will require compliance with the PICMG 3.1 specification. However, since different Local Area Network (LAN) devices with a SERDES interface might use different DC-biasing and have different signaling voltage levels, there is no single SERDES-SERDES circuit that allows the LAN to work properly with every different possible pair of LAN components. This document is intended to provide basic circuit information; design considerations and testing for PICMG 3.1 compliance that should help a designer overcome many of these issues.
Read the full Designing SerDes Applications for Intel® GbE Controllers Note.