[SI-LIST] Re: DDR simulation

Dear Zhangkun,

It looks like you are daisy chaining the loads.
The "bad" signal you see at the first load is
very typical of daisy chain xmission lines.

Best Regards
Charles Grasso
Senior Compliance Engineer
Echostar Communications Corp.
Tel:  303-706-5467
Fax: 303-799-6222
Cell: 303-204-2974
Pager/Short Message:  3032042974@xxxxxxxx
Email: charles.grasso@xxxxxxxxxxxx;  
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of steve weir
Sent: Saturday, February 26, 2005 3:16 AM
To: zhang_kun@xxxxxxxxxx; si-list
Subject: [SI-LIST] Re: DDR simulation


Zhangkun, did you forget the series damping resistors?
Steve.
At 01:58 PM 2/26/2005 +0800, Zhangkun wrote:

>Dear all
>I am simulating about DDR. The topology is following:
>
>                            (800mil) 
>Driver==================================================r_pull
>            (4000mil)      |       |      |      |
>                           |       |      |      |
>                          load    load   load   load
>
>The simulaiton result shows that the waveform at the first load is very
>bad. How to improve it? The DDR is of 400MHz. The stub at near load is 
>only 100mil.
>
>Best Regards
>
>Zhangkun
>2005.2.26
>
>
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