[SI-LIST] Re: Memory bus datapattern
- From: <npatel@xxxxxxxxxx>
- To: <homer.si.mpson66@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 24 Apr 2007 10:15:37 -0600
For Crosstalk using a PRBS pattern on the aggressor will give you ISI
only. Using a clock pattern - 1010 on the aggressor and a PRBS pattern
on the victim will give you crosstalk only and no ISI. I normally use a
32 bit PRBS pattern on the aggressor and a different PRBS pattern on the
vitim. This takes into account both crosstalk and ISI. The PRBS pattern
can be identified by taking the settling time / bit time and no of bits
ideally is N * 2^N. =20
Nikhil
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Peter Johansson
Sent: Tuesday, April 24, 2007 9:52 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Memory bus datapattern
Hi everybody,
I have a problem with how to define a reasonable worst case datapattern
on a DDR data bus to calculate crosstalk and SSN on the power supply.
Should I assume that all 32 bits start in a low/high state and change
simultaneously or is there a better choice?
I mean, all bits will not change at the same time, which means that I
will design towards a worst worst case instead of a real worst case.
Have someone made some statistical analysis of how many bits are
high/low and how many will change state every cycle?
Any ideas?
BR
Peter
PS I'm a Homer fan if someone wonders
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=20
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