A technique, developed by Cincinnati Electronics and Jet Propulsion Laboratory, of utilizing charge integration with InSb photovoltaic arrays is described. This device uses a MOSFET switched silicon multiplexer to sequentially connect each detector to a common line and JFET amplifier. A noise model is presented which can be used to predict performance of the detector/multiplexer system. Performance prediction curves are included that allow comparisons and decisions related to system design. This noise model can be generalized to calculate performance characteristics, particularly D* and NEP, for any detector/multiplexer configuration.