A 64x8 pixel 3-D CMOS time-of flight image sensor for car safety applications

For car safety applications a 64x8 pixel 3-D CMOS image sensor based on the time-of-flight principle (TOF) has been developed and successfully tested. The illumination source used is a pulse modulated (PM) class 1 laser operating at 910nm wavelength. The sensor employs the so called "multiple double short time integration (MDSI)", which compensates for sensor as well as scene nonidealities, like reflectance variations, and it suppresses the effects of background illumination. An optimised pixel circuit presented in this paper enables the detection of objects with a distance resolution of 2.2mm in the range up to 20m. This result has been achieved by reducing the noise equivalent power (NEP) of the sensor in comparison to previous approaches. The chip has been realized in a 0.5µm n-well standard CMOS process. The pixel pitch is 130µm with a fill factor of about 100%.