All Digital High Speed Visible Imaging Array

A study of the application for a visible light camera based on placing a Delta Sigma modulator at each pixel to provide per pixel A/D showed the potential for superior performance compared to alterate APS designs. It was demonstrated that substantiallyhigher fill factor and smaller pixel size could be achieved using common CMOS technology. Well capacity and linearity of the sensor were also shown to be superior to both CCD and APS designs. The approach, multiplexed oversample A/D, MOSAD is based on amodification of the well understood Delta Sigma A/D technology. A new design for a large high speed monolithic visible light camera will be developed with this technology. The potential to achieve high frame rates, beyond 1,000 fps, in a large array ofover 4,000 X 3,000 pixels will be developed with demonstration of working hardware. The development will be based on using off the shelf CMOS processes to design and build a custom camera sensor array chip. Optimum sensitivity will be achieved using afront side illuminated silicon photo diode detector. Projected fill factor of the monolithic sensor will exceed 48% at pixel sizes down to a 5.4 micron pitch. A complete camera system will be demonstrated at the conclusion of the program.Visible lightcameras developed using CCD and APS approaches have been severely limited in the ability to sense bright high photon count scenes. Both approaches are limited in well capacity and linearity and must be stopped down to work in bright scenes. APS is furtherlimited by high nonuniformity limiting applications to about 8 bits at most. The MOSAD technology improves the sensor for bright scene application by providing the well capacity and linearity necessary without stopping down in the optics. This will allowgreater dynamic range needed in the medical instruments and industrial control systems. Objects lost in the shadows with CCD and APS cameras will be visible with MOSAD cameras.