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

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ID 821801
Date 11/18/2024
Public
Document Table of Contents
Document Table of Contents x
1. Introduction 2. Overview of Agilex™ 5 Package 3. VPBGA PCB Layout Guideline 4. MBGA PCB Routing Guidelines 5. EMIF PCB Routing Guidelines (VPBGA and MBGA) 6. MIPI Interface Layout Design Guidelines (VPBGA and MBGA) 7. True Differential I/O Interface PCB Routing Guidelines (VPBGA and MBGA) 8. Power Distribution Network Design Guidelines 9. Document Revision History for the PCB High-Speed Signal Design Guidelines: Agilex™ 5 FPGAs and SoCs
2. Overview of Agilex™ 5 Package x
2.1. BGA Footprint and Land Pattern
3. VPBGA PCB Layout Guideline x
3.1. Overview of VPBGA 3.2. VPBGA HSSI Reference PCB Stack-up 3.3. General Design Considerations 3.4. Agilex™ 5 GTS Transceiver 3.5. GTS Transceiver PCIe* Gen4 16 GT/s NRZ Interface Design Guidelines 3.6. GTS Transceiver Ethernet 25 Gbps NRZ Interface Design Guidelines 3.7. Other Connectors
3.3. General Design Considerations x
3.3.1. Impedance Tolerances 3.3.2. Reference Planes 3.3.3. Layer Assignment 3.3.4. Via Drill Size 3.3.5. Fiber Weave 3.3.6. PCB Traces 3.3.7. PCB Vias 3.3.8. AC Coupling Capacitors 3.3.9. Others
3.4. Agilex™ 5 GTS Transceiver x
3.4.1. HSSI Pin-Field Breakout for VPBGA
3.5. GTS Transceiver PCIe* Gen4 16 GT/s NRZ Interface Design Guidelines x
3.5.1. GTS Transceiver Channel Recommendations 3.5.2. General Guidelines for GTS Transceiver PCIe* Gen4 Interface 3.5.3. PCIe* Add-in Card Edge Finger
3.6. GTS Transceiver Ethernet 25 Gbps NRZ Interface Design Guidelines x
3.6.1. GTS Transceiver Channel Recommendations 3.6.2. General Guidelines for GTS Transceiver Ethernet Interface 3.6.3. QSFP Connector Routing 3.6.4. SFP Connector Routing
3.7. Other Connectors x
3.7.1. ADM/F Connectors 3.7.2. DP and HDMI Connectors 3.7.3. FMC+ Connectors
5. EMIF PCB Routing Guidelines (VPBGA and MBGA) x
5.1. General DDR Signal Routing Guideline on PCB 5.2. LPDDR5 Interface Design Guidelines 5.3. LPDDR4 Interface Design Guidelines 5.4. DDR4 Routing Guidelines 5.5. LPDDR5, LPDDR4 and DDR4 Simulation Strategy
5.4. DDR4 Routing Guidelines x
5.4.1. VREF_CA/RESET Signal Routing Guidelines for Memory Down Topologies 5.4.2. Skew Matching Guidelines for DDR4 Memory Down Configurations 5.4.3. Power Delivery Recommendation for DDR4 Discrete Configurations
8. Power Distribution Network Design Guidelines x
8.1. Agilex™ 5 Power Distribution Network Design Guidelines Overview 8.2. Power Delivery Overview 8.3. Board Power Delivery Network Recommendations 8.4. Board LC Recommended Filters for Noise Reduction in Combined Power Delivery Rails 8.5. PCB PDN Design Guideline for Unused GTS Transceiver 8.6. PCB Voltage Regulator Recommendation for PCB Power Rails 8.7. Board Power Delivery Network Simulations 8.8. Agilex™ 5 Device Family PDN Design Summary
8.1. Agilex™ 5 Power Distribution Network Design Guidelines Overview x
8.1.1. Device Guidelines Status for Agilex™ 5 Devices
8.2. Power Delivery Overview x
8.2.1. Power Architecture 8.2.2. Rail Merger Requirements 8.2.3. Power Rails Specification 8.2.4. Decoupling Capacitors Recommendation
8.2.1. Power Architecture x
8.2.1.1. Power Budget 8.2.1.2. Power Tree
8.2.1.2. Power Tree x
8.2.1.2.1. Recommended Power Tree for the Agilex™ 5 E-Series and D-Series Devices with SmartVID and GTS Transceiver in the Device Packages 8.2.1.2.2. Recommended Power Tree for the Agilex™ 5 E-Series and D-Series Devices with Non-SmartVID and GTS Transceiver in the Device Packages
8.2.3. Power Rails Specification x
8.2.3.1. Power Nets 8.2.3.2. Power Rails Tolerance 8.2.3.3. Power Nets and Transient Specifications
8.2.3.1. Power Nets x
8.2.3.1.1. Agilex™ 5 Package Power Nets and Subsystems Details
8.2.4. Decoupling Capacitors Recommendation x
8.2.4.1. Agilex™ 5 FPGA Packages Board-Level Decoupling Capacitors Summary 8.2.4.2. Agilex™ 5 GTS Transceiver Board-Level Decoupling Capacitors Summary
8.3. Board Power Delivery Network Recommendations x
8.3.1. Board Decoupling Capacitors Guide 8.3.2. FPGA Core Fabric VCC Voltage Regulator Selection 8.3.3. Remote Sense Connections 8.3.4. Load Line Requirements 8.3.5. VCC Core Board Current Slew Rate
8.4. Board LC Recommended Filters for Noise Reduction in Combined Power Delivery Rails x
8.4.1. GTS Transceiver Rail Board Connection and LC Filter Recommendation under Noisy Voltage Regulator
8.5. PCB PDN Design Guideline for Unused GTS Transceiver x
8.5.1. PDN Design Guideline for Unused GTS Transceiver
1. Introduction
2. Overview of Agilex™ 5 Package
3. VPBGA PCB Layout Guideline
4. MBGA PCB Routing Guidelines
5. EMIF PCB Routing Guidelines (VPBGA and MBGA)
6. MIPI Interface Layout Design Guidelines (VPBGA and MBGA)
7. True Differential I/O Interface PCB Routing Guidelines (VPBGA and MBGA)
8. Power Distribution Network Design Guidelines
9. Document Revision History for the PCB High-Speed Signal Design Guidelines: Agilex™ 5 FPGAs and SoCs

