Extreme Measurements
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This blog series is born out of an idea from SIJ Editorial Advisory Board (EAB) member Steve Sandler, and it is open to any engineer who wants to record (brag, or otherwise complain) about an extreme measurement challenge. If you have an extreme measurement and want to ask the SIJ EAB for help getting started, you can ask your question here. But first, check out the below posts to see what others are doing!

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The Challenge of Measuring a 40 µΩ (2000 Amp) PDN With a 2-Port Probe: The Measurement Result With Another VNA

In the final installment of this blog series, Benjamin Dannan, Heidi Barnes, and Steve Sandler discuss how to calculate the minimum CMRR with a PDN impedance measurement using a 2-port probe, demonstrating how is possible to measure a sub-40 µΩ impedance using a 2-port probe when using an isolator that has sufficient CMRR using two different VNAs, the Bode 100 and E5061B. Achieving sub-40 µΩ impedance measurements is challenging, but completely realistic with the proper test equipment. 


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The Ultimate Power Rail Noise Measurement

Do I really need to use a power rail probe to measure ripple and noise? Power rail probes are single ended, so does that mean I can only monitor one power rail at a time? Are there other, more affordable options available? In this blog post, Steve Sandler answers to these questions and more.


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Determining FPGA Dynamic Load Current

In this Extreme Measurement story, the goal was to determine the dynamic current of the FPGA by measuring the AC current in an external VRM using a transformation of the PCB S-parameters and the simultaneous measurement of the AC voltages across the PDN.


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A Bode Plot Without Access to the Control Loop

This extreme measurement seems more impossible than difficult.  The traditional stability assessment method for voltage regulators is the Bode plot.  Access to the control loop is required and a small signal is injected into the control loop, usually via a resistor, placed at the top of the voltage sense divider. Without access to this voltage divider, there isn’t a place to inject a signal into the control loop, and therefore the Bode plot is seemingly impossible…


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