A
system and method are provided for isolating an input without adding significant
distortion and without significantly adversely affecting the bandwidth of input circuits. In one embodiment, a single ended
signal is substantially cancelled by an arrangement including an
input resistance path in parallel with a
negative resistance path wherein both paths substantially match in resistance. In another embodiment, a differential
signal is substantially cancelled by a pseudo differential arrangement including two independent
input resistance paths each in parallel with a corresponding
negative resistance path, wherein the resistance paths substantially match the
input resistance paths. In yet another embodiment, a differential
signal is substantially cancelled by a differential arrangement including two resistance paths wherein a first
negative resistance path is coupled between the first differential input and the second differential output and the second negative resistance path is coupled between the second input and the first output. In yet another embodiment, a current controlled
current source may provide the negative amplification for the negative resistance path.