A novel predistorter using a balanced type IM3 generator

초록

This paper presents a novel linearization scheme for a nonlinear RF amplifier. It is based on the amplitude modulation with envelope signal. The 3(rd) order distortion generator is composed of two FETs and it adopts a balanced structure for the purpose of main carrier cancellation. The amplitude and phase of the IM3 components can be controlled at RF band. This predistorter is implemented and tested at the KOREA PCS Tx. band (1840similar to1870MHz). Experimental results of two-tone test show that the IM3 cancellation is achieved about 30-40 dB for the wide dynamic range. The adjacent channel power ratio is improved by over 10 dB at the CDMA signal with a peak to average power ratio of 10 dB, and this improvement is maintained over a wide range of output power levels.