Losing sleep over critical net routing and layout?

By Kanchan Vaidya

High-speed memory interfaces and other sensitive connections multiply design complexity, forcing designers to meet tighter and tighter constraints on an ever-growing number of critical nets. But why lose sleep over it?

All you need for routing critical nets are a good understanding of the constraints, knowledge of how to use them in the layout process, and a good constraint management tool to tie the constraints and routing together. The end result is a fast, efficient feedback loop that results in a reliable board design.

PADS Professional seamlessly integrates constraints with layout, then adds sketch routing to save PCB designers a lot of time and effort.

Simply follow these 3 steps:

  1. Set up constraints: PADS Professional enables the user to enter high-speed constraints such as differential pairs, length, delays, etc. in a very easy-to-use, spreadsheet-based constraint management platform. Constraints can be defined, altered, and verified throughout the design cycle and are automatically synchronized between schematic and layout.
  2. Sketch Route: Once the clearances between PCB objects, class-to-class clearances, and trace widths have been defined in the constraint manager, the designer can simply sketch where the traces should go. With PADS Professional, you can route multiple traces simultaneously, while adhering to all design rules.
  3. Tune the nets: Once you’ve routed the nets with sketch route, you can tune them to match length and delay constraints. You can either fine-tune each net with manual tuning as shown in the picture below.

    Or you can use “auto-tune” to quickly tune nets at the push of a button. With the speed of sketch route and auto-tune you can leverage the two-step process as a ‘what-if’ procedure. Quickly lay down traces, tune, and decide whether the traces are optimal.

Check out my latest webinar “Dealing with dense highly constrained designs in PADS Professional” to get more details on how to make the routing of complex busses a matter of minutes not hours.

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This article first appeared on the Siemens Digital Industries Software blog at