Mathematical Modeling of Non-Linearity due to Charge Injection Effect in CMOS Imagers

The remedial techniques which have been implemented for suppression of noise in CMOS imager with correlated double sampling (CDS) circuit being the center of them; the undesired effect of charge dispersion is still under addressed. To understand the effect of charge injection phenomenon, detailed analysis of variation in individual parameters of CMOS imager is presented in this work. Mathematical model of deviation due to non-linearity revealed that the application of additional circuitry to overcome the problem of charge injection will only prove effective if the basic structure of imager and CDS circuits consider some specific design standards viz. technology scaling, W/L ratio of transistors, and capacitance value. Suggestions on future remedial techniques with discussion on charge injection effect on dynamic range and noise of CMOS imager and CDS are also included.