This is an archive of Bogatin’s Rules of Thumb posts. To see the most recent updates, visit the Bogatin’s Rules of Thumb blog.

All of Eric Bogatin’s “Rule of Thumb” articles.



Rules of Thumb #0: Using Rules of Thumb Wisely 11.19.2013 Eric Bogatin, Signal Integrity Evangelist, Teledyne LeCroy, embarks on a mission to spell out some common rules of thumb for electrical engineers in a new series of columns. This column kicks off the series by outlining Rules of Thumb “Do” and “Don’t” suggestions.Read More…

Rule of Thumb #1: Bandwidth of a signal from its rise time 11.19.2013 Eric Bogatin, Signal Integrity Evangelist, Teledyne LeCroy, embarks on a mission to spell out some common rules of thumb in a new series of columns. Here is the first rule of thumb and first challenge.Read More…

Rule of Thumb #2: Signal bandwidth from clock frequency 12.05.2013 Here’s a quick way to determine the bandwidth of a signal when all you know is the clock frequency.Read More…

Rule of Thumb #3 Signal speed on an interconnect 12.17.2013 Eric Bogatin, Signal Integrity Evangelist, Teledyne LeCroy, explains a rule of thumb that estimates the speed of a signal on an interconnect.Read More…

Rule of Thumb #4: Skin depth of copper 01.03.2014 This rule of thumb estimates the effective current distribution in a conductor at high frequency.Read More…

Total loop inductance/length in 50 Ohm transmission lines: Rule of Thumb #6 02.07.2014 This rule of thumb estimates the loop inductance per length in all 50 Ohm transmission lines in FR4.Read More…

Total inductance in the return path: Rule of Thumb #7 02.19.2014 This rule of thumb estimates the total inductance in the return path of a flat, wide conductor.Read More…

How to estimate ground bounce in a connector: Rule of Thumb #8 03.13.2014 This rule of thumb estimates the amount of ground bounce to expect in a connector or package lead.Read More…

Loss in a channel: Rule of Thumb #9 04.04.2014 This rule of thumb enables us to estimate the attenuation at the Nyquist for a lossy, uniform channel.Read More…

How much attenuation is too much?: Rule of Thumb #10 04.17.2014 This rule of thumb enables us to estimate how much attenuation is in the loss budget of a serial channel.Read More…

How much return loss is too much?: Rule of Thumb #12 05.21.2014 Return loss and S-parameters are mysterious, even to many practitioners. Learn how return loss equates to signal loss – S11 to S21 – and how much is too much.Read More…

Sheet inductance of a cavity: Rule of Thumb #16 09.18.2014 Separating power planes by as little as possible is ideal, but maybe not why you think it is.Read More…

The quarter-wave stub frequency: Rule of Thumb #17 10.06.2014 High frequencies and bit-rates require point-to-point routing. Learn how to estimate the suckout caused by a via or stub, and therefore, what signals the line can handle.Read More…

How to engineer acceptable far-end crosstalk: Rule of Thumb #21 12.10.2014 Far-end crosstalk can often cause a product to fail. Unless you select the transmission line features carefully, FEXT will likely be an issue.Read More…

When to worry about a capacitive discontinuity: Rule of Thumb #23 01.21.2015 Capacitive discontinuities will act as RC filters with the impedance of a line, introducing single-pole filters, decreasing the signal bandwidth, and increasing the rise time of a signal.Read More…

When to worry about trace corners: Rule of Thumb #24 02.04.2015 We all know never to use 90 degree corners in PCB traces. But is this really a concern?Read More…

What is the aspect ratio for 50Ω microstrip?: Rule of Thumb #27 05.04.2016 All 50Ω microstrip lines in FR4 have the same aspect ratio. Using a 2D field solver, we can explore what this ratio is for a specific value of Dk and conductor thickness.Read More…

What is the spatial extent of an edge?: Rule of Thumb #29 07.06.2016 If you really want to build your engineering intuition about signal integrity, the most important principle you can apply is the Zen approach, “be the signal”.Read More…