CMOS image sensor active pixel capable of changing operation mode and image sensor thereof

Abstract

The invention relates to active pixels of a CMOS image sensor which can transform the working mode, and the image sensor thereof. Each active pixel comprises a first MOS tube source, a second MOS tube source and a third MOS tube gate; the connection points between the first and the second MOS tube sources and the third MOS tube gate are taken as storage nodes; a fifth MOS tube drain, a second MOS tube drain and a third MOS tube drain are connected with an anode of a power supply; a third MOS tube source is connected with a fourth MOS tube drain, a fourth MOS tube source is an output voltage signal, a fourth MOS tube gate is a line gating control line; a second MOS tube gate is a reset signal; a fifth MOS tube gate is a T5 gating signal, and a first MOS tube gate is a T4 gating signal. An exposure control module is respectively connected with the T4, the T5 gating signals and the reset signal of each active pixel; a line decoder is respectively connected with the line gating control line of each active pixel; a multiplexer is respectively connected with the output voltage signal of each active pixel; a 4T / 5T mode switching unit which is respectively connected with the exposure control module through 4T and 5T buses; and the 4T / 5T mode switching unit is connected with the multiplexer through the output data of the image sensor. The active pixels can greatly reduce the imaging noise under the dark light situation.

Description

Technical field [0001] The invention relates to an image sensor. In particular, it relates to a CMOS image sensor active pixel and its image sensor with a switchable working mode that can meet the practical application of the CMOS image sensor in the fields of high-speed monitoring, security protection and the like. Background technique [0002] The CMOS image sensor chip is a single-chip imaging system that collects image information through a large-scale two-dimensional photosensitive pixel array and converts its optical signals into corresponding analog or digital signals, which can realize high-speed and low-power electronic imaging functions . Among them, the CMOS active pixel as a photoelectric conversion unit occupies a core position in the entire CMOS image sensor architecture, and the quality of its structural design will directly affect the imaging performance of the CMOS image sensor. [0003] In practical applications in the fields of high-speed monitoring, security p...

AI Technical Summary

Problems solved by technology

Therefore, the full parallel exposure of four-tube pixels actually adopts the serial frame output method of "Sth frame exposure→Sth frame readout→S+1th frame exposure→S+1th frame readout", which cannot adapt to The need for high-speed image sensing up to 1,000 frames per second in monitoring and other fields

And because the T4 tube is shared by the whole frame, the reset signal located before the readout signal (Readout) cannot be output to the external double sampling circuit at one time. The reset signal obtained by the external double sampling circuit is actually specially designed for double sampling after the signal is read out. The reset signal generated by the reset operation has no time correlation with the readout signal, so the reset noise cannot be eliminated, which limits the application of this pixel structure in the field of large dynamic range.

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