Development of a ToF Pixel With VOD Shutter Mechanism, High IR QE, Four Storages, and CDS

Abstract

In this paper we discuss the development of an indirect time-of-flight (ToF) pixel in the 0.11- $\mu \text{m}$ CMOS image sensor technology. The pixel design is based on a pinned-photodiode structure with a novel vertical overflow drain (VOD) shutter mechanism used for fast modulation. We present the second generation of the pixel, with a greatly improved VOD structure that enables a fast shutter efficiency better than 1:100 and a deeper photodiode collection depth for better quantum efficiency in the near-infrared wavelengths. We present a new 6.7- $\mu \text{m}$ pixel design with four pinned storage diodes (SDs) that feature in-pixel complete charge transfer and enable correlated-double-sampling readout as well as an almost simultaneous global shutter exposure of up to four interleaved frames to be used for the scene depth computation. The novel design features a low readout noise of 7.5e- and a full-well-capacity of 9500e- per SD (a total of 38 000e- per pixel).