[SI-LIST] Re: Hspice vs. Eldo
- From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
- To: <heyfitch@xxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Sat, 3 Nov 2007 12:11:05 -0700
Vadim
You make it sound so easy. My experience is quite different. I used to
work for an EDA company, Mentor. We were trying to get Eldo models out of
one of the larger silicon vendor and ran into all kinds of difficulties.
They had historically supplied encrypted HSPICE models but refused to offer
Eldo models. They had enough problems making their HSPICE models compatible
with all the different versions of HSPICE they didn't want to support
another flavor of SPICE. When offered free tools to do it they declined.
When offered free resources to do this for them they declined. There was a
policy and the policy was NO to anything other than HSPICE. This vendor did
not view the effort to validate models in another format as a trivial matter
and took their responsibility to provide accurate models are very important.
Differences between the HSPICE and Eldo outputs had to be understood,
explained and fixed.
I'm also reminded of a number of system vendors who tried to tie POs for ICs
to availability of IBIS models. Many times the system vendors got the ICs
with broken promises of models.
I'm sure reality is between these two extremes in perceived effort but
perception of difficulty can stop good ideas.
Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
tom@xxxxxxxxxxxxx
www.teraspeed.com
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Vadim Heyfitch
Sent: Friday, November 02, 2007 8:00 PM
To: si-list@xxxxxxxxxxxxx
Cc: Chris.Cheng@xxxxxxxx
Subject: [SI-LIST] Re: Hspice vs. Eldo
Julia, and all:
having been on three sides of this table - systems, silicon vendor - both
fabless and fabbed, and EDA vendor - I'd like to comment.
Every silicon vendor using TSMC as a foundry, receives spice process cards
from them in three formats: HSpice, Spectre, and Eldo. All - unencrypted. (I
don't know about UMC and other foundries.) It's circuit design group almost
certainly uses just one simulator, let's say HSpice (for example sake). That
does not preclude other organizations within a silicon company from taking
the HSpice netlist and running it with other simulators, that understand
HSpice netlist but use other process cards (Eldo or Spectre).
The effort of validating spice models under a different simulator is rather
small .... as long as you are not trying to map a set of process parameters
from a one-off, in-house-developed-by-TCAD-department, non-BSIM4.5 . (It is
not an issue for a fabless semi vendor). And if there are differences
between your simulations , there is not much you can do about it anyway. To
make a Hspice netlist run under Eldo - is a few minute effort: add a few
short lines at the top and bottom of the netlist, and point to different
libraries. Encryption is as trivial as it is in HSpice: one command at the
cmd prompt. It takes much less than one part-time apps engineer to support
on-going releases of IO buffer models in an additional format or two.
If systems companies were more persistent in asking silicon vendors for IO
buffer models in Spectre and Eldo, they would receive them. Some silicon
vendor already provide such models (Altera Stratix1, for example).
It's is incorrect to assume that all silicon is designed with HSpice. I've
heard that actually HSpice share of designs has shrunk. Yet I am sure that
silicon vendors designing with Spectre and Eldo still generate HSpice IO
models for their customers to make them happy. I completely agree with Chris
that 9 out of 10 times a customer does nothing with the IO spice model after
receiving it. Yet, having this model available (as a "collateral") makes a
silicon vendor credible with the customer, thus generating sales.
- Vadim
MetaRAM
On 11/1/07, Chris Cheng <Chris.Cheng@xxxxxxxx> wrote:
>
> In an ideal world, we can have whatever we want.
>
> But in a real world, ask yourself if you are a silicon vendor will you =
> willing to :
> a) pay extra to get an AMS tool that has nothing to do with your silicon =
> design flow
> b) invest in the manpower to qualify your internal SPICE (most likely =
> HSPICE) model with ELDO or whatever AMS standard
>
> HSPICE with S-parameter or W element is a problematic path to say the =
> least. But I can get around it with other tools that can generate =
> something HSPICE can feed on and work. That are plenty of free or low =
> cost vector fitting tools that can help you get around the S-parameter =
> or W-element problem with HSPICE.=20
>
> Ask yourself this question, with all the hype about IBIS 4.2 with SSO, =
> how many silicon vendor even border to publish that ?=20
>
> Tool vendors can promise you a lot of things. At the end of the day, it =
> is your silicon vendor that has to do it.
>
> And coming from experience from both sides of the table, I have seen =
> plenty of customers that demand certain models in HSPICE, IBIS etc and =
> just sit on it after they are delivered. I have done audit on usage of =
> models after customers received them and surprise surprise less than 10% =
> of them are actually simulating anything with them. This is hardly a =
> statistic that encourage me to invest in generating extra models.
>
> You may be the busy bee out there that work on simulating every net you =
> have with every model you get. But there are plenty of CAD or System =
> managers out there that demand this and want that but end up sitting =
> with a $100K+ tool and super complicated model accurate down to 1 pico =
> second and do nothing about them.
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Tom Biggs
> Sent: Thursday, November 01, 2007 1:36 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Hspice vs. Eldo
>
>
> If a company doesn't have a dedicated SI person, a tool that is most
> useful is not necessarily the 'standard' SPICE. Instead, they will look
> for a tool that integrates well with the schematic/board layout process
> and is easy to use for all the designers (who only occasionally use the
> tool), and has IBIS, SPICE and for the future AMS.
