PCB Design Guidelines (HSSI, EMIF, MIPI, True Differential, PDN) User Guide: Agilex™ 5 FPGAs and SoCs

ID 821801
Date 8/29/2025
Public
Document Table of Contents

6.5.2. Single Rank ×16 Memory Down Topology

Single Rank ×16 Memory Down Topology

A single channel with single rank and ×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).

Figure 67. Stripline Routing for DDR4 Single Rank ×16 Discrete TopologyThis figure illustrates the single rank ×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 ×16 or dual-rank ×16)
Figure 68. Microstrip Routing on the Outer Layer for DDR4 Single Rank ×16 Memory Down TopologyThis figure illustrate the design example of single rank ×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).
Table 13.  Stripline Routing Guideline for GPIO Inner PinsThis table shows the stripline routing guideline for BGA inner pins and microstrip routing for BGA outer pins with single rank memory down topology. In this table, h represents the trace-to-nearest-reference-plane height or distance. SL stands for stripline routing recommendation and US stands for upper surface (microstrip) routing recommendation.
Signal Group Segment Routing Layer Maximum Length (mil) Target Zse (Ω) Trace Spacing S1 (mil): Within Group Trace Spacing S2 (mil): CMD/CTRL/CLK to DQ/DQS Trace Spacing S3 (mil), DQ Nibble to Nibble Trace Spacing (mil), Within DIFF pair Trace Spacing (mil), DQS pair to DQ Trace Spacing (mil), CLK pair to CMD/CTRL/CKE Rtt/Ctt
Segment Total MB
CLK BO1 US 50 To first DRAM: 4000

To last DRAM: 6800

  3 3h   4   3h

R1=36 Ω

C1=10 nF

BO2 SL 1000   3 3h   4   3h
M SL   40   3h   4   3h
BI1 US 50     3h   4   3h
BI2 SL 700 50+   3h   4   3h
T1 SL 300     3h   4   3h
T2 US 50     3h   4   3h
CMD/CTRL/Alert BO1 US 50 To first DRAM: 4000

To last DRAM: 6800

  3 3h         R1=36 Ω
BO2 SL 1000   3 3h        
M SL   40 2h 3h        
BI1 US 50   2h 3h        
BI2 SL 700 50+ 2h 3h        
T1 SL 300   2h 3h        
T2 US 50   2h 3h        
DQ BO1 US 50 5000   3   3h        
BO2 SL 1000   3   3h      
M SL   45 2h   3h      
BI US 50   2h   3h      
DQS BO1 US 50 5000         4 3  
BO2 SL 1000         4 3  
M SL   45       4 3h  
BI US 50         4 3h  
Table 14.  Microstrip Routing Guideline for GPIO Edge PinsIn this table, h represents the trace-to-nearest-reference-plane height or distance. SL stands for stripline routing recommendation and US stands for upper surface (microstrip) routing recommendation.
Signal Group Segment Routing Layer Maximum Length (mil) Target Zse (Ω) Trace Spacing S1 (mil): Within Group Trace Spacing S3 (mil): DQ Nibble to Nibble Trace Spacing (mil), Within DIFF pair Trace Spacing (mil), DQS pair to DQ
Segment Total MB
DQ BO US 100 3000  

MBGA package: 3

VPBGA package: 4

     
M US   45 3h 3h    
BI US 300   4      
DQS BO US 50 3000      

MBGA package: 3

VPBGA package: 4

MBGA package: 3

VPBGA package: 4

M US   45     4 4h
BI US 300       4 4