Design007 Magazine

PCBD-Dec2016

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62 The PCB Design Magazine • December 2016 You are Sparks, the go-to specialist who will take care of business. But this isn't standard PCB design; this is RF design with different, unusual design requirements that require specific design tool resources to complete the design. So, let's take a look at some of the common require- ments of RF design, and what specific design software enhancements are needed to help PCB designers to better accomplish their task. One of the first things that will help the PCB designer in the RF world is the ability to manually modify their components on the fly as needed. Often the quickest way to get the desired shape in an RF component is to simply do a manual change to the part, and RF specific design tools offer the designer this flexibility. Changes in a pin shape, moving a pin, or add- ing fill should be able to easily be done at the component level. RF specific design tools will also feature many routing enhancements. Among those is the ability to add via fencing automatically. It is very helpful for the designer to be able to specify an area either by selecting a pre-existing object to use as a fence template or by manu- ally drawing in the fence shape that the design tool will then fill in with vias. These via fill algo- rithms will usually include the ability to specify the via part to be used, the net, the spacing and how many rows of vias are required. Another important routing enhancement is the ability to copy sections of routing. This will give the designer the ability to reuse copied sec- tions of routing, or export routing to another design. Different options here allow copying to other layers, copying specific portions of rout- ing, setting anchor points for the copied routing to paste to, etc. The ability to copy routing is a pretty standard function for PCB design tools, but in RF design there can be an even heavier reliance on these capabilities. Area fills will also have enhanced function- ality, and one of those is the ability to create an area fill as if it were a routed trace. This is very useful for RF designers so that instead of manu- ally digitizing multiple vertices of a complex area fill, they can instead route in their area fill as if they were routing in a very fat trace. Other area fill enhancements will include the ability to change the parameters of the fill to specify cross-hatching and outline widths. Also, there will be specific control over pins in the fill to specify pad sizes, clearances, and thermal di- mensions for all pads or just specific pads and/ or specific layers. And it is also helpful to be able to create fills within component shapes that can then be replicated for each placed instance of that component. One enhancement that we've found really useful in the RF design realm is the ability for de- signers to manually draw in primitive graphical shapes, and then convert those shapes to intelligent net ob- jects. This gives the designer the ability to draw in either primitive paths or poly- gons, or complex polygonal shapes such as arcs, circles and rectangles—and then convert those primitives to intelligent traces and area fills that carry net informa- tion. This eliminates the need for a designer to spend lots of time trying to create a uniquely specified area fill shape when instead they can create their shape out of the standard drawing tools "SPARKS" TO THE RESCUE IN RF DESIGN

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