A new adaptive feedforward amplifier using imperfect signal cancellation

This paper describes a new adaptive feedforward amplifier for WCDMA system using an imperfect signal cancellation. Due to the complicated signal statistics, the distortion generated by the error amplifier is significantly reduced by the imperfect signal cancellation. Therefore, the performances of feedforward amplifier are improved with this new adaptation technique., especially for the modulated signals with a high peak-to-average ratio. For verification, a 2.14 GHz feedforward amplifier with 80 W output power has been implemented and tested with digital control circuits. The results, compared to the perfect signal cancellation, show more than 7 dB improvement of ACLR at 80 W output power. The efficiency is also improved from 7.5 % to 9 % at the same ACLR's.