CMOS image transducer

Abstract

The CMOS image sensor comprises a pixel matrix, a row decoder correspondingly connected to the rows in the pixel matrix, and a column decode correspondingly connected to the columns in the pixel matrix through a correlated double sampling circuit. The pixel matrix is composed of a group of pixel element circuits, which are logarithm type response pixel element circuits. The logarithm type response pixel element circuits includes a transistor connected to power supply and working at sub-threshold area for use in implementing the logarithm type response of the pixel element circuit. In the invention, an A / D conversion by a multi resolution quantization A / D converter can be adopted to make A / D conversion, amplify the signal at low light level and compress the signal at high light level in order to get a dynamical range over 80 db.

Description

technical field [0001] The invention relates to integrated circuit design in the technical field of electronic circuits, in particular to a CMOS image sensor. Background technique [0002] With the development of CMOS process technology and circuit design technology, the performance of CMOS image sensor has been greatly improved, which is reflected in: the readout noise is effectively reduced by adopting a new process and correlated double sampling circuit, and the filling is improved by using microlens technology. coefficient, the use of buried photodiodes and small-size CMOS technology effectively reduces the dark current of the photodetector. Therefore, CMOS image sensors are developing towards high resolution, low noise, high integration and wide dynamic range. [0003] However, current CMOS image sensors still have defects such as low signal-to-noise ratio, low quantum efficiency, and narrow dynamic range. [0004] The CMOS image sensor in the prior art mainly include...

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Problems solved by technology

[0013] It can be seen from this that the existing CMOS image sensor is due to the inherent defect of the linear quantization method, that is, the signal-to-noise ratio is sufficient when the signal is large, and the signal-to-noise ratio is insufficient when the signal is small, so that the setting of the programmable gain amplifier, that is, the PGA, is indispensable. This requires a large capacitor array or resistor array, which brings the defects of high power consumption, narrow dynamic range and low integration, that is, the area of ​​the CMOS image sensor is too large

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