The low-frequency distortion in D-class amplifiers

Michael Margaliot*, George Weiss

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


D-class amplifiers use pulsewidth modulation to transform an input signal u into a rectangular signal p whose duty cycle linearly depends on the input signal u. After low-pass-filtering p to suppress the switching frequency and its harmonics, we obtain the output signal y that is a good approximation of u. This kind of an amplifier is attractive (as compared with the classical A-class and B-class amplifiers) due to its high efficiency. A buck power supply may be regarded as a particular instance of a D-class amplifier. While the operating principle of the D-class amplifier is intuitively clear, a rigorous mathematical analysis of this system is not trivial, as the amplifier is time-varying and nonlinear. We derive a rigorous proof of the fact that the signal p is a good approximation of u in the low-frequency range, and we provide precise error bounds for this approximation.

Original languageEnglish
Article number5587881
Pages (from-to)772-776
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Issue number10
StatePublished - Oct 2010


  • D-class amplifier
  • Parseval's theorem
  • pulsewidth modulation (PWM)
  • sampling theorem
  • switched power converter
  • uniform sampling

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