Power Integrity

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Build Your Own Low-Cost Power Rail Probe

Probing signals with a bandwidth below 100 MHz and voltage sensitivity above 100 mV is a no-brainer. Regardless of the type of signal or the source impedance, the venerable 10x passive probe is the answer. However, at bandwidths >100 MHz and with voltage sensitivity <100 mV, the 10x passive probe may not be the best option. In this article, SIJ technical editor Eric Bogatin introduces an easy-to-implement, low-cost alternative to the 10x passive probe specifically for power-rail measurements.


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The Goldilocks TDR

It pains me to say this, but there is such a thing as turning the TDR up too high and it is also easy not to have enough. If there is a “too high,” and a “not high enough,” there must also be a “just‐right,” or Goldilocks, setting. Using measurements, and a smattering of math, the Goldilocks setting answers
will be clear. Read on to find out how.


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Current Distribution, Resistance, and Inductance in Power Connectors

Engineers who design and model power distribution networks require accurate component level models from high frequency down to DC.  Accurate modelling of power connectors can guarantee best power transfer and minimize power-induced noise.  In this paper, which won a DesignCon 2020 Best Paper Award, the authors analyze the frequency-dependent resistance and inductance of various power connectors as well as pin patterns.


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A Simple Demonstration of Where Return Current Flows

This simple measurement demonstrates the most important principle in SI/PI and EMI: that the return current will flow in the path of lowest resistance below about 10 kHz. But above about 10 kHz, the return current will begin to redistribute in the return path to be adjacent to the signal conductor. Read on to learn more.


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