An artificial retina chip with current-mode focal plane image processing functions

Author

Funatsu, Eiichi ; Nitta, Yoshikazu ; Miyake, Yasunari ; Toyoda, Takashi ; Ohta, Jun ; Kyuma, Kazuo

Author_Institution

Adv. Technol. R&D Center, Mitsubishi Electr. Corp., Hyogo, Japan

Volume

44

Issue

10

fYear

1997

fDate

10/1/1997 12:00:00 AM

Firstpage

1777

Lastpage

1782

Abstract

This paper describes an artificial retina chip consisting of an array of Variable Sensitivity Photo-Detector cells (VSPDs) which accomplishes both nondestructive output and programmable positive or negative sensitivity. Despite its simple structure, this VSPD array realizes programmable focal plane image processing by employing between-pixel current mode calculations, together with a novel addressing method in which filtering is executed by varying the addressing pattern generated by a scanning unit. The n-MOS VSPD pixel which we have designed consists of a pn photodiode and an n-MOS differential amplifier; the VSPD circuit has been optimized by SPICE simulation. Using a 2-μm n-MOS process gives a pixel size of 35 (H)×26 (V) μm² with a photodiode fill factor of 25%. The artificial retina chip which has been fabricated incorporates 256×256 pixels, 16 parallel output ports, and a random access function. The photosensitivity is 0.8 μA/lx for a 1-ms accumulation time. We demonstrate image capture in video mode and edge extraction mode, and light spot tracing using pattern matching in conjunction with the random access function

Keywords

MOS integrated circuits; SPICE; array signal processing; circuit analysis computing; circuit optimisation; differential amplifiers; focal planes; image processing equipment; image sensors; nondestructive readout; programmable filters; video signal processing; 1 ms; 2 mum; 256 pixel; 26 pixel; 35 pixel; 65536 pixel; 910 pixel; SPICE simulation optimization; VSPD array; accumulation time; addressing pattern generation; artificial retina chip; between-pixel current mode calculations; current-mode focal plane image processing functions; edge extraction mode; image capture; n-MOS VSPD pixel; n-MOS differential amplifier; nondestructive output; parallel output ports; photodiode fill factor; photosensitivity; pixel size; pn photodiode; programmable filtering; programmable focal plane image processing; programmable negative sensitivity; programmable positive sensitivity; random access function; scanning unit; variable sensitivity photodetector cell array; video mode; CMOS technology; Circuits; Filtering; Gallium arsenide; Image processing; Image sensors; Photodiodes; Pixel; Retina; Sensor arrays;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/16.628836

Filename

628836