Cellular radio networks become more and more versatile. The amount of data they have to handle is increasing rapidly. This is only made possible by a continuing advance in communication standards and the extension of spectral resources.
In order to take full advantage of the increasing diversity, infrastructure components are required to genuinely support multiband/multistandard operation, which is particularly challenging in the design of analog frontends.
In this context, three subprojects (all within the framework of BMBF project CoMoRa) are concentrated at our institute.
One subproject deals with advanced PA designs, simultaneously featuring high bandwidth and high average efficiency for modulated signals with high crest factor. Supplementary to this, research on digital predistortion and signal conditioning algorithms for multiband/multistandard PAs is performed.
Another subproject concerns active filtering techniques applied to transceivers systems.
An active filter uses selective feedback to increase the overall selectivity and therefore relaxes the specifications of classical filtering elements (i.e. duplexers).
Particular attention is paid to perform a feasibility study regarding the delay in the feedback chain and stability issues of the overall system.