KR-20260067777-A - IMAGE SENSOR AND OPERATION METHOD THEREOF

Abstract

An image sensor according to the present invention includes a first pixel configured to output a first output voltage corresponding to light incident on the first photodiode and a second pixel configured to output a second output voltage corresponding to light incident on the second photodiode. The first pixel further includes a first transmission gate connected between a first photodiode and a first floating diffusion (FD) node, a first FD select gate connected between a first node and a first FD node, a first LOFIC select gate connected between a first FD node and a first LOFIC (lateral overflow integration capacitor) node, and a first capacitor connected between a first LOFIC node and a first reset voltage, and the second pixel further includes a second transmission gate connected between a second photodiode and a second FD node, a second FD select gate connected between a second node electrically connected to the first node and a second FD node, a second LOFIC select gate connected between a second FD node and a second LOFIC node, and a second capacitor connected between a second LOFIC node and a first reset voltage.

Inventors

• 허진석
• 장동영

Assignees

• 삼성전자주식회사

Dates

Publication Date

20260513

Application Date

20241106

Claims (20)

1. In image sensors, A first pixel comprising a first photodiode and configured to output a first output voltage corresponding to light incident on the first photodiode; and It includes a second pixel comprising a second photodiode and configured to output a second output voltage corresponding to light incident on the second photodiode, and The above first pixel is: A first transmission gate connected between the first photodiode and the first floating diffusion (FD) node; A first FD selection gate connected between the first node and the first FD node; A first LOFIC select gate connected between the first FD node and the first LOFIC (lateral overflow integration capacitor) node; and It further includes a first capacitor connected between the first LOFIC node and the first reset voltage, and The above second pixel is: A second transmission gate connected between the second photodiode and the second FD node; A second node electrically connected to the first node and a second FD selection gate connected between the second FD node; A second LOFIC select gate connected between the second FD node and the second LOFIC node; and An image sensor further comprising a second capacitor connected between the second LOFIC node and the first reset voltage.
2. In Article 1, Each of the first and second capacitors is an image sensor that is one of a MIM (Metal-Insulator-Metal) capacitor, a MOM (Metal-Oxide-Metal) capacitor, a MOSCAP (Metal-Oxide-Semiconductor Capacitor), a polysilicon capacitor, and a DRAM capacitor.
3. In Article 1, When the image sensor operates in LOFIC mode, the first and second FD selection gates are turned off and the first and second LOFIC selection gates are turned on, so that the first FD node and the first capacitor are electrically connected and the second FD node and the second capacitor are electrically connected.
4. In Paragraph 3, The above first pixel is: A first LOFIC reset gate connected between the first LOFIC node and the second reset voltage; and It further includes a first discharge switch connected between the first reset voltage and the second reset voltage, The above second pixel is: A second LOFIC reset gate connected between the second LOFIC node and the second reset voltage; and An image sensor further comprising a second discharge switch connected between the first reset voltage and the second reset voltage.
5. In Article 4, When the above image sensor operates in the LOFIC mode: The first FD node and the first capacitor are reset through the first LOFIC reset gate and the first discharge switch, and The second FD node and the second capacitor are image sensors that are reset through the second LOFIC reset gate and the second discharge switch.
6. In Article 1, The above first pixel is: A first LOFIC reset gate connected between the first LOFIC node and the third LOFIC node; A third LOFIC reset gate connected between the third LOFIC node and the second reset voltage; A first discharge switch connected between the first reset voltage and the second reset voltage; and It further includes a third capacitor connected between the third LOFIC node and the first reset voltage, and The above second pixel is: A second LOFIC reset gate connected between the second LOFIC node and the fourth LOFIC node; A fourth LOFIC reset gate connected between the fourth LOFIC node and the second reset voltage; A second discharge switch connected between the first reset voltage and the second reset voltage; and An image sensor further comprising a fourth capacitor connected between the fourth LOFIC node and the first reset voltage.
7. In Article 1, When the image sensor operates in a shared mode, the first and second LOFIC select gates are turned off and the first and second FD select gates are turned on, so that the first and second FD nodes are electrically connected.
8. In Article 7, The first pixel further includes a first reset gate connected between the first node and the pixel voltage, and The image sensor further comprising a second reset gate connected between the second node and the pixel voltage, wherein the second pixel is the second pixel.
9. In Article 8, When the image sensor operates in the shared mode, the first and second FD nodes are image sensors that are reset through the first reset gate or the second reset gate.
10. In Article 1, The above first pixel is: A first reset gate connected between the first node and the third FD node; and It further includes a third reset gate connected between the third FD node and the pixel voltage, and The above second pixel is: A second reset gate connected between the second node and the fourth FD node; and An image sensor further comprising a fourth reset gate connected between the fourth FD node and the pixel voltage.
11. In Article 1, The above first pixel is: third photodiode; and It further includes a third transmission gate connected between the third photodiode and the first FD node, and The above second pixel is Fourth photodiode; and An image sensor further comprising a fourth transmission gate connected between the fourth photodiode and the second FD node.
12. In Article 1, The above image sensor is: It further includes a third pixel comprising a third photodiode and configured to output a third output voltage corresponding to light incident on the third photodiode, and The above third pixel is: A third transmission gate connected between the third photodiode and the third FD node; A third node electrically connected to the first and second nodes and a third FD selection gate connected between the third FD node; A third LOFIC select gate connected between the third FD node and the third LOFIC node; and An image sensor further comprising a third capacitor connected between the third LOFIC node and the third reset voltage.
