Abstract: A CMOS image sensor array has rows and columns of active pixels, and column lines in communication with the active pixels in the respective columns. Each active pixel has an output connected to a column line and includes a photodetector that produces a signal proportional to incident light intensity that is coupled to an active pixel output based on column select and row select signals. Each active pixel has a reset transistor for resetting the active pixel, wherein each reset transistor has a first gate terminal and a second gate terminal. The reset transistors have a variable threshold capability that allows increased sensor array dynamic range or mitigation of the effects of temperature or radiation induced transistor threshold voltage shifts. Row select, column select, and sense transistors can also be configured to have variable thresholds.

Abstract: Active pixel sensors are defined on double silicon on insulator (SOI) substrates such that a first silicon layer is selected to define radiation detection regions, and a second silicon layer is selected to define readout circuitry. The first and second silicon layers are separated by an insulator layer, typically an oxide layer, and the layers can be independently doped. Doping can be provided in the silicon layers of the SOI substrate during assembly of the SOI substrate, or later during device processing. A semiconductor substrate that supports the first and second layers can be removed for, for example, back side radiation detection, using a second insulator layer (typically an oxide layer) as an etch stop.