The use of Nonlinear Curvefitting in Digital Predistortion for Linearizing RF Power Amplifiers

Nonlinearity has long been recognized as a problem endemic in power amplifiers (PA) with a high power. Digital predistortion (DPD) is one of most effective method to solve this problem. In this paper we used nonlinear curve-fitting to perform digital predistortion. We applied our technique to a RF power amplifier that nominally operates at 885MHz with 30 watts output. When the IS95 standard test signal is applied to the power amplifier with its output power pushed to 45 watts, we found that nonlinearity of power amplifiers can be greatly improved (8dB in ACLR) by our technique. Experimental results demonstrate the success and the feasibility of this method.