We propose to investigate the feasibility of developing a 64x64 far infrared germanium focal-plane array with the following key design features: 1- Four top-illuminated, 32x32 germanium sub-arrays will be tiled together to form a 64x64 mosaic array. Germanium offers very low noise and proven performance in the 50-140¿m range. 2- The array will use four SB349 CTIA readout multiplexers which are manufactured using advanced cryo-CMOS process. The unit-cell design is optimized for far IR detectors, eliminates detector debiasing, and improves pixel uniformity. The readout is operational down to at least 1.6K. 3- A novel, layered-hybrid design using planar bump-bond technology will be employed to assemble the focal plane. This integrated design offers superior noise performance and effectively addresses the readout glow, detector heating, and thermal mismatch between the detector and the readout. In addition to the large format, this is the key discriminator of this project. This is by far the largest far IR photodetecor array produced with projected sensitivity of ≤ 1x10E-18 W/√Hz. This effort fits well within the scope of the SBIR Subtopic S4.01 and will be a benefit to advanced instrumentation of NASA¿s astronomical missions, in particular SOFIA.