A fixed point approach to wideband amplifier compensation for IS-2000

A digital baseband predistorter based on the "fixed point" approach (FPPD) is developed to compensate a nonlinear high power amplifier (HPA) in an IS-2000 system. The FPPD incorporates a memoryless nonlinear HPA model derived from samples of the HPA's input and output signals to overcome shortcomings in previous FPPDs. Link performance for a perfectly linear HPA, nonlinear HPA, and compensated HPA are compared using an IS-2000 forward link simulator. The FPPD reduces spectral regrowth of the sidebands caused by using a nonlinear HPA by about 7 dB within 1.5 MHz of the carrier frequency.