13. In Article 1, The first pixel further includes a first source follower and a first select gate connected in series between the pixel voltage and the first column line, and the gate terminal of the first source follower is connected to the first FD node, and The second pixel further includes a second source follower and a second select gate connected in series between the pixel voltage and the first column line, and the gate terminal of the second source follower is connected to the second FD node, and Each of the above first and second output voltages is an image sensor output through the first column line.
14. In Article 1, The first pixel further includes a first source follower and a first select gate connected in series between the pixel voltage and the first column line, and the gate terminal of the first source follower is connected to the first FD node, and The second pixel further includes a second source follower and a second select gate connected in series between the pixel voltage and the second column line, and the gate terminal of the second source follower is connected to the second FD node, and The first output voltage is output through the first column line, and The above second output voltage is an image sensor output through the above second column line.
15. In Article 1, The above image sensor is: 1st semiconductor die; It includes a second semiconductor die that is laminated to the first semiconductor die and configured to be electrically connected to the first semiconductor die through a connection structure, The first photodiode and the second photodiode are formed on the first semiconductor die, and The first capacitor and the second capacitor are image sensors formed on the second semiconductor die.
16. In a method of operating an image sensor including first and second pixels, The first pixel comprises a first photodiode, a first floating diffusion (FD) node, a first shared floating diffusion (SFD) circuit connected to the first FD node, and a first lateral overflow integration capacitor (LOFIC) circuit connected to the first FD node. The first pixel comprises a second photodiode, a second FD node, a second SFD circuit connected to the second FD node, and a second LOFIC circuit connected to the second FD node, and The method of operation of the above image sensor is as follows: In a shared mode, deactivating the first LOFIC circuit and activating the first SFD circuit to electrically connect the first FD node and the second FD node, and performing a sensing operation for the first pixel based on the first and second FD nodes; and In LOFIC mode, the first SFD circuit is deactivated and the first LOFIC circuit is activated to electrically connect the first FD node and the first capacitor included in the first LOFIC circuit, thereby performing a sensing operation based on the first FD node and the first capacitor. During the sensing operation for the first pixel in the above-mentioned sharing mode, the first capacitor is electrically isolated from the first FD node, and A method of operation in which the second FD node is electrically separated from the first FD node during a sensing operation for the first pixel in the LOFIC mode.
17. In Article 16, The sensing operation for the first pixel in the above-mentioned sharing mode is: During the first interval, the step of electrically connecting the first FD node and the second FD node, and resetting the first and second FD nodes; A step of sampling a reset value of a low conversion gain corresponding to the voltages of the first and second FD nodes during a second section after the first section; During the third section following the second section, the first and second FD nodes are electrically isolated, and a reset value of the high conversion gain corresponding to the voltage of the first FD node is sampled; During the fourth section following the third section, the step of transmitting photoelectrons of the first photodiode of the first pixel to the first FD node; A step of sampling a signal value of high conversion gain corresponding to the voltage of the first FD node during the fifth section after the fourth section; A method of operation comprising the step of electrically connecting the first FD node and the second FD node during the sixth section after the fifth section, and sampling a signal value of a low conversion gain corresponding to the voltages of the first and second FD nodes.
18. In Article 16, The sensing operation for the first pixel in the above LOFIC mode is: A step of sampling a reset value of a high conversion gain corresponding to the voltage of the first FD node during the first interval; A step of transferring photoelectrons of the first photodiode to the first FD node during the second section following the first section; A step of sampling a signal value of high conversion gain corresponding to the voltage of the first FD node during the third section after the second section; During the fourth section following the third section, the step of electrically connecting the first FD node and the first capacitor, and sampling a LOFIC signal value corresponding to the voltage of the first FD node and the first capacitor; During the fifth section following the fourth section, the step of resetting the first FD node and the first capacitor; and A method of operation comprising the step of sampling a LOFIC reset value corresponding to the voltage of the first FD node and the first capacitor during the sixth interval following the fifth interval.
19. In Article 16, The sensing operation for the first pixel in the above LOFIC mode is: During a first interval, electrically connecting the first FD node and the first capacitor, and sampling a LOFIC signal value corresponding to the voltage of the first FD node and the first capacitor; A step of resetting the first FD node and the first capacitor during the second section after the first section; A step of sampling a LOFIC reset value corresponding to the voltage of the first FD node and the first capacitor during the third section after the second section; During the fourth section following the third section, the step of electrically isolating the first FD node and the first capacitor, and sampling a reset value of the high conversion gain corresponding to the voltage of the first FD node; During the fifth section following the fourth section, the step of transferring photoelectrons of the first photodiode to the first FD node; and An operation method comprising the step of sampling a signal value of high conversion gain corresponding to the voltage of the first FD node during the sixth interval following the fifth interval.
20. Regarding image sensors First photodiode; A first transmission gate connected between the first photodiode and the first floating diffusion (FD) node; A first shared floating diffusion (SFD) circuit connected to the first FD node; A first LOFIC (lateral overflow integration capacitor) circuit connected to the first FD node and including a first capacitor; A first source follower comprising a first gate terminal connected to the first FD node; and It includes a first selection gate connected between the first source follower and the first column line, and In the sharing mode of the image sensor, the first SFD circuit is configured to electrically connect the first FD node to another second FD node, and An image sensor configured such that, in LOFIC mode of the image sensor, the first LOFIC circuit electrically connects the first FD node to the first capacitor.

