The Value of Integrated Schematic Libraries

Why talk about schematic libraries in a blog focused on system verification?  Most systems (printed circuit boards on up) are still designed using schematic capture software.

I was talking to a manager at a medical devices company the other day about his company’s schematic symbol library.  Like most libraries, it contained schematic symbols and a few “extra bits” of data such as internal part numbers and references to the PCB footprints.  I then asked if his engineers typically ran signal integrity analysis and functional verification.  He said yes, these were common tasks.  Finally, I asked how the engineers passed the correct model names into the SI tool and how they brought the VHDL/Verilog models and correct timing into the simulations and was told “Its a manual process”.

A well planned schematic library provides all the hooks needed for downstream design and verification processes including functional simulation and signal integrity analysis.  All the major “big company” design systems support these capabilities.  But none of them do it out of the box.

Any company designing high speed and/or complex boards should be using a customized schematic library that supports their entire design process.  Using the basic out of the box library architecture with a high end design system is like running a Maserati on cheap gas.  It may look like you are saving a little money but, you are not getting the performance you paid for when you bought the more expensive tool set and your engineers are wasting time on manual processes.

Unfortunately, when most companies purchase their first copies of a new design system, they are in a hurry to get started using it and do not take the time to think about how the libraries should be structured.  Once they have done a few designs, changing the libraries becomes too disruptive to even consider.  So, they plod on for years, living with the limitations imposed by their first library architecture.  At some point, if a company plans to stay in business and keep using the same tool set for a long time, they need to calculate the long term return on an investment in upgrading their schematic library.

If you decide to redesign the library at your company, you may find everything you need to know in your tools documentation.  If you need help, call me.

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