Out in Front: March 14, 1996

As pc-board clock and data rates rise, you face an increasingly difficult problem of designing complex, high-frequency systems. Three companies—Viewlogic, Interconnectix, and Incases—have recently announced products to help you get the job done. Viewlogic's Interconnect Signal Integrity Synthesis (ISIS) software constrains board placement and routing (P&R) simultaneously in multiple domains. ISIS combines Cooper and Chyan's Specctra floorplanning, P&R technology with Quad Design's Motive timing and TLC/XTK signal-integrity (SI)-analysis tools. You use the ISIS spreadsheet-based Constraints Management System (CMS) to define and add constraints during the front end of your board design before component P&R. This capability allows you to perform what-if analyses on your design. You can define your own system constraints or, using clock and component model data along with Quad's analysis tools, ISIS' Automatic Constraint Synthesis (ACS) automatically generates the timing and SI constraints to meet system specifications. ISIS then uses these constraints to drive the Specctra P&R tools.

You use ISIS within a Mentor Graphics design flow, in which the tool integrates with the company's Design Architect and BoardStation tools. ISIS comes in three versions: Floorplanner (floorplanning and first-order timing analysis), Analyzer (ISIS floorplanner, CMS, EDA interface and first-order transmission-line analysis), and Designer (ISIS Analyzer, autointeractive high-speed routing, high accuracy analysis and ACS). Viewlogic plans to add other options, including electromagnetic compliance (EMC), power and thermal analyses, this year. ISIS will be available for Unix-based systems in the second quarter and for Windows-based systems in the third quarter. Prices start at $12,000.

Interconnectix has expanded its current interconnect-synthesis EDA offerings with two new products, IS_Optimizer and IS_Multiboard. IS_Optimizer optimizes routed board interconnects according to your timing and SI specifications. The tool takes a physical description of a routed board, employs a transmission-line simulator and parameter extractor to detect any electrical-rule violations, and generates an improved layout that meets timing and SI constraints. The simulator uses I/O Buffer Information Specification (IBIS) behavioral models to help determine if the design meets electrical specifications. You can integrate IS_Optimizer with EDA-design-tool suites from Cadence (San Jose, CA), Mentor Graphics (Wilsonville, OR), PADS Software (Marlborough, MA), and Zuken Redac (Santa Clara, CA), allowing you to take designs from these tools and import them to IS_Optimizer for network optimization.

You use IS_Multiboard for systems comprising multiple physical subsystems, including pc boards, multichip modules, connectors and cables. The tool uses a spreadsheet input, describing the entire physical system, to analyze and verify timing and SI for networks that span these physical subsystems. IS_Multiboard lets you use Spicelike representations for parts of the multiboard system that you have not yet physically implemented. You then replace these abstract descriptions, used for feasibility studies and system partitioning early in the design process, with physical descriptions as you define them. IS_Multiboard also supports IBIS models for components, which it uses to analyze system performance. To help you meet your specifications, the tool performs termination synthesis and driver optimization on system-level nets. IS_Optimizer and IS_Multiboard run on Unix-based workstations and cost $25,000 and $15,000 respectively.

In version 4.1, Incases adds several features to Theda, a pc-board-design system that Incases acquired from Computervision (Van Nuys, CA). Theda derives some of its new features from EMC-Workbench, a suite of EMC tools obtained from Siemens Nixdorf (Burlington, MA). Theda now includes SI- and electromagnetic-radiation analysis to guide board P&R.

Theda accesses a library of more than 7000 components, many containing EMC data. Theda links its library to the Exlin EMC-simulation library, allowing you to use EMC models during your design. Theda also supports IBIS for SI models. Talc, a transmission-line program from EMC-Workbench, calculates transmission-line models for SI analysis. After board P&R, Theda passes the data to the Fast Reflection And Crosstalk (FREACS) and Computation of Radiation (COMORAN) SI and EMC simulators.

FREACS provides a 2-D simulation of reflection and crosstalk for multilevel pc boards with uniform ground planes. The program uses transmission-line electrical parameters that Talc determines. COMORAN provides a 3-D electromagnetic near- and far-field analysis on multilevel pc boards. You use COMORAN to determine radiated spectrum, field scan, and radiation pattern. After running FREACS and COMORAN, you check if the design meets SI and EMC specifications. If not, you can redo violating portions of component P&R to eliminate any problems.

Theda runs on Unix-based workstations from Hewlett-Packard, IBM, Silicon Graphics, and Sun. Incases is working on a Windows NT version of the software, with an anticipated release in the second half of the year. Prices for Theda 4.1 start at $18,000.
—by Jim Lipman

Incases Engineering North America, Dallas, TX. (214) 373-7344.

Interconnectix, Portland, OR. (503) 684-6641.

Viewlogic Systems, Marlborough, MA. (508) 480-0881.