US-20260129317-A1 - IMAGE SENSOR

US20260129317A1US 20260129317 A1US20260129317 A1US 20260129317A1US-20260129317-A1

Abstract

An image sensor includes a plurality of pixels, each pixel of the plurality of pixels includes, a first photodiode, a second photodiode, a first transfer transistor connected to a first floating diffusion node, a second transfer transistor connected to a second floating diffusion node, a first reset transistor configured to reset the first floating diffusion node with a first reset power supply voltage, a second reset transistor configured to reset the second floating diffusion node with a second reset power supply voltage, a switch transistor connecting the second floating diffusion node to the first floating diffusion node, and a first driving transistor configured to output an output voltage according to a voltage of the first floating diffusion node.

Inventors

Eunji PARK
Jungwook Lim

Assignees

SAMSUNG ELECTRONICS CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20260107
Priority Date: 20221221

Claims (20)

1 . An image sensor comprising: a first photodiode on a first pixel region in a plan view; a second photodiode on a second pixel region in the plan view adjacent to the first photodiode and having a smaller light-receiving area than a light-receiving area of the first photodiode in the plan view; a first transfer transistor between the first photodiode and a first floating diffusion node; a second transfer transistor between the second photodiode and a second floating diffusion node; a first reset transistor connected to the first floating diffusion node; a capacitor connected to a first power supply voltage; a first conversion gain transistor between the capacitor and the second floating diffusion node; a second reset transistor connected to the capacitor and the second floating diffusion node; a first driving transistor connected to the first floating diffusion node; and a second driving transistor connected to the second floating diffusion node.
2 . The image sensor of claim 1 , further comprising: a first selection transistor connected to the first driving transistor; and a second selection transistor connected to the second driving transistor.
3 . The image sensor of claim 2 , wherein the first selection transistor is connected to a first column line, and wherein the second selection transistor is connected to a second column line different from the first column line.
4 . The image sensor of claim 2 , wherein the first selection transistor is connected to a first column line, and wherein the second selection transistor is connected to the first column line.
5 . The image sensor of claim 1 , further comprising: a second conversion gain transistor between the first floating diffusion node and the first reset transistor.
6 . The image sensor of claim 2 , wherein the first transfer transistor and the first driving transistor are disposed on the first pixel region on the plan view, and wherein the second transfer transistor and the first conversion gain transistor are disposed on the second pixel region on the plan view.
7 . The image sensor of claim 5 , further comprising a device isolation layer between the first photodiode and the second photodiode.
8 . The image sensor of claim 6 , wherein the first pixel region and the second pixel region are disposed in a first direction in the plan view, wherein the first driving transistor and the first selection transistor are disposed in a second direction in the plan view, and wherein the first direction is neither parallel nor perpendicular to the second direction in the plan view.
9 . The image sensor of claim 7 , wherein the first driving transistor is connected to a second power supply voltage different from the first power supply voltage.
10 . The image sensor of claim 2 , wherein the first and second selection transistors are configured to receive a second power voltage different from a first power supply voltage.
11 . An image sensor comprising: a first photodiode provided in a first pixel region; a second photodiode provided in a second pixel region, the second pixel region having an area smaller than an area of the first pixel region and provided adjacent to the first pixel region; a first transfer transistor between the first photodiode and a first floating diffusion node; a second transfer transistor between the second photodiode and a second floating diffusion node; a capacitor; a first conversion gain transistor between the capacitor and the second floating diffusion node; a first reset transistor configured to receive a first power supply voltage and configured to reset the first floating diffusion node; and a second reset transistor configured to receive the first power supply voltage and configured to reset the second floating diffusion node.
12 . The image sensor of claim 11 , further comprising: a second conversion gain transistor between the first floating diffusion node and the first reset transistor.
13 . The image sensor of claim 11 , wherein the capacitor is connected to a second power supply voltage different from the first power supply voltage.
14 . The image sensor of claim 11 , further comprising: a first driving transistor connected to the first floating diffusion node; a second driving transistor connected to the second floating diffusion node; a first selection transistor connected to the first driving transistor; and a second selection transistor connected to the second driving transistor.
15 . The image sensor of claim 14 , wherein the first selection transistor is connected to a first column line, and wherein the second selection transistor is connected to a second column line different from the first column line.
16 . The image sensor of claim 14 , wherein the first selection transistor is connected to a first column line, and wherein the second selection transistor is connected to the first column line.
17 . The image sensor of claim 14 , wherein the first and second selection transistor are disposed in the first pixel region in a plan view.
18 . The image sensor of claim 17 , wherein the first selection transistor and the first driving transistor are arranged in a first direction in the plan view, and wherein the second selection transistor and the second driving transistor are arranged in a second direction different from the first direction in the plan view.
