Design And Research Of Low Noise Image Sensor Readout Circuit Based On CMS

With the continuous development of the semiconductor industry,CMOS image sensors have been widely used in aerospace cameras,medical imaging,and video surveillance.In order to cope with the fiercely competitive image sensor market,their research and development needs are increasing.Therefore,as an image sensor,the readout circuit of the component part,the performance requirement for this also increases accordingly.In the current study,the noise in the readout circuit always limits the imaging quality of the image sensor.Therefore,the realization of low noise in the image sensor readout circuit has become one of the important goals of industry researchers.CMS(Correlation multiple sampling)is a method of correlating multiple sampling,which can subtract signals of a certain correlation through multiple sampling,so as to effectively reduce the noise and errors of homology or correlation.Therefore,according to the characteristics of CMS technology,it is reasonably applied in the analog readout circuit to achieve low noise readout.The research and design of the CMOS image sensor readout circuit are carried out.Based on the noise analysis of the CMOS image sensor readout circuit and the modeling study of the CMS technology,the relationship between the parameters and noise in the CMS technology is simulated by matlab modeling.Therefore,a low-noise readout circuit is proposed and realized.The main research content and research results of this paper are as follows:(1)The noise of the CMOS image sensor is analyzed.Through the analysis of different noise types,it is concluded whether the corresponding type of noise can be reduced by CMS technology.Thus,the noise level of the readout circuit can be grasped.(2)A readout circuit with CMS function is designed.In the sample-and-hold circuit,through the design of the passive device switches and capacitors,the readout circuit can complete up to16 sampling operations.Through 16 correlated multiple samplings,the noise of the readout circuit can be reduced by 30%,and the equivalent input noise of the readout circuit can reach about 50?V.(3)The designed readout circuit supports high frame rate mode and low noise mode by changing the timing control of the sampling and readout switches according to the application scenarios and requirements.(4)This design uses xfab 0.18?m process.Use Cadence software for circuit design,circuit simulation,layout drawing and post-simulation.A design of readout circuit based on CMS is obtained,which achieves the purpose of effectively reducing noise.