A CMOS image sensor with analog pre-processing capability suitable for smart camera applications

Abstract

This work presents a novel CMOS sensor which is suitable for analog image processing operations and describes the benefits of analog pre-processing over digital algorithms. All needed modifications to read out a spatial NxN pixel matrix simultaneously are presented regarding pixel wiring, row decoder and column multiplexer as well as descrambling the order of the outputs. The outputs are connected via a buffer stage to the analog pre-processing circuits. As an example for such an analog computation, an averaging filter is described from design constraints to the actual implementation. Simulation results show a very low current consumption of just 55.3 μA under worst-case conditions and a computation time below 200 ns. This corresponds to a power-time product ratio of 1:18.75 compared to a digital state-of-the-art implementation.