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Back Board Design

Back Board Routing Topology


Back board routing topology included Centralized Switching,Distributed Switching,Hybrid Switching,Holst/Slave Switching.

Centralized Switching

            Centralized Switching

Distributed Switching

Distributed Switching

Hybrid Switching

Hybrid Switching

host switching

Host/Slave Switching

The Structure of Back Board


VITA standard required the dimension of back board,tooling hole position and size,direction,each solt,and case heat dissipation etc.

back pcb structure

Back Board Connector


Back Board use MULTIGIG RT connector,the pin of connector includes power, single signal,differential signal.the speed of differential is 10Gbps.

connector

Back Board stack up design


Follow the signal speed to choose material. Design PCB stack up according board thickness and impedance requirement.For example: VPX Back Board, use TU-752 material,4mm board thickness,18 Layers, Layer stack up like below:

Layer stack up

layer stack up

Layout Rule


Back board layout is BUS layout,each group trace don’t across and smooth. Highlight each BUS is better for planing.

layout

Equate length


For high speed differential trace,required trace equate length.

impedance trace

Power Design


The main power +12V,+5V,ensure current is adequate when design.

power design

power design

Anti-Pad design


For the vias of certain layer stack up,impact impedance factors includes vias size,pad size, anti-pad size, Stub length,ground vias position etc.

antipad

Standard and requirement


For example VITA68:

      Insertion Loss (IL)

      Fitted Attenuation (FA)

      Insertion Loss Deviation (ILD)

      Return Loss (RL)

      Insertion Loss to Crosstalk Ratio (ICR)

      Intra-pair skew

     Lane-lane skew

 

For example: RapidIO

rapidIO

rapid-2

rapdi-3

rapid-4

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