A 310 k pixel bipolar imager (BASIS)

Abstract

A bipolar imager with an amplification function in each pixel has been developed using BiCMOS technology. The imager, which stores photocarriers in the base regions of the bipolar transistor pixels, is called the base-stored image sensor (BASIS). BASIS-type devices have been faced with three problems: (1) a reset transistor is needed in each pixel to initialize base voltage; (2) nonuniformity of offset voltage appears as fixed pattern noise; and (3) blooming is induced by intense light. Effective methods of dealing with these problems have been found. A BASIS imager with 310 k pixels in a 2/3-in optical format is described. The device specifications and characteristics of the imager are summarized.<>