Pressures to increase resolution, achieve compact packages, and lower costs continue to drive focal plane readout circuits to highly complex designs with lowered yields in cutting edge processes. By designing a set of signal processing electronics into a 3D structure, cost and performance goals can be met while using higher yielding readouts and existing focal plane hybrids. The approach described in this paper allows existing designs from 480 X 4 through 480 X 640 to be used in compact sensor designs in a wide variety of applications. The demonstration of the approach uses an existing InSb photovoltaic hybrid array in a 120 X 160 configuration. Functions for non- uniformity correction, memory, and analog-to-digital conversion have been incorporated into a structure compatible with conventional dewar assemblies for military and commercial applications. The technology for these 3D focal planes is applicable to sensor functions for non- uniformity correction, analog-to-digital conversion, spatial and temporal filtering, fovea vision, event-driven multiplexing, data compression and coding, and pattern recognition.