>
> And more than likely there will not be enough budget for more than one
> tool. The sacrifice is that encrypted HSPICE models could become
> useless. Sometimes with lots of pleading, you can sign lots of NDAs and
> get an unencrypted model. Chip companies want to sell chips, so I'm sure
> there is going to be more and more pressure on them to provide models
> that don't restrict a customer to a tool they may not have and don't
> have the budget to go out and get.
>
> This has been discussed before: there should be some sort of encrypted
> AMS standard so the industry has something useful to go forward with.
>
> -tom
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Dan Bostan
> Sent: Thursday, November 01, 2007 11:40 AM
> To: Aubrey_Sparkman@xxxxxxxx; fialka113@xxxxxxxxx; scott@xxxxxxxxxxxxx;
> weirsi@xxxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Hspice vs. Eldo
>
> You get what you pay for.
> Go for the HSPICE as it is the standard in the Spice SI space.
> /dan
>
>
> ----- Original Message ----
> From: "Aubrey_Sparkman@xxxxxxxx" <Aubrey_Sparkman@xxxxxxxx>
> To: fialka113@xxxxxxxxx; scott@xxxxxxxxxxxxx; weirsi@xxxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx
> Sent: Thursday, November 1, 2007 10:53:06 AM
> Subject: [SI-LIST] Re: Hspice vs. Eldo
>
>
> When Schedules and Time to Market are important, you can justify the
> cost even if the tool is used only a few months a year. When the work
> load is high and constant, the ease of use argument gets weaker as you
> can better benefit from re-use and scripting and the (re-)learning
> curve goes away.
> Aubrey Sparkman
> Enterprise Engineering Signal Integrity Team Dell, Inc.
> Aubrey_Sparkman@xxxxxxxx
> (512) 723-3592
> "Discovery consists of seeing what everybody has seen and thinking what
> nobody else has thought." - Jonathan Swift=3D20
>
> =3D20
>
> ________________________________
>
> From: Julia Nekrylova [mailto:fialka113@xxxxxxxxx]
> Sent: Thursday, November 01, 2007 12:35 PM
> To: Sparkman, Aubrey; scott@xxxxxxxxxxxxx; weirsi@xxxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx
> Subject: Re: [SI-LIST] Re: Hspice vs. Eldo
>
>
> 2) Depends on how constant your work load is. If it is high and
> constant, then yes, I would agree with you that 50 % more cost is
> easily
> justifiable. Btw, Hspice costs 100 % more.
>
>
> ----- Original Message ----
> From: "Aubrey_Sparkman@xxxxxxxx" <Aubrey_Sparkman@xxxxxxxx>
> To: scott@xxxxxxxxxxxxx; weirsi@xxxxxxxxxx
> Cc: fialka113@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> Sent: Thursday, November 1, 2007 8:14:00 PM
> Subject: [SI-LIST] Re: Hspice vs. Eldo
>
> In addition to Steve and Scott's comments, I would like to add two more
> comments:
> 1) OFTEN, model accuracy is much more important than which simulator
> you
> use.
> 2) If you have a choice of simulators, (you don't with encrypted
> models)
> how important is ease of use? For instance, if one simulator costs 50%
> more, but enables you to get 3 times as much done, do you care?
>
>
> Aubrey Sparkman=3D3D20
> Enterprise Engineering Signal Integrity Team=3D3D20
> Dell, Inc.=3D3D20
> Aubrey_Sparkman@xxxxxxxx=3D3D20
> (512) 723-3592=3D3D20
> "Discovery consists of seeing what everybody has seen and thinking what
> nobody else has thought." - Jonathan Swift
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Scott McMorrow
> Sent: Thursday, November 01, 2007 11:32 AM
> To: weirsi@xxxxxxxxxx
> Cc: fialka113@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Hspice vs. Eldo
>
> I'd agree with Steve. Usually encrypted models is the deal breaker.
> Otherwise, Eldo is technically superior to HSPICE in the handling of
> s-parameters.
>
>
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> (401) 284-1827 Business
> (401) 284-1840 Fax
>
> http://www.teraspeed.com <http://www.teraspeed.com/>=3D20
>
> Teraspeed(r) is the registered service mark of
> Teraspeed Consulting Group LLC
>
>
>
> steve weir wrote:
> > Julia, Synopsys has two almost unassailable market advantages with
> HSPICE:
> >
> > *A lot of models are supplied only as encrypted HSPICE models. If
> you
>
> > don't have HSPICE you can't play.
> > *HSPICE is used for silicon sign-off with a number of fabs.
> >
> > If either of the above issues are material to you, then the
> technical=3D3D20
> > merits of one simulator versus another are moot.
> >
> > Steve
> >
> > Julia Nekrylova wrote:
> > =3D3D20
> >> Dear SI professionals,
> >> My question is about Eldo vs. Hspice comparisson. With the former
> being roughly 2 times cheaper than the later, I wonder if it offers a
> similar performance. I've heard that Eldo has an improved t-line
> modeling and handles S-parameters in a more advanced fashion. I just
> never had a chance to work with Eldo, but pricewise it's a big
> difference for a small company like ours.
> >>
> >> Thanks again for your help,
> >> Julia Nekrylova
> >>
> >> 74ze Engineering
> >>
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