US Patent 7948312 Multi-bit class-D power amplifier system

Techniques for designing an efficient power amplifier are described. In one aspect, multiple single unit instance class-D power amplifiers with coupled outputs are utilized to increase efficiency and reduce quantization noise. In another aspect, multiple groups of single unit instance class-D power amplifiers are coupled at the outputs thereof with each group of power amplifiers configured to resonate at unique frequency. This results in increased efficiency and reduction of quantization noise at multiple frequencies bands.