( DAC 04 Item 25 ) --------------------------------------------- [ 02/09/05 ]
Subject: Cadence Virtuoso, Mentor IC Station, Synopsys Cosmos
OLDE GUARD -- In the custom layout, Cadence Virtuoso rules the roost. Sure
Mentor IC Station and Synopsys Cosmos try to put up a good fight, but users
overwhelmingly stick with Virtuoso. In start-up land, Silicon Canvas Laker,
Paragon SE, and Pulsic Lyric are the wannabe challengers to Virtuoso.
Cadence Virtuoso:
Cadence presented the new and improved Virtuoso VLE and Turbo (not the
XL) at DAC. More than five years after the ACPD flow birth, VXL code
is not as solid as expected, so more than 80% of users do not want to
use it. Cadence is trying now to enhance the Turbo version of LE, so
it will be an easier transition to VXL in the future. A few European
offices are trying now to bring VXL to "free of bugs" status. The only
difference between the 2 versions, VXL and LE will retain connectivity
between schematic/netlist and layout.
- LE has now a built-in GUI to develop process dependent devices with
graphical models called Qcell that can be imported in VXL and the
next release they can be merged with Pcells written in VXL.
- All generated devices can use a standardized tech file definition
or a local override; even capacitors and resistors end up with all
dimensions correct.
- Design Rules Driven feature (DRD) gets to next level - will have an
ENFORCER - exact rules ONLY for now. Unfortunately cannot handle
complex progressive 90 nm rules YET, so it is not as good or fast
as BindKey. But the good news is that Optimize, the compactor
bought from Qdesign is gaining ground, covers almost all the 90 and
65 nm rules and it is free in VXL. Cannot be better than that!
- VLE now understands ERC so user can delete nets, propagates
connectivity across hierarchy.
- Due to customer demand (!) it is possible in the new version to
build static menus for most repeated tasks.
- Cadence works with a small company, STX Cadware, who developed a lot
of Skill overlay. This will help power users to customize functions
and solve some LE limitations. If and when this is ready, Cadence
Virtuoso LE Turbo can beat Silicon Canvas's Laker tools that make
waves in Taiwan. STX addresses the lack of usability issues with
Virtuoso polygon pushing features.
- Users can clone devices from within the hierarchy and from arrays.
- VCP places devices and cells in rows and all the flow is easy to
setup. The newest feature includes an option to place devices
"area" based not only "rows".
- A new feature is that the user can copy from schematic pins and
create rails before transistor placements.
- When import GDSII, Virtuoso knows how to propagate nets based on
electrical connectivity. This is a very useful feature for post
Place & Route fixes.
With the additions of Optimize online compactor and VCP/VCR tools,
Virtuoso XL is now a very capable automated environment. I hope that
Cadence will work hard to move to Open Access database and develop a
strong verification tool. Maybe then, we can expect the same level of
integration as from Cosmos today.
- Dan Clein, author of "CMOS IC Layout"
We are getting VCAR and will have a better report next time. From the
demo, Lyrix also looks reasonable.
- [ An Anon Engineer ]
Virtuoso I use.
- [ An Anon Engineer ]
For the polygon pushers:
Cadence Virtuoso and Mentor IC Graph (I assume you ment IC Graph rather
than IC Station), are pretty much equivalent, with possibly a light
edge to Cadence. However the Cadence tools are rather tightly
integrated with each others so unless you use Cadence's design capture
tools you might not want Virtuoso.
- [ An Anon Engineer ]
Mentor IC Station/Cadence Virtuoso: These are the only two worth
considering.
I find IC Station much easier and more intuitive to use than Virtuoso.
A lot of things I had trouble figuring out how to do in Virtuoso were
easy in IC Station. It is much easier for the end user to customize
and its SDL features and device generators allow the layout designer
more flexibility. It has a very good interactive routing tool called
IRoute that makes quick work of wiring up circuits. Its basic polygon
manipulation features are also easier to access.
Calibre is built into the tool in the form of ICRules/ICTrace and
makes for lightning fast DRC/LVS runs. I've used Cosmos-Hercules and
Virtuoso-Assura and neither are in the same ballpark. What takes the
others a minute or more ICTrace/ICRules can do in seconds.
I also prefer the Mentor interface, its much nicer and everything is
contained in a single window. You are able to change the look and
feel very easily. I never liked the pop-ups and multiple windows in
the Cadence/Synopsys environment. Ample is much easier to write code
in vs. Skill, which makes macro/script creation a less daunting
proposition.
