Splitting an input signal at an input coupling means into first and second in-phase coupled signals. The ratio of the second coupled signal power, p2, to the first coupled signal power, pu is K = ... dB, with pi and p2. in milliwatts.
Processing the first coupled signal at a first nonlinear device and the second coupled signal at a second nonlinear device. The first nonlinear device having a gain, Gi dB and a third order output intercept point OIP31dBm. The second nonlinear device having a gain, G2 dB and a third order output intercept point OrP32 dBm. The relationship of the first and second nonlinear, devices and the coupling means being most nearly 2(OIP3l - OIP32) = 3(G! - G2 - K), where G, is not equal to G2 + K.
Subtracting the output signal of the second nonlinear device from the output signal of the first nonlinear device to yield a final output signal that substantially reduces third order nonlinear distortion.