( ESNUG 486 Item 5 ) -------------------------------------------- [10/08/10]
Subject: (DAC'10 #2) Jim Hogan ranks the variation-aware full custom tools
> FULL CUSTOM ADD-ON: The company that ranked the second most user interest
> at DAC'10 was Solido, which sells a set of fancy schmancy variation tools
> for custom design. (Insert other custom buzzwords here.) Oddly enough,
> the Munich-based MunEDA, which has been in this niche for nearly 10 years
> now, barely even got lip service from most users compared to Solido.
From: Jim Hogan <jim=user domain=tela-inc got calm>
Hi John,
I liked that the #2 tool in your recent DAC Report was Solido because they
also caught my eye some time ago. That is, your analysis is in line with
my own analysis. As an investor, I have constructed a meta map of custom
IC design commercial offerings for due diligence purposes. I thought your
readers might be interested in it, too.
First, I categorize the main custom IC design tools as follows:
- Front-end design. Schematic editors, Design environments, Waveform
Viewers.
- Back-end design. Layout editors, Design Rule Checkers (DRC),
Electrical Rule Checkers (ERC), Parasitic Extraction.
- Front/back interfaces. Tools that tie front and back end such as
Layout vs. Schematic (LVS).
- Simulation - SPICE simulators, FastSPICE simulators, RF simulators,
and mixed-signal simulators.
- Variation-aware design. Variation-aware design tools include Process
Voltage Temperature (PVT) analysis and corner extraction, Monte Carlo
analysis and corner extraction, High-Sigma Monte Carlo analysis and
corner extraction, variation sensitivity analysis, and
Layout-Dependent Effects (LDEs).
- Modeling / Optimization. Tools such as behavioral modeling and
optimizers.
- Digital characterization. Standard cell characterization, memory
characterization, and Statistical Static Timing (SSTA).
VARIATION-AWARE CUSTOM IC DESIGN: CONTEXT
Here are different types of variation analysis done for custom IC design.
I'm defining them beforehand so you'll see how I have ranked each tool
based on them:
- PVT corner analysis. In PVT analysis, the designer aims to get the
circuit to pass market specifications across a list of PVT corners. A
PVT corner has a global process value (P) such as Fast Fast (FF), and
environmental values such as voltage (V), temperature (T), load, etc.
Designers have traditionally had a few PVT corners. However, in
smaller geometries, there can be a model set variable for each device
type, plus the traditional V and T variables; this leads to an
exponential explosion of possible PVT corners. The designer needs
fast, accurate ways to identify the PVT corners that matter.
- Monte Carlo analysis. At about 90 nm and below, PVT corners alone have
become inadequate to deal with increased process variability. So, in
Monte Carlo analysis, the local and global process variations are
modeled by the fabs as distributions, and the designer aims to improve
statistical quantities like parametric yield. With Monte Carlo, >50
samples in a design loop gets too time consuming; the designer needs
fast ways to extract relevant statistical corners.
- High Sigma Analysis. Required on a variety of circuits being
replicated many times like bit cells, sense amps, and digital standard
cells where one failure in a million (or a billion) matters. Millions
of basic Monte Carlo simulations take too long; billions is not
feasible.
- Variation sensitivity analysis. Helps identify weak spots in the
design, but can be costly in terms of simulation. For example, a
1000-device design with 10 local process variables per device has
>10,000 process variables, leading to >10,000 simulations.
- Layout-Dependent Effects (LDEs). These well proximity effects, STI
stress, and parasitics further degrade circuit performance.
VARIATION-AWARE CUSTOM IC DESIGN: VENDOR RANKING
Cadence, Synopsys and Mentor seem to be using a strategy of providing basic
variation functionality and partnering with Solido and/or Muneda to provide
more advanced variation capabilities. In contrast, Magma is trying to do
it all - they acquired Sabio Labs to fill out some of their capability in
conjunction with the introduction of their simulator FinSim.
And, finally, here's my ranking (and the reasoning behind each ranking)
of all known commercial "variation-aware" custom IC design tools:
#1. SOLIDO
Variation Designer. "New kid on the block with a surprisingly complete
offering."
- PVT. In addition to basic PVT corner analysis, Solido's "PVT+" tool
includes a "Design of Experiments" approach to extract the worst-case
from hundreds to thousands of possible corners. Solido claims their
PVT analysis speed is 10-50x faster than just using SPICE simulations
to simulate all possible combinations.
- Monte Carlo. Solido's "Monte Carlo+" tool runs Monte Carlo analysis,
and displays the results in tables, histograms / density curves, and
scatter plots. It has task-specific stopping such as "stop when yield
is verified." Its "sigma-driven" corner extractor returns statistical
corners at a pre-specified sigma (yield) level. Offers Monte Carlo,
Latin Hypercube, and their own propriety 'Optimal Spread Sampling'
which they claim to be 2-10x faster than Monte Carlo or Latin
Hypercube.
