Modified Polar Sigma-Delta Transmitter for Multiradio Applications
© Martha Liliana Suarez Penaloza et al. 2010
Received: 7 June 2010
Accepted: 16 September 2010
Published: 30 September 2010
Radio transmitters capable of transforming variable envelope signals into constant envelope signals can be associated with high-efficiency switched mode power amplifiers. One of the techniques providing this conversion is Polar Sigma-Delta ( ) architecture. This approach provides efficient solution for high-dynamic signals, and, moreover, it offers flexibility in a multiradio environment. The overall concept of the polar transmitter is presented here along with novel modifications and improvements. Namely, when recombining the envelope and the phase signals, it is suggested to replace the analog mixing by a digital mixing. The impact of a frequency synthesizer with a switched loop bandwidth and its imperfections on the overall polar architecture is investigated as well. The Mobile WiMAX standard has been chosen for validation due to very high requirements in terms of power dynamics and the variable channel bandwidth. Simulation results are presented in this paper, and advantages and drawbacks of this novel approach are pointed here as well.
To access the full article, please see PDF.
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.