This paper presents a CMOS Time-of-Flight (TOF) range imager using pinned-photodiode based high-speed 4-tap lock-in pixels with lateral-electric-field charge modulators (LEFM) in a 0.11 um CIS process. The proposed lock-in pixel structure using lateral electric field control is suitable for implementing a multiple-tap charge modulator while achieving high-speed charge transfer for high time resolution. The TOF imager with the multiple-tap charge modulators is expected to have background light cancelling capability in one frame and to improve range resolution with the 4 time windows for a range-shifted light pulse. Measurement results of the implemented TOF imager with 160×240 pixels are reported.
We have been researching and developing a CMOS image sensor that has 2.8 μm x 2.8 μm pixel, 33-Mpixel resolution
(7680 horizontal pixels x 4320 vertical pixels), 120-fps frame rate, and 12-bit analog-to-digital converter for “8K Super
Hi-Vision.” In order to improve its sensitivity, we used a 0.11-μm nanofabricated process and attempted to increase the
conversion gain from an electron charge to a voltage in the pixel. The prototyped image sensor shows a sensitivity of 2.4
V/lx•s, which is 1.6 times higher than that of a conventional image sensor. This image sensor also realized the input-referred
random noise as low as 2.1 e-rms.