- High-Sigma. Solido offers the "High-Sigma Monte Carlo" tool, claiming
100-1000x speedup compared to typical Monte Carlo, in finding failure
cases and estimating yield.
- Layout-dependent effects (LDEs). Solido's "Proximity+" tool is used
to estimate proximity effects prior to layout. It automatically
guides layout designers as to which devices need guardbanding against
well proximity effects. Additionally, Variation Designer links to
Cadence Virtuoso for estimating LDEs.
- Sensitivity Analysis. PVT+, Monte Carlo+, and Proximity+ each report
sensitivity of performances to variation parameters, without requiring
additional simulation.
- Interfaces. Variation Designer can be used with Spectre, Hspice, and
Eldo SPICE simulators, plus Berkeley DA AFS, APS, UltraSim, HSim and
FineSim FastSPICE simulators. It is integrated with Cadence Virtuoso
Analog Design Environment (ADE), Synopsys Custom Designer or a
netlist-only flow.
- Scalability. Supports parallel processing. Solido claims their tools
scale to designs with 100,000 devices. Sensitivity analysis and
corner extraction run without needing to perturb all parameters.
- Accuracy. SPICE-accurate because SPICE in the loop. Monte Carlo+ has
confidence intervals for yield estimates (statistical quantities) and
sensitivities.
#2. CADENCE
Virtuoso Analog Design Environment (ADE). "Old school, the people's choice
for decades."
- PVT. Cadence Virtuoso has a basic infrastructure that lets you set up
PVT corners, simulate them, and visualize the results in tables and
waveforms. One of the early benefits of Cadence's offering was the
use of an extension language (SKILL) that enabled specific customer
tools and extensions.
- Monte Carlo. You can also run Monte Carlo analysis, and visualize the
results in the form of histograms / density curves and scatter plots.
You can pick statistical corners off Monte Carlo analysis, for use
elsewhere. Offers Monte Carlo and Latin Hypercube statistical
sampling.
- High-Sigma. Nothing.
- Layout-dependent effects. The schematic editor allows user-specified
parasitic values. Also, support quick partial layouts (through layout
automation) to get quick estimates of parasitic effects and other
layout-dependent effects.
- Sensitivity analysis. Virtuoso allows sensitivity analysis of process
and environmental variables.
- Interfaces. Monte Carlo analysis only works with Spectre and APS;
the parasitic-aware features only work with Spectre, APS, and UltraSim.
ADE is integrated with Solido, Muneda, Agilent, and PDF Solutions for
improved variation capabilities.
- Scalability. Supports parallel processing. Sensitivity analysis
requires perturbing all variables and simulating for each.
- Accuracy. SPICE-accurate because SPICE in the loop.
#3. MAGMA
Titan family, FineSim, FineSim family. "Hot simulator, nascent variation
analysis capability. Magma could do quite well if they can deliver."
- PVT. Titan ASE (Analog Simulation Environment) has basic PVT corner
simulation. Titan ADX (Analog Design Accelerator) extracts models of
design variables for performance across PVT corners, then supports
fast analysis and design on those models.
- Monte Carlo. ASE also has MC simulation, and visualizing the results
in tables, histograms, etc. To my knowledge, ADX does not support
statistically-modeled effects. Offers only Monte Carlo statistical
sampling.
- High-Sigma. Magma's FineSim Pro simulator has a new "Fast Monte
Carlo" capability, where Magma claims a 100x+ speedup compared to
Monte Carlo analysis.
- Layout-dependent effects. Titan AVP (Analog Virtual Prototyper) is a
fast layout prototyper, which they claim can be used for early
prediction of parasitic or proximity effects. Titan ALX (Analog
Layout Accelerator) speeds layout design, to derive more accurate
layout effects.
- Sensitivity analysis. ADX has fast sensitivity analysis of PVT
parameters (but not statistical ones).
- Interfaces. To the best my knowledge, the Titan tools only integrate
with Magma's own FineSim and FineSim Pro simulators.
- Scalability. Supports parallel processing. Not sure how well the ADX
models scale. The sensitivity analysis in ASE requires perturbing all
variables and simulating for each.
- Accuracy. ASE is SPICE-accurate because SPICE in the loop. But ADX
is only as good as its underlying models.
#4. MUNEDA
WiCkeD family. "More an optimizer than a variation-aware design tool."
- PVT. Muneda's WCO (Worst Case Operation) tool has partial PVT
functionality: it finds worst-case conditions across voltage and
temperature.
