Temperature sensor

Abstract

An integrated circuit comprising a temperature sensor is disclosed. The temperature sensor 100, 200 comprises a negative temperature coefficient thermistor 101, comprising doped metal oxide semiconduc

Description

TECHNICAL FIELD

[0001] The present disclosure concerns a temperature sensor. More particularly, but not exclusively, the present disclosure concerns an integrated circuit comprising a temperature sensor. The present disclosure also concerns a method of operating a temperature sensor in an integrated circuit and a method of manufacturing an integrated circuit comprising a temperature sensor. BACKGROUND

[0002] Temperature sensors are used in many different applications. Temperature sensors often incorporate a thermistor as a temperature sensing element. A thermistor is a type of resistor whose resistance is strongly dependent on temperature. There are two main categories of thermistor: negative temperature coefficient (NTC) thermistors and positive temperature coefficient (PTC) thermistors. NTC thermistors have a resistance that decreases as a temperature of the thermistor increases. PTC thermistors have a resistance that increases as a temperature of the thermistor increases. By monitoring the resistance of the thermistor, it is possible to monitor changes in temperature of the thermistor.

[0003] Thermistors are generally operated as contact temperature sensors (i.e. they are arranged to be in direct contact with the object they are sensing); however, this requirement can often mean that a thermistor should be located apart from its associated signal processing electronics. Thermistors are generally discrete components which are not integrated with the integrated circuit that processes their output. Thermistors are typically also relatively expensive compared to other temperature sensing technologies (such as thermocouples and thermopiles). There is therefore a need for low-cost temperature sensors that can be embedded within an integrated circuit.

[0004] The present disclosure seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present disclosure seeks to provide an improved temperature sensor. SUMMARY

[0005] A first aspect of the present disclosure relates to an integrated circuit comprising a temperature sensor, the temperature sensor comprising: a negative temperature coefficient thermistor comprising doped metal oxide semiconductor material and coupled between a supply voltage and an output node of the temperature sensor; and a resistor coupled between the output node and ground.

[0006] A second aspect of the present disclosure relates to a method of operating a temperature sensor in an integrated circuit, the method comprising: providing a negative temperature coefficient thermistor formed of doped metal oxide semiconductor material; and determining, on the basis of a measured resistance of the thermistor, a temperature of the thermistor.

[0007] A third aspect of the present disclosure relates to a method of manufacturing an integrated circuit comprising a temperature sensor, the method comprising: forming a negative temperature coefficient thermistor of doped metal oxide semiconductor material coupled between a supply voltage and an output node of the temperature sensor; and forming a resistor coupled between the output node and ground.

[0008] It will of course be appreciated that features described in relation to one aspect of the present disclosure may be incorporated into other aspects of the present disclosure. For example, the method of the present disclosure may incorporate any of the features described with reference to the apparatus of the present disclosure and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 shows a schematic view of a temperature sensor according to the present disclosure;

[0010] Figure 2 shows a schematic view of a temperature sensor according to the present disclosure;

[0011] Figure 3 shows a graph of the variation in output voltage with respect to temperature of an example temperature sensor according to the present disclosure;

[0012] Figure 4 shows a functional block diagram illustrating the steps of a method of operating a temperature sensor according to the present disclosure; and

[0013] Figure 5 shows a functional block diagram illustrating the steps of a method of manufacturing an integrated circuit comprising a temperature sensor according to the present disclosure. DETAILED DESCRIPTION

[0014] Figure 1 shows a schematic view of a temperature sensor 100 according to the present disclosure. The temperature sensor 100 comprises part of an integrated circuit.

[0015] Temperature sensor 100 comprises a negative temperature coefficient (NTC) thermistor 101. Thermistor 101 is coupled between a supply voltage (VDD) and an output node (OUT) of the temperature sensor 100. Thermistor 101 comprises doped metal oxide semiconductor material.

[0016] A thermistor 101 comprising doped metal oxide semiconductor material can be embedded into an integrated circuit. Embedding a thermistor comprising doped metal oxide semiconductor material into an integrated circuit can also allow the temperature sensor to exhibit an improved response time. It will be appreciated that the response time for a temperature sensor is the time taken for an output of the temperature sensor to change to reflect a change in temperature of the object being monitored.

