RESET SIGNAL COMPENSATOR CIRCUIT AND CMOS IMAGE SENSOR WITH THE SAME

摘要

A reset signal compensating circuit and a CMOS image sensor with the same are provided to restore original white points by compensating black point due to excessive illuminance. If a strong light enters, a reset signal detector(310) is operated to output a voltage according to a sampled output voltage of a unit pixel(200) falling below a certain threshold voltage in a state that a signal sampling switch(SHS) of a correlation dual sampling circuit(250) is turned on after a reset signal is turned off. A current generator(320) sends a current to an output node of the unit pixel in response to the voltage from the reset signal detector to charge a capacitor of the correlation dual sampling circuit into the original reset voltage to turn on a reset sampling switch(SHR). A difference between a signal sampled at the signal sampling switch and a signal sampled at the reset sampling switch becomes equal to the maximum output voltage of the unit pixel to restore original white color.