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!

## 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.

## The Challenge of Measuring a 40 µΩ, 2000 Amp PDN With a 2-Port Probe: The Measurement Result

Having determined the amount of CMRR needed for 2-port measurement in the previous installment of this blog, Steve Sandler and  Benjamin Dannan follow up return with a demonstration of how to create a DUT and make a 40 µΩ impedance measurement with the 2-port probe.

## The Challenge of Measuring a 40 µΩ, 2000 Amp PDN With a 2-Port Probe: How Much CMRR is Needed?

In this blog, Steve Sandler and Benjamin Dannan demonstrate how to determine how much CMRR is needed when introducing a ground loop isolator to correct the error in a 2-port measurement.

## Ultra-Ultra-Low Impedance (4 micro-ohm) Measurements

With increasingly significant amounts of current necessary for modern processor solutions, Ben Dannan broaches the topic of the resulting lowered impedance targets. Specifically, how to achieve impedance targets below 10 uOhms. Read on to find out how he does it.

## How Can You Measure a HUGE Inductance with DC Bias?

Steve Sandler was recently asked to measure a 25 mH inductor. Read on to find out what happened next.

## 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.

## 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.

## How Fast is the Switching Speed of a GaN Switch?

Check out this latest installment in the Extreme Measurements Blog that covers the measurement challenges for GaN switches.

## How Can You Determine the Turns Ratio of a Power Transformer in a Sealed DC-DC Module?

I do not know if there was a legitimate reason for this request, but I was once asked to determine the turns ratio of a power transformer inside a sealed, DC-DC converter module.  In any case, there is not much usable information since the module is sealed, but we can apply a simple trick. Check out this latest installment in Extreme Measurements.