Altos Design Automation Inc. Releases Variety MX, for Statistical Memory Characterization

New tool adopted by STARC for their STARCAD-CEL Statistical Design Flow

SAN JOSE, Calif.--( BUSINESS WIRE)-- Altos Design Automation Inc. today announced Variety MX, a fast and accurate statistical timing model generator for embedded memories. The new tool generates instance-specific Liberty® models for use by Cadence’s Encounter® Timing System GXL, Extreme DA’s Goldtimetm and Synopsys PrimeTime® VX.

Variety MX leverages technology from Liberate MX to perform “automatic probing” and "dynamic partitioning" to address the runtime and accuracy challenges that arise from statistical characterization of large macro blocks that often comprise millions of transistors. Since a “dynamic partition” represents just the active critical path for a given timing arc and is typically only a few hundred transistors, it can be characterized using similar techniques as those deployed for statistical characterization of standard cells. This includes characterizing the sensitivity of both delay and timing constraints to global (systematic) and local (random) process variations. Variety MX is able to characterize memory sizes that cannot be adequately simulated using brute Monte Carlo methods or even with fast sampling techniques.

Nobuyuki Nishiguchi, vice president and general manager at STARC said, "Our member companies are all very concerned about the impact of process variation when designing at advanced nodes and chartered STARC to develop a statistical design flow that will enable them to productively create robust, power efficient advanced SoC designs. A key missing piece in our STARCAD-CEL 3.0 flow was the ability to perform statistical timing analysis on critical paths that contain embedded memory.”

Nishiguchi continued, "We adopted Altos’ Variety MX to solve this problem because of its impressive performance that is independent of memory size. We were able to confirm that the tool’s accuracy for both delay mean and sigma satisfied our criteria perfectly when compared against Monte Carlo simulation of a complete memory instance. As often over 50% of chip area is embedded memory, we believe being able to create accurate statistical memory models in very reasonable time will greatly enhance the usefulness of any statistical design methodology.”

"STARC has been pioneering and validating the use of statistical static timing analysis (SSTA) as an improved methodology for advanced complex designs for a number of years," said Jim McCanny, Altos CEO. "We have enjoyed working with them on the deployment of our Variety standard cell statistical characterizer and are proud to have our tools adopted for the very challenging task of creating accurate SSTA models for embedded memory. STARC is widely recognized for its very detailed and thorough validation of new technology so to be included in their STARC-CEL design flow is a great endorsement of Altos’ memory characterization tool suite.”

The Variety MX Advantage

Variety MX uses “dynamic partitioning”, i.e. partitioning based on a full chip simulation of a circuit using a “fast-spice” simulator. This has the advantage of being able to account for effects common at advanced process nodes such as interconnect coupling, power supply gating and transistor stress. As “dynamic partitions” are small, they can be characterized by a “true-spice” simulator providing highly accurate results. Furthermore, without partitioning nearly all memory instances are too large to be simulated with traditional or fast Monte Carlo methods rendering statistical characterization impossible.

To account for the impact of process variation Variety MX leverages Altos’ proprietary “inside view” methods that reduce the overhead of local (random) variation characterization to 3X or less of nominal characterization, in contrast to Monte Carlo simulation which will be at least two or three orders of magnitude slower. The statistical library models generated by Variety MX are consistent with those created by Varietytm for standard cells. This includes support for statistical current source model formats, CCS VA from Synopsys and S-ECSM from Cadence.

Variety MX supports multiple “fast-spice” simulators including Synopsys CustomSim (HSIM®, NanoSim® and XA), Mentor’s ADiT and Cadence’s Virtuoso® UltraSim Full Chip Simulator for “fast-spice”. Synopsys Hspice®, Cadence’s Spectre®, Mentor’s Eldo® and Altos’ Alspice are all supported for “true-spice” simulation.


Variety MX is available now. Altos’ products are sold directly in Europe, India and North America and via distributors in Japan, Taiwan and Korea.

About Altos

Altos Design Automation provides ultra-fast, fully-automated characterization technology for the creation of library views for timing, signal integrity and power analysis and optimization. Altos’ products support standard cells, I/Os, embedded memories and custom macros. Altos advanced modeling solutions are used by both corner-based and statistical-based design implementation flows to reduce time to market and improve yield.

Privately held, Altos was founded in 2005 in Santa Clara, CA. Its corporate headquarters is at 4020 Moorpark Ave., Suite 100, San Jose, CA 95117. Telephone: (408) 980-8056. On the Web at:




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