In this study, advanced range measurement method using a TOF sensor with 4-tap output pixels and small-duty short light pulse is presented. A CMOS TOF range imager with pinnedphotodiode high-speed charge modulator pixels using lateral electric field (LEF) control has been implemented by a 0.11-μm CIS process with high near infrared sensitivity. In order to improve the range resolution while maintaining the measurable range, multiple time-windows are used for range measurements. Compared with the conventional single time window, the use of N time-windows theoretically improve the range resolution by a factor of N1.5 if the back ground light shot noise is dominant. In the measurement for N=2, the range resolution is improved by a factor of 2.8 compared with the case of N=1 while maintaining the same distance range.
This paper reports high time-resolved imaging technique using a lateral electric field charge modulator with bipolar-gates. The proposed pixel structure achieved high time-resolved signal detection by using negative bias effect by work function difference between the p-type gate and p-substrate. The test chip fabricated in 0.11 um CIS technology demonstrates the high-speed charge modulation, and the modulation contrast is measured to be 97%.