Issue link: https://resources.pcb.cadence.com/i/1533022
Creating Bespoke Design Rules Tailored for Each PC Board Maybe it's the way I was raised but I want to start out with the analog nets and highlight those. A well-trained eye can pick out the RF traces from the antenna or connector through the matching network and right to the radio. Where there's an input, there's an output; sometimes more of one than the other. There's something to be said for browsing through the data before jumping into the board design. Refine those rules to the extent possible so that you have an easier time as the job proceeds towards tape-out. You may find that the component footprints leave something to be desired. If you don't want to see copper pour under your inductors, you can create the voids after the fact once the ground copper is poured. A more efficient way is to put a route keep-out between the pads as part of the footprint. You draw one route keep-out and update the inductor (or whatever) so that every time you pour a new shape, it honors the keep-out regions for all instances. The general idea is to capture design intent in a way that makes it less likely that a defect of some kind makes it all the way to tape-out. Figure 1. A slice of the physical constraint window where different classes of connections receive their width requirements. The red box indicates the location where we invoke the filter to narrow down the field. Note in Figure 1, the DIFF100 class is expanded to show line width and air-gap for each layer type along with a neck-down width and gap for tight routing channels. All other air-gaps are controlled in the Spacing tab. The red box near the upper left-hand corner indicates the area where you can Right-Mouse-Click to access the Filter. Just below the constraint manager is a bit of graphics that show what happens when you cross into a Constraint Region. Traces going south of the green Constraint Region outline automatically slim down to a preset regional rule. I would use those regions sparingly, affecting as few layers as possible. The neck-down option is more flexible for trace widths. The regions are best for supporting dynamic copper where you can use a smaller air-gap in support of fine-pitch devices. I would start with the default rule set. It can be copied and modified to allow the shapes to close in on the other geometry. The trace widths would remain the same as the default rules unless that is going to be impossible to fan-out. The idea is to maximize the copper web for the power and ground plane layers. Again, I would rather create constraint regions one layer at a time than the blunt instrument of an all-layer region. This gives us more latitude to handle exceptions. 3 www.cadence.com Controlling Trace Width Using OrCAD X and Allegro X Tools