A 97% Efficiency Power Stage Design for High Performance Class D Adudio Amplification
High performance audio amplification relies on high efficiency and minimal distortion. During the last decades, most research on class D amplifiers has focused on how to eliminate simultaneous conduction in the switching power stage. In the industry adopted N/N MOSFET totem pole configuration, dead times are inserted at the switching moment in order to prevent command overlapping between high side and low side MOSFETs. Unfortunately, this workaround does not solve the problem of simultaneous conduction caused by the association of Miller effect and fast switching times that are needed to lower switching power losses. The result is a considerable amount of power losses. Moreover, errors due to dead-time insertion are the most significant contributors to distortion in the output stage of a class D amplifier. This paper presents an innovative high power conversion solution based on a source follower totem pole configuration. The smart association of a high side N MOSFET and a low side P MOSFET in the power stage leads to a unique command referenced to the MOSFET’ sources, and combines the dynamic parameters of each MOSFET, so that only one drive signal is used and the risk of skew due to command overlapping is eliminated. The results are 97% efficiency, low distortion and exceptional sound restitution applications. The proposed solution known as Gemincore is patented and an integrated 150 W audio amplifier module is available.
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