Modelling of a Parallel Hybrid Power Audio Amplifier

Parallel audio amplifier are hybrid amplifiers thatcouple a linear and a switching stage with a parallel connection. Aproper control must be designed so that the voltage is controlledby the linear stage, while most of the current is driven by theswitching stage. So doing the overall architecture achieves thetypical efficiency of the switching stage and the distortion of thelinear stage. In summary a nice trade-off between efficiency anddistortion can be achieved, allowing to reduce heat dissipationkeeping a pleasant sound reproduction.The above purposes can be achieved only with a proper controlthat must set accurately the balance between the two stages, andits implementation is very critical. The paper deals with the modelof the hybrid audio amplifier architecture aiming at retriving themost critical items, and at defining simple relationships for theoptimal design of the amplifier.A prototype hybrid amplifier was realized, that confirms theeffectiveness of the proposed method.