Patent ID: 7702120

Claim:
A switching power amplifier apparatus, comprising: a power supply and filtering stage; an input transformer; a variable gain amplifier; dual comparators and output drivers; an amplitude scaling triangle waveform generator; and a switching power amplifier output stage, a 2-pole compensated error amplifier with negative feedback from the switching power amplifier output stage, wherein an audio signal is coupled to inputs of the input transformer; outputs of the input transformer are coupled to inputs of the variable gain amplifier; the output of the variable gain amplifier is coupled to an input of the 2-pole compensated error amplifier; the error amplifier is driven by the switching power amplifier output stage; an in-phase version of the error amplifier output is coupled to a first input of a first comparator of the dual comparators; an anti-phase version of the error amplifier output is coupled to a first input of a second comparator of the dual comparators; the amplitude scaling triangle waveform generator is connected to the power supply; a triangle waveform from the amplitude scaling triangle waveform generator is coupled to second inputs of the first comparator and the second comparator; outputs of the dual comparator are coupled to the output drivers, each of which provides complimentary digital outputs; and the complimentary digital outputs are coupled to inputs of the switching power amplifier output stage.