Patent ID: 7005919

Claim:
A differential circuit that reduces or eliminates even order harmonic distortion comprising: a first active circuit element having an input and an output; a second active circuit element having an input and an output; a first pair of impedances connected in series with respect to each other and coupled with a first common node disposed therebetween, said first pair of impedances connected between respective outputs of said first and second active circuit elements; a second pair of impedances connected in series with respect to each other and coupled with a second common node disposed therebetween, said second pair of impedances connected between respective inputs of said first and second active circuit elements; a feedback connection connected between said first common node and said second common node; a balun having first and second windings, the first winding of said balun being connected to said output of one of said first and second active circuit elements other than through said first pair of impedances, and the second winding of said balun being connected to said output of another of said first and second active circuit elements other than through said first pair of impedances; and whereby when respective signals are applied to said inputs of said first and second active circuit elements, said input and output of said second active circuit element are respectively substantially out of phase with respect to said input and output of said first active circuit element.