ABSTRACT
The first CMOS-based sensor chips were developed in the 1960s, but the world of solid-state imaging was revolutionized by another invention. In 1970, charge-coupled devices (CCDs) were invented at the Bell laboratory. Very soon, CCDs took over all the competing technologies. For approximately 20 years, from the invention of CCDs to the late 1980s, CMOS sensors were confined to very specialized applications, namely, infrared focal-plane detectors [1]. In the past decade, however, CMOS sensors gained popularity again due to the extremely fast development of CMOS technologies, which gives the possibility to implement large-area CMOS chips with many millions of components and to implement very small transistors and therefore small pixels. Further, the pixel matrix and readout circuits can be implemented on the same chip, which allows high parallelization of the readout and improves readout speed.
