Patent ID: 8417197

Claim:
A method for linearizing a power amplifier circuit having as input signal a digital base-band input signal, a power output signal, a power amplifier and a linearizer module (LM), the method comprising the steps of: extracting a radio frequency (RF) feedback signal from the power output signal; down-converting the RF feedback signal to an intermediate frequency (IF) feedback signal; filtering the IF feedback signal with a band-pass filter; digitally converting the filtered IF feedback signal into a feedback digital signal; converting the feedback digital signal into a frequency-domain using a Fast-Fourier Transform (FFT) on blocks of n-samples to obtain feedback-FFT (FB-FFT) blocks; averaging at least two blocks of feedback FB-FFT blocks to obtain an averaged FB-FFT block; converting the input base-band digital signal into a frequency-domain using FFT on blocks of n-samples to obtain input feed-forward-FFT (FF-FFT) blocks; averaging at least two blocks of input FF-FFT blocks to obtain an averaged FF-FFT block; dividing the averaged FF-FFT block with the averaged FB-FFT block to obtain FFT correction values; obtaining time domain (TD) filter coefficient values based on FFT correction values; applying the TD filter coefficient values to a digital band-pass filter, the input of said digital filter being the input base-band digital signal; converting the output of the digital band-pass filter into analog with a digital to analog converter to obtain a corrected IF input signal; applying the band-pass filter to the corrected IF input signal; up-converting the filtered corrected IF input signal to obtain a corrected RF input signal; and applying the corrected RF input signal to the power amplifier so as to produce the power output signal.