Thermal imaging pixel, thermal imaging sensor, and bolometer

Patent metadata

Field	Value
Publication number	US-12590843-B2
Application number	US-202318227488-A
Country	US
Kind code	B2
Filing date	Jul 28, 2023
Priority date	Jan 4, 2023
Publication date	Mar 31, 2026
Grant date	Mar 31, 2026

Abstract

A thermal imaging pixel, including a variable resistor array; and a pixel readout circuit configured to read electrical signals corresponding to a composite resistance of the variable resistor array, wherein the variable resistor array includes a plurality of variable resistor subarrays electrically connected in series, wherein each variable resistor subarray of the plurality of variable resistor subarrays includes a plurality of variable resistor cells electrically connected in parallel, and wherein each variable resistor cell of the plurality of variable resistor cells has a resistance which changes according to temperature.

First claim

What is claimed is:

1 . A thermal imaging pixel comprising:
a variable resistor array; and a pixel readout circuit configured to read electrical signals corresponding to a composite resistance of the variable resistor array, wherein the variable resistor array comprises a plurality of variable resistor subarrays electrically connected in series, wherein each variable resistor subarray of the plurality of variable resistor subarrays comprises a plurality of variable resistor cells electrically connected in parallel, wherein each variable resistor cell of the plurality of variable resistor cells has a resistance which changes according to a temperature change, wherein each variable resistor cell comprises a magnetic tunnel junction (MTJ) having a random telegraph noise (RTN) characteristic in which a parallel (P) state and an antiparallel (AP) state are determined probabilistically according to a temperature change, wherein a resistance in the P state is different from a resistance in the AP state, and wherein the thermal imaging pixel does not require a reset operation to set the MTJ into either the P state or the AP state.

2 . The thermal imaging pixel of claim 1 , wherein the each variable resistor cell comprises:
a pinned layer having a fixed magnetic polarity; an insulation layer positioned adjacent to the pinned layer; and a free layer positioned adjacent to the insulation layer and having a variable magnetic polarity.

3 . The thermal imaging pixel of claim 2 , wherein a direction of the fixed magnetic polarity of the pinned layer is parallel to a direction in which the pinned layer extends.

4 . The thermal imaging pixel of claim 2 , wherein a direction of the fixed magnetic polarity of the pinned layer intersects a direction in which the pinned layer extends.

5 . The thermal imaging pixel of claim 2 , wherein based on a magnetization direction of the free layer being parallel to a magnetization direction of the pinned layer, the free layer has a first energy level, and
wherein based on the magnetization direction of the free layer being antiparallel to the magnetization direction of the pinned layer, the free layer has a second energy level different from the first energy level.

6 . The thermal imaging pixel of claim 1 , wherein the plurality of variable resistor cells are arranged in a matrix.

7 . The thermal imaging pixel of claim 1 , wherein a first variable resistor cell from among the plurality of variable resistor cells is adjacent to a second variable resistor cell from among the plurality of variable resistor cells, and
wherein a distance between the first variable resistor cell and the second variable resistor cell is greater than or equal to a length of the first variable resistor cell in a direction of the distance.

8 . The thermal imaging pixel of claim 1 , wherein an average of the composite resistance over time varies according to the temperature.

9 . The thermal imaging pixel of claim 1 , wherein an average of the composite resistance over time decreases as the temperature increases.

10 . The thermal imaging pixel of claim 1 , wherein a length of the variable resistor array is greater than or equal to 5 micrometers.

11 . The thermal imaging pixel of claim 1 , wherein at least one variable resistor cell of the plurality of variable resistor cells has a length in units of nanometers.

12 . The thermal imaging pixel of claim 1 , wherein the pixel readout circuit is further configured to supply a current to the variable resistor array from a current source.

13 . The thermal imaging pixel of claim 1 , wherein the electrical signals comprise a voltage corresponding to the composite resistance of the variable resistor array, and
wherein the pixel readout circuit is further configured to read the voltage.

14 . A thermal imaging sensor comprising:
a thermal imaging pixel comprising a variable resistor array; and a readout circuit configured to read electrical signals corresponding to an average of a composite resistance of the variable resistor array over time; wherein the variable resistor array comprises a plurality of variable resistor subarrays electrically connected in series, wherein each of the plurality of variable resistor subarrays comprises a plurality of variable resistor cells electrically connected in parallel, wherein each variable resistor cell of the plurality of variable resistor cells has a resistance which changes according to a temperature change, wherein each variable resistor cell comprises a magnetic tunnel junction (MTJ) having a random telegraph noise (RTN) characteristic in which a parallel (P) state and an antiparallel (AP) state are determined probabilistically according to a temperature change, wherein a resistance in the P state is different from a resistance in the AP state, and wherein the thermal imaging pixel does not require a reset operation to set the MTJ into either the P state or the AP state.

15 . The thermal imaging sensor of claim 14 , wherein a temperature range detected by the thermal imaging sensor comprises a range of 200 Kelvin to 400 Kelvin.

16 . The thermal imaging sensor of claim 14 , wherein a wavelength range of electromagnetic radiation detected by the thermal imaging sensor comprises a range of 10 micrometers to 14 micrometers.

17 . The thermal imaging sensor of claim 14 , wherein the readout circuit comprises an integrator circuit configured to integrate electrical signals output from the thermal imaging pixel.

18 . The thermal imaging sensor of claim 17 , wherein an integrating time of the integrator circuit used to operate the thermal imaging sensor at a thermal sensitivity of 1 Kelvin is less than 1 ms.

19 . The thermal imaging sensor of claim 17 , further comprising an analog to digital converter (ADC) configured to convert an analog signal output from the integrator circuit into a digital signal.

20 . A bolometer comprising:
a variable resistor array comprising a plurality of variable resistor subarrays electrically connected in series, wherein each variable resistor subarray of the plurality of variable resistor subarrays includes a plurality of variable resistor cells electrically connected in parallel, wherein each variable resistor cell of the plurality of variable resistor cells has a resistance which changes according to a temperature change, wherein each variable resistor cell comprises a magnetic tunnel junction (MTJ) having a random telegraph noise (RTN) characteristic in which a parallel (P) state and an antiparallel (AP) state are determined probabilistically according to a temperature change, wherein a resistance in the P state is different from a resistance in the AP state, and wherein the thermal imaging pixel does not require a reset operation to set the MTJ into either the P state or the AP state.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Jinmyoung
• Song Byonggwon
• You Jangwoo
• Lee Duhyun

Classifications

• H04N25/21

  for transforming thermal infrared radiation into image signals · CPC title

• G01J2005/202

  Arrays · CPC title

• G01J2005/0077

  Imaging · CPC title

• G01J5/48

  Thermography; Techniques using wholly visual means · CPC title

• G01J5/0853

  having infrared absorbers other than the usual absorber layers deposited on infrared detectors like bolometers, wherein the heat propagation between the absorber and the detecting element occurs within a solid · CPC title