Back Board Routing Topology
Back board routing topology included Centralized Switching,Distributed Switching,Hybrid Switching,Holst/Slave Switching.
Centralized Switching
Distributed Switching
Hybrid 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 Board Connector
Back Board use MULTIGIG RT connector,the pin of connector includes power, single signal,differential signal.the speed of differential is 10Gbps.
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:
Layout Rule
Back board layout is BUS layout,each group trace don’t across and smooth. Highlight each BUS is better for planing.
Equate length
For high speed differential trace,required trace equate length.
Power Design
The main power +12V,+5V,ensure current is adequate when 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.
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
