Linearization of high-efficiency power amplifiers using digital baseband predistortion with iterative injection

This paper presents the linearization of a high-efficiency compressed power amplifier (PA) by iterative digital predistortion with suppression of memory effects. Iterative injection of the odd-order in-band distortion components is used to enhance the nonlinearity compensation and achieve the optimal ratio of linearization degree to computational complexity by adjusting the number of injections. Baseband equalization of the input signal minimizes memory effects. The proposed linearizer is designed within the baseband block, and does not require additional radio-frequency components. The experimental investigation is carried out with EDGE signals for an up-link PA. Up to 18 dB improvement in spectral re-growth and 10 dB reduction in a 500-kHz offset adjacent channel power ratio (ACPR) are achieved for 200-kHz EDGE signal at 880 MHz.