Image Number 7 for United States Patent #7986187.
An audio power amplifier includes a first and a second amplification unit, each including a switching voltage amplifier, an output filter, a current compensator, an inner current feedback loop feeding a measurement of current measured at the output inductor back to a summing input of the current compensator, a voltage compensator coupled to the summing input of the current compensator, and an outer voltage feedback loop. A controlled signal path provides the output of the voltage compensator of the first amplification unit to the current compensator of the second amplification unit. The first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load. A second pair of amplification units may be added and operated together with the first pair to drive a single speaker with a parallel pair of amplifiers on each side of a bridge-tied-load.