Design of real-time VGA 3-D image sensor using mixed-signal techniques

We have developed the first real-time 3D image sensor with VGA pixel resolution using mixed-signal techniques to achieve high-speed and high-accuracy range calculation based on a light-section method. Our mixed-signal position detector, which consists of an adaptive threshold circuit and time-domain approximate ADCs, provides significant information for range finding quickly during high-speed analog-to-digital conversion. Moreover the position address and the intensity profile of a projected beam are selectively provided by the next digital stage to reduce data transmission. Our 3D imager also has a standard analog readout circuit to get a 2D image. Measurement results show that it achieves 65.1 range-maps/sec with 0.87 mm range resolution at 1200 mm distance.