A Tangent Approximation Coefficient Extraction Method for Instantaneous Sample Indexed Magnitude-Selective Affine Behavioral Model

The coefficients of digital predistortion (DPD) models are often extracted by the least square (LS) method, which has high computational complexity because of the operations of the large matrix. In this letter, a low complexity coefficient extraction method for instantaneous sample indexed magnitude-selective affine (I-MSA) model is proposed. The proposed method uses the tangent of the midpoint of the piecewise function to fit the curve. Therefore, the LS coefficient extraction only needs a small amount of data near the midpoint, rather than using all the data in the segmented region. Simulation and experimental results have confirmed that compared with the original LS method, the proposed method has similar modeling accuracy and linearization performance, but the computational complexity of coefficient extraction is greatly reduced.