Issue link: https://resources.pcb.cadence.com/i/1526746
22. Look at the cell named Conductor in the image above, then to its right, click on the field value in the column named Min (found under the Lined Width column). 23. Now highlight the value there and change it to whatever your minimum trace width needs to be for any power trace (10 mils, or 0.254 mm in this example). 24. Notice the units are listed under the Min column header at the top. Now, the Physical Constraint Set (POWER1) that you applied to your Net Class (POWER) can be changed at any time to set all traces in the power class to the desired width. Impacts: f Power Consumption - Easy to specify minimum trace width to ensure proper current carrying capacity, regardless of the net, as long as it's in the right class or a ground/power net. f Signal integrity - Easy to specify impedance on any traces within the same class, regardless of protocol. f Efficiency - No need to individually set trace widths. Apply one rule to many nets and objects all at once by capitalizing on classes for physical properties. However, while net classes are very powerful, we may not always want to set the same physical or electrical properties to all nets in a protocol for instance. That's why we also need to be able to set properties and rules by groups of nets that may not have the same physical or electrical properties. In the next section, we will address the addition of net groups. 2. Net Groups Definition: A net group is a collection of nets that are common (usually in functionality and operation) across all domains. Application: Use Net Groups when you need to apply general rules across multiple property domains, i.e., even if traces have different physical and electrical properties and constraints. In most cases in PCB design, we have nets and traces that can't carry the same widths or impedances, but they're nonetheless part of the same protocol or device. In other words, devices can carry nets that require different physical and electrical properties. When this happens, we still want to remain organized, so we introduce nets that belong to a specific group, regardless of their physical or electrical properties. In this section, we will: f Create a Net Group f Distinguish between Net Classes, Net Groups, and their benefits f Understand why both Net Groups and Net Classes are important We will first create the net group and then a general spacing rule, and then we will apply that general spacing rule to that net group, even though some of the nets are part of their own classes and have their own physical and electrical properties. 13 www.cadence.com Part 1 of 5