Volume control in class D amplifier using variable supply voltage

摘要

A Class D audio amplifier including a gain stabilization feedback loop in which volume control is achieved by varying the bus voltage. Changes in the bus voltage are compensated for by complementary changes in the gain of a compensation element in feedback loop so the signal level at the output of the Class D stage can be adjusted independent of the feedback. A digital attenuator can be employed ahead of the amplifier to shift the effective gain of the amplifier output to provide additional volume control range.