Signal Integrity Journal

Validating the Validators: Measuring the New Ultra-Low Impedance PDNs

Mon, 12 Aug 2024 12:00:00 -0400

In this installment, Steve Sandler discusses measuring new ultra-low impedance PDNs using newly created usable test standards in the 20 µΩ range for accurate results.

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

Sat, 20 Jan 2024 00:00:00 -0500

In the final installment of this blog series, Benjamin Dannan, Heidi Barnes, and Steve Sandler continue their discussion of how to calculate the minimum CMRR with a PDN impedance measurement using a 2-port probe, demonstrating how to measure a sub-40 µΩ impedance 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

Thu, 04 Jan 2024 09:15:04 -0500

Having determined the amount of CMRR needed for 2-port measurement in the previous installment of this blog, Steve Sandler and Benjamin Dannan 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?

Wed, 20 Dec 2023 00:00:28 -0500

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

Tue, 26 Jul 2022 00:00:00 -0400

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?

Thu, 19 May 2022 00:00:00 -0400

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

Thu, 05 May 2022 00:00:00 -0400

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

Tue, 15 Feb 2022 00:00:00 -0500

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?

Tue, 25 Jan 2022 00:00:00 -0500

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?

Tue, 28 Dec 2021 00:00:00 -0500

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.

A Bode Plot Without Access to the Control Loop

Tue, 23 Nov 2021 00:00:00 -0500

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…

Cable Shield Resistance Issue in a 2-port Impedance Measurement

Mon, 15 Nov 2021 00:00:00 -0500

In this Extreme Measurement Example, see how measurements were used to resolve the shield resistance issue, where the authors redesigned the PCB to clear the DUT contact, but also identified alternate solutions in the event they could not wait for a new PCB.

What is an Extreme Measurement?

Tue, 02 Nov 2021 00:00:00 -0400

This first post in a new blog series, Extreme Measurements, introduces how an extreme measurement is defined. Find out how your extreme measurement story can end up on SIJ!