Electromagnetic evaluation of Class-D switching schemes

Class-D audio amplifiers may significantly contribute to the electromagnetic emissions of electronic devices. This work deals with the electromagnetic emissions created by Class-D amplifier output stages. Output stage switching schemes of traditional and filterless Class-D amplifiers are analyzed concerning their ability to create electromagnetic disturbances. Three different switching schemes are compared, namely Class-AD, Class-BD, and Ternary switching. Finally, commercially available Class-D amplifier ICs are measured and compared using an electromagnetic compatibility measurement setup according to IEC61967-4-A1.