Electronic circuit for compensating a voltage level against a variation of temperature, and an image sensor including the same

Patent metadata

Field	Value
Publication number	US-11792545-B2
Application number	US-202217678268-A
Country	US
Kind code	B2
Filing date	Feb 23, 2022
Priority date	Jul 7, 2021
Publication date	Oct 17, 2023
Grant date	Oct 17, 2023

Abstract

An image sensor including: a pixel array including first and second pixels connected to a column line; a row driver to provide the first pixel with a first selection signal based on a clamp voltage, and to provide the second pixel with a second selection signal based on a selection voltage, wherein the first pixel outputs a first output voltage in response to the first selection signal, and the second pixel outputs a second output voltage in response to the second selection signal, wherein the first and second output voltages are output as a pixel signal through the column line, wherein a voltage of the pixel signal corresponds to a voltage obtained by clamping the second output voltage with the first output voltage, and wherein a change in a voltage level of the first output voltage due to a temperature is compensated for by the clamp voltage.

First claim

What is claimed is:

1. An image sensor, comprising:
a pixel array including a first pixel and a second pixel, wherein the first pixel and the second pixel are connected to a column line;
a row driver configured to provide the first pixel with a first selection signal based on a clamp voltage, and to provide the second pixel with a second selection signal based on a selection voltage,
wherein the first pixel outputs a first output voltage in response to the first selection signal, and the second pixel outputs a second output voltage in response to the second selection signal,
wherein the first output voltage and the second output voltage are output as a pixel signal through the column line,
wherein a voltage of the pixel signal corresponds to a voltage obtained by clamping the second output voltage with the first output voltage, and
wherein a change in a voltage level of the first output voltage due to a temperature is compensated for by the clamp voltage.

2. The image sensor of claim 1 , further comprising:
a clamp voltage generating circuit configured to generate the clamp voltage.

3. The image sensor of claim 2 , wherein the clamp voltage generating circuit includes:
a bandgap reference circuit configured to generate a first voltage; and
a buffer circuit configured to generate the clamp voltage based on the first voltage.

4. The image sensor of claim 3 , wherein a voltage level of the first voltage decreases as the temperature increases.

5. The image sensor of claim 3 , wherein the clamp voltage generating circuit further includes:
a temperature feedback circuit configured to generate a second voltage based on a temperature signal including information about a temperature change and to adjust the second voltage to correspond to the temperature change, and
wherein, as the temperature increases, a voltage level of the clamp voltage is decreased by the first voltage and the second voltage.

6. The image sensor of claim 1 , wherein the first pixel includes a first select transistor connected with the column line,
wherein the second pixel includes a second select transistor connected with the column line,
wherein the row driver provides the first selection signal, which is based on the clamp voltage, to a gate terminal of the first select transistor and provides the second selection signal, which is based on the selection voltage, to a gate terminal of the second select transistor,
wherein the first select transistor has a threshold voltage, a voltage level of which decreases as the temperature increases, and
wherein a change in the voltage level of the first output voltage due to a variation in the temperature, is compensated for by the clamp voltage.

7. The image sensor of claim 1 , wherein the row driver includes:
a selection controller configured to provide the clamp voltage or the selection voltage based on a plurality of control signals.

8. An electronic circuit, comprising:
a clamp voltage generating circuit configured to generate a first voltage, wherein a voltage level of the first voltage decreases as a temperature increases; and
a transistor directly connected to a column line of a pixel array and configured to output a second voltage based on the first voltage, wherein a voltage level of a threshold voltage of the transistor decreases as the temperature increases,
wherein a change in a voltage level of the second voltage, which results from a change in the temperature, is compensated for by using the first voltage.

9. The electronic circuit of claim 8 , wherein the clamp voltage generating circuit includes:
a bandgap reference circuit configured to generate a third voltage; and
a buffer circuit configured to generate the first voltage based on the third voltage.

10. The electronic circuit of claim 9 , wherein a voltage level of the third voltage decreases as the temperature increases.

11. The electronic circuit of claim 9 , wherein the clamp voltage generating circuit includes:
a temperature feedback circuit configured to generate a fourth voltage based on a temperature signal including information about a temperature change.

12. The electronic circuit of claim 11 , wherein the temperature feedback circuit adjusts a level of the fourth voltage to correspond to temperature change, and
wherein, as the temperature increases, a voltage level of the first voltage is decreased by the third voltage and the fourth voltage.

13. The electronic circuit of claim 11 , further comprising:
a temperature sensor configured to sense the temperature change and to generate the temperature signal.

14. The electronic circuit of claim 13 , wherein the temperature sensor includes a thermocouple, a resistance thermometer, a thermistor, an integrated circuit temperature sensor, a magnetic temperature sensor, a thermopile, or a pyroelectric temperature sensor.

15. The electronic circuit of claim 9 , wherein the bandgap reference circuit includes:
a first current generator including a first resistor, and configured to generate a first current proportional to the temperature;
a second current generator configured to output a second current that is a mirrored version of the first current to an output node at which the first voltage is formed;
a second resistor connected with the output node, and configured to receive the second current; and
a bipolar junction transistor connected with the second resistor.

16. The electronic circuit of claim 15 , wherein the clamp voltage generating circuit further includes:
a temperature feedback circuit configured to generate a fourth voltage based on a temperature signal including information about a temperature change,
wherein a voltage level of a voltage across the second resistor increases as the temperature increases, and
wherein the temperature change is sensed based on the increased voltage level.

17. The electronic circuit of claim 15 , wherein a voltage level of the third voltage decreases as the temperature increases.

18. An operating method of an electronic device, comprising:
generating a clamp voltage, wherein a voltage level of the clamp voltage decreases as a temperature increases;
applying the clamp voltage to a transistor that is directly connected to a column line of a pixel array, wherein a voltage level of a threshold voltage of the transistor decreases as the temperature increases; and
compensating for a change in a voltage level of an output voltage of the transistor, which is due to a change in the threshold voltage, based on the clamp voltage.

19. The method of claim 18 , wherein the generating of the clamp voltage includes:
sensing a temperature change;
generating a temperature compensation voltage based on the temperature change; and
generating the clamp voltage based on the temperature compensation voltage and a first voltage that a bandgap reference circuit generates.

20. The method of claim 19 , wherein the temperature change is based on a change in a voltage level of an internal voltage of the bandgap reference circuit.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Jun Jaehoon
• Yang Han

Classifications

• H04N25/75

  Circuitry for providing, modifying or processing image signals from the pixel array · CPC title

• H04N25/709 Primary

  Circuitry for control of the power supply · CPC title

• H04N25/67 Primary

  applied to fixed-pattern noise, e.g. non-uniformity of response · CPC title

• H04N25/779

  Circuitry for scanning or addressing the pixel array · CPC title

• H04N25/671

  for non-uniformity detection or correction · CPC title