[SI-LIST] Re: Altera's PDN Design tool - what changed?
- From: steve weir <weirsi@xxxxxxxxxx>
- To: "Peterson, James F (EHCOE)" <james.f.peterson@xxxxxxxxxxxxx>
- Date: Mon, 12 Apr 2010 13:32:39 -0700
Jim, I am glad to hear that it all worked out for you.
Best Regards,
Steve.
Peterson, James F (EHCOE) wrote:
> Steve,
> Thanks for the follow-up. By fail I meant that we no longer meet our
> target-Z. With the previous version of the tool, actually it was v0.5 I
> think, our decoupling-Z was well below our target-Z. With this new
> version (v2.0) the decoupling-Z is larger than target-Z.
>
> We got a reply from Altera regarding this. They said that indeed the
> results will change from an earlier version of their tool and that v2.0
> is more accurate. (not too many details on how it was more accurate.)
>
> We got some good news also. An Altera app note AN574 pg 17-19 gives us
> some relief. It turns out we were being too conservative in our Power
> rail sharing approach...without going into too much detail here, they
> allow several separate circuits inside their Stratix lll to share the
> same power rail, and they specify the steps to decouple that shared
> rail. This approach allowed us to pass our decoupling analysis.
>
> Thanks again,
> Jim Peterson
> Honeywell
>
> -----Original Message-----
> From: steve weir [mailto:weirsi@xxxxxxxxxx]
> Sent: Friday, April 09, 2010 3:59 PM
> To: Peterson, James F (EHCOE)
> Cc: si-list
> Subject: Re: [SI-LIST] Altera's PDN Design tool - what changed?
>
> Jim, how do you mean fail? Is the impedance wrong? Does it cover the
> wrong frequency range? Did you move your power cavity? You can call me
>
> if you like and I will help you straighten this out.
>
> Best Regards,
>
>
> Steve.
> Peterson, James F (EHCOE) wrote:
>
>> We use the Altera PDN design tool to evaluate the decoupling of their
>> Stratix lll FPGAs. We just upgraded our older version of this tool to
>> the newest version (Version 2.0), and our decoupling solution that had
>> margin now fails miserably...
>>
>> Any other Altera users seeing this problem? We can't figure out what
>> caused it. It looks like more inductance, but we've zeroed out most of
>> that and we still fail. (We don't have visibility into the actual
>> equations.)
>>
>> Anyway, if an Altera expert is listening, your input (and all
>> SI-Listers) is welcome to help us understand this. (we've also
>>
> initiated
>
>> an inquiry within Altera.)
>>
>> Thanks,
>> Jim Peterson
>> Honeywell
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>
--
Steve Weir
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