We’ve come to the end of our first complete year of online publication. Our Editorial Advisory Board (EAB) has done a superb job of nudging us in the right direction, contributing high value technical pieces and reviewing all the technical content submitted to the Signal Integrity Journal. As a final passing favor to the SI, PI and EMC community of readers, we want to leave all of our readers with a year-end holiday gift.

Following is a list of free tools or resources which our panel of experts use and recommend. We hope you will find them as useful as our EAB members do.

Eric Bogatin: Every engineer needs to have a version of SPICE on their desktop. This is the simplest to use, best graphical interface, and is S-parameter savvy. QUCS: http://qucs.sourceforge.net/

Istvan Novak: Another free version of SPICE that is easy to use and especially well-suited to power integrity simulations is LT SPICE, http://www.linear.com/solutions/ltspice. (ed comment: Istvan is too modest to mention his web page, http://www.electrical-integrity.com/Links.html, which has an incredible collection of free resources and industry links. It’s a must see.)

Bert Simonovich: When I want to display S-parameters in the frequency or time domains, as single ended or differential, I like the free version of LeCroy’s SI Studio: http://teledynelecroy.com/resources/details.aspx?doctypeid=16&mseries=380

Rula Bakleh: When optimizing the selection of capacitors for a PDN to achieve a flat impedance profile following the approach Larry Smith recommends, the Altera PDN tool is great. https://www.altera.com/support/support-resources/support-centers/signal-power-integrity/power-distribution-network.html 

Doug Smith: I suggest the inductance calculator at UMR. There are other calculators there as well, such as for transmission lines. You can never anticipate when you will need to know the inductance of an isosceles triangle loop!  http://emclab.mst.edu/inductance/

Larry Smith: Here is a link to our free PDN resonance calculator. There is a section for EM extraction of the inductance and resistance of planar and vertical (via/bump/ball) structures.  There is another section that calculates the PDN frequency-domain characteristic impedance, impedance peak, resonant frequency, and the expected time domain voltage responses for impulse, step and resonance currents.  The documentation for this spread sheet is in chapter 10 of our book, Principles of Power Integrity for PDN Design.  http://pdnpowerintegrity.com/wp-content/uploads/2017/04/PRC-spreadsheet_Ch10_Principles-of-Power-Integrity.xls

Vladimir Dmitriev-Zdorov: This is the important part of the book: J. Choma, Circuit analysis and design by S-parameter, Krieger, 1991. I used this book when initially studying S-parameters. https://pdfs.semanticscholar.org/2a36/86dd1bd9e2d673d4638f00f79c536dc8dd5c.pdf

Steve Slater: The FlexDCA Express is a free waveform viewing software tool, that enables you to load waveforms from any source (text files, csv, etc), and then apply a wide variety of time-domain signal measurements and eye-mask measurements (from a library of compliance masks).  The user can further inject jitter, noise, and perform filtering, math functions and transforms.  There is even a basic TDR mode, all for free. https://www.keysight.com/main/campaign.jspx?cc=US&lc=eng&ckey=2033975&id=2033975&cmpid=zzfindflexdca_express

Jay Diepenbrock: The Cadence® Allegro®/OrCAD® FREE Physical Viewer is a free download that allows you to view and plot databases from Allegro PCB Editor, OrCAD PCB Editor, Allegro Package Designer, and Allegro PCB SI technology.  Requires 64 bit Windows OS. https://www.cadence.com/content/cadence-www/global/en_US/home/tools/allegro-downloads-contact.html

Al Neves: PyBERT, written by David Banas, is a serial communication link bit error rate tester (BERT) simulator with a graphical user interface (GUI), written in Python and making use of the Enthought Traits/UI packages. It is intended to give serious students and engineers the ability to play with serial communication link design concepts. https://github.com/capn-freako/PyBERT/wiki 

Yuriy Shelpnev: (ed comment) Yuriy is too modest to mention his web site which is a wonderful source of great technical articles and YouTube videos visualizing how interconnects work.  Check out his videos here: http://www.simberian.com/ScreenCasts.php and application notes here:  http://www.simberian.com/AppNotes.php

Lisa Ward: This is an electronic copy of the VNA fundamentals book which normally sells for $70 but the pdf is free. I like the electronic copy because one can search for terms easily https://www.rohde-schwarz-usa.com/VNA-Fundamentals.html

Steve Sandler (ed note: not officially on the EAB, but a long time contributor to the SI Journal): This is my favorite book of all time on control theory.  It went out of print, making it free for download.  http://www.cds.caltech.edu/~murray/amwiki/index.php/Main_Page

Happy holidays from everyone at Signal Integrity Journal