A unit pixel in a CMOS image sensor is employed to reduce a threshold voltage
of
a reset transistor by modifying a unit pixel circuit. The unit pixel in the CMOS
image sensor including: a semiconductor substrate including an epitaxial layer
in which an active area and a FOX area are defined; a photodiode formed in the
epitaxial layer; a transfer transistor including source/drain regions disposed
between the photodiode and a floating diffusion node, wherein a control signal
is applied to a gate thereof; a reset transistor including source/drain regions
disposed between the floating diffusion node and a VDD terminal, wherein a control
signal is applied to a drain thereof; a drive transistor of which a gate is connected
to the floating diffusion node and a drain is connected to the VDD terminal; and
a selection transistor of which a drain is connected to the drain of the drive
transistor and a source is connected to an output terminal, wherein a control signal
is applied to a gate thereof.
