FreeLists / si-list / [SI-LIST] Re: Stimulus Patterns

[Scott McMorrow <scott@xxxxxxxxxxxxx>]

Nikhil,

The length of the PRBS used depends on what you're trying to do.  If 
you're simulating a serial channel, you would use a PRBS that has a 
maximum run length that is as large or 1 bit larger than the worst case 
pattern run length in the channel.  For 8B10B encoding, the maximum run 
length is 5 bits, so a PRBS7 would be adequate for simulation purposes.

If you are concerned with pattern dependent ISI, then you'll need a 
pattern that is long enough to just encompass the channel memory time. 
Channel memory time is the time that it takes for a channel to return to 
it's quiescent state after a unit impulse excitation, or a unit step 
excitation. It is the amount of time in bits, that it takes for all 
ringing to dampen and die off.  I would usually use a PRBS pattern that 
is 1 bit longer than the expected channel memory time, just to be sure.

regards,

Scott

Scott McMorrow
Teraspeed Consulting Group LLC
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(401) 284-1827 Business
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npatel@xxxxxxxxxx wrote:
> Hello all,
>
> I wanted to know if there is a way to determine what stimulus pattern
> and length would be adequate to use in SI simulations. For example 32
> bit PRBS, 24 bit PRBS etc.
>
> How does one find out which stimulus will cover all scenarios.
>
> Thanks,
> Nikhil =20
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