Reduction of EMC Power Amplifier Intermodulation by Using Digital Signal Predistortion

The current EMC IEC 61000-4-3 standard includes multiple complex signals like multitone as a possible input signal for radiated immunity test. Nevertheless, due its nonlinear behavior, amplifiers can distort the multitone input signal to some degree, generating intermodulation products at the output which will result in unwanted and additional frequencies applied to the EUT that may affect the results of the test. This paper presents a predistortion method based on the Generalized Memory Polynomial model to compensate for the system nonlinearities. Simulations in MATLAB are performed considering a mathematical model of the physical EMC Sonoma 330 Broadband RF amplifier. The proposed predistortion method could successfully remove the intermodulation distortion products.