Design and test of a digital system based on a CMOS 0.35μm logarithmic pixel for time of flight measurement applications

This paper describes the design and test of a digital system, whose purpose is to work as an optical detector for "time of flight" measurements. The system is based on a logarithmic pixel with binary output. Design technology is AMS 0.35 mum CMOS. This structure presents four blocks: i) Receptor block, sensitive to the light excitement, ii) Inverter block to amplify the signal, iii) Feedback block to control the memory effect until next measurement and iv) Ramp Memory block to detect the arriving time of the first laser pulse within the detection window. Experimental results show good response at working frequencies of 100 kHz.