Improved Class-K amplifier for headset applications

This paper proposes an improved Class-K audio amplifier as an alternative solution to Class-AB and Class-G audio amplifiers for Headset applications. The Class-K architecture consists in a linear and a switching amplifier connected in parallel to the same speaker. The advantage of this solution is to associate the power efficiency of the switching amplifier with the linearity of a linear amplifier. However, the Class-K may suffer from static consumption. Three methods are presented in order to compensate the topology´s disadvantages: a ternary modulation, a two-stage linear amplifier and a low idle switching amplifier. In this paper, we present the Class-K operating principle, a topological comparison and solutions to improve high static consumption. The simulation results prove the validity of these solutions, achieving less than 2mA of static current.