A METHOD OF CALIBRATING A LINEAR-LOGARITHMIC IMAGE SENSOR PIXEL

摘要

A method of performing two point calibration of a linear-logarithmic image sensor pixel includes a step of measuring voltages of a floating diffusion region of the pixel after establishing a plurality of unequal sub-threshold currents through a transfer transistor of the pixel. These sub-threshold currents operate to sequentially increase a voltage of the floating diffusion region to respective voltage levels that enable knee-point (KNPT) voltage and logarithmic sensitivity (LOGS) determination. The method also includes a step of depleting a photodiode within the pixel by driving a cathode of the photodiode with a pull-up current in advance of establishing the sub-threshold currents. The method is photocurrent-independent.