Abstract: A Class D switching audio amplifier incorporating four state modulation, input-to-output drive and feedback signal isolation, dual topology output filtration, and a low inductance board layout. The four state modulation results in a common mode voltage in the absence of audio. The input-to-output isolation of drive and feedback signals allows for elimination of large power transformers in applications without user-accessible outputs. Such isolation may make use of optical isolators. The output filter includes common mode and differential topology filter stages. The low inductance board layout treats the amplifier and power supply boards as modules, and utilizes both sides of the amplifier board in order to minimize trace length.

Abstract: A Class D switching audio amplifier incorporating four state modulation, input-to-output drive and feedback signal isolation, dual topology output filtration, and a low inductance board layout. The four state modulation results in a common mode voltage in the absence of audio. The input-to-output isolation of drive and feedback signals allows for elimination of large power transformers in applications without user-accessible outputs. Such isolation may make use of optical isolators. The output filter includes common mode and differential topology filter stages. The low inductance board layout treats the amplifier and power supply boards as modules, and utilizes both sides of the amplifier board in order to minimize trace length.