Description

Image sensor and method of operation thereof The present invention relates to an image sensor, and more specifically, to an image sensor and a method of operating the same. An image sensor acquires image information about an external object by converting light reflected from the external object into an electrical signal. An electronic device including an image sensor can display an image on a display panel using the acquired image information. Image sensors are installed in various types of electronic devices. For example, electronic devices containing image sensors can be included as components of various types of electronic devices such as smartphones, tablet personal computers, laptop personal computers, and wearable devices. FIG. 1 is a drawing showing an image system according to an embodiment of the present invention. Figure 2 is a circuit diagram showing an example of a pixel included in an image sensor. Figure 3 is a block diagram showing the image sensor of Figure 1. Figure 4 is a drawing showing the pixel array of Figure 3. Figure 5 is a circuit diagram showing some pixels of the pixel array of Figure 4 in detail. Figure 6 is a flowchart showing the operation of the image sensor of Figure 3. FIGS. 7a to 7c are drawings for explaining the operation of the first and second pixels of FIG. 5 in a shared mode. FIGS. 8a to 8c are drawings for explaining the operation of the LOFIC mode of the image sensor of FIG. 3. FIGS. 9A and FIGS. 9B are drawings for explaining the operation of the LOFIC mode of the image sensor of FIG. 3. Figure 10 is a timing diagram to explain the operation of the image sensor of Figure 3. FIG. 11 is a circuit diagram showing in detail some pixels of the pixel array of FIG. 4. FIG. 12 is a circuit diagram showing in detail some pixels of the pixel array of FIG. 4. FIG. 13 is a circuit diagram showing in detail some pixels of the pixel array of FIG. 4. FIG. 14 is a circuit diagram showing some pixels of the pixel array of FIG. 4 in detail. FIG. 15 is a drawing showing some pixels included in the pixel array of FIG. 2. FIG. 16 is a drawing showing some pixels included in the pixel array of FIG. 2. Figure 17 is a drawing showing some pixels of the pixel array of Figure 2. Figure 18 is a diagram showing the stacked structure of the image sensor of Figure 2. Figure 19 is a diagram showing the stacked structure of the image sensor of Figure 2. FIG. 20 is a diagram illustrating pixels included in the image sensor of the stacked structure of FIG. 19. FIGS. 21a to 21e are drawings showing some pixels included in the image sensor of the stacked structure of FIG. 19. FIG. 22 is a block diagram of an electronic device including a multi-camera module. FIG. 23 is a detailed block diagram of the camera module of FIG. 22. In the following, embodiments of the present invention will be described clearly and in detail so that a person skilled in the art can easily practice the present invention. FIG. 1 is a drawing showing an image system according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of a pixel included in an image sensor. Referring to FIG. 1, the image system (10) may include a lens (11), an image sensor (100), and an image signal processor (12). In one embodiment, the image system (10) may be implemented as part of various electronic devices such as a camera, a smartphone, a wearable device, an Internet of Things (IoT) device, a home appliance, a tablet PC (Personal Computer), a PDA (Personal Digital Assistant), a PMP (Portable Multimedia Player), a navigation system, a drone, an Advanced Driver Assistance System (ADAS), a traffic surveillance camera, a CCTV, etc. Additionally, the image system (10) may be mounted on an electronic device equipped as a component in a vehicle, furniture, manufacturing equipment, a door, various measuring instruments, etc. The lens (11) can receive light reflected from an external object. The image sensor (100) can generate an electrical signal based on the light received through the lens (11). For example, the image sensor (100) can be implemented as a CMOS (Complementary Metal Oxide Semiconductor) image sensor (CIS; CMOS Image Sensor), etc. However, the scope of the present invention is not limited thereto, and the image sensor (100) can be implemented based on various image sensors such as a DVS (dynamic vision sensor), a DPS (digital pixel sensor), etc. The image sensor (100) can output an image (IMG) based on the generated electrical signal. In one embodiment, the image sensor (100) may include a plurality of pixels, and each of the plurality of pixels may generate photoelectrons based on light received or incident through the lens (11). Each of the plurality of pixels may store the generated photoelectrons in a floating diffusion (FD) node and output an electrical signal corresponding to the voltage level of the FD node. As an example, as illustrated in FIG. 2, the zero pixel (pix0) may include a zero photod