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This technology is favored among the graphics set. It's a common request when doing MIPI and HDMI or other graphics pipelines. A quick look at application notes from NXP regarding display port recommends 5 mil lines separated by 7 mils. One lane of two tracks adds up to 17 mils plus the personal space that a diff-pair wants adds 15 mils per side so 47 mils (1.2 mm) total. Fortunately, the spacing rule does not stack so only the higher of the two values apply when traces with different spacing rules meet, not the total. Figure 4. The Net Class-Class tab is where priorities can be set. As usual, the Objects columns named Type, S, and Name are where the filter can be invoked with a right mouse-click. Creating or managing Net Class membership is started with a right mouse-click on the net or class names in the Name column. In this case, the POWER GROUP is up for editing. My first exposure to the differential pairs was on an edge router. These are big enterprise boards that carry the data from the main internet connection to users throughout the office. I did two of these things on a six-month contract. On the outside, it's a box with a row of ethernet ports across the front panel. On the inside, it had four individual processors, a memory controller and a row of expansion slots after the solder-down memory. One part of the 12-layer board was set aside for the power supply. The power supply is normally a separate thing since it runs hot. It's also one of the most likely failure points once everything has settled into the bathtub curve for reliability. The rest of the board was separated from the power supply with a wide route keep-out zone that covered the ten internal layers and parts of the outer layers. That wasn't my idea. There was a man in Rochester NY who was a Regulatory Engineer. He was managing the power supply from 110/120VAC in to 5VDC out. He had width and air gap provisions for every node. A big transformer or inductor (make a fist!) connects to a thumb-sized resistor. It was tricky bringing the two leads together without breaking the rules for the transformer and inductor. 5 www.cadence.com Controlling Air Gaps Using OrCAD X and Allegro X Tools