Review: Right The First Time, by Lee Ritchey

-September 29, 2013

One of the most common questions I receive as an EMC consultant have to do with PC board design. And, no wonder. As clock and data frequencies increase towards 10 GHz, proper PC board design becomes an imperative for proper functioning of the system. The typical "rules of thumb" we used for low frequency boards no longer seem to apply.

So, when I ran across Lee Ritchey's self-published book, Right The First Time - A Practical Handbook on High Speed PCB and System Design (Volume 1), I was intrigued. Both this book and the follow-on volume 2 (Advanced Topics) are available on his web site. Volume 1 is now out of print, but available separately as a 295 page PDF file for just $25. However, both volumes may be purchased for the special price of $95 (the price of volume 2, alone) - a deal I highly recommend.  I'll be reviewing volume 2 later.

There is a huge amount of controversy and continuing discussion regarding rules of thumb, such as rules about decoupling capacitors, right angle bends in clock traces, use of guard traces, splitting of ground planes, and so forth - many of which have been accepted without adequate proof they were even valid for the particular application. Ritchey launches into this early on and much of the book includes simulations and physical experiments proving or disproving many of these "urban legends."

The book includes theory, but is loaded with practical advice, backed up with experimental evidence, on all aspects of PC board design for high speed circuits. Ritchey pulls all this from his over 30 years experience designing hundreds of high-performance, high frequency board designs in his own board design and fabrication shop.

The first chapters cover basics, such as real versus ideal components, transmission lines and how energy moves along them (hint, it's not current flow), the concept of power and ground planes, impedance and reflections, signal integrity and terminations, calculating and measuring impedance, right angle bends, and drivers and loads. Later, he discusses bus protocols, crosstalk and coupling, and single-ended versus differential signaling.

His co-author, John Zasio, contributed several chapters on power integrity - designing the power subsystem, considering DC drop, decoupling capacitors, power system inductance and estimating power dissipation. He also provides a detailed example of a typical power subsystem design, including EMI results.

Richey goes on to discuss IC packages, ground bounce (simultaneous switching noise), examples of good and poorly designed BGA packages, noise margins for various logic families, PCB fabrication and materials, PCB stack-ups, and types of vias. He then goes into the entire PCB design process, including all the recommended tools - extremely valuable for the engineer that has never specified a high frequency PC board. The book concludes with methods of routing traces and documentation of the engineering, fabrication and assembly drawings, as well as outlining the "ideal" component data sheet.

He includes a 24-page glossary of terms used in high speed design and PC board fabrication and also includes bonus information including an extensive bibliography, anatomy of a plated through hole, selecting PCB suppliers, useful equations, and more.

What really struck me was the extensive use of experimental PC boards he fabricated. Never accepting the standard rules of thumb for PC board design, he constructed a number of high speed board designs just for the purposes of publishing accurate design information. This is only something that the owner of a PC board fabrication shop, such as Ritchey, would have the luxury of doing.

Highly recommended and a valuable addition to your design library.

I'll be reviewing Ritchey's volume 2 (advanced concepts) later, stay tuned.

For more on the relationship between signal integrity and EMC:

Signal Integrity & EMC Are Linked - Get Used to It

EMI and SI Relationships

Lee Ritchey's web site

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