Characterization of the power amplifier group delay by using predistortive cancellation technique

This paper proposes a novel memory effect measurement technique in RF power amplifiers (PAs) using two-tone intermodulation distortion (IMD) signal with very simple and intuitive algorithm. Based on the proposed predistortive tone cancellation technique, the proposed measurement method is capable of measuring relative phase and magnitude of the third-order and fifth-order IMD as well as the fundamental signal. The measured relative phase between the higher and lower IMD signal for specific tone spacing can be interpreted as the group delay information of the IMD signal concerned. From the group delay analysis, we can conclude that adaptive control of group delay as well as the magnitude and phase is a key function in increasing the linearization bandwidth and the dynamic range in the predistortion (PD) technique.