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Image sensor and high-conversion-gain and low-noise pixel readout circuit

A technology of image sensor and readout circuit, which is applied in the direction of TV, electrical components, color TV, etc., and can solve the problems of occupying chip area and being unsuitable for high-density CMOS image sensors, etc.

Inactive Publication Date: 2010-12-01
HIMAX IMAGING LIMITED
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Figure 1C The pixel circuit will occupy a considerable chip area, so it is not suitable for modern high-density CMOS image sensors

Method used

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  • Image sensor and high-conversion-gain and low-noise pixel readout circuit
  • Image sensor and high-conversion-gain and low-noise pixel readout circuit
  • Image sensor and high-conversion-gain and low-noise pixel readout circuit

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Embodiment Construction

[0019] Figure 2A A four-transistor (4T) pixel circuit of a complementary metal oxide semiconductor (CMOS) image sensor according to an embodiment of the present invention is shown, which is shared (4S) by four pixels. This embodiment can reduce the overall area of ​​the pixel array of the CMOS image sensor, or can free up more space for the photodiodes. In this embodiment (and other embodiments in this specification), the pixel circuit is shared by four pixels, but is not limited to four; in addition, the pixel circuit of the present invention is not limited to containing four transistors (4T ), for example, 5T or more transistors. In the illustrated 4T 4S pixel circuit, four photodetectors corresponding to four pixels (for example, pinned photodiode) D 1 -D 4 Respectively connected to the transfer transistor M tx1 -M tx4 . In this embodiment, the transfer transistor M tx1 -M tx4 It is an n-type metal oxide semiconductor (NMOS) transistor. Photodiode D 1 -D 4 Is reverse bias...

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PUM

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Abstract

The invention provides a pixel circuit of a CMOS (complementary metal oxide semiconductor) image sensor, which is characterized by using at least two transferring transistors for respectively transferring the accumulated optical signals of corresponding photodetectors to a first node, using a resetting transistor for resetting the voltage of the first node as the preset resetting voltage of a second node, and using a source follower for buffering the integrated optical signals. In the embodiment of the invention, a capacitor is connected between the first node and the second node, so as to reduce the impact of the effective capacitance comprising the capacitance in the floating diffusion areas and the stray capacitance in the photodetectors and transferring transistors.

Description

Technical field [0001] The present invention relates to a complementary metal oxide semiconductor (CMOS) image sensor, in particular to a pixel readout circuit of a CMOS image sensor with a smaller area, and a pixel readout circuit with a feedback (or switching) capacitor Out of the circuit. Background technique [0002] A CMOS image sensor is an electronic device that captures images, for example, used in a camera to convert light intensity into electric charge, then convert it into voltage and read it out. Figure 1A A passive pixel sensor (PPS) is shown, which is a kind of traditional CMOS image sensor. For ease of description, only two pixels in the pixel array are shown in the figure. Each pixel contains a photodiode D and access transistor (or switch) M acc . Word line (e.g. WL 1 ) Are connected to pixels in the same row, and bit lines (such as BL) are connected to pixels in the same column. There is an amplifier 10 at the end of each bit line BL. [0003] Figure 1B The ...

Claims

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Application Information

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IPC IPC(8): H04N5/335H04N3/15H04N5/217
CPCH04N25/59
Inventor 印秉宏米特拉·艾米特林积劭
Owner HIMAX IMAGING LIMITED
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