Class-D audio amplifiers with separated baseband for low-power mobile applications

In this paper, a digital real-time implementation of a binary zero-position coding concept with separated baseband is presented. This coding concept applies to highly power efficient class-D amplification for use in low-power mobile audio equipment. With its separated baseband, which by theory is free of distortion, this concept enables the design of ultra linear class-D power amplifiers. The implemented coding system has a dynamic range of 70 dB and a separated baseband extending from 0 to 42 kHz with a resulting switching rate of only 97.6 kHz. Theory, implementation considerations and measurement results are discussed.