( DAC'20 Item 07b ) ----------------------------------------------- [11/23/21]
Subject: Empyrean Skipper beats Virtuoso in chip finishing Best of 2020 #7b
THE NEED FOR SPEED: Empyrean's Skipper chip finishing tool does GDS views
and edits of final chip layouts. Users like its blindingly fast full
chip loading and net tracing. One user even said its hierarchical display
only takes seconds -- compared to minutes for Virtuoso.
"I cannot overemphasize how good a layout review tool Skipper is. It's
significantly faster than Virtuoso. When we have a chip finishing
question before shipping our GDS, I go to Skipper for a quick review.
Open it. Do my work. Close it.
And I don't have to worry about leftover temporary files."
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"Skipper's tracing is faster than Virtuoso, so we use Skipper for
tracing on our bigger networks. I use this feature a lot.
I can do better debug of LVC/DRC errors with tracing. I can take
any signal, make a trace, and can figure out if there is short
there; e.g., the signal shouldn't be branching to a block."
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"Skipper was fastest tool we found. It can handle an entire chip with
billions of transistors and output OASIS format in under 2 hours.
Our in-house tool took 3 to 5 hours for the same chip, plus
another 1.2 hours to convert the format to OASIS."
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QUESTION ASKED:
Q: "What were the 3 or 4 most INTERESTING specific EDA tools
you've seen in 2020? WHY did they interest you?"
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We use Empyrean Skipper as a quick "swiss knife" chip finishing tool
for our layout reviews. Skipper handles our big databases faster
than Virtuoso from what we've seen. They clain it loads 138GB GDS
in 1 sec. What we see is close to that. We use Skipper for our
analog layout reviews after using Cadence Virtuoso for our core
layout design.
Skipper Inputs:
- Our semiconductor mask drawing
- Our GDS files <-- We can use it with GDS and compressed GDS
(GDS.gz). Skipper works with both of them, so we don't
have to compress/decompress.
It's so good that I don't even see a performance drop. It
also saves us on file size and transferring time, which is
another plus.
- Our foundry PDKs (this doesn't change between designs if
it's the same foundry process)
- tech file with layer info
- display file which tells Skipper how to draw each layer.
- layer map
Skipper Output:
- On screen display where you can do reviews and edits
EMPYREAN SKIPPER VS CADENCE VIRTUOSO
My comparisons where they are relevant:
1. PDK/GDS loading
- Cadence Virtuoso requires the user to do PDK and GDS streaming;
we must compile the foundry file into our database first.
- Empyrean Skipper loads this automatically, so it's much
quicker to do reviews.
2. Hierarchical display with drill-down to individual cells
- Cadence Virtuoso: longer to display; it takes minutes each
time to drill down.
- Empyrean Skipper: loading only takes seconds -- *much* faster
to load a layout in Skipper than in CDNS.
3. Net tracing
- Cadence Virtuoso: We use Virtuoso editor for this first.
- Empyrean Skipper: If there are performance issues with
Virtuoso, such as too many nodes, we then use Skipper
4. Boolean operations
- Both tools have this.
- We use Empyrean Skipper for rigor of their flow
5. Layout Comparison
- Both Skipper's GUI and Virtuoso's GUI let us view/compare two
drawings
- I use Empyrean's GUI for the layout display/editor GUI to do
this. Because I use Skipper for my review, I can compare
layouts quickly on the fly, without going back to Cadence.
This is very useful to me.
6. Full-chip net tracing & debug
- Skipper's tracing is faster than Virtuoso, so we use Skipper
for tracing on our bigger networks.
- I use this feature a lot. I can do better debug of LVC/DRC
errors with tracing. I can take any signal, make a trace, and
can figure out if there is short there; e.g., the signal
shouldn't be branching to a block.
- For the tracing function, we can gray out the non-relevant
parts of our design, and then use color to identify the nets
faster.
7. "Layout server" mode to share layout data
- Skipper also has a feature where multiple people can look at
the same drawings, but I haven't used it yet.
8. Preparing FIB data for device analysis & instruction
We use FIB data to make silicon changes and for temporary fixes.
Virtuoso doesn't do this function, only Skipper.
Skipper will:
- First, Skipper displays the most visible information when
looking at top view of die.
- Next, Skipper shows the coordinate to work on, identifies
the point of change (including the layer with to) and
the change itself.
