CN-121978712-A - Large dynamic range time-of-flight method three-dimensional pixel, control method, pixel array and image sensor

CN121978712ACN 121978712 ACN121978712 ACN 121978712ACN-121978712-A

Abstract

The invention discloses a three-dimensional pixel with a large dynamic range and a flight time method, a control method, a pixel array and an image sensor. The three-dimensional pixel with the large dynamic range time-of-flight method comprises PPD, wherein the PPD is connected with a modulation transmission gate source electrode, a modulation transmission gate drain electrode is connected with a voltage conversion transmission gate source electrode, a modulation transmission gate is connected with a storage node, the voltage conversion transmission gate drain electrode is connected with a charge-voltage conversion node, the charge-voltage conversion node is connected with a source follower gate electrode and a transverse overflow gate source electrode, the transverse overflow gate drain electrode is connected with a reset switch source electrode and a non-grounded end of a transverse overflow gate capacitor, the reset switch drain electrode is connected with a source follower drain electrode and then is connected with a power supply, the source follower source electrode is connected with a row gate switch drain electrode, and the row gate switch source electrode is connected with a column tap gate signal. The invention solves the problem that the farther the measuring distance is, the more serious the light intensity reflected by the modulated light decays in the TOF three-dimensional imaging technology.

Inventors

XU JIANGTAO
MA QIANYUE
CHEN QUANMIN
CHEN QIAN
NIE KAIMING
GAO JING

Assignees

天津大学

Dates

Publication Date: 20260505
Application Date: 20251223

Claims (10)

1. The three-dimensional pixel is characterized by comprising a clamping photodiode PPD, wherein one end of the clamping photodiode PPD is grounded, the other end of the clamping photodiode PPD is connected with a modulating transmission gate TG0 and a source electrode of the modulating transmission gate TG1, the drain electrodes of the modulating transmission gate TG0 and the modulating transmission gate TG1 are respectively connected with a voltage conversion transmission gate TX0 and a source electrode of the voltage conversion transmission gate TX1, a storage node SD0 is connected between the modulating transmission gate TG0 and the voltage conversion transmission gate TX0, the drain electrodes of the modulating transmission gate TG1 and the voltage conversion transmission gate TX1 are respectively connected with a charge-voltage conversion node FD0 and a charge-voltage conversion node FD1, the charge-voltage conversion node FD0 is connected with a gate electrode of a first source follower SF and a source electrode of a transverse overflow gate SG0, the drain electrode of the transverse overflow gate SG0 is connected with a source electrode of a first reset switch SF and a non-grounded end of a transverse overflow gate capacitor Cs0, the drain electrode of the first reset switch is connected with a first source follower drain electrode after the modulating transmission gate TG0, the drain electrode of the modulating transmission gate TG1 and the voltage conversion transmission gate TX1 is connected with a storage node SD1, the drain electrode of the second reset switch SF is connected with the second drain electrode of the second reset switch SF 1, and the drain electrode of the transverse overflow gate SF 1 is connected with the second drain electrode of the second drain electrode SF 1.
2. The large dynamic range time of flight three-dimensional pixel of claim 1, wherein the ungrounded terminal of the clamp photodiode PPD is connected to the source of a charge leakage gate LG, the drain of which is connected to a power supply VDD.
3. The large dynamic range time-of-flight three-dimensional pixel according to claim 2, wherein the modulation transfer gate TG0, the modulation transfer gate TG1, the voltage conversion transfer gate TX0, the voltage conversion transfer gate TX1, the lateral overflow gate SG0, the lateral overflow gate SG1, the first source follower SF, the second source follower SF, the first row gate switch SEL, the second row gate switch SEL, the first reset switch RET, the second reset switch RST, and the charge leakage gate LG are NMOS transistors.
4. The large dynamic range time of flight three-dimensional pixel of claim 1, wherein the lateral overflow gate capacitance Cs0 and the lateral overflow gate capacitance Cs1 are LOFIC capacitances.
5. The high dynamic range time of flight three-dimensional pixel according to claim 1, wherein the storage nodes SDO, SD1 employ storage diodes.
6. The method for controlling a three-dimensional pixel according to any one of claims 1 to 5, wherein in a three-dimensional operation mode, modulation of a pixel array is realized in a global exposure mode, during exposure, modulation transmission gate TG0 and modulation transmission gate TG1 perform modulation transfer control on photo-generated charges in a clamp photodiode PPD by using complementary-phase modulation signals, and four-phase optical signals are obtained by two-frame exposure, so that a complete signal is synthesized.
7. The method for controlling a three-dimensional pixel according to the large dynamic range time-of-flight method of claim 6, wherein during the readout period, the charge leakage gate LG is turned on, signals in the clamp photodiode PPD are guided to the power supply VDD in real time through the leakage process, interference to effective imaging signals is avoided, pixels in the rows of 1095 in the exposure stage 0 ~ are reset through time sequence control, and the pixels begin to be sequentially read row by row after the exposure stage is finished.
8. The method according to claim 7, wherein the lateral transfer gates SG0 and SG1 are turned off first during reading, and the reset levels of the charge-voltage conversion nodes FD0 and FD1 are read; then, starting voltage conversion transmission gates TX0 and TX1, transferring the photoelectric charges stored in storage nodes SD0 and SD1 to charge-voltage conversion nodes FD0 and FD1 nodes, obtaining corresponding signal levels, and completing double sampling reading operation in a high conversion gain mode; And in the state, firstly, reading the signal level in a low gain mode to realize quantitative acquisition of short-distance strong light signals, and then resetting the relevant nodes through a first reset switch and a second reset switch to read the corresponding low conversion gain reset level.
9. A pixel array comprising the high dynamic range time-of-flight method three-dimensional pixel of any one of claims 1-5.
10. An image sensor comprising the pixel array of claim 9.

