Design and Experimental Evaluation of a LINC Transmitter for OFDM Systems

The LInear amplification using Nonlinear Components (LINC) technique is a well-known power amplifier linearization method to reduce out-of-band interferences in a nonconstant envelope modulation system. Its major drawback is the inherent sensitivity to gain and phase imbalances between the two amplifier branches. In this paper a digital correction method, which corrects these gain and phase imbalances, is implemented and verified. Commercial analog devices and a digital platform for signal processing purposes are used. The experimental results applied in an OFDM transmitter show a linearity improvement close to 20 dB without reducing the output power and without increasing the in-band distortion.