Predicting amplifier intermodulation distortion from single-tone measurement/simulation

Official URL: https://dx.doi.org/10.1109/APMC65046.2025.11378877

Two closely spaced fundamental tones are usually required to measure or simulate the intermodulation distortion characteristics of amplifiers. This paper explores the possibility of predicting third-order intermodulation distortion (IMD3) characteristics from single-tone measurement and/or simulation. Comparison of single-tone and two-tone harmonic balance simulation results shows that it is possible to predict the input power dependence of IMD3 from the former and therefore the third-order intercept point (IP3), too, better than from the well-known approximate relationship between IP3 and the single-tone 1-dB gain compression point (P1dB). Measured single-tone X-parameters of an amplifier are also shown to give a reasonable estimate of its IP3.