A novel bipolar imaging device - BASIC (BAse stored imager in CMOS Process)

A new pixel structure named base stored imager in CMOS process (BASIC), is proposed and realized with a conventional 1.5 μm CMOS process. The BASIC cell comprises three pMOSFETs and a new photosensor, which has the gate-body tied nMOSFET structure. The BASIC cell achieves high responsivity because the photosensor amplifies the photogenerated electron-hole pairs. Dynamic range is improved by using the reset of the base through the pMOSFET and correlated double sampling operation. The structure and operation principles of the BASIC cell are presented together with measurement results from the fabricated samples. It is shown that the BASIC cell can be scaled down for large arrays and it is adequate for low voltage operation.