An intermodulation products generator for predistortion of base station HPAs

This paper presents the design of an intermodulation (IM) products generator for predistortion of high-power amplifiers (HPAs) used in the base stations of cellular mobile systems. The IM products generator composes of two simple mixers constructed with Schottky diodes, has a simple structure and requires no external dc bias voltage. Simulation and measurement results show that the generator has a low conversion loss and low spurious frequency components. Studies of the IM3 generator for predistortion of a practical base station HPA are also carried out by simulation and measurements. Measurement result of a two-tone test shows that the predistorter can suppress the 3^rd intermodulation distortion (IMD) products by 15 dB.