Metal oxide semi-conductor image sensor

Abstract

The invention relates to the field of image sensors and discloses a metal oxide semi-conductor image sensor. According to the invention, the function of bimodule reading is realized through the structure of the metal oxide semi-conductor image sensor, the dynamic range of the image sensor can be expanded effectively, and both the circuit structure and the logic control are simpler. Through related double sampling, noise can be reduced effectively, and S / N ratio of readout signals can be improved greatly. Under the condition of stronger ambient light, reading is performed in a PPS (Passive Pixel Sensor) mode, and electric charge is read directly without magnification, so that the circumstance of saturation of C-APS (Active Pixel Sensor) due to excessively strong light can be avoided, however, under the condition of poor ambient light, reading is performed in a C-APS (Active Pixel Sensor) mode, and variable gain reading is realized through different offsets, therefore, the dynamic range of the metal oxide semi-conductor image sensor can be expanded greatly.

Description

technical field [0001] The invention relates to the field of image sensors, in particular to dual-mode metal oxide semiconductor image sensor technology. Background technique [0002] As we all know, an image sensor is a semiconductor device that converts an optical image into an electrical signal. Image sensors can be roughly classified into charge-coupled device (Charge-Coupled Device, “CCD” for short) and complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, “CMOS” for short) image sensors. [0003] Existing CMOS image sensors can be roughly divided into passive pixel sensors (Passive Pixel Sensor, referred to as "PPS"), active pixel sensors (Active Pixel Sensor, referred to as "APS") and digital pixel sensors according to their readout methods. (Digital Pixel Sensor, referred to as "DPS") three types. [0004] PPS is also known as a passive pixel sensor, which consists of a reverse biased photodiode and a switch tube. A photodiode is essent...

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Problems solved by technology

[0009] Dual-mode CMOS image sensors usually include C-APS and PPS two readout methods, but the inventors of the present invention have found that the dual-mode CMOS image sensors in the prior art either have complex circuits, resulting in a relatively small fill factor of the image sensor, or Control logic is too complex

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