A Brief How To: Analyzing Control Loop Stability with Bode Plots Using Modern Oscilloscopes

Focus:

Also published in EE Power, this 2-page article introduces the technique of making Bode Plot measurements using an oscilloscope rather than a frequency response analyzer or vector network analyzer. It takes advantage of new oscilloscope capabilities, although the relevant scope models are not noted. After explaining why Bode measurements are needed to access stability, concepts such as gain and phase margin, and the basics of taking Bode measurements are explained with some guidelines on requirements for signal injection and probing. Look to other sources for more details and examples of how to take the measurements. For example, see R&S app note GFM321_1e, “Tips and Tricks on how to verify control loop stability”.

What you’ll learn:

• How to make Bode plot measurements using oscilloscopes with this feature (an introduction)
• How to understand the principles of Bode plot stability measurements

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Author & Publication:

Dr. Marcus Herdin, Market Segment Industry Manager, Components, Research & Universities, and Marcus Sonst, Application Development, both at Rohde & Schwarz, Bodo's Power Systems, Jan 01 2020

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