Volterra characterization and predistortion linearization of multi-carrier power ampliflers

The linearization of RF power amplifiers (PA) can benefit from the availability of the generalized Volterra coeflicients characterizing its non-linear response. In this work a large-signal network analyzer is used to acquire the amplitude and phase of the 3rd intermodulation terms Ym3- and Ym3+ of an LDMOSFET PA. The frequency dependence and difference between Ym3- and Ym3+ reveals the memory effects of the RF amplifier. A new vectorial digital predistortion linearization with 3rd and 5th order corrections is implemented to account for the difference in memory effits in the lower and upper side bands. The two band predistortion . linearization can linearize independently each band of a 2-carrier WCDMA in a LDMOSFET RF amplifier providing up to 40 dBc ACPR. The extension from 2-carrier to multi-carrier power amplifiers could proceed by further dividing the bandwidth in additional bands.