[0017] Thermistor 101 may be formed of (for example, consist of) doped metal oxide semiconductor material For example, the doped metal oxide semiconductor material may comprise semiconductor materials selected from one or more of: ZnO, SnO?, NiO, SnO, Cu2O, ln2O3, LiZnO, ZnSnO, InSnO, InZnO, HflnZnO, InGaZnO, ZnxNy, ZnOxNx, and any other suitable metal oxide semiconductor material. It will be appreciated that zinc oxynitride semiconductor materials have a general chemical formula of ZnOxNy. It will be further appreciated that this formula denotes a material composed of zinc (Zn), oxygen (0), and nitrogen (N) in varying proportions. The exact stoichiometry (the values of x and y) can vary depending on the synthesis method and the desired properties of the material. In some cases, the formula can be more specifically written as ZnOi-xNx, where x represents the proportion of oxygen atoms that are replaced by nitrogen atoms.

[0018] Temperature sensor 100 further comprises a resistor 103 coupled between the output node (OUT) and ground (GND). Resistor 103 may comprise a positive temperature coefficient (PTC) resistance temperature detector (RTD). Resistor 103 may comprise a length of metal track. The resistance temperature detector may comprise (for example, consist of) a metal selected from one or more of: Titanium, Nickel, Palladium, Platinum, Iron, Osmium, Molybdenum, Tungsten, Aluminium, Copper, Silver, Palladium, Platinum, Gold, Rhodium, Iridium, Zinc, Steel, Nichrome, Nichrome V and any other suitable positive temperature coefficient metal or metal alloy. For example, the resistance temperature detector may comprise (for example, consist of) a metal selected from one or more of: Nickel, Iron, Molybdenum, Tungsten, Aluminium, Copper, Silver, Platinum, Gold, Zinc, Steel, Nichrome, and Nichrome V, and any other suitable positive temperature coefficient metal or metal alloy.

[0019] Thermistor 101 and resistor 103 may be arranged to form a potential divider. Thus, a voltage of the output node (OUT) may be determined by the ratio of the resistance of thermistor 101 to the resistance of resistor 103. A temperature sensor comprising a potential divider formed of an NTC thermistor and a PTC resistor can provide increased gain compared to a temperature sensor based on only one of an NTC thermistor and a PTC resistor.

[0020] Thermistor 101 may be configured such that its resistance decreases as a temperature of thermistor 101 increases. Resistor 103 may be configured such that its resistance increases as a temperature of resistor 103 increases.

[0021] The supply voltage (VDD) may be a positive supply voltage. Thus, an increase in a temperature of the temperature sensor 100 may cause an increase in a voltage of the output node (OUT). The voltage of the output node (OUT) may be directly related (for example, directly proportional) to the temperature of the temperature sensor 100.

[0022] The supply voltage (VDD) may be a negative supply voltage. Thus, an increase in a temperature of the temperature sensor 100 may cause a decrease in a voltage of the output node (OUT). The voltage of the output node (OUT) may be inversely related (for example, inversely proportional) to the temperature of the temperature sensor 100.

[0023] It will be appreciated that a “positive supply voltage” in this context refers to a voltage supply that is at a positive voltage compared to ground (GND). Similarly, a “negative supply voltage” in this context refers to a voltage supply that is at a negative voltage compared to ground (GND). It will also be appreciated that references to “ground” are intended to refer merely to a reference voltage in the electronic circuit of temperature sensor 100 and are not limited to a connection to the Earth. It will further be appreciated that in this context, references to an “increase” in a voltage of a node indicate the voltage of that node becoming more positive (or less negative) relative to ground, and not necessarily an increase in magnitude of the potential difference between the node and ground. Similarly, references to a “decrease” in a voltage of a node indicate the voltage of that node becoming more negative (or less positive) relative to ground, and not necessarily a decrease in magnitude of the potential difference between the node and ground.

[0024] Resistor 103 may be configured such that its resistance increases as a temperature of resistor 103 increases. Thus, it may be that an increase in the temperature of the temperature sensor 100 can cause the resistance of thermistor 101 to decrease and the resistance of resistor 103 to increase. Where the voltage supply (VDD) comprises a positive voltage supply, this results in an increase in the voltage of the output node (OUT). Alternatively, resistor 103 may be configured such that its resistance remains substantially constant as a temperature of resistor 103 varies. Thus, it may be that an increase in the temperature of the temperature sensor 100 can cause the resistance of thermistor 101 to decrease while the resistance of resistor 103 remains substantially constant. Where the voltage supply (VDD) comprises a positive voltage supply, this results in an increase in the voltage of the output node (OUT). It will be appreciated by the skilled person that (for both cases above), if the voltage supply (VDD) comprised a negative voltage supply, an increase in temperature would instead result in a decrease in the voltage of the output node (OUT).