- Then, Skipper outputs PDF instructions for our FIB house
Skipper's report restricts the information for our FIB house to
only what is needed, so we don't give out more detail than needed.
We define the window of information that we want to share.
We use Skipper a lot for this.
Conclusion
I recommend Skipper for layout display and review. It has all I need.
Its performance is great, especially for full-chip layouts.
I cannot overemphasize how good a layout review tool Skipper is. It's
significantly faster than Virtuoso. When we have a chip finishing
question before shipping our GDS, I go to Skipper for a quick review.
Open it. Do my work. Close it.
And I don't have to worry about leftover temporary files.
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Empyrean Skipper chip finishing
We use Skipper Chip for merging and editing our layout. It lets
us view our digital layout conveniently.
We are happy with Skipper. It merges our GDS faster than Virtuoso.
It's net tracing/searching are also quick.
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We use Empyrean Skipper layout viewing and editing tool; its functions
include IP Merge, LVS, LVS debug and other layout visuals.
Before we bought Skipper, we tested it against a handful of layout
viewing/editing tools, including our in-house tool. Our main reasons
for deciding to go with Skipper were:
1. Primarily speed. In chip finishing, we use it on our full chip,
so we need it to work fast.
- Skipper was fastest tool we found. It can handle an entire
chip with billions of transistors and output OASIS format in
under 2 hours.
- Our in-house tool took 3 to 5 hours for the same chip, plus
another 1.2 hours to convert the format to OASIS.
2. Storage.
- Skipper reads in GDSII and outputs OASIS. This saves storage
(and time). OASIS is gaining traction; OASIS is more compressed
and is only about 1/20th the file size as GDSII.
- Our in-house tool only read/wrote GDSII, which we then needed to
convert to OASIS format to save for storage. (Which takes another
hour.)
I've been using Skippers' IP merge function for my IP layout integration
for over a year. Our chips are composed of many blocks and functions.
We have all types of IP, including analog elements, digital elements,
and standard cells.
Skipper's IP merge assembles them into a full coherent chip in our
layout. It doesn't look at the elements' functionality, instead it
treats them as shapes to layout.
Skipper is a visual tool, but I use it in a non-visual way for chip
assembly.
The tool's inputs are:
- GDSII files
- Configuration file with setting. The tool settings like input
GDS may have certain parameters that are not retained by default,
so the setting keeps them intact.
- Tcl file. For example, we write one line Tcl script to say
just do IP merge.
I'd recommend Skipper. It is efficient to use, and runs screamingly
fast. Empyrean's support is good also. If we have an issue, we
email our AE and they usually respond within a few hours.
If R&D needs to be involved, it only takes a couple days.
In the future we have interest in learning about Skipper's full-chip
net tracing and debug function, also.
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Empyrean Skipper Chip Finishing
We use it to do our chip finishing -- for merging and editing our
layout. It lets us view our digital layout conveniently.
We are happy with Skipper. It merges our GDS much faster than Virtuoso
does. It's net tracing/searching are also efficient.
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We use Empyrean Skipper.
It's capacity and performance meet our requirements. Our GDS size is
usually around 50 gigabytes after GZIP.
Some tasks we use Skipper for:
- Simple layout editing
- Layout Comparisons
- Merging standard cells and IPs
- DRC/LVS result review and debug
Skipper is easy to use, plus it reads our GDS fast. I'd recommend it.
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Empyrean Skipper is our layout chip finishing analysis tool that does
pad report, density analysis, tracing, LVL (layout vs layout),
3D viewing and P2P (point-to-point).
Skipper quantifies some of our layout parameters and helps us to
optimize layout.
It's performance is super fast -- but we can't comment on capacity
because our GDS layout files are usually only around 100 megabytes.
We find Skipper's full-chip net tracing/debug, and DRC/LVS results
debugging features to be especially useful. We also use Skipper
for layout editing and layout comparisons, though.
I recommend Skipper; its debug functions like net tracing and P2P,
are very helpful to us.
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Empyrean Skipper is our layout review tool. We've used it to do:
1. layout editing does hierarchy, searching, and Boolean operations
2. comparing layout vs layout
3. checking and debugging our DRC results
4. full-chip net tracing & debug
5. IP merging
I can recommend Skipper to others for its fast speed, plus its UI is
easy to use.
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