| Stability, noise, and EMI problems occur in all types of electronic systems, both large and small. As electronics technology continues to evolve, many of the conventional techniques used to assess stability, noise, and EMI issues are proving inadequate. Building block components such as op amps, voltage references, linear regulators, and switching regulators are inadequately characterized in vendor datasheets. Even worse, IC datasheets often advise use of external components that degrade component performance, creating stability or noise problems in the user’s application. These issues make it imperative that circuit designers verify the performance of their building block analog and power components on the bench, preferably in system. Unfortunately, many conventional test techniques for assessing component stability and noise performance in-system fall flat because many components do not allow access to internal control loops, or do not lend themselves to in-system testing, or do not adequately characterize component performance. In some cases, conventional test instruments and test setups lack the bandwidth, selectivity, or sensitivity to adequately assess component performance in or out of system.
In this 8-part video series, Steve Sandler of AEi Systems and Picotest discusses essential concepts, relationships and test methods needed to identify and correct stability, noise and EMI issues in electronic components and systems. Relationships between stability, noise and impedance are discussed, and methods for assessing stability and noise issues (both in and out of system) using impedance measurements are described at length. Many of the test methods described rely on the use of vector network analyzers or VNAs (available from multiple instrument vendors) and specialized adapters (available from the presenter’s company. Picotest). The use of VNAs represents a departure from conventional approaches using frequency response analyzers (FRAs) or oscilloscopes, but promises higher fidelity and the ability to make measurements that the other instruments cannot. However, as Sandler discusses in this video series, to fully address stability, noise and EMI issues, designers need to make measurements in multiple measurement domains—time, frequency, spectrum, and impedance. To that end, he presents test methods using VNAs, spectrum analyzers, and oscilloscopes, explaining how to optimize the test setups and interpret measurement results. Summaries and links for the individual videos in this series appear below along with links to the references cited in the videos. All of these videos are posted on How2Power’s YouTube channel where you’ll also find comments on the videos in this series. Viewers are encouraged to post their comments on the videos as well or to email their comments to the editor.
* This video series was originally presented in the May 2013 through January 2014 issues of the HOW2POWER TODAY newsletter.
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Steven Sandler is the founder and chief engineer of AEi Systems, where he leads development of high-fidelity simulation models for all types of simulators as well as the design and analysis of both power and RF systems. Sandler has over 30 years of experience in engineering and is a recognized author, educator and entrepreneur in the areas of power, RF and instrumentation.