[SI-LIST] Re: Bit pattern for high speed serial link simulation
- From: "Ken Willis" <kwillis@xxxxxxxxxxx>
- To: <perry.qu@xxxxxxxxxxx>, "steve weir" <weirsi@xxxxxxxxxx>, "si-list" <si-list@xxxxxxxxxxxxx>
- Date: Wed, 30 Nov 2005 10:05:41 -0500
Hi Perry,
We also had trouble coming up with that golden worst case data pattern.
It is very channel-specific, hence the high-capacity channel simulation
approach. In the cases we looked at, it showed the "worst case" approach
to actually be optimistic. So you can run huge bit streams this way and
build the encoding in automatically, without dictating the specific
driver
and receiver model language your suppliers have to use.
If you have questions, please contact me off-line.
Ken
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Perry Qu
Sent: Monday, November 28, 2005 5:00 PM
To: 'steve weir'; 'si-list'
Subject: [SI-LIST] Re: Bit pattern for high speed serial link simulation
Steve:
Thanks for the suggestion. This is through encoder. I'm running a PRBS15
pattern simulation right now (already a week) and I do noticed closure
of eye mask due to the pattern. May try an even longer pattern but the
simulation in hspice is just too slow. Will probably look into Allegro
PCB SI channel analysis tool.
Regards
Perry
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Perry Qu=20
Design & Qualification, Alcatel Canada=20
600 March Road, Ottawa ON, K2K 2E6=20
DID: 613-7846720 Fax: 613-5993642=20
Email: perry.qu@xxxxxxxxxxx=20
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-----Original Message-----
From: steve weir [mailto:weirsi@xxxxxxxxxx]
Sent: Monday, November 28, 2005 4:26 PM
To: Perry.Qu@xxxxxxxxxxx; si-list
Subject: Re: [SI-LIST] Bit pattern for high speed serial link simulation
Perry, if you are bypassing the encoder/decoder, then PRBS7 generates
sufficient run-length. If you are driving the encoder, you want a run
length > 15, so PRBS21 or PRBS31 would be a better choice.
Steve.
At 03:21 PM 11/28/2005 -0500, Perry Qu wrote:
>Hi,
>
>What will be a realistic bit pattern to use for simulation of a serial=20
>link
>(3Gbps) with 8B/10B encoding ? Right now I used PRBS7 pattern but I'm=20
>not sure whether it captured the worst case pattern compared to=20
>reality, where the live data traffic is a lot more random. 8B/10B has a
>run length of 5 but if it's fed with say a PRBS31 bit stream, will I=20
>get more spectrum peaks than just a pure PRBS7 pattern without encoding
>which repeat itself every
>127 bits ?
>
>Thanks
>
>Perry
>
>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
>Perry Qu
>
>Design & Qualification, Alcatel Canada
>
>600 March Road, Ottawa ON, K2K 2E6
>
>DID: 613-7846720 Fax: 613-5993642
>
>Email: perry.qu@xxxxxxxxxxx
>
>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
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>
>
>
>
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