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December 2016 • The PCB Design Magazine 63 within the layout application, and then convert it to an area fill. RF designs incorporate a variety of differ- ent design elements than what the average PCB designer is used to seeing. For instance, certain sections of routing are actually components in the schematic. They are referred to as routed components, and the PCB design tools that are enhanced for RF design will have the ability to route a parametric component. The designer will start routing the parametric component, and the design tools will add virtual pins to each end of each segment allowing for those lumped components to be represented in the schematic. The design tools will also assign and store for each lumped component the model type for ex- ternal RF simulation tools. This brings us to one of the most important enhancements of RF-specific PCB design tools: the ability to connect to external RF simula- tion tools with a bi-directional data transfer. In this way, the external simulation tools can send their designs over to the PCB design tools for incorporation into the design, and the design tools can send over their data for simulation. The bi-directional work flow between the two tools will allow the designer to easily simulate and then incorporate those simulation changes back into the main design. This is a much more efficient design flow than what was available with older single-directional design flow tools that would force the designer to have to re-cre- ate the design changes manually once the simu- lation was complete. The last enhancement to talk about is the ability to add RF specific components dynami- cally to the design. Older design flows would require the manual creation of a specific RF component shape on the layout side as well as the addition of a corresponding symbol in the schematic. Once annotated, the user would then go through a process of many manual ed- its and annotations in order to get the correct size and shape of that component finalized in the layout. With the ability to automatically generate RF components parametrically, however, the designer need only get the component attri- butes forward-annotated from the schematic into the layout, and then the parametric com- ponent generator can create the RF component on the fly. With a parametric component gen- erator, the shape and parameters of the compo- nent can be altered by the designer in the layout without having to manually alter and annotate a regular static component. For instance, the parametric generator can change the size, trace width, and ring count of a spiral inductor producing the desired part that now only needs to be placed and routed. Since the parametric generator creates RF com- ponents with reference designators, the design can be easily annotated back and forth with the schematic and will also be in synch with exter- nal RF simulators. RF design can bring some real challenges to the table, and as we've discussed, the unique requirements of an RF design can be greatly helped with some of these RF design specific software enhancements. None of us will prob- ably ever need to connect the admiral with the joint chiefs in Washington DC to avert an in- ternational conflict like Sparks did on the late, late show. But hopefully some of what we've covered here can help you and the rest of your design team to be successful in your efforts and to become those go-to RF design specialists that everyone depends on. Aye, aye, sir! PCBDESIGN Tim Haag is manager of customer support and training at Intercept Technology. "SPARKS" TO THE RESCUE IN RF DESIGN