LAUSR

In this letter, a robust multisampling rate digital predistortion (DPD) scheme is proposed to linearize ultra‐broadband power amplifiers (PAs) under the limited DAC sampling rate. In the ultra‐broadband scenarios, it is no longer affordable to employ DACs with 3‐5 times over‐sampling rate, which will inevitably lead to spectrum aliasing for the sake of high order basis function and compromise the DPD performance. In order to improve the modeling accuracy, the input signal with low sampling rate will be up‐sampled firstly to generate nonaliasing basis functions. Then, after filtering and down‐sampling operation, the coefficients are extracted with low sampling rate. Moreover, the conventional behavioral model is modified with the linear‐spline basis functions to improve the stability and complexity. Measurements on Doherty PA and class‐AB PA with 100 MHz, 200 MHz, and 500 MHz bandwidth input signal at 2.1 GHz carrier frequency show the EVM can be improved to 0.71%, 0.94%, and 1.86% respectively.