System and method for eliminating fixed mode noise by dummy pixels

A technology of fixed pattern noise and dummy pixels, applied in the field of CMOS image sensing

Inactive Publication Date: 2008-11-19
APEXONE MICROELECTRONICS SHANGHAI +1
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  • Application Information

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Problems solved by technology

[0005] Aiming at the technical defects of CMOS image sensors in the prior art in eliminating fixed patte

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  • System and method for eliminating fixed mode noise by dummy pixels
  • System and method for eliminating fixed mode noise by dummy pixels
  • System and method for eliminating fixed mode noise by dummy pixels

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Embodiment Construction

[0028] The specific implementation manners of the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] figure 1 A schematic diagram showing the distribution of dummy pixels using an 18×18 pixel array as an example for eliminating fixed pattern noise according to one aspect of the present invention. like figure 1 As shown, in the 18×18 pixel array, if we define the first row as "0" row and the first column as "0" column, the position of any pixel in the pixel array is expressed as M(m,n) , then the value ranges of m and n are both 0-17. Moreover, those skilled in the art should understand that based on the one-to-one correspondence between M(m, n) and a single pixel in the pixel array, we can also express M(m, n) as the pixel corresponding to the corresponding pixel position value. refer to figure 1 , the present invention selects the first and last two rows and the first and last two columns of the pixel array a...

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Abstract

The invention discloses a system used for eliminating the Fixed Pattern Noise (FPN). The system includes a pixel array, a reading circuit used for reading the pixel value of each pixel unit, a programmable gain amplifier (PGA) algorithm unit, an A/D conversion unit and an FPN elimination unit; the system adopts the dummy pixel values of the current row and the current column for compensation; the invention also discloses an implementation method for eliminating the FPN, including that the pixel array is read; the read result is inputted to the PGA algorithm unit; a pixel offset is added to each pixel unit; the operation result is processed with A/D conversion; the dummy pixel values of the current row and the current column are used for compensation. Based on the system and the method for eliminating the FPN, each pixel in the pixel array not only can use the dummy pixel of the current row to eliminate the column FPN, but also can use the dummy pixel of the current column to eliminate the row FPN; besides, because the data of the dummy pixels in the pixel array are acquired real-timely, the dummy pixel data have certain compensation effect on the FPN caused by the power disturbance.

Description

technical field [0001] The invention relates to CMOS image sensing technology, in particular to a method for eliminating fixed pattern noise in a CMOS image sensor. Background technique [0002] In today's CMOS image sensors, FPN (Fixed Pattern Noise: fixed pattern noise) has always been a difficult problem for designers. The main factors that form the FPN include: the mismatch between the pixel circuit and the related read amplifier circuit, the noise introduced by the disturbance of the power supply, and the like. [0003] In order to eliminate the FPN in the image sensor, two types of solutions are generally adopted in the prior art. One is a CDS (Correlated Double Sampling: correlated double sampling) method. US Patent No. 6,538,695 B1 representing the CDS method discloses a method for calibrating on-chip fixed pattern noise in a CMOS image sensor. The method first reads two data values ​​from each bit line to calculate the offset and gain error for a column of pixels...

Claims

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Application Information

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IPC IPC(8): H04N5/217G06F3/03G06F3/033H04N5/367
Inventor 李碧洲
Owner APEXONE MICROELECTRONICS SHANGHAI
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