Study of a modified Polar Sigma-Delta transmitter architecture for multi-radio applications

Polar sigma delta architecture has been previously proposed as a universal architecture able to offer multi-radio transmission for mobile systems. This paper describes polar sigma delta transmitter architecture and proposes modifications to it in terms of replacing analog mixing by digital mixing when recombining envelope and phase signals. Simulations of the modified architecture have been carried out for the mobile WiMAX standard. Impact of the frequency synthesizer on the performance of the architecture is also investigated considering the switched loop bandwidth topology. Results are presented and new architectures advantages and drawbacks are pointed out.