"Just like that, we've come to the end of another successful year of online and print publication here at SIJ. The Editorial Advisory Board (EAB) continues to do a fantastic job curating and producing high value technical features and exclusive content for our readers. As a closing gesture to the SI, PI, and EMC/EMI community, we want to leave all of you with a year-end holiday gift for your continued support.
See below for the latest list of free tools and resources which our panel of experts use and recommend. We hope you will find them as useful as our EAB members do. Eric Bogatin: First is the Saturn PCB tool. It is a collection of common approximations useful for designing PCBs, such as maximum current, the characteristic impedance and the effective Dk of a microstrip.
My second recommendation is the new student version of Ansys’s electronics desktop. This includes HFSS, SI2D and Q3D, all for free. This is not a trial version. This is a standalone version, no registration needed, free to anyone. It is limited to 65k mesh elements, but otherwise is the same as the full featured version. It is available here. I reviewed it here.
For more ideas, see the article that I wrote with Jay Diepenbrock, "Low-Cost and Free Tools Fit for an Engineer’s Personal Budget". Jay Diepenbrock: Here are my favorites:
tinySATM: The Hugen tinySA is a 350/960 MHz spectrum analyzer with a 71 mm (2.8 inch) color display and USB port. It’s available for approximately USD $50 from Alibaba, AliExpress, and R&L Electronics (in USA).
nanoVNA: The nano VNAs, available from Amazon and R&L Electronics, are incredibly low cost network analyzers. There are multiple models, which have color touch screen displays, and are controlled by a personal computer using VNA-QT software for Linux or Windows:
V1, 10 kHz-1.5 GHz, 2.8” display, USD $55
V2, 50 KHz-3 GHz, 2.8” display, USD $106
V2, 50 KHz-3 GHz, 4.3” display, USD $153
Now available with a cell phone interface:
KiCAD: Free, open source printed circuit board layout package for Windows, Mac and Linux. Easy to learn, easy to use, compatible with a number of fabrication shops. Gerber file output.
QUCS: Quite Universal Circuit Simulator. This is a free, full-featured tool that does all the normal SPICE simulations and specifically S-parameter simulation, reading and exporting TouchstoneTM files.
Barry Katz: If you’re interested in high-speed parallel/serial link analysis with IBIS-AMI and MATLAB, see the new Signal Integrity Toolbox. Available to nearly all students at little or no charge.
Istvan Novak: My favorite free tool is the open-source signal integrity software. My other recent favorite free tool is the Ansys Electronics Desktop Student version that Eric already wrote about in one of his columns.
Steve Sandler: Last year I recommended my favorite control loop book, which is now a free download. This year, I will recommend my favorite thesis of all time, on the topic of magnetics. Written by Abraham A. Dauhajre at Caltech in 1986, this is a phenomenal study of the estimation of leakage inductance related to physical winding geometries. He toys with the mathematics in crazy ways to produce results that seem counter-intuitive. That he did it all without the benefit of a computer is mind boggling. Download it for free here.
Two bonus gifts:
Originally published by Lawrence Radiation Laboratory at Berkely in 1962, this is a study of the rise time of coaxial cables and the first publish representation of the “dribble effect”, which separates the rise time into two parts. Up to 50% amplitude and 50%-100% amplitude, showing the rise time is much faster from 0-50% than from 50%-100%. The equation for the rise time is developed and many cables were measured for, and presented in, this paper. You’ll notice the dribble effect in almost all eye diagrams today. You can find the paper here, though many universities also have it.
I’m an avid book collector and this year, I’ll recommend another book. Inductance Calculations, by Frederick W. Grover was published in 1946. Grover provided equations for inductance of everything imaginable and is the source of many online inductance calculators. It’s been republished and is available for less than $20.
Here is a BONUS gift feature from SIJ Technical Editor, Eric Bogatin: "A Free Impedance Analyzer on your Desktop". Impedance is the most fundamental and important electrical property of any component. With a very simple technique, anyone can simulate the impedance of any circuit in seconds using any version of SPICE, for free. Read on to learn more.
Thought that was it?... You can also view the original list of "Gifts for SIJ Readers" tools and resource recommendations here. Eric Bogatin would like me to note that this list still applies today.
Happy holidays from everyone at Signal Integrity Journal"