Circuitos analógicos em tecnologia CMOS para aplicações em próteses retinianas.

Abstract

This work has the main propose of doing a bibliographic research about analog circuits used for the implementation of retinal prosthesis. More specifically, the concept of Cellular Neural Network is studied, as well as the main blocks of analog circuits used for this kind of structure. First, a study about the human visual system is made, in order to understand the operation of its main organs and specially, the retina. A brief comparative between the functional and structural retina models is made, as well as an analogy between the operation of the retina itself and the cellular neural network. Then, the basic concept of neural network is explained, with an emphasis on the kind of network that is focused on its physical implementation, called Full Signal Range. In sequence, circuits as analog multipliers, current conveyors and current memories are shown. The operation of each block is then described. Their advantages and disadvantages are addressed, in addition to the placement of each block in a wider context in cellular neural networks.