[0025] Thus, the temperature sensor 100 may be configurable to operate in two modes of operation. For example, in a first mode of the two modes of operation, the supply voltage (VDD) may be configured to be a positive supply voltage. In the first mode of operation, an increase in a temperature of the temperature sensor 100 causes an increase in a voltage of the output node (OUT). In a second mode of the two modes of operation, the supply voltage (VDD) may be configured to be a negative supply voltage. In the second mode of operation, an increase in a temperature of the temperature sensor 100 causes a decrease in a voltage of the output node (OUT). The supply voltage (VDD) may be configurable to be either a positive supply voltage or a negative supply voltage. The temperature sensor 100 may comprise a control circuit (not shown) configured to control the polarity of the supply voltage (VDD). For example, the control circuit may comprise an H-bridge.

[0026] It will be appreciated that each component in an integrated circuit occupies a respective portion of the area of the integrated circuit (when the integrated circuit is viewed in plan view - i.e. in a direction orthogonal to a plane of the layers of the integrated circuit). The area of the integrated circuit occupied by a component can be referred to as a footprint of the component. It will be further appreciated that, where an integrated circuit comprises multiple layers, it may be that the footprints of components can overlap (for example, where those components exist within different ones of the multiple layers).

[0027] A footprint of thermistor 101 may be located at least partially within a footprint of resistor 103. A first portion of the footprint of thermistor 101 may be within the footprint of resistor 103, and a second, different portion of the footprint of thermistor 101 may be outside of the footprint of resistor 103. The footprint of thermistor 101 may be located entirely within the footprint of resistor 103. It may be that no portion of the footprint of thermistor 101 is outside of the footprint of resistor 103.

[0028] Thermistor 101 and resistor 103 may be formed in separate layers of the integrated circuit. Thus, thermistor 101 may overlay resistor 103 (or vice-versa). Where resistor 103 comprises a metal track, it may be that resistor 103 is formed within a routing layer of the integrated circuit.

[0029] Figure 2 shows a schematic view of a temperature sensor 200 according to the present disclosure. Temperature sensor 200 may have similarities to temperature sensor 100 described above, but has one or more differences as described below. Any or all of the optional features described above in respect of temperature sensor 100 may also be present in temperature sensor 200. Like temperature sensor 100, temperature sensor 200 comprises part of an integrated circuit.

[0030] Temperature sensor 200 comprises a plurality of NTC thermistors 201a-j. The plurality of thermistors 201 a-j may each be formed of (for example, consists of) doped metal oxide semiconductor material. For example, the doped metal oxide semiconductor material may comprise semiconductor materials selected from one or more of: ZnO, SnO2, NiO, SnO, Cu2O, ln2O3, LiZnO, ZnSnO, InSnO, InZnO, HflnZnO, InGaZnO, ZnxNy, ZnOxNx, and any other suitable metal oxide semiconductor material. Whilst Figure 2 shows temperature sensor 200 as having ten thermistors 201 a-j, it will be appreciated that any number of thermistors may be used. Temperature sensor 200 may comprise at least two thermistors, at least three thermistors, at least four thermistors, at least five thermistors, at least six thermistors, at least seven thermistors, at least eight thermistors, at least nine thermistors, at least ten thermistors, at least eleven thermistors, at least twelve thermistors, at least thirteen thermistors, at least fourteen thermistors, at least fifteen thermistors, at least sixteen thermistors, at least seventeen thermistors, at least eighteen thermistors, at least nineteen thermistors, or at least twenty thermistors. Temperature sensor 200 may comprise no more than fifty thermistors, no more than forty-five thermistors, no more than forty thermistors, no more than thirty-five thermistors, no more than thirty thermistors, no more than twenty-five thermistors, no more than fifteen thermistors, no more than ten thermistors, or no more than five thermistors. Each of the thermistors 201 a-j in the plurality may be coupled between the supply voltage (VDD) and the output node (OUT). Two or more (for example, all) of the plurality of thermistors 201a- j may be connected in series. Two or more (for example, all) of the plurality of thermistors 201 a-j may be connected in parallel. Four or more (for example, all) of the plurality of thermistors may be connected in parallel. Four or more (for example, all) of the plurality of thermistors may be connected in series.

[0031] Temperature sensor 200 further comprises a resistor 203 coupled between the output node (OUT) and ground (GND). Resistor 203 may comprise a positive temperature coefficient (PTC) resistance temperature detector (RTD). Resistor 203 may comprise a length of metal track. The resistance temperature detector may comprise (for example, consist of) a metal selected from one or more of: Titanium, Nickel, Palladium, Platinum, Iron, Osmium, Molybdenum, Tungsten, Aluminium, Copper, Silver, Palladium, Platinum, Gold, Rhodium, Iridium, Zinc, Steel, Nichrome, Nichrome V and any other suitable positive temperature coefficient metal or metal alloy. For example, the resistance temperature detector may comprise (for example, consist of) a metal selected from one or more of: Nickel, Iron, Molybdenum, Tungsten, Aluminium, Copper, Silver, Platinum, Gold, Zinc, Steel, Nichrome, and Nichrome V, and any other suitable positive temperature coefficient metal or metal alloy.

