Architectures for High Dynamic Range, High Speed Image Sensor Readout Circuits

The stringent performance requirements of many infrared imaging applications warrant the development of precision high dynamic range, high speed focal plane arrays. In addition to achieving high dynamic range, the readout circuits for these image sensors must achieve high linearity and SNR at low power consumption. Two high dynamic range image sensor schemes that have been developed for visible range imaging were reviewed first and discuss why they cannot meet the stringent performance demands of infrared imaging. A new dynamic range extension scheme, folded multiple capture, was then described that can meet these performance requirements. Dynamic range is extended using synchronous self-reset while high SNR is maintained using few non-uniformly spaced captures and least-squares fit to estimate pixel photocurrent. The paper concludes with a description of a prototype of this architecture targeted for 3D-IC IR focal plane arrays