An infrared sensor, comprising a focal plane array (FPA) of resistance microbolometer infrared detectors connected in such a manner to produce different pixel formats to meet specific detection requirements. Typically each imaging pixel may be a mosaic comprising a number of sub-pixels connected in parallel (although other configurations are possible), resulting in enhanced performance and ease of manufacture by micro-fabrication methods. The FPA may be integrated with a readout microcircuit on the same substrate so that with appropriate signal processing one is capable of forming an image of the field of view of interest, facilitating target recognition and very low false alarm rate.