Uncooled Microbolometer Infrared Focal Plane Array Without Substrate Temperature Stabilization

This paper presents a novel and compact compensation architecture for uncooled microbolometers without substrate temperature stabilization. The substrate temperature-induced nonuniformity and nonlinear resistance characteristics of the microbolometer array elements are investigated in detail. We propose an analytical model to identify the main nonideal effects and dispersion sources caused by the substrate temperature and their respective impacts on the uncooled microbolometers array. This proposed compensation approach is based on a differential current mirror readout architecture, which allows pixel response and offset correction to be performed as a function of the uncooled infrared focal plane array (IRFPA) sensor´s operating temperature. An experimental FPA chip based on this approach has been designed and implemented on silicon using a 0.5- μm CMOS technology and surface micromachining process. The proposed architecture allows the microbolometer array nonuniformity control over a wider range of readout integrated circuits substrate temperatures while maintaining better than 63-mK noise equivalent temperature difference with f/1 optics. As a result of the elimination of the temperature stabilization requirement, the IRFPA turn-on time for high performance imaging can be greatly reduced. Power, volume, and weight of the IRFPA are also significantly reduced. This approach is ideally suited for high-volume, low-cost, low-power, and low-weight production applications.