Memory correction for a WCDMA amplifier using digital-controlled adaptive analog predistortion

A digital-controlled adaptive analog predistorter, described in, is extended to accommodate wider bandwidth WCDMA signals and to provide memory correction. The desirable characteristics of the original system are preserved, which include low cost, low insertion delay, adaptive coefficient estimation, and a data acquisition system using sub-Nyquist asynchronous sampling. The predistortion function is based on a zero-crossing structure derived from the input signal envelope and its derivative. Memoryless distortion is corrected using the input envelope only whereas the memory correction also includes the derivative of the input envelope. A Matlab simulation modeling a class AB biased amplifier verifies the feasibility of wide bandwidth operation. Tests using a WCDMA input signal with a 101-carrier configuration indicate that memory correction can improve the ACLR2 by 2.7 dB, which is comparable to the results presented in.