[SI-LIST] Re: In Most of the DDR 3 design there are used Daisy chain routing forAddress bus. Why?

The answer is pretty simple , daisy chain takes advantage of flyby routing , 
meaning the end of the chain is terminated in a 50 ohm pullup to voltage , thus 
minimizing reflection , where as star routing presents an impedance mismatch . 
Also daisy chain is easier to route.

Justin Tabatchnick
Intel

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
Behalf Of Lee Ritchey
Sent: Thursday, September 17, 2009 9:36 AM
To: Prakash Mohanraj, TLS-Chennai; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: In Most of the DDR 3 design there are used Daisy chain 
routing forAddress bus. Why?

Prakash,

If you simulate these two topologies in any good SI tool you will see the
difference in waveform quality vs degree of difficulty in routing the
traces.


> [Original Message]
> From: Prakash Mohanraj, TLS-Chennai <mprakash@xxxxxx>
> To: si-list@xxxxxxxxxxxxx <si-list@xxxxxxxxxxxxx>
> Date: 9/17/2009 10:32:32 AM
> Subject: [SI-LIST] In Most of the DDR 3 design there are used Daisy chain
routing forAddress bus. Why?
>
> Hi ,
>           In Most of the DDR 3 design there are used Daisy chain routing
for Address bus. Why?
>           Is there any advantage between Star topology and Daisy chain
topology?
>
> Thanks & Regards,
> Prakash
>
>
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