Issue link: https://iconnect007.uberflip.com/i/981887
MAY 2018 I DESIGN007 MAGAZINE 71 nology required for fabrication of the board, and the parameters for assembly are complex and have to be agreed by the designer in con- junction with the production team. When con- sensus is reached, the EDA system needs to be flexible enough to accommodate these param- eters in the technology files that form part of the design database. All of this might seem a like lot to replace a simple piece of paper, but this addresses prob- lems that have held back constraint-driven design over the last couple of years. Tools such as the CR-8000 now provide engineers with a practical constraint-driven design approach. What used to require a multi-tool and often a multi-vendor, mix-and-match system, is now possible with a single, coherent modern design tool allowing constrained-driven design on single-board and multi-board systems in both 2D and 3D. DESIGN007 Ralf Bruening is a product manager and senior consultant at Zuken's EMC Technology Centre in Paderborn Germany, focused on Zuken's high-speed design, SI & EMI verification tools. Constraining for EMC/EMI Next, constraints concerning the electromag- netic compatibility capability (EMC/EMI) of a design need to be considered in a similarly integrated way as the signal integrity, thermal and manufacturing issues. However, this poses a slightly different set of problems. Because EMI is closely related to the physical layout of the design, any analysis is only valid once the design has reached the physical stage. So for efficient design verification, algorithms devel- oped with the University of Missouri-Rolla (now Missouri University of Science and Tech- nology) have been implemented into a fast EMI worst-case prediction checker (Figure 7). This allows an EMI analysis on differential and common mode noise (such as parasitic antennae and I/O coupling) at given frequen- cies, as well as analysis of radiation from power planes, including decoupling analysis. Such an approach is better suited to a concurrent PCB design process, rather than traditional full wave numerical EM analysis approaches. But there is always the risk of over-constrain- ing, rendering a design unbuildable or eco- nomically unviable. The engineering trade-offs in the number of layers, manufacturing tech- Figure 7: Embedded fast EMI verification of PCBs.