Description

Large dynamic range time-of-flight method three-dimensional pixel, control method, pixel array and image sensor Technical Field The present invention relates to the field of image sensor pixel design technologies, and in particular, to a three-dimensional pixel with a large dynamic range and a time-of-flight method, a control method, a pixel array, and an image sensor for realizing a large measurement distance by using a lateral overflow integrated capacitance technology. Background The measurement range of a Time of flight (TOF) voxel sensor refers to the minimum and maximum distances that can effectively detect and measure target objects, and is one of the core indexes for determining the sensor application scene and performance. The structure of a typical three-dimensional 2-tap pixel device is shown in fig. 1, under the three-dimensional working condition, not all integrated signals are effective optical information, the background light in the environment can lead to early saturation of the pixel, and if the background light is too high, the depth solution can be invalid when serious, so that the improvement of the full-well capacity of the pixel is a design problem of the current TOF three-dimensional pixel. The current method for solving the problem is to add a storage diode SD0/SD1 and a modulation transmission gate TG0/TG1 between a clamping photodiode (Pinned Photodiode, PPD) and a voltage conversion transmission gate TX0/TX1, as shown in fig. 2, the existing method solves the problem of early saturation of pixels caused by background light by increasing the full well capacity of the pixels, expands the minimum distance in distance measurement, but the measurement of the maximum distance still requires the pixels to have higher sensitivity to improve the measurement accuracy, and the pixel structure of the existing method cannot realize higher weak light sensitivity. Disclosure of Invention The invention aims to overcome the defects and the shortcomings of the prior art, and provides a large dynamic range time-of-flight three-dimensional pixel, a control method, a pixel array and an image sensor, wherein the large dynamic range time-of-flight three-dimensional pixel is particularly a time-of-flight three-dimensional pixel device adopting a transverse overflow integrated capacitance technology, the weak light sensitivity of a pixel structure can be improved, the full trap capacity under small distance measurement can be considered, the distance range of the pixel device can be measured, and the problem that the more the measuring distance is far, the more the light intensity reflected by modulated light is seriously attenuated in a TOF three-dimensional imaging technology is solved. The first object of the present invention is to provide a large dynamic range time-of-flight method three-dimensional pixel, which comprises a clamping photodiode PPD, wherein one end of the clamping photodiode PPD is grounded, the other end of the clamping photodiode PPD is connected with a modulating transmission gate TG0 and a source electrode of the modulating transmission gate TG1, drain electrodes of the modulating transmission gate TG0 and the modulating transmission gate TG1 are respectively connected with a voltage converting transmission gate TX0 and a source electrode of the voltage converting transmission gate TX1, a storage node SD0 is connected between the modulating transmission gate TG0 and the voltage converting transmission gate TX0, a storage node SD1 is connected between the modulating transmission gate TG1 and the voltage converting transmission gate TX1, a charge-voltage converting node FD0 and a charge-voltage converting node FD1 are respectively connected with a gate electrode of a first source follower SF, a source electrode of the transverse overflow gate SG0 is connected with a source electrode of a first reset switch and a non-grounded end of a transverse overflow gate capacitor Cs0, and a drain electrode of the first reset switch is connected with a source electrode of the first follower SF; the source electrode of the first source follower SF is connected with the drain electrode of the first row strobe switch SEL, the source electrode of the first row strobe switch SEL is connected with the Col_tap0, the charge-voltage conversion node FD1 is connected with the grid electrode of the second source follower SF and the source electrode of the transverse overflow grid SG1, the drain electrode of the transverse overflow grid SG1 is connected with the source electrode of the second reset switch and the non-grounding end of the transverse overflow grid capacitor Cs1, the drain electrode of the second reset switch is connected with the drain electrode of the second source follower SF and then is connected with the power supply VDD, the source electrode of the second source follower SF is connected with the drain electrode of the second row strobe switch SEL, and the source electrode of the second r