Image sensing device for obtaining high dynamic range image and imaging device including the same

An image sensing device comprising:

• a plurality of image sensing pixels, each image sensing pixel detect incident light to generate a pixel signal indicative of the detected incident light;
• and
• an analog-to-digital converter configured to convert the pixel signal into image data,
• wherein each of the image sensing pixels includes:
• a photoelectric conversion element configured to generate photocharge corresponding to the detected incident light;
• a floating diffusion region configured to accumulate the generated photocharge at the floating diffusion region;
• and
• a P-channel Metal Oxide Semiconductor (PMOS) transistor coupled to the floating diffusion region to produce a dual conversion gain and to provide additional capacitance to the floating diffusion region,
• wherein the PMOS transistor is turned off in a case that a voltage of the floating diffusion region is higher than a threshold voltage of the PMOS transistor.

An image sensing device comprising:

• a photoelectric conversion element configured to detect incident light to generate photocharge corresponding to the detected incident light;
• a floating diffusion region coupled to the photoelectric conversion element to accumulate the generated photocharge at the floating diffusion region;
• and
• a dual conversion gain transistor configured to provide additional capacitance to the floating diffusion region, and including a gate connected to the floating diffusion region,
• wherein the dual conversion gain transistor is turned on or turned off in response to a voltage of the floating diffusion region,
• wherein the dual conversion gain transistor is a P-Chanel Metal Oxide Semiconductor (PMOS) transistor, and
• wherein the PMOS transistor is turned off in a case that a voltage of the floating diffusion region is higher than a threshold voltage of the PMOS transistor.