A 128×96 pixel event-driven phase-domain ΔΣ-based fully digital 3D camera in 0.13μm CMOS imaging technology

Low-cost 3D image capture devices are enabling new applications in the gaming, robotics, automotive and surveillance industries. A number of approaches are competing for a share of these markets. Stereoscopic cameras employ intensive image processing to interpret distance from the correlation of two separate image streams [1], structured light systems analyse the deformation of pat terned light projected over the scene, while time-of-flight (TOF) cameras require custom frequency-modulated image sensors and optical sources to measure the phase or return time of reflected light pulses. As rapid progress is made on com pact, high-frequency NIR LEDs, much research is being devoted to improve ments in the size, sensitivity and resolution of TOF image sensors. Analog pixel approaches provide compact pixel implementations but accuracy is limited by noise sources and nonlinearities of the analog electronics [2]. Single Photon Avalanche Diodes (SPADs) circumvent these issues and enable fully digital dis tance computation down to millimetric accuracy [3] by either direct or indirect demodulation schemes.