- Monte Carlo. Muneda's MCA (Monte Carlo Analysis) and MMA (Mismatch
Analysis) tools offer basic Monte Carlo simulations, and visualizing
the results in tables, histograms, and scatter plots. The WCA (Worst
Case Analysis) tool extracts design-specific statistical corners, and
specifies the sigma level for each corner. Offers only Monte Carlo
statistical sampling.
- High-Sigma. Nothing.
- Layout-dependent effects. The Cadence Virtuoso link allows for
"quick" layouts and estimating LDEs, after layout (no pre-layout
estimation).
- Sensitivity Analysis. MCA / MMA offer sensitivities to process
variables. The Response Surface Modeling (RSM) tool extracts response
models, which can be used for detailed sensitivity analysis. Process
(but not environmental) sensitivities with Monte Carlo without extra
simulation runs.
- Interfaces. Through the Simulator-Framework-Interface (SFI), WiCkeD
works with simulators from Cadence, Mentor, Synopsys, and Berkeley DA;
and with environments from Cadence, Mentor, and Synopsys. It also has
a Scripting Interface (SCR).
- Scalability. The sensitivity analysis in MCA/MMA requires perturbing
all variables and simulating for each.
- Accuracy. WiCkeD is SPICE-accurate because SPICE in the loop;
however, some of the underlying algorithms assume linear responses.
Confidence intervals in Monte Carlo yield estimates.
#5. SYNOPSYS
Galaxy Custom Designer (CD). "They may have a gold standard simulator,
but they're new to full custom design."
- PVT. In the last year, Synopsys has built PVT corner setup,
simulation, and visualization into CD.
- Monte Carlo. Synopsys also added basic Monte Carlo analysis and
visualization. You can pick corners off Monte Carlo analysis, for use
elsewhere. Offers only Monte Carlo and Latin Hypercube statistical
sampling.
- High-Sigma. Nothing.
- Layout-dependent effects. Custom Designer has a fully-integrated
layout editor (LE) and schematic-driven layout (LE), to get to layout
smoothly. CD has automated device generation and placement, but not a
full "quick" solution for fast estimation of layout effects.
- Sensitivity Analysis. CD allows sensitivity analysis of process and
environmental though it takes extra simulation effort beyond PVT or
Monte Carlo analysis.
- Interfaces. As far as I know, Synopsys CD is only integrated with
their HSPICE simulator and Waveview. Synopsys is also integrated with
Solido and Muneda for advanced variation capabilities.
- Scalability. Supports parallel processing. Sensitivity analysis
requires perturbing all variables and simulating for each.
- Accuracy. SPICE-accurate because SPICE in the loop.
#6. MENTOR
IC Analyst, IC Station. "Really old school."
- PVT. IC Analyst has basic capabilities for PVT corner setup,
simulation, and visualization.
- Monte Carlo. Monte Carlo analysis and visualization. Visualizations
include performance tables (per corner), histograms, and scatter plots.
The "Smart Monte Carlo" feature enables stopping once a statistical
measure is sufficiently accurate. Offers just Monte Carlo statistical
sampling.
- High-Sigma. Nothing.
- Layout-dependent effects. IC Station Schematic, IC Station Layout,
and IC Station SDL provide a smooth flow between front and back end
design, and there is a degree of layout automation.
- Sensitivity Analysis. Allows sensitivity analysis of process and
environmental though it costs extra simulation effort beyond PVT or
Monte Carlo analysis.
- Interfaces. IC Analyst only integrates with Mentor simulators.
- Scalability. Supports parallel processing. Sensitivity analysis
requires perturbing all variables and simulating for each.
- Accuracy. SPICE-accurate because SPICE in the loop.
#7. THE OTHERS
I am mentioning these companies for the sake of completeness; they are not
active players in this market.
- PDF Solutions Circuit Surfer. "Service-ware, not actively marketing a
product." Used to market a variation product called Circuit Surfer,
which did basic Monte Carlo analysis and visualization. PDF Solutions
even OEM'd the tool through Cadence around 1999/2000. PDF seems to
have stopped marketing a separate product and is focused on offering
general yield improvement services.
- Agilent EESof ADS. "Microwave and RF focused." Some PVT and Monte
Carlo analysis and visualization capabilities, but niche player
focused on Microwave and RF.
- Infiniscale TechModeler, TechAnalyzer, TechYielder. "Euro-Centric,
not much data outside of their website." Offer model-based Monte
Carlo analysis with visualization.
I hope this analysis helps your readers, John, as they navigate through the
variation-aware custom IC design space. Also, the market moves fast, so if
I missed anything from any of the vendors in my snapshot, I encourage them
to chime in to supplement my summary.
- Jim Hogan
Tela Innovations Los Gatos, CA
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