Backside-illumination 14µm-pixel QVGA time-of-flight CMOS imager

Abstract

This paper presents a BSI(backside-illumination) 14μm-pixel QVGA CMOS image sensor SOC(System On a Chip) measuring TOF(Time-Of-Flight) by 20MHz-intensity modulation of 850nm-wavelength light. The 34% of overall QE(Quantum Efficiency) at 850nm-wavelength is acquired by BSI structure and optimized micro-lens. The DE(Depth Error) less than 1.5% within 6m is achieved with imaging lens of f/1.2 and LED array of which the optical intensity is 0.6W/m2 at 1m-distance. Additionally, the depth linearity is measured as that the coefficient of determination is equal to 0.9999. In order to operate under background light illumination on a scene, dual CG(Conversion Gain) scheme is implemented in each pixel.