Modified Polar Sigma-Delta Transmitter for Multiradio Applications

• Main Authors: Maršálek Roman, Suarez Penaloza MarthaLiliana, Valenta Václav, Baudoin Geneviève, Villegas Martine
• Format: Article
• Language: English
• Published: SpringerOpen 2010-01-01
• Series: EURASIP Journal on Wireless Communications and Networking
• Online Access: http://jwcn.eurasipjournals.com/content/2010/979120

<p/> <p>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 (<inline-formula> <graphic file="1687-1499-2010-979120-i1.gif"/></inline-formula>) 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 <inline-formula> <graphic file="1687-1499-2010-979120-i2.gif"/></inline-formula> 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 <inline-formula> <graphic file="1687-1499-2010-979120-i3.gif"/></inline-formula> 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.</p>