Title:RF Transmitter Architectures for Nomadic Multi-radio: A Review of the Evolution Towards Fully Digital Solutions
VOLUME: 6 ISSUE: 2
Author(s):Antoine Diet, Fabien Robert, Genevieve Baudoin, Martine Villegas, Philippe Cathelin, Pascal Triaire and Ajib Bahi
Affiliation:L2S-DRE. UMR8506. Supélec, F-91192 Gif S/ Yvette, France.
Keywords:EER, ET, fully digital architecture, linearisation, LINC, RF architecture.
Abstract:In this paper, a review of the major evolution steps of mobile transmitter architectures is summarized. We propose
a classification and discuss about improvements and evolutions towards the full-digital solutions. This discussion is
mandatory while the cognitive-radio concept implies the design of new structures for multi-radio front-ends. Technological
process improvements, for example CMOS for high frequency, opens new possible solutions thanks to digitally based
buildings blocks and functions. The conception of fully digital architectures is discussed in that idea. Our work in this
domain is presented as a contribution in the study of transmitter architecture for multi-radio. Two ways are explored: (1)
improvements of analog and digitized architectures, and (2) digital architectures. We present, in these two fields, a state of
the art of published works and patents [US20130051440A1], [US20130084816A1], [US20120320957A1]. The Multiradio
context drives us to redefine the important figures of merit for the architecture design, as seen in recent publications
and patents such as [US20130049854A1], [US20130009710A1], [US8432219], [EP2541781A1]. The traditional efficiency/
linearity trade-off has to be considered with a mandatory frequency flexibility and power control ability, defined
here as “power scale-ability”. These constraints made the conception of fully digital architectures attractive, thanks to the
flexibility of digital systems. The first part of this paper will present the challenges of designing transmitter architectures
for cellular and wireless local/extended area networks (WLAN and WIMAX for example), under the hypothesis of nomadic
communication system. The design method in that context is consequently different from classical architecture design.
In the second part, a classification of the RF transmitter architectures and their evolution are proposed. Evolution
from linearization to linear architectures and introduction of digitized functions are presented, in that order. Solutions are
appreciated differently, considering the multiple tradeoffs on efficiency, linearity, flexibility and complexity, while taking
into account integration and realization (process).
