This paper deals with sound source localization in mobile robotics. This context opens new areas of research as it involves some specific constraints such as real time perfor- mance or embeddability. Quite often, broadband beamform- ing techniques are sought for, exploiting small-sized micro- phone arrays. A new approach to the design of broadband nearfield or farfield beamformers is first described, based on modal analysis and convex optimization. Original consid- erations related to the involvement of the theoretical beam- pattern into the real integrated acoustic sensor are then pre- sented, which lead to alleviate some constraints during the optimization process and enable the use of smaller arrays. The whole method is illustrated on an example.