Technical Publications
Distributed Autorouting Using XtremeAR
Learn about XtremeAR process flow for faster autorouting of PCBs by connecting multiple workstations working together, real-time, on the same design. This process can be used as the ultimate team design environment. Faster results can lead design teams to try different routing options to find the optimum route strategy. This paper covers system setup, the required environmental variables and the necessary licenses to start the XtremeAR session. It also describes the strategies for session controls through the XtremeAR client Manager, XtremeAR recording/playback & the performance analysis for XtremeAR session.
IBIS Modeling of LVDS Buffers
This report provides detailed information on a study of the effects of internal series termination between positive and negative I/O pads in LVDS buffers. Comparisons between IBIS and SPICE simulations are used to emphasize these effects. Different loading conditions and modeling approaches are considered. IBIS modeling approaches for LVDS buffers are presented. Model validation shows the power of these approaches over other conventional techniques.
Data Management for Electronic System Design Environment
"An integrated client/server database is used as both an information source and an exchange platform..."
This paper discusses methods for shortening design cycles, collaborative design, and the need for a master database accessible by all team members. Exchange channels needed to connect workgroup and desktop environments are described, and ways to facilitate synchronization and updating processes are given. This object-oriented approach to managing part, library, and product data allows for sophisticated control and coordination of design information.
Web-Based Part Development
"Efficient, accurate EDA library?for design-anywhere, build-anywhere methodology."
This paper explores the universal need for a web-based part development system that would make searching for and gathering reliable information easier and faster. This paper describes the principles behind a web-based part development system, and explains where such a system would fit in the overall design workflow.
Design Data Management for Multi-Site, Multi-EDA Tool Organizations
This paper describes the Mentor Graphics Data Management System (DMS) program for the collaborative Product Definition management (cPDm) market, the challenges this program faces, and ways that these challenges have been met. Major DMS functions are discussed, and summaries from DMS installations are included. Also included is an Executive Summary, information on the DMS core functionality, program and product assessments, DMS success stories, and user information.
ODA Table Symbol Reference Guide
"[Implementing] naming conventions that are easy to recognize and use…[making] storing and finding symbols within the library very easy."
This reference guide details the differences between the ODA Master Library and the standard Mentor Central Library. Several procedures for using the ODA Master Library are explained, including setup, schematic symbols, cells (PCB footprints) including padstacks, and PDBs. The use of symbols in the library is explained, as are symbol partitions and symbol naming conventions. Detailed information on creating symbols is provided, and instructions for editing existing symbols are provided. There are numerous examples, including graphics and tables, which illustrate how to create and modify symbols. Finally, portions of two ODA symbol libraries have been included to provide further information and examples.
Printed Circuit Board Routing at the Threshold
During the past several years, we have witnessed an unparalleled wave of technological innovation, followed by rapid market adoption. Spurred on by global competitive pressures, new product introductions have come fast and furiously. Sustaining this blistering pace means decreasing both the time and cost of product design cycles. To successfully collapse design cycles in this way, manufacturers must achieve a significant increase in productivity -- the holy grail of the technology-driven marketplace. It follows that design tools must also become more productive to facilitate attainment of this goal. This paper discusses the market drivers leading to tool innovations and a few results, including: high-density routing, high-speed design, and PCB design environments.
Integration of Embedded Components within PCB Structures
Electronics companies are seeing an increased use of embedded components in their PCB designs. Embedded components are fabricated into a printed circuit board and allowed on internal and surface layers. There are several factors driving the trend to use of embedded components over discrete components.
Increased functionality of active devices has the number of passive components growing. The number of discrete passive components is, in many cases 70 to 80% of the total part count and continues to rise as passive-to-active ratios grow. While active devices are being packaged into large pin Ball Grid Arrays (BGAs) the ideal surface placement space for discrete passive components becomes more difficult to obtain.
Also, increased numbers of capacitors are needed as device speeds and digital content increases. Capacitors must be placed close to the IC pin to avoid unacceptable noise or timing delays. Eliminating discrete passive components from the surface layers and embedding them, thus frees surface space and allows the passive devices to be closer to active pins.
Embedded passive components allow for higher frequency (faster) PCBs. The linearity of signals through embedded passive components reduces inductance of "core to surface, return to core" signal paths. Along with lower inductance, embedded passive components can lower power system impedance and radiated emissions - improving the overall electrical performance of a PCB. Also, reliability of the PCB is improved through reducing the overall number of solder joints.
For leading-edge companies, there is also the need for embedded active devices. While additional surface space is made available for other active devices, embedded active devices are not packaged, leading to smaller footprints for the active device. The driving factor to use embedded active devices is reduction in the PCB size format while increasing the active functions.
TeamPCB: The Next Paradigm Change Begins
Everyone in the electronics industry is looking for ways to increase productivity, reduce costs and shorten time-to-market. Processes have been reviewed and tweaked over and over, and serial methods of round-the-clock and round-the-world design of large boards has become popular again. Since PCB software vendors heralded design reuse and variants tools in the early-to-mid 1990's breakthrough methodology adjustments or paradigm changes that can enable dramatic productivity improvements have not been unveiled. It seems as if just keeping up with new manufacturing technology and high-speed requirements has kept EDA vendors fully occupied-until now. The Systems Design Division of Mentor Graphics delivers TeamPCB and a series of other new products this year.
TeamPCB is available as an add-on option for Board Station and Expedition PCB , running on Windows and Unix platforms.
Simultaneous Design Technology: A Revolution
New software technology has been developed that enables effective parallel design of a circuit board. This technology enables multiple designers, processes and heterogeneous tools to work on the same design database simultaneously and achieve significant gains in design productivity. But, unlike classical divide - and conquer methods that break down a design into pieces and operate on them independently, this new technology enables concurrent progress on a common database, automatically synchronizing changes and resolving conflicts - a first in the EDA industry. This paper focuses on the methods and applications of new parallel design technology that offers a novel paradigm for circuit board design. Topics include:
- Review of design problems and concurrent methods
- Parallel design architecture
Applying the parallel design technology to:
- Layout
- Autorouting
- Circuit and Board Design
- System Design
Unbalanced Tracks and Differential Impedance
"The calculation of the differential impedance of unbalanced tracks is more complicated…because geometrical and electrical symmetry cannot be used."
This paper discusses the effect of track unbalance on the differential impedance value and provides a method for calculating that value. Differential impedance was determined from the capacitance and inductance matrices of the unbalanced tracks, and the results for both edge-coupled microstrip and stripline are given. Several tables and graphs illustrate the variations.