Large size photodiode used in high speed CMOS image sensor pixel suffers from slow signal charges transfer speed and
large image lag. To solve these problems, in this paper, we present a new device structure for high speed CMOS image
sensor pixel with lateral graded-doping profile pinned photodiode and non-uniform doped channel transfer gate. Theory
analysis and TCAD simulation results indicate that the proposed pixel can increase the signal charges transfer speed and
reduce the image lag effectively. The measurement results show that, the proposed pixel is able to achieve 40ns readout
time and 0.44% image lag. Compare to conventional pixels, 64 times higher readout speed enhancement and five times
lower image lag were achieved.
This paper presents the design and the simulation of pixel for real time three dimensional (3D) measurements based on
Time of Flight (TOF) technique. The pixel is designed to detect the time delay between transmitted and reflected light.
Based on 4T active pixel, A TXD transfer gate is added to realize TOF function. In order to enhance lateral drift field,
the pixel adopts a split device structure. The implant energy and dose of photodiode are simulated in 2D carefully with
simulation tool TCAD. 3D simulation is presented to verify the 3D measurement function of the pixel. The simulation
results show that proposed pixel can achieve 10ns transfer time and meet the requirement for TOF.