OnTrack · 27 Jan 2026 · 58m · Episode 331
Todd Hubing, president of LearnEMC, explains that grounding myths stem from confusing signal integrity return paths with EMC ground structures, arguing that high-frequency currents follow the path of least impedance and do not cause ground loops on chassis connections. He debunks the rule that decoupling capacitor placement matters on boards with closely spaced power and ground planes, noting that plane capacitance dominates at high frequencies. Hubing also advises against using common mode chokes on unbalanced power inputs, recommending instead that designers focus on minimizing common mode voltage sources to prevent radiated emissions.
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Hosts Carl and Corey discuss PCB layout tips for hobbyists, focusing on component placement and power plane design. They cover decisions like single-sided vs. double-sided assembly, grouping components by functional blocks, and the critical importance of placing decoupling capacitors near IC pins. The conversation also addresses thermal management, power plane sizing, via current capacity, and the use of positive vs. negative layers in CAD tools.
Hank Zumbahlen, an application engineer at Analog Devices, discusses the critical importance of grounding, power supply decoupling, and PCB layout in analog design. He explains how digital return currents and high-frequency effects can corrupt sensitive analog signals, emphasizing the need to separate analog and digital grounds and manage impedance. The conversation covers specific technologies like MEMS accelerometers, sigma-delta ADCs, and digital isolators, highlighting how integration and physical layout impact performance. Zumbahlen also shares anecdotes about testing high-power regulators and designing audio DACs, stressing that understanding the underlying physics is essential even with highly integrated chips.
Tom Anderson, an engineer at Keysight Technologies who also consults for Alembic, explains the fundamentals of radio frequency (RF) electronics, clarifying that RF issues arise from voltage differentials on wires due to signal propagation delays. He demystifies RF jargon like dBm and Smith charts (which he calls 'dollhouses') and discusses practical design strategies, such as managing clock rise times, avoiding ground plane slots, and tuning antennas using varactors. The conversation also covers the specific electronic challenges of high-end bass guitars, including EMI shielding and signal-to-noise ratios.
Chris Gammell and Dave Jones discuss PCB layout best practices, specifically regarding long traces, analog/digital separation, and ground planes, while also covering the IEEE membership structure and the manufacturing of custom drone batteries. They review the CHMT36VA pick-and-place machine, noting its hardware quality versus software limitations, and touch on the low cost of modern PCB prototyping via services like JLCPCB. The conversation concludes with a look at the Hayabusa 2 asteroid landing and the safety implications of shipping lithium batteries from China.
Eric Bogatin, Dean of the Teledyne LeCroy Signal Integrity Academy, explains the foundational physics of signal integrity, emphasizing that engineers must understand Maxwell's equations and the concept of 'being the signal' to grasp how voltage waves propagate on transmission lines. He outlines three essential rules of thumb: bandwidth is approximately 0.35 divided by rise time, signals travel at roughly 6 inches per nanosecond in FR4, and a 50-ohm microstrip requires a line-to-dielectric thickness ratio of 2:1. Bogatin discusses the importance of using 2D and 3D field solvers like those from Polar Instruments for accurate impedance calculation, particularly with hatched ground planes, and critiques common misconceptions about inductance and capacitance in power distribution networks.
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