Patent ID: 8243960

Claim:
An electronic device comprising: an audio amplifier, comprising; a planar inductor structure comprising: a first plurality of windings, formed on layers of a first circuit board, the first plurality of windings adjacent an output stage of the audio amplifier; a second plurality of windings, formed on layers of a second circuit board, the second plurality of windings adjacent a switching stage of the audio amplifier; a first core structure, comprising a material having a magnetic permeability μ in the range of 4 to 200 substantially enclosing the first plurality of windings; and a second core structure, comprising ferrite substantially enclosing the second plurality of windings; the first structure and the second structure configured so that they form a combined structure having cavities that accommodate the first plurality and the second plurality of windings, wherein the inductance of the inductor is proportional to μ.