( DAC 04 Item 31 ) --------------------------------------------- [ 02/09/05 ]
Subject: Silvaco Expert & SmartSpice
CRAZY IVAN -- The CEO of Silvaco, Ivan Pesic, is known for his two big
lawsuits (one vs. Avanti and another vs. Circuit Semantics.) The thing is
that he wins these suits, so he was right all along. Put Circuit Semantics
out of business. The other thing is that Ivan sells good tools cheap;
and he provides good support, too. Maybe not so crazy, this Ivan...
Actually, I am not a hands-on SmartSpice user. Just an over worked,
under paid, design automation / support kind of guy. I do help support
SmartSpice, and have done so for many years.
When we did our evaluation of SmartSpice, it was in comparison to
MetaSoftware's HSPICE - back in 1997. Avanti had purchased Meta
Software, and raised tool and support costs through the roof. At
the same time, under Avanti, service and support of HSPICE went
down the drain.
We found SmartSpice to be a viable competitor. Accuracy was on par, it
had better speed. Initial cost and support costs were both much less
expensive. And Silvaco appeared to be more capable of supporting their
own tool, as Avanti was facing mass defections of their MetaSoftware
people.
We totally replaced HSPICE with SmartSpice, with no trouble at all, and
have not looked back since.
We do have 3 or 4 Spectre licenses, but they are not in any of our
production flows, and are only used sporadically.
We talked to the Nassda folks earlier this month, and expect to
evaluate their software sometime soon. But certainly can not make
any comparisons at this time.
I have personally found Silvaco to be a good company to work with.
They are straight forward, and honest. When they make a deal, they
stick to it. They do a good job of supporting their tool, and
helping out, sometimes directly, our design community.
Sorry that I did not uncover any warts. This is not a growing area
at Lattice. We are doing more modeling and Verilog type simulations.
Analog circuit simulation is just holding its own. And SmartSpice
is holding its own as our analog circuit simulation tool.
- Nate Nicholson of Lattice Semiconductor
The Cadence schematic capture tool is generally superior to the Silvaco
"Scholar" tool that I use. The Cadence schematic capture GUI is
seamlessly integrated with the simulation results providing easy access
to simulation results. The Cadence "calculator" is superior the to
Silvaco equivilence as well.
I find both the Silvaco and Cadence simulation engines to be very good.
I believe the the Silvaco engine is faster than that of Cadence, but
convergence is perhaps slightly better for Cadence (although I have
never spent too much time trying to get Silvaco to converge.) I would
never buy Cadence over Silvaco in spite of their overall slight
performance advantage because of two reasons. First, the cost of the
Cadence tools is much greater than the Silvaco tools. Second, I found
the Cadence tools to require a team of "Unix jockeys" for support.
I opted for the Windows XP version of Silvaco and pleasantly found out
that no corresponding "Windows jockeys" are required. I am NOT a PC
power user and have found no occasion that required one.
The Silvaco layout tools I believe are superior to the Cadence tools.
Both layout tools are fairly easy to use and quite powerful, the
Silvaco tools are a little easier to use (no hidden ".donotset" Unix
switches). I find the DRC scripts easy to write and VERY fast to run.
When submitting a chip to a local foundry for fabrication, the foundry
performs a DRC check on my submission to verify that no layout rules
have been violated. They run their script using a Cadence box using
the PDK that they developed. They tell me that it typically takes
4 hours to run their script on the top level chip layouts that I
submit to them.
On my Windows box, using the Silvaco PDK that I developed, it typically
takes about 10 minutes to run my DRC script on the top level. (I have
a Dell PC with a single processor running at 3 GHz.) I also find the
P-cell language very simple and intuitive and have written many P-cells,
some with a fair degree of complexity. The Silvaco LVS tool is
extremely fast. A top level extraction takes about 10 minutes while
the actual LVS takes perhaps 10 seconds to perform. A typical part
that I design has approximately 10,000 devices (MOSFETs, BJTs,
resistors, capacitors, and diodes).
- John Leighton of Analog Action LLC
My experience with SmartSpice is at evaluation level. Namely, I
evaluated the tool for about 1-month. Although we like SmartSpice
engine, we have not made any decision to purchase the tool yet.
Right now, I am mainly a Spectre and HSPICE user, so I cannot comment
much on HSIM or Eldo.
What I like about SmartSpice:
- DC convergence is better than HSPICE, simulation engine not bad.
- Functionality same as HSPICE (netlist HSPICE compatible). This
is good because all foundries give out HSPICE-syntax model libs.
- SmartSpice-RF option is there so you can do harmonic-balance.
We're an analog/RF shop, so it's an important consideration for us.
What I don't like about SmartSpice:
- The graphical user interface. The interaction with schematic,
plotting, no DC-bias back-annotation, simple functions take way
too many clicks to do, interface not intuitive.
From technical point of view, if money is no object, we would prefer
using simulators in this order
1) Cadence Spectre
2) Silvaco SmartSpice
3) Mentor Eldo
4) Synopsys HSPICE
But, if you consider price of the software, SmartSpice gives pretty
good value compared to Spectre in my view. So, when we are in the
market for new SPICE, we'll seriously consider SmartSpice.
- Aleksander Dec of Epoch Microelectronics, Inc.
As far as the actual analog simulation engine is concerned, SmartSpice
is superb. We haven't seen any results in SmartSpice that were wrong
or different from Spectre. A couple of years ago, Silvaco added a
Verilog-A simulator to the mix. Initially the engine was quite buggy,
but recent releases have improved, although it has been reported to me
that the Verilog-A debugger still has some quirks.
Recently, they have also added a Verilog simulator as well and packaged
it with the other simulators in a tool called Harmony-AMS, but we have
not yet tried it.
I should note at this point that we are currently Windows based for
SmartSpice, so I can't comment on the LINUX versions but I think most
of the development work is done in the UNIX environment so it is
probably reasonable to expect better performance in the native
environment.
The convergence of SmartSpice is generally good. We did see some issues
with the Mextram bipolar model, but they eventually got it to converge.
As far as simulation speed is concerned, again it seems to be adequate.
In fact we had the opportunity a few years back to do a complete 5 GHz
design in the Cadence environment with customer provided CAD systems,
and recently we had the opportunity to design a similar design in our
standard flow with SmartSpice. We found that we could simulate much
faster in our Silvaco environment because we had more licenses and also
because our PCs were much better performing than the Sparc servers
our customer provided.
In the past, I think Silvaco was sometimes overly aggressive releasing
products and making promises of new features, and this lead to releases
that sometimes were buggy. Over the past year or two I have sensed
they have shifted their strategy and are now taking a more conservative
approach.
- Joel Zolnier of Integrated Circuit Designs, Inc.
Silvaco Expert strengths:
- excellent user interface.
- intuitive especially if you are familiar with the Cadence and other
layout tools on the market.
- powerful & easy-to-use/learn DRC.
- powerful & easy-to-use/learn layout automation/scripting language.
- runs on Windows and Linux.
- great applications support.
- good performance even on modest hardware.
- easily expandable via custom menus and access to C++ APIs
outside of tool.
Expert weaknesses:
- not all editing commands (i.e., measurement) execute across multiple
views of the same layout.
- no sub-nm design grid capability yet.
We've been using it since 1998-9 so we're obviously biased in favor of
Expert. We've used the Cadence tool, evaluated L-Edit, and used our
own proprietary layout editor for a while. We're happy with Expert.
- Mark Babasa of Intel
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