Investigation of switching frequency variations and EMI properties in self-oscillating class D amplifiers

Dennis Nielsen, Arnold Knott, Gerhard Pfaffinger, Michael A. E. Andersen

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Class D audio amplifiers have gained significant influence in sound reproduction due to their high efficiency. One of the most commonly used control methods in these amplifiers is self-oscillation. A parameter of key interest in self-oscillating amplifiers is the switching frequency, which is known for its variation. Knowledge of switching frequency variations is of great importance with respect to electromagnetic interference (EMI). This paper will investigate, whether the switching frequency is depended on modulation index and audio reference frequency. Validation is done using simulations, and the results are compared with measurements performed on a 50 W prototype amplifier. The switching frequency is tracked through accurate spectrum measurements, and very good compliance with simulation results are observed.
Original languageEnglish
Title of host publicationProceedings of the 127th AES Convention
Number of pages10
Publication date2009
ISBN (Print)978-0-937803-71-4
Publication statusPublished - 2009
Event127th AES Convention - New York, NY, United States
Duration: 9 Oct 200912 Oct 2009
Conference number: 127


Conference127th AES Convention
CountryUnited States
CityNew York, NY
Internet address

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