I've always been perplexed by Virtuoso's market dominance. Don't get
me wrong, Virtuoso is a good tool, it has some nice features. But
I'm much more productive with IC Station.
- Robert Maxwell of MediaWorks ISI
Mentor Graphics IC Station:
Mentor Graphics IC Station layout environment did not impress me very
much. The DAC demo was very poor so I had to get the feature info from
friends! It has a new updated look and feel with raised 3-D buttons on
standard and custom palettes and new tool bars to suit user preference.
- A floorplanning tool with area estimation, auto pin and port
placement and optimization and hierarchy management.
- An automatic constraint driven router for N layers which can be used
on selected nets or globally on the fly - not seen yet.
- An interactive router, which can do shielding, and busses with push
and shove, similar to IC Craftsman, while displaying length and
parasitic information on the fly - moving toward Cosmos idea.
- Connectivity driven layout with ECO support from Schematics, Verilog
gate level netlist or Spice netlist using our new LDL cockpit GUI.
- Hierarchical devices (Pcells within Pcells).
- New Library manager ICstudio organizes data by, project, library and
component, with multiple views per component, similar to the Cadence
Library manager.
- Cadence work and look alike version with streamlined menu system and
tool bars that works like Virtuoso including the selection paradigm
and hotkey mapping and operation.
- Started to bring forward some of the technology from CAECO - allows
cells to be placed as close as possible based on design rules in
the tech file.
I do not consider Mentor a major player, as I did not see too many new
features and development to challenge the leaders.
- Dan Clein, author of "CMOS IC Layout"
The custom IC market attracts more and more players, which shows the
need and growing of analog/RF component in SoC designs. Cadence is
still the undisputed leader here. When you look at the complete front
end to back end flow, Mentor is the closest run-up, although a very
distant second. Avanti Cosmos is simply a joke. If focusing on back
end layout, there are quite a few vendors competing for the second
spot. Among all those we looked at before, Paragon and Laker are
coming up pretty strong, with good features and easy interface with
third party front end designs.
- [ An Anon Engineer ]
Synopsys Cosmos: My therapist tells me its good to talk about it and
that post-traumatic stress syndrome fades with time... Using Cosmos
is something I don't want to repeat. I spent months doing what should
have taken a few weeks. Its shortcomings are just too numerous to
list... My advice to them was to bin the whole thing and just start
over. Why keep torturing their customers?
Run for your life if ever offered Cosmos (even if its free!).
- Robert Maxwell of MediaWorks ISI
Synopsys Cosmos:
Synopsys answer to Cadence Virtuoso in the full custom world is Cosmos.
This tool proves that when motivated big companies can deliver new,
gorgeous products. Started as a small and cheap environment to allow
users to fix Astro/Apollo issues for chip finishing, under the name
Discovery, then Enterprise, the developers ended up with a very
competitive full custom environment. The Cosmos environment is made
of 3 basic tools: SE - Schematic Editor, Scope - support for HSPICE
and HSPICE RF, and LE - Layout Editor. No noticeable features with
the schematic editor, same as others.
On the Cosmos LE front there are a lot of things that users would like
to see in other's tools:
- The environment has similar to Pcell approach for device generation
based on schematics input.
- Automated placement of devices - far from perfect but mimics the
schematic architecture or can be based on a given aspect ratio for
the cell size - not row based but routing cost. Routing by hand or
ECO with online DRC recognition equivalent with Cadence DRD, is a
very nice feature.
- Autoroute router in Cosmos is kind of rough but good enough if the
looks are less important than the simulated extraction quality.
- Online query on nets, devices, for R, C, etc. are nice features
that Cadence is following now in the OA version coming soon.
The biggest feature of Cosmos is the integration and the common
database. All the tools exchange through Milkyway so no need for GDSII
or any other exchange standard format. It can include live window
waveforms for parts - probing capabilities from Layout, Schematic to
Parasitic results and Simulation data. Push button back annotation of
parasitic to schematic!!!
Synopsys provides a very competitive environment for Schematic, Layout,
Parasitic Extraction, and Simulation of results. The graphical
interface to view and probe at any stage, and all are bundled in an
integrated database that makes everything fast and accurate.
An environment worth evaluating if you start for the first time into
the full custom design flow. Unfortunately like any new good thing
created in a big company, Cosmos may have to fight to win its survival
against the ASIC (digital) wing or will die for political reasons.
I consider Cosmos the only serious contender to Cadence Virtuoso.
- Dan Clein, author of "CMOS IC Layout"
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