Circuit designers, particularly power supply designers, are frequently required to measure power supply ripple. Nevertheless, many engineers struggle with this measurement as sensitivity, selectivity, and bandwidth limitations degrade the accuracy of oscilloscope results. But as Steve Sandler explains in this 7-minute video, specialized probes and adapters can improve the results obtained from the conventional time-domain approach to measuring ripple, while other approaches to measuring ripple in the spectrum and impedance domains can yield more accurate and more insightful results.
And by taking measurements across all three test domains, designers can trace power supply ripple-related problems back to root causes such as switching frequency, load dynamics, and PCB crosstalk as explained here. Various test setups, which include instruments from Picotest and other vendors, and measurement techniques are described in this video and results of example ripple measurements using different point of load regulators (POLs) are discussed. Along the way, Sandler gives test tips to help engineers avoid common measurement pitfalls.