A Comparative Study of RF-QAM and Conventional Transmitter Architectures

The new philosophy of realizing high-order modulation schemes directly in the RF domain enables the generation of spectrally efficient $4^{M}$ quadrature-amplitude-modulated $(4^{M}$ QAM) symbols using the vectorial summation of $M$ quadrature phase-shift keying (QPSK) signals. As will be shown in this paper, this approach, called RF-QAM, leads to several remarkable advantages in power amplification and signal formation in terms of both performance and power consumption. This paper presents a study of the RF-QAM transmitter (TX) and a comparison with the conventional architecture, as well as analytical studies and simulations to verify the superior performance of the RF-QAM transmitter compared to the conventional counterpart.