SAN JOSE, Calif. — Cadence Design Systems Inc. says it has boosted the depth and accuracy of its analog, mixed-signal tool set by adding the Nebula fast field solver technology of Agere Systems to the latest version of Cadence's Assura RCX parasitic extraction and layout platform.

Agere Systems granted Cadence exclusive rights to commercialize and productize Nebula, which Cadence has renamed the Assura-FS (field solver).

Kathy Krisch, director of modeling and design kits at Agere, said Assura-FS brings a supplementary fast field solver capability to Cadence's device-level extractor. "Nebula was built in-house at Agere by David Long and Sharad Kapur, and we used the tool in conjunction with Cadence's RCX for our own designs," said Krisch. "We licensed the Nebula technology to Cadence and both companies worked together to make it a product."

The tool will be offered as an option to the Assura-RCX pattern-matching extractor, said Terry Ma, senior product-marketing manager at Cadence. Users will perform full-chip extraction with the RCX tool and use Assura-FS for critical nets and regions.

Kapur, a member of Agere's technical staff, said that the field solver by default is accurate within 2 percent of Spice. Users can adjust the FS option to get accuracy within 1.5, 1 and 0.5 of a percentage point of Spice, but run-times will increase twofold for each half-percentage point of accuracy, he said.

Until now, Cadence has not had its own field solver technology, so RCX users were required to run RCX and then do another extraction with third-party field solvers. The new combo, said Krisch, allows customers to run both tools simultaneously on a design from one graphical user interface. The tools then will generate a merged netlist.

"One of the things that drives a CAD decision today is not just the standalone capability," said Krisch. Integration and how a tool fits into a flow are also important. "This is integrated into a tool that we are using here for the full chip, and that tool [in turn] is integrated into a CAD environment that we are using at Agere to do our entire design."

Block by block

Using a common GUI or text entry box, users can choose the nets or blocks they want the field solver to handle. Then, RCX will run extraction on the rest of the design as a default. "You can also do each sub-block with the FS tool and then run RCX for the final check on the full chip," said Kapur.

Kapur said that the field solver has unlimited capacity but gives the right mix of performance and accuracy on blocks at 1,000 transistors or less. Above the 1,000-transistor level, "it will take longer to run. You can put in an entire chip, but it is going to take you a week to do it," he said.

Cadence said that in addition to being proven to work with RCX at Agere, boosting the accuracy of overall extraction, the Nebula can also account for numerous issues that are popping up in nanometer-scale designs. The tool, for example, can account for via effects, trapezoidal wires, conformal dielectrics, air gaps and process bias, according to Kapur.

The RCX and FS combination is a part of the Cadence Analog Design Environment tool suite. A fully loaded RCX tool with FS and other features licenses for approximately $100,000. The RCX tool alone starts at $65,000.

For current RCX users, a perpetual license for the RCX-FS add-on is priced at $60,000, while a one-year time-based license is priced at $21,600.