Patent ID: 7911268

Claim:
An apparatus for improving the feedback linearity of a 1.5-bit Σ-Δ class-D amplifier, comprising: a control circuit; a power stage coupled to said control circuit, said control circuit operating said power stage to provide a tri-level output voltage of said 1.5 bit Σ-Δ class-D amplifier, the apparatus being coupled in a feedback path of said 1.5-bit Σ-Δ class-D amplifier between an output of said power stage and an input of said control circuit thereof; an input terminal receiving a first positive feedback signal and a first negative feedback signal from the output of said power stage; a conversion circuit connected to the input terminal of said apparatus, said conversion circuit comprising a plurality of operational amplifiers and a plurality of switches coupled therebetween, said switches selectively configuring positive and negative interconnections between said operational amplifier, said switches in at least one state crossing said positive and negative interconnections to invert or mix the first positive feedback signal and the first negative feedback signal received from said power stage of said 1.5-bit Σ-Δ class-D amplifier to determine a second positive feedback signal and a second negative feedback signal; and an output terminal of said apparatus connected to the conversion circuit and providing the second positive feedback signal and the second negative feedback signal to the input of said control circuit of said 1.5-bit Σ-Δ class-D amplifier for feedback control thereof.