19 . An image sensor comprising: a first photodiode provided in a first pixel region; a second photodiode provided in a second pixel region, the second pixel region having an area smaller than an area of the first pixel region and provided adjacent to the first pixel region; a first transfer transistor between the first photodiode and a first floating diffusion node; a second transfer transistor between the second photodiode and a second floating diffusion node; a capacitor; a first conversion gain transistor between the capacitor and the second floating diffusion node; a first reset transistor configured to receive a first power supply voltage and configured to reset the first floating diffusion node; and a second reset transistor configured to receive the first power supply voltage and configured to reset the second floating diffusion node. a first driving transistor connected to the first floating diffusion node; a second driving transistor connected to the second floating diffusion node; a first selection transistor connected to the first driving transistor; and a second selection transistor connected to the second driving transistor, wherein the first driving transistor is configured to receive a second power supply voltage different from the first power supply voltage.
20 . The image sensor of claim 19 , wherein the first selection transistor is connected to a first column line, and wherein the second selection transistor is connected to a second column line different from the first column line.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. patent application Ser. No. 18/390,867, filed on Dec. 20, 2023, which is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2022-0180891, filed on Dec. 21, 2022, in the Korean Intellectual Property Office, the disclosure of each of which is incorporated by references herein in their entirety. BACKGROUND Various example embodiments relate to image sensors, and more particularly, to image sensors including a split-photodiode (split-PD) pixel to which a reset transistor or a driving transistor is added and image sensors including a plurality of current sources. Image sensors are used to capture 2D or 3D images of objects. Image sensors generate images of objects by using photoelectric conversion elements that react according to the intensity of light reflected from the objects. Owing to the recent development of the complementary metal-oxide semiconductor (CMOS) technology, CMOS image sensors using CMOS are widely used. According to a split photodiode (split-PD) technique developed to increase the dynamic range of image sensors, a plurality of photodiodes having different light-receiving areas are included in one pixel. Thus, research into obtaining an image signal from a plurality of photodiodes included in a split photodiode without deterioration is required. SUMMARY Various example embodiments provide image sensors and pixels for processing a reset signal and a pixel signal obtained from each of a plurality of photodiodes of a split-photodiode structure without image quality deterioration. According to various example embodiments, there is provided an image sensor including a plurality of pixels. Each pixel of the plurality of pixels includes a first photodiode, a second photodiode adjacent to the first photodiode and having a smaller light-receiving area than a light-receiving area of the first photodiode, a first transfer transistor having an end connected to the first photodiode and another end connected to a first floating diffusion node, a second transfer transistor having an end connected to the second photodiode and another end connected to a second floating diffusion node, a first reset transistor having an end connected to a first reset power supply voltage and configured to reset the first floating diffusion node with the first reset power supply voltage, a second reset transistor having an end connected to a second reset power supply voltage and configured to reset the second floating diffusion node with the second reset power supply voltage, a switch transistor having an end connected to the second reset transistor and connecting the second floating diffusion node to the first floating diffusion node, and a first driving transistor configured to output an output voltage according to a voltage of the first floating diffusion node. Alternatively or additionally, according to various example embodiments, there is provided an image sensor including a pixel configured to output a pixel signal through a first column line. The pixel includes a first photodiode provided in a first pixel region, a second photodiode provided in a second pixel region, the second pixel region having an area smaller than an area of the first pixel region and provided adjacent to the first pixel region, a first reset transistor provided in the first pixel region, the first reset transistor having an end connected to a reset power supply voltage and configured to reset a first floating diffusion node, a first driving transistor provided in the first pixel region and having a gate connected to the first floating diffusion node, a first selection transistor provided in the first pixel region and having an end connected to the first driving transistor, a second reset transistor having an end connected to the reset power supply voltage and configured to reset a second floating diffusion node, a second driving transistor provided in the first pixel region and having a gate connected to the second floating diffusion node, and a second selection transistor provided in the first pixel region and having an end connected to the second driving transistor, wherein another end of the first selection transistor and another end of the second selection transistor are connected to the first column line. Alternatively or additionally, according to various example embodiments, there is provided an image sensor including a pixel configured to output pixel signals through a first column line and a second column line. The pixel includes a first photodiode provided in a first pixel region, a second photodiode provided in a second pixel region, the second pixel region having an area smaller than an area of the first pixel region and provided adjacent to the first pixel region, a first reset transistor provided in the first pixel region, the first reset transistor having an end connected to a reset power supply voltage and configured t