A Time-of-Flight CMOS Range Image Sensor Using 4-Tap Output Pixels with Lateral-Electric-Field Control

Abstract

This paper presents a 160×240-pixel CMOS Time-of-Flight (TOF) range imager with a 4-tap charge modulator using pinned-photodiode high-speed lock-in pixels in a 0.11μm CIS process. The proposed lock-in pixel structure using lateral electric field (LEF) control is suitable for implementing a multiple-tap charge modulator while achieving high-speed charge transfer for high time resolution. A CMOS TOF range imager with the multiple-tap charge modulators is expected to have background light cancelling capability in one frame and to improve range resolution with shifted short double light pulses. In this paper, we report the design, implementation and evaluation results of the TOF range imager using the 4-tap LEF modulator (LEFM). The TOF range imager has a range resolution of less than 3.2mm for the range from 1.0m to 2.0m at the frame rate of 15.7fps.