Novel two-tone measurement of the nonlinearity and memory effects of mixers in different amplitude regions of large carrier signals

The conventional two-tone test method cannot measure the amplitude and phase of IM3 products under different operating conditions. The nonlinearity and memory effects of mixers under different operating conditions have not been characterized in existing research. This paper presents a new two-tone measurement method for characterizing the nonlinearity and memory effects of mixers under the excitation of large carrier signals of different amplitudes. This new test method differs from the conventional two-tone test in that the two-tone test signal is superimposed on a large carrier signal. The role of the large carrier signal is to excite mixers into different operating conditions. The amplitude and phase of the IM3 product of the mixer could be measured to characterize the nonlinearity and memory effects under different operating conditions using this method. This novel method is based on a vector network analyzer (VNA) and signal generator (SG). Compared with the conventional method of only using a spectrum analyzer and SG, the VNA can remove the system error through a calibration algorithm to ensure the accuracy of the IM3 product measurement results. The measurement results, for the first time, demonstrated the nonlinearity and memory effects of mixers in different amplitude regions of a large carrier signal. These findings are advantageous and can facilitate further research to simplify the digital pre-distortion model of mixers under different operating conditions.