Image sensor

An image sensor comprising:

• a first pixel area and a second pixel area sharing a single microlens, the first pixel area including a first photodiode and a second photodiode;
• a device isolation layer electrically isolating the first pixel area and the second pixel area from each other;
• at least one transfer transistor connected to the first pixel area, the at least one transfer transistor including a first transfer transistor connected to the first photodiode and a second transfer transistor connected to the second photodiode;
• and
• at least one drain terminal connected to the second pixel area and configured to have a power supply voltage applied thereto.

An image sensor comprising:

• a normal pixel group configured to generate an image;
• and
• an autofocusing pixel group configured to provide an autofocusing function,
• the autofocusing pixel group and the normal pixel group having substantially a same sensitivity as each other,
• the autofocusing pixel group including unit pixels sharing a single microlens and each including a single photodiode, a device isolation layer electrically isolating the unit pixels from each other, and a drain terminal configured to have a constant voltage input thereto,
• the autofocusing pixel group including photodiodes,
• the photodiodes in the autofocusing pixel group including a first photodiode group and a second photodiode group, and
• the drain terminal being connected to the second photodiode group,
• the first photodiode group configured to generate electric charges that migrate from the first photodiode group to a floating diffusion region of a substrate, and
• the second photodiode group configured to generate electric charges that are discharged to the drain terminal.