Minimal detectable signal during current measurement in a CISPR 25 set-up

Zongyi Chen, Jin Jia, Stephan Frei, Syed Huq, David Pommerenke

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

This paper investigates instrumentation effects that may limit the usefulness of pre-compliance bench-top test methods for e.g. CISPR 25 radiated field measurements. Here the radiated fields are dominated by common-mode currents along the test cable bundle especially when the frequency is below several hundred MHz. From a known current distribution, fields can be computed. The currents can be measured using current probes with measurement instruments like oscilloscopes or spectrum analyzers (SAs). However, because of the low CISPR limits, very small currents (amplitude and phase) need to be measured. In this paper, as first step, the current values that lead to emissions at the CISPR limit are determined using method of moment (MoM) simulations. For analyzing the practical sensitivity of typical current measurement instruments, the noise figures of oscilloscopes and SAs are approximately measured and the compete measurement system is optimized with respect to probe selection and pre-amplification. It is shown that oscilloscopes and SAs achieve similar sensitivities, and both having noise figures in the range of 15-25 dB without pre-amplification. By setting corresponding fast Fourier transformation (FFT) parameters it is possible to obtain the same bandwidths in an oscilloscope as in a SA for the bandwidths typically used in electromagnetic interference (EMI) measurements. Further, oscilloscope-based phase measurement is explained. The noise induced errors are shown for the magnitude and phase indicating a lower minimal detectable signal of about -25 dBμA for less than 15° phase error.

Original languageEnglish
Title of host publication2016 Asia-Pacific International Symposium on Electromagnetic Compatibility, APEMC 2016
PublisherInstitute of Electrical and Electronics Engineers
Pages845-848
Number of pages4
ISBN (Electronic)9781467394949
DOIs
Publication statusPublished - 26 Jul 2016
Externally publishedYes
Event7th Asia-Pacific International Symposium on Electromagnetic Compatibility, APEMC 2016 - Shenzhen, China
Duration: 17 May 201621 May 2016

Publication series

Name2016 Asia-Pacific International Symposium on Electromagnetic Compatibility, APEMC 2016

Conference

Conference7th Asia-Pacific International Symposium on Electromagnetic Compatibility, APEMC 2016
CountryChina
CityShenzhen
Period17/05/1621/05/16

Keywords

  • CISPR 25
  • current probe
  • noise figure
  • oscilloscopes
  • spectrum analyzers (SAs)
  • spurious

ASJC Scopus subject areas

  • Radiation
  • Computer Networks and Communications
  • Hardware and Architecture
  • Electrical and Electronic Engineering
  • Instrumentation

Fingerprint Dive into the research topics of 'Minimal detectable signal during current measurement in a CISPR 25 set-up'. Together they form a unique fingerprint.

  • Cite this

    Chen, Z., Jia, J., Frei, S., Huq, S., & Pommerenke, D. (2016). Minimal detectable signal during current measurement in a CISPR 25 set-up. In 2016 Asia-Pacific International Symposium on Electromagnetic Compatibility, APEMC 2016 (pp. 845-848). [7522886] (2016 Asia-Pacific International Symposium on Electromagnetic Compatibility, APEMC 2016). Institute of Electrical and Electronics Engineers. https://doi.org/10.1109/APEMC.2016.7522886