A linearizer reduces nonlinear intermodulation distortion in radio frequency and microwave systems by first directly generating in-phase and quadrature nonlinear intermodulation products of the system input. Controllable amounts of each phase are then added back into the system such that the vector sum of nonlinear intermodulation products at the output is reduced or eliminated by destructive interference, while the fundamentals are substantially unaffected. The quadrature distorted signals are generated with two lightly-biased and thus overdriven differential pairs having gain-determining degeneration impedances that are in quadrature with each other. The amount of each quadrature phase summed to the output is controlled with electronically tunable four-quadrant variable attenuators. The quadrature phasing enables rapidly convergent tuning to minimize distortion using conventional scalar spectral analysis. The advantages of a linearizer using rectangular vector coordinate system are significant.