US Patent 7683709 Low frequency power amplifier employing high frequency magnetic components

A low frequency amplifier uses a switched bridge circuit, providing a first frequency output. A transformer circuit receiving the first frequency output from the switched bridge circuit. Power from the transformer is output from a plurality of secondaries and the power from the secondaries is supplied to the corresponding output switching circuits and provided as switched outputs from the transformer circuit. The switched outputs from the transformer circuit are responsive to a transformer output from the transformer at the first frequency, and switch the transformer outputs in a timed sequence to provide a combined second frequency output. The second frequency output has a lower frequency than the transformer outputs.