There is an old saying, “You get what you pay for.” Does this mean that you should not expect too much from free software? After all, free software usually comes at a price: the results might be inaccurate, the software might be time-consuming to set up and use, and the tool might overlook issues that require a revision to mitigate.
But HyperLynx DRC is the exception to the rule. In this month’s column, I will review Mentor’s new HyperLynx DRC Free Edition, which provides analysis tools that complement any PCB layout tool that can export ODB++ or IPC-2581B formats.
Amazingly enough, this software is free. You’ll need to confirm registration annually, but that is not a problem; the tool remains free. There is also a more comprehensive, affordably priced Gold Edition.
HyperLynx DRC is an electrical design rule checking (DRC) tool that can automate the verification of complex digital design rules that are not easily detected, such as rules for traces crossing split planes and electromagnetic compliance (EMC). It does not require expert knowledge and can literally save hours of manual inspection. The tool helps one avoid costly errors and oversights, directing the novice high-speed PCB designer to the source of signal integrity (SI), power integrity (PI) and EMC issues.
Even experienced designers make mistakes and overlook small issues that can become major headaches further down the design, assembly, test or production processes. This is particularly true with complex, high-speed designs that have multiple planes and return paths, requiring elaborate constraints on every class of technology. Sure, we can enter hundreds of rules to constrain copper pours, placement and routing, but there is always some manual adjustment that needs to be made as each design is different and has specific requirements. Online DRCs in EDA tools are a great safeguard, but they do slow the design process somewhat. They warn you when a physical or electrical rule is violated and allow the designer to steer clear of common obstacles.
Although the complete list of design rules is very broad, one must manage the following constraints at a minimum:
- High-speed signals–impedance and differential pairs
- Plane and copper pours
- Test points (if required)
Impedance discontinuities and crosstalk can be controlled to some extent by PCB designers during the routing phase if they understand these concepts, which many, unfortunately, do not. Although pre-layout analysis detects issues before they occur, signal integrity, power integrity and EMC issues cannot be properly evaluated until the design has been completed and a post-layout analysis is implemented.
To read this entire column, which appeared in the April 2018 issue of Design007 Magazine, click here.