1. EMI Reduction in Class-D Amplifiers by Actively Reducing PWM Ripple.
- Author
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Lokin, Christiaan E., van der Zee, Ronan A. R., Schinkel, Daniel, and Nauta, Bram
- Subjects
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PULSE width modulation transformers , *DIGITAL filters (Mathematics) , *PULSE width modulation inverters , *HIGH voltages , *ANALOG-to-digital converters , *ELECTROMAGNETIC interference , *PULSE width modulation - Abstract
Class-D amplifiers switch high voltages and currents at high frequencies and hence produce electromagnetic interference (EMI). This work presents a technique to reduce the high frequency ripple, which is still present after the output filter. A Class-A ripple reduction amplifier is put in parallel to the output of the Class-D amplifier, each having their own feedback loop with digital filters. High ripple reduction loop gain is achieved at the PWM frequency by using a resonator as digital loop filter. Dissipation in the Class-A amplifier is reduced by using a low common-mode signaling technique. Common-mode and differential-mode switching components at the PWM frequency are reduced by 27 dB and 18 dB respectively. Total system efficiency is 79% at 40 W output power. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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