Digital In-Pixel Uncooled LWIR Bolometer Camera

Current uncooled bolometer readout integrated circuits (ROICs) utilize in-pixel analog circuitry with analog-to-digital conversion (ADC) accomplished in the camera electronics or in the ROIC in the column circuitry. Locating ADC function in-pixel will provide much higher dynamic range and frame rate for uncooled longwave infrared (LWIR) imaging in large array formats. Benefits are also expected for production costs, signal-to-noise ratio, and CMOS foundry flexibility for commercial applications. The proposed Phase I effort will show, by design, proof of concept of digital in-pixel circuitry to achieve 1280x1024 format imaging in 12 m pixel pitch with 16-bits signal dynamic range and frame rate 240 Hz. The Black Forest Engineering (BFE) ADC approach utilizes an ADC circuit compatible with both scaled CMOS and 3D IC stacking. On Phase I, BFE will compare implementation methods addressing performance, cost, and risk. On Phase II the all-digital ROIC will be fabricated with bolometers and wafer level vacuum packaging. The ROIC will be integrated into a camera system prototype to demonstrate capability (performance and features) of digital in-pixel circuitry.