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We designed and fabricated a vision chip for edge detection with a 160×120 pixel array by using 0.35 ㎛ standard complementary metal-oxide-semiconductor (CMOS) technology. The designed vision chip is based on a retinal structure with a resistive network to improve the speed of operation. To improve the quality of final edge images, we applied a saturating resistive circuit to the resistive network. The light-adaptation mechanism of the edge detection circuit was quantitatively analyzed using a simple model of the saturating resistive element. To verify improvement, we compared the simulation results of the proposed circuit to the results of previous circuits.

CMOS vision chips for edge detection based on a resistive circuit have recently been developed. These chips help develop neuromorphic systems with a compact size, high speed of operation, and low power dissipation. The output of the vision chip depends dominantly upon the electrical characteristics of the resistive network which consists of a resistive circuit. In this paper, the body effect of the MOSFET for current distribution in a resistive circuit is discussed with a simple model. In order to evaluate the model, two 160×120 CMOS vision chips have been fabricated by using a standard CMOS technology. The experimental results have been nicely matched with our prediction.

In this paper, a vision chip for a contrast-enhanced image based on a structure of a biological retina is introduced. The key advantage of this structure is high speed of signal processing. In a conventional active pixel sensor (APS), the charge accumulation time limits its operation speed. In order to enhance the speed, a logarithmic APS was applied to the vision chip. By applying a MOS-type photodetector to the logarithmic APS, we could achieve sufficient output swing for the vision chip in natural illumination condition. In addition, a CMOS buffer circuit, a common drain amplifier, is commonly used for both raw and smoothed images by using additional switches. By using the switch-selective resistive network, the total number of MOSFETs for a unit pixel and the fixed-pattern noise were reduced. A vision chip with a 160×120 pixel array was fabricated using a 0.35 mm double-poly four-metal CMOS technology, and its operation was experimentally investigated.

In this paper, a vision chip for edge detection based on the structure of a biological retina is introduced. The key advantage of the structure is high speed of operation. However, the charge accumulation time of a conventional active pixel sensor limits its operation speed. In order to enhance the operation speed, a logarithmic APS using a metal-oxide-semiconductor-type photodetector was applied into the vision chip. By applying a MOS-type photodetector to a logarithmic APS, we could achieve sufficient output swing for a bio-inspired vision chip. We fabricated a 160times120 bio-inspired complementary metal-oxide-semiconductor vision chip using 0.35 mum two-poly four-metal complementary metal-oxide-semiconductor technology, and then investigated.