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unstable high speed board

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taring77

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hyperlynx si megaupload

Hi all,
i would seek advise on routing of high speed board.
My board have 8 layers one MCU --MC9328MX21VM, MAPBGA-289.. 2 SDRAM and 1 flash..plus other components

After changing a flash component on my board, it seems that the whole board is unstable. My engineer suspects (issit true??) its the 31 data lines and 25 address pins. So anyone know in what way will routing help to stablize the board...any references?

Thanks all
 

abhi002

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Hi taring,

You should use any post simulation software for Si analysis of all address and data nets.

There are no of ways for high speed routing
- you should route all critical nets in stripline layers.
- avoid 90 degree turns
- use shielding for high frequency nets.

these are few thumb rules.Other than you can refer book -- High Speed Digital Design (Johnson & Graham.

Hope it helps!!!
 

taring77

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may i know where can i get the book?
 

abhi002

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you can find this book in this forum itself.

link is as follows


if you face any problem ,let us know
 

taring77

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hi,
the topic was said to be removed thus i couldn't get the book any other way to get the book?

thanks
 

abhi002

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topic is there.I tried the same ,its working

try once more ,otherwise give ur mail id i will mail u.

try once more with the following link
 

melc

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taring77 said:
Hi all,
i would seek advise on routing of high speed board.
My board have 8 layers one MCU --MC9328MX21VM, MAPBGA-289.. 2 SDRAM and 1 flash..plus other components

How looks your layer stack and how exactly did you route data and address bus (on which layers) ?

After changing a flash component on my board, it seems that the whole board is unstable. My engineer suspects (issit true??) its the 31 data lines and 25 address pins. So anyone know in what way will routing help to stablize the board...any references?

Thanks all
 

taring77

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hi abhi002 ....
i've sucessfuly downloaded the 3 parts of the book but each time i unzip error occurs do you know y?
 

nathan80

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well,what speed are you talking about when you mentioned high speed?

previously i was experiencing some problems with my board; expecially with the high speed traces in particular. i was experiencing some crosstalk and unwanted noise at the output of my boards(my board was designed for 3.125gbps).

i have no experience in SI analysis. therefore i did not know how to use hyperlynx or ADS to model by board before redesign. however, i tried using a software called appcad.

you can download from this link: h**p://www.hp.woodshot.com/. it is a freeware.

you can key in the board material (ex. FR4 etc), layer thickness and other information to get correct trace length for matching impedance for desired speed.
i managed to get a desired output eye at my high speed traces after changing my design parameters according to simulation using appcad.
also remember to follow other basic high speed design rules as mentioned by abhi002
 

buenos

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whole board?
maybe the power planes are resonating. but with an IMX21 processor, i dont think so.
check with siwave, or with speedXP.
 

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