What your Differential Pairs Wish You Knew with Rick Hartley - AltiumLive Keynote
Why Hacker News recommends it
HN engineers cite Hartley as the intuitive, field-based alternative to cargo-cult PCB advice, especially on differential pair routing, reference planes and EMI.
What it is
Rick Hartley's AltiumLive keynote on differential pairs in PC boards. He argues the rules from cables and twisted pairs do not carry over, and covers which pair geometry gives the best impedance control, the right spacing, routing practice and how much skew is acceptable.
Recommended by 5 HN commenters across 6 different months, 2021 to 2026.
What Hacker News said
Strong rec thrtythreeforty · 2023-04 · on “High Speed Printed Circuit Board (PCB) Design Guidelines”
Basically, go watch every Rick Hartley video on YouTube. He is awesome at explaining. It will become intuitive instead of being a bunch of cargo cult advice. (Normally I dislike long videos but this is absolutely worth your time if you design PCBs.) [this video]
Strong rec mordae · 2023-05 · on “The Mysterious 50 Ohm Impedance: Where It Came from and Why We Use It”
The article is not that good, but whatever. I am new to electronics myself and quite fascinated how has the art progressed in the past hundred or so years. There are people remembering "we were doing it wrong". Incredible. Anyway, if you are interested in signals traveling inside those cute green multi-GHz boards you make your living off, go watch Rick Hartley. [LINK] (How to Achieve Proper Grounding) [this video] (What your Differential Pairs Wish You Knew)
Strong rec aaronmdjones · 2025-07 · on “Vibe-Coding a PCB – surprisingly good”
I have some further video recommendations: [LINK] ("How to achieve proper grounding") [LINK] ("Keys to control noise, interference, and EMI in PCBs") [this video] ("What your differential pairs wish you knew") [LINK] ("Secrets of PCB optimization") These are all by Rick Hartley (from GP's comment) and they are all worth watching in this order.
Strong rec dgroshev · 2026-04 · on “How I leared what a decoupling capacitor is for, the hard way”
I found Phil's lab content [1] [2] indispensable for just this. Phil is a great communicator and gives in-depth explanations, so I didn't just watch most of his youtube, but also bought his mixed signals course and was very happy with it. Phil also recommends this lecture in one of his videos [3], which is still one of my all time favourite lectures ever. [1] [LINK] [2] [LINK] [3] [this video]
Recommends datenwolf · 2023-03 · on “PCIe for Hackers: The Diffpair Prelude”
> First off, you want to keep both of the pair’s signals close to each other throughout their length. The closer the two signals are, the better external interference cancellation works, and the less noise they radiate (…) Wrong! This is a myth that's stubbornly difficult to weed out. The coupling between the wires of a pair is only ~12% the amount of coupling to the reference plane. On a PCB it's best to treat each signal on its own and route it as a single ended, coplanar waveguide surrounded by reference planes. This allows to use far thicker widths, which reduces inductance, which also reduces the coupling to radiating EM fields. If you want a longer talk on the topic: [this video]
Recommends aaronmdjones · 2024-09 · on “The magic of DC-DC voltage conversion (2023)”
> so wouldn't it be better to put power/ground on the outer layers and keep signals in the middle? Signals must never cross a break or split in the plane they're referencing (usually 0V or ""ground""). This creates huge EMI problems. Your proposal would have signals on layer 2 crossing a split in the ground plane on layer 1 (that split caused by power traces). Some interesting material on the subject: [LINK] [this video] [LINK] [LINK]
Cites foxfluff · 2021-12 · on “I bought 1000 meters of wire to settle a physics debate [video]”
"I have never in my life length matched the two lines of a differential pair, including at 10 GHz. Never." - Rick Hartley [this video]
Cites dkbrk · 2021-12 · on “I bought 1000 meters of wire to settle a physics debate [video]”
> He claims that the way EE is taught is a "lie" The thing is: this is sort of true. Now, all electrical engineers are very familiar with transmission line theory, that's pretty much their bread and butter. And all EEs know that if you're not working with well-defined transmission lines (like coaxial cables), you need to use a field solver. 2D field solvers are often sufficient, but if not 3D field solvers can and will be used. And then most of those same EEs, despite having just used a field solver which clearly shows that all the power is in the fields, which are in the dielectric space between the conductors, persist in using the mental model that electrical power moves in wires. This isn