| Summary: | 碩士 === 國立交通大學 === 電子工程系所 === 97 === The mammalian retina is comprised of five different kinds of cells, for each kind can be divided into more types. Besides transducing the visual world into neural signals, these cells are in charge of 0.3% of the visual function of the brain. In this research, we try to understand the retinal functions from the engineering point of view.
In this thesis, a new design methodology is proposed to implement CMOS neuromorphic chips which imitate the ON sluggish sustain ganglion cell set of rabbits’ retinas. A retinal chip based on the biological model derived from the mammalian retina is proposed.
The retinal chip contains a focal plane sensory array of 32x32 similar basic cells that perform the functions. Each basic cell contains photo-input, photoreceptor, horizontal cell, on bipolar cell, off bipolar cell, amacrine cell and ganglion cell. ESD protection circuit for I/O pads, address decoders and readout circuits are also included in this chip.
Finally, the results of HSPICE simulation and chip measurement are compared with that of the original model to examine the consistency and the difference for further improvement. The measurement results on the fabricated CMOS neuromorphic chip are consistent with the biological measurement results. Thus the biological functions of the chip have been successfully verified. It can be used to understand more biological behaviors and visual language of retina under different input optical images which have not yet been tested in biological experiments. Based on the results, the full ganglion cell sets of retina can be designed. Otherwise, many potential applications of retinal chips on motion sensors, computer vision, retinal prosthesis, and biomedical devices are feasible.
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