AIRS is a key facility instrument on the first post meridian platform as part of NASA'a Earth Observing System (EOS) program. The Atmospheric Infrared Sounder measurement technique is based on passive IR remote sensing using a high spectral resolution grating spectrometer. The structure of the infrared focal plane for the AIRS instrument has been defined and is presented in this paper. The optical footprint of 8.1 mm by 36.3 mm along with the necessary support and interface components leads to a focal plane assembly of 53 mm by 66 mm, the largest ever built at LIRIS. With 4208 diodes and 274 photoconductors in the same focal plane to achieve the wide spectral coverage from 3.7 to 15.4 micrometers , a modular approach is required. Ten PV modules utilize silicon readout integrated circuits (ROICs) joined to the detector arrays as either direct or indirect hybrids while two PC modules cover the 13.7 to 15.4 mm range, optically chopped and led out to uncooled preamplifiers. The simultaneous operation of PV and PC devices in the same focal plane has required unique approaches to shielding, ROIC output design and lead routing. High D*'s of 7E14 and 3E11 cm- Hz1/2/W are needed to meet the sensitivity requirements of the 4.2 and 15.0 micrometers regions respectively. The 35 micrometers by 800 micrometers PC detectors on a 50 micrometers pitch have necessitated modifications to standard delineation techniques, while the MW performance is nearly D* BLIP for PV devices. Dispersed energy is presented to the modules through 17 narrow band filters packaged into a single precision assembly mounted within 0.18-0.25 mm of the focal plane surface. The more than 50 components comprising the focal plane in conjunction with the tightly spaced optical pattern presented by the grating add a high degree of complexity to the assembly process. This paper focuses on the architectural constraints derived from performance, interface, and reliability requirements. Key aspects of these requirements are presented and their impact on the partitioning of the 12 modules is discussed. The rationale for the spectral range assigned to each module is reviewed relative to PV and PC performance capabilites. ROIC design guidelines and physical contraints due to manufacturability and assembly. Results of structural and thermal analyses for the various module configurations and assembled focal plane to determine compliance with the stringent stability and positional requirements are presneted. Specific features of the module carrier/interface boards and the multilayered focal plane carrier/interface board are included as well as a review of the overall assembly sequence of the focal plane as influenced by repairability and reliability considerations. The comprehensive redundance strategy applied to the design of the FPA/dewar assembly will be reviewed, and the approach for operation/survival in the radiation environment is discussed. Key features of the ROIC, PV, and PC array designs will be presented along with results of analyses performed.