High-Frequency PCB Co-Design Solution Obsoletes File Translation
By Michael C. Heimlich, AWR, and Per Viklund, Mentor Graphics Corporation

For more than a decade, printed circuit board (PCB) and microwave design have been converging as engineers create products that increasingly integrate analog, digital, and RF/microwave circuits within the same board. Over the same period of time, EDA tools have been slow to converge and failed to provide an integrated flow across these electrical design domains, instead lengthening the time required to bring a product from concept to creation and adding significantly to its cost.

However, AWR and Mentor Graphics have introduced a converged EDA solution to this cross-domain problem, called AWR Connected for Mentor Graphics Expedition, which the companies jointly developed. It provides the first truly integrated flow between PCB and high-frequency design. The product links AWR’s Microwave Office high-frequency design software and Mentor Graphics’ Expedition PCB design layout tool, and allows all levels of the design flow, from library management to schematic entry, layout editing, circuit simulation, electromagnetic (EM) analysis, and design rule checking, to be fully and seamlessly integrated.

Prior attempts at creating an integrated flow between PCB and RF/microwave domains have relied on file translation (IFF format), which offered only partial integration because it accounted only for the ability to capture library, schematic, and layout information. Even then, the transferred schematics often could not be simulated in the high-frequency software for lack of models, or could not be laid out in the PCB tool because part number information was missing or incorrect. In short, there has continued to be a lack of automated access to microwave EM analysis and circuit simulation from the PCB design tool, or to PCB data management and design rule checking (DRC) from the high-frequency design tool. As a result, even the best solutions require manual intervention, as someone spends significant time (1 man year or more) to perform “library” work only to realize that the resulting solution is broken with each updated release of the tools.

AWR Connected for Mentor Graphics Expedition represents an entirely new approach to high-frequency co-design because it obsoletes file translation and its idiosyncrasies. The key to this new integrated flow is that it is not based on file translation but rather on a dynamic, real-time library synchronization flow that eliminates manual, time-intensive library work that has so stymied past attempts. With AWR Connected for Mentor Graphics Expedition, the RF/microwave library in Microwave Office is created at the touch of a mouse button, dynamically and transparently, with no user intervention. It begins with the first transfer of data from Expedition and includes all the information about parts and manufacturing required for the high-frequency circuit design, including symbol, part number, model, footprint, padstacks, and layer stack-up. This information is constantly updated from the master corporate library on the Mentor Graphics side of the flow every time information is transferred between the two environments.

When integration occurs at the database level, as it does with AWR Connected for Mentor Graphics Expedition, the resulting data and messaging model behave similarly in many respects to that of Web servers and the Internet. That is, it can connect multiple Microwave Office projects or RF blocks to a single Mentor Graphics PCB design without the need to know the type of workstation on which either tool is running or where it can be accessed in the user’s virtual private network. As a result, EM analysis and circuit simulation can be performed in Microwave Office software from Mentor’s tools on the same computer, via a network, or over the Internet.

Likewise, schematic messages are sent to the appropriate part of the Microwave Office toolset or to Mentor’s DxDesigner or Design Architect schematic capture tools depending on the direction of the flow, and layout is accomplished similarly in both Microwave Office software and the Mentor Graphics tools. Messages can include requests for library, schematic, layout, simulation, or analysis events with a complete set of data to handle full and incremental actions. The process is illustrated graphically in Figure 1.

Past PCB libraries rarely had high-frequency circuit simulation models and so could not compensate for the difference between PCB pin location and RF or microwave modeling reference planes. AWR Connected for Mentor Graphics Expedition uses dynamic model creation to eliminate this problem and allows pin locations to be moved without breaking connectivity as the design moves back and forth between the two design environments. Extractions can also be created for AWR’s ACE circuit extraction tool or AXIEM 3D planar electromagnetic (EM) simulator as well as any third-party EM solver integrated within AWR’s open design environment EM Socket. The extractions are performed while preserving the ability to perform circuit simulations with Microwave Office, including its APLAC harmonic balance engine, directly from Mentor circuits, or after transferring schematics and layouts from Mentor to AWR at any point in the design flow. The required AWR-specific parts library is created “on the fly,” including symbols, part numbers, footprints, and even models.

The value of this synergistic approach is perhaps most evident at the end of the design process when trying to negotiate a DRC-correct circuit that has accurate line spacing and parts placement within RF or other blocks, while still meeting RF circuit simulation performance. Real-time DRC can be run from within Expedition to ensure manufacturability, while updated circuit performance simulated in Microwave Office simultaneously achieves the desired electrical performance.

AWR Connected for Mentor Graphics Expedition has been thoroughly evaluated by a number of large multi-national firms and in particular at Alcatel Lucent. “We use Mentor Graphics tools for PCB design and AWR’s Microwave Office for RF simulation,” said Xavier Leblanc, hardware tools manager at the Alcatel Lucent France Platform Hardware Center. “During our testing of the integrated flow between these two tools, we were able to significantly cut our design times. By concurrently designing the RF circuits in the context of the rest of the PCB, we were also able to reduce our design and manufacturing re-spins, which helps us meet aggressive time-to-market goals.”

Summary
AWR Connected for Mentor Graphics Expedition is the first cross-vendor solution that provides full, automated integration between dissimilar PCB and high-frequency circuit design flows. It is unique in its ability to include all aspects of the process, not only including library management, schematic entry, and layout editing, but also circuit simulation, EM analysis, and design rule checking. The resulting synchronized approach eliminates the enormous amount of work required with file-based approaches, and allows teams to design next-generation products in far less time at less cost. More information and a video demonstration about AWR Connected for Mentor Graphics Expedition is available at www.awrcorp.com

AWR
www.mentor.com
TXTLINX.COM104
Email this article to a friend!