5.3. LPDDR4 Interface Design Guidelines

This section describes LPDDR4 interfaces PCB layout guideline. Agilex™ 5 E-Series group B devices support LPDDR4 interfaces for memory down configuration only. Both thin and thick PCB stack-ups are supported.

LPDDR4 Memory Down Topology (up to 32 bits interface)

LPDDR4 memory down supports single rank and dual-rank configurations up to 32 bits. There are four DRAM interface signal groupings, namely: data group, command-address group, control group, and clock group. The connection between the FPGA and DRAM device uses point-to-point topology as depicted in the following two figures.

The following figure illustrates the stripline routing for inner pins.

Figure 59. Stripline Routing for Data, CA, CTRL and Clock Signals Point-to-Point Topology

The following figure illustrates the Reset signal routing topology, recommend using 1.0K Ohm pull-down resistor for Reset signal termination.

Figure 60. Stripline Routing for Reset Signals

The following figure illustrates the microstrip routing for the edge pins of BGA per byte.

Figure 61. Microstrip Routing on the Outer Layer for Data Signals Point-to-Point Topology

The following figure shows the daisy-chain and T-Line connections topology for CA, CLK, CTRL signals for LPDDR4.

Figure 62. Stripline Routing for CA, CLK, CTRL Daisy-chain and T-Line Topology

The following tables provide comprehensive routing guidelines for each of the LPDDR4 signals based on memory down topology, such as the trace impedance, the total trace length, and the maximum main segment trace length that can be derived by subtracting the break-out segment and break-in segment trace length from the total trace length.

Table 8.  Stripline Routing Guide for LPDDR4 Memory Down Topology
Table 9.  Microstrip Routing Guide for LPDDR4 Memory Down Topology

Reset signal routing design also follows the CMD/ADD/CTRL routing design. Keep the space at least 3xh between the Reset signal to other signals on the same layer (measured edge to edge).

Skew matching for LPDDR4 interfaces consists of both package routing skew and PCB physical routing skew. Use 3 time of dielectric height (h) for serpentine routing spacing. Skew matching of CA and CTRL with respect to the clock signals to ensure signals at the receiver are correctly sampled. In addition, there are skew matching requirement for DQ and DQS within a byte group, DQS and CLK. The following table provides a detailed skew matching guideline.

Table 10.  Skew Matching Requirement for LPDDR4 Memory Down Topology

LPDDR4 eye margin is sensitive to crosstalk, especially when the signals are routed on deep layers. Note the deep-layer vertical transition induces more vertical coupling and crosstalk between signals. You can run simulation to determine the routing layer and whether to use backdrilling or not.

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