Quantification of self-damping of power mosfet in a synchronous buck converter

Keong Kam*, David Pommerenke, Ankit Bhargava, Bob Steinfeld, Cheung Wei Lam, Federico Centola

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Ringing in the switching waveform of the switching power supply (e.g., synchronous buck converter) is known to cause broadband electromagnetic interference problems in the 30-300 MHz range. The measured switching waveform shows overshoot and, then, exponential decay of the ringing. It has been observed that this exponential decay rate varies significantly between using different low-side FETs; thus, the low-side FET dominates the attenuation of the ringing. This paper provides a novel method for quantifying the losses by using the measureable quantity R$\rm oss, which is equivalent to the loss of the output capacitance C $\rm oss of the FET. This paper describes the method of measuring R$\rm oss and explains its relevance to the self-damping of the switch ringing. The method permits selection of a low-side FET to optimize the electromagnetic compatibility performances of the supply.

Original languageEnglish
Article number5985517
Pages (from-to)1091-1093
Number of pages3
JournalIEEE Transactions on Electromagnetic Compatibility
Issue number4
Publication statusPublished - 1 Nov 2011
Externally publishedYes


  • broadband EMI
  • Buck converter electromagnetic interference (EMI)
  • FET device parameter R$
  • switch ringing

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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