Title :
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
fDate :
10/1/1997 12:00:00 AM
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;
Journal_Title :
Electron Devices, IEEE Transactions on
