The effect of quantization in a digital signal component separator for LINC transmitters

Spectrally efficient modulation schemes have been chosen for the second generation of cellular systems in the United States and Japan, as well as for private mobile radio (PMR) systems. This paper analyzes the effect of quantization in a digital signal component separator (SCS) for linear amplification with nonlinear components (LINC) transmitters. The analysis relies on the fact that the two signal components can be obtained as the source signal plus/minus a signal in quadrature to the source signal. The equations derived are vital because they allow the designer to optimize digital signal processor (DSP) power consumption and bandwidth. The word lengths that are required for the source signal and the quadrature signal can be calculated from the amplifier gain characteristic, the probability density function for the modulation scheme, and the specified adjacent channel interference (ACI). The validity of the analysis has been verified by means of simulations.