Comparison and Experimental Verification of Two Low-complexity Digital Predistortion Methods

Recently, many papers have been published on the designs of predistortion systems for power amplifiers (PA). Most of these studies are based on computer simulations. In this work, we examine our predistorter (PD) designs on a practical microwave PA in a laboratory setup. The objective is to validate two PDs of different design approaches. The first PD is modeled using a simplicial canonical piecewise linear (SCPWL) function while the second one is modeled using a polynomial function. The former exploits the properties of the SCPWL function to develop a reduced complexity PD identification method. The latter utilizes the secant method to iteratively search for the signal at the PD output, thus parameter identification is avoided. The implementation complexity and effectiveness of the PDs are compared. The limitations of the measurement system for predistorter design is also discussed briefly