PCB High-Speed Signal Design Guidelines: Agilex™ 5 FPGAs and SoCs

ID 821801
Date 11/18/2024
Public
Document Table of Contents

5.4. DDR4 Routing Guidelines

This section describes DDR4 interfaces PCB layout guideline. Agilex™ 5 E-Series group B devices support DDR4 single rank and dual-rank for memory down configurations. Both thin and thick PCB stack-ups are supported. The following design example demonstrates a single rank x 8 memory down topology. You can adjust the design based on the actual PCB design (single rank x 8 or dual-rank x 8).

Single Rank x 8 Memory Down Topology

The single rank x 8 discrete interface covers data bytes (DQ/DQS), address signals, command signals (BA, BG, RAS, CAS, WE, ACT, PAR), control signals (CKE, CS, ODT) and CLKs.

The following figure illustrate the single rank x 8 memory down topology stripline routing for the BGA inner pins design example.

Figure 63. Signals Connections for Supported Signals in Single Rank x 8 Discrete Topology

The following figures illustrate the single rank x 8 memory down topology for microstrip routing on the outer layer for BGA edge pins.

Figure 64. Microstrip Routing on the Outer Layer for DDR4 Single Rank x 8 Memory Down Topology

The following tables show the stripline routing for BGA inner pins and microstrip routing for BGA outer pins with the single rank x 8 memory down topology.

Table 11.  Stripline Routing Guidelines for Single Rank Discrete Memory Topology
Table 12.  Microstrip Routing Guideline for Single Rank Discrete Memory Topology

Single Rank x 16 Memory Down Topology

A single channel with single rank and x 16 memory devices, this interface covers data bytes (DQ/DQS), address signals, command signals (BA, BG, RAS, CAS, WE, ACT, PAR), control signals (CKE, CS, ODT) and clocks (CLK).

The following figures illustrate the single rank x 16 memory down topology of stripline routing for BGA inner pins. You can adjust the design topology based on the actual PCB design (single rank x 16 or dual-rank x 16).

Figure 65. Stripline Routing for DDR4 Single Rank x 16 Discrete Topology

The following figures illustrate the design example of single rank x 16 memory down topology microstrip routing for BGA outer pins. You can adjust the design based on the actual PCB design (single rank or dual-rank).

Figure 66. Microstrip Routing on the Outer Layer for DDR4 Single Rank x 16 Memory Down Topology

The following tables shows the stripline routing guideline for BGA inner pins and microstrip routing for BGA outer pins with single rank memory down topology.

Table 13.  Stripline Routing Guideline for GPIO Inner Pins
Table 14.  Microstrip Routing Guideline for GPIO Edge Pins