[Arm-netbook] Multiple PCB designs

[Bari Ari]

On 01/11/2012 08:12 AM, jonsmirl at gmail.com wrote:
> Have you considered multiple PCB designs? The high speed core part of
> the layout would be identical on all of them. Just change the
> peripherals around. Doing it that way eliminates the need for getting
> all of the extra signals out on the EOMA board.
>
> 1) EOMA
> 2) HDMI stick (put a wifi module on it that already has FCC approval,
> USB for power)
> 3) VGA out
> 4) Component HD or SD TV out
> 5) Dev board with everything accessible
> 6) SODIMM
> 7) HDMI MDL
>
> This project does not need to pass UL or FCC radiator so there is no
> large regulatory cost associated with multiple designs. You still get
> volume component pricing since all PCBs will use the same core
> components.
>
> I suspect #2 would be the top seller.
>
Sure we can.

I also want to point out that the DDR3 layout is not that scary and 
complicated. Traditionally PCB layout has been handed off to technical 
people with the skillsets of draftsmen vs RF engineers. This is why 
projects have problems with high speed PCB layout. They expect to just 
layout traces based on a few settings in the autorouter or follow a 
limited number of design rules such as stick to 6 mil trace and space 
with 10 mil vias with whatever stackup for the via was found in the CAD 
library. They don't treat the PCB layout as part of the circuit so why 
would they expect it to work reliably? They get away with this design 
philosophy with lower speed designs under a narrow range of operating 
conditions. This approach however falls short when the traces themselves 
become a critical component of the circuit at very high speeds.

-Bari