Design of Class-D amplifier for audio portable solutions

Summary form only given. Audio Amplifier in portable systems (i.e. Mobile Phones) or in thermally close environment (i.e. car radio) faced the historical problem of low efficiency while using linear amplifier classical approach such as Class A/B/AB. In latest year the adoption of Class-D switching amplifier has been widely accepted for their higher efficiency (~90%) thus removing the problem of wasting power and thermal dissipation. Moreover, latest smartphone business creates new multimedia experience requiring more and more loudness with small speaker. This leaded to an explosion of R&D activity to linearize the Class-D amplifier´s behavior and improve mixed-signal solution with a clear benefit of sub-nm lithography. In this lecture the latest design development for portable system is described showing all design solution for improving audio quality, speaker´s safety and loudness.