Patent ID: 7061317

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 pair of impedances connected in series with respect to each other and coupled with a common node disposed therebetween, said pair of impedances connected between respective outputs of said first and second active circuit elements; first and second baluns, each having a pair of windings, respectively connected to said inputs and said outputs of said first and second active circuit elements, said first and second baluns being connected diagonally symmetrically such that one of said pair of windings of said first balun is connected between a non-grounded input signal source and said input of one of said first and second active circuit elements, and one of said pair of windings of said second balun is connected between said output of another of said first and second active circuit elements and a first input of a combiner or directional coupler having an output connected to a non-grounded output signal terminal; and further comprising: a third active circuit element having an input connected, to said common node and an output connected to a second input of said combiner or directional coupler; and whereby when respective signals are applied to said pair of windings of said first balun, said outputs of said first and second active circuit element are respectively substantially out of phase with respect to each other.