Agilent - Tips and Techniques for Making Power Supply Noise Measurements with an Oscilloscope

Reprinted courtesy Agilent Technologies


The electronics in today's designs feature higher-speed switching, faster slew rates, more active pins per package, and smaller signal swings than ever before. As a result, designers are more concerned about power supply noise in new digital designs, in everything from cell phones to servers. Real-time oscilloscopes are commonly used to measure power supply noise. This application note illustrates techniques for analyzing power supply noise and discusses selection and evaluation of tools for power supply noise measurements.

The problem

As switching speeds and signal slew rates increase, and as the number of active pins on devices increase, more switching noise is induced in power supplies. At the same time, circuits are becoming more susceptible to power supply noise. Decreased unit intervals mean shrinking timing margins. Reduced signal amplitudes translate to reduced noise margins. As with all engineering problems, understanding the problem and having accurate and precise measurement data to characterize the problem are essential to solving it.

Insights to "noise"

Ideally, there wouldn't be any noise on your power supplies. How did it get there?...

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