No.11（2016）16.Development of a harmonic noise source identification module in multiple clock operation

Hiroyasu Sano，Hidekatsu Sasaki

  On a high-speed communication board, the harmonic noise of a clock signal poses a serious problem in radiated emission tests. One of the reasons for this is that clock signals generally have a high level of radiated noise in the steady state. Although near field measurement can be used as a means to explore the noise distribution of clock signals, as multiple clocks are implemented in electronic devices in recent years, the harmonic noise of each clock signal overlaps, making it impossible to identify which clock IC and circuit wiring is causing the radiated noise.
 In this study, the clock IC and circuit wiring causing the radiated noise in a radiated emission test is identified by studying ways to inject signals to resolve these problems, creating prototype modules, and carrying out near field distribution measurements and far field measurements when these signals are injected into the product circuit boards and test circuit boards.

Keywords
Emission noise, Near field magnetic noise, Clock harmonic noise

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