<title>Active pixel sensors: are CCDs dinosaurs?</title>

Abstract

Charge-coupled devices (CCD's) are presently the technology of choice for most imaging applications. In the 23 years since their invention in 1970, they have evolved to a sophisticated level of performance. However, as with all technologies, we can be certain that they will be supplanted someday. In this paper, the Active Pixel Sensor (APS) technology is explored as a possible successor to the CCD.An active pixel is defined as a detector array technology that has at least one active transistor within the pixel unit cell. The APS eliminates the need for nearly perfect charge transfer --the Achilles' heel of CCDs. This perfect charge transfer makes CCD's radiation "soft," difficult to use under low light conditions, difficult to manufacture in large array sizes, difficult to integrate with on-chip electronics, difficult to use at low temperatures, difficult to use at high frame rates, and difficult to manufacture in non-silicon materials that extend wavelength response. With the active pixel, the signal is driven from the pixel over metallic wires rather than being physically transported in the semiconductor.This paper makes a case for the development of APS technology. The state of the art is reviewed and the application of APS technology to future space-based scientific sensor systems is addressed.

Ultra Low Noise CMOS Image Sensors

“…E. R. Fossum was the first to take advantage of this aspect. He proposed the in-pixel integration of charge transfer and source follower buffering in 1993 [22,23] and gave it the name of active pixel sensor (APS). This CMOS structure used a photogate as a detection device.…”

Empowering Low-Cost CMOS Cameras by Image Processing to Reach Comparable Results with Costly CCDs

“…BW ij (9) By dividing the total intensity (TI) in a grayscale image to the total number of WPs, the intensity per white pixel (I/WP) parameter is defined.…”

“…toys, cell phones [9], [10]) due to their inherent advantages such as low power consumption,lowcost,compactnessandhighintegration. Recently, this traditional misconception started to dissolve and CMOS imagers started to show up in both high quality Digital Single Lens Reflex (DSLR) cameras and biological applications.…”

Systematic experimental study on stitching techniques of CMOS image sensors

“…Comparing with CCD, CIS has the major advantages of low power consumption, single voltage power supply and compatibility with well-established standard silicon process in high-volume wafer plants [2,3,4]. The CIS preserved all the desirable features of CCD, yet circumvented the major weaknesses of the CCD technology [5], making the CIS become the most common and highest yielding process in the world by far. Because of the reticle size limitation, the size of CIS were constrained within 26 mm  33 mm, left the semiconductor industry with no choice but to adopt Stitching Techniques to continue the scaling of technology.…”