[0032] A footprint of at least one of the thermistors 201 a-j in the plurality may be located at least partially (for example, entirely) within a footprint of resistor 203. The footprints of multiple (for example, all) thermistors 201 a-j in the plurality may be located at least partially (for example, entirely) within a footprint of resistor 203. At least one of the plurality of thermistors 201 a-j may be formed in a separate layer of the integrated circuit to resistor 103. Multiple (for example, all) thermistors 201 a-j in the plurality may be formed in a separate layer of the integrated circuit to resistor 103. It will be appreciated that, in such cases, the multiple thermistors 201 a-j need not necessarily be formed in the same separate layer. For example, a first thermistor of the multiple thermistors 201 a-j may be formed in a first layer, a second thermistor of the multiple thermistors 201 a-j may be formed in a second layer, and resistor 203 may be formed in a third layer. Thus, one or more (for example, all) of thermistors 201 a-j may overlay resistor 203 (or vice-versa).

[0033] Multiple (for example, all) thermistors 201 a-j in the plurality may be distributed across the footprint of resistor 203. It will be appreciated in this context that it is the locations of individual thermistors 201 a-j in the plurality which are distributed across the footprint of resistor 203, rather than each individual thermistor being spread across the footprint of resistor 203. Multiple (for example, all) of the plurality of thermistors 201 a-j may be distributed substantially evenly across the footprint of the resistor. It will be appreciated that substantially evenly in this context means that the density of thermistors located in any given area of the footprint of resistor 203 is substantially constant. The multiple (for example, all) thermistors 201 a-j may be distributed symmetrically across the footprint of the resistor.

[0034] The present disclosure provides an integrated circuit comprising a temperature sensor (for example, temperature sensor 100 or temperature sensor 200). The integrated circuit may be a flexible integrated circuit.

[0035] In accordance with the present disclosure a “flexible integrated circuit” (flexible IC or flexIC) is a type of integrated circuit that is designed to be flexible and conformable, allowing it to bend, twist, and conform to non-flat or irregular surfaces. Unlike traditional rigid ICs, which are typically made on silicon wafers and are inflexible, flexible ICs, in accordance with the present disclosure, are fabricated on flexible substrates using appropriate materials and thin-film processes. The substrate is typically formed of an appropriate flexible polymer material. Nevertheless, the flexible substrate may be formed from any other materials that provide suitable electrical, chemical, and / or structural properties. The flexible substrate may be formed from a single common material, may be formed from a plurality of different materials, or may be formed from a plurality of different types of the same material. The flexible substrate may, for example, comprise one or more materials selected from the following list of materials: flexible glass, polymer materials, metal oxide materials, resin materials, resist materials, foil materials, paper, insulator coated metals, or any other suitable material.

[0036] Where a polymer based material is used, the substrate may comprise one or more polymers selected from: polyethylene naphthalates, polyethylene terephthalates; polymethyl methacrylates; polycarbonates, polyvinyl alcohols, polyvinyl acetates, polyvinyl pyrrolidones, polyvinyl phenols, polyvinyl chlorides, polystyrenes, polyimides, polyamides (e.g. Nylon); poly(hydroxy ethers), polyurethanes, polycarbonates, polysulfones, parylenes, polyarylates, polyether ether ketones (PEEKs); acrylonitrile butadiene styrene (ABS), 1 Methoxy 2 propyl acetates, Benzocyclobutenes (BCB), polylactic acid (PLA), polyhydroxyalkanoates (PHAs), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), cellulose polymers, or any other suitable polymer material.

[0037] Where a metal oxide based material is used, the substrate may comprise one or more metal oxides selected from: AI2O3, SiOxNy, SiO2, SisN4, or any other suitable metal oxide. Where a resin based material is used, the substrate may comprise one or more resins selected from: a UV-curable resin or any other suitable resin. Where a resist based material is used, the substrate may comprise one or more resists selected from: nanoimprint resists, photoresists such as, for example, Bisphenol A novolac epoxy (SU-8) or polyhydroxybenzyl silsesquioxane, or any other suitable resist. Where a foil based material is used the substrate may comprise one or more foils selected from: polymeric foils or any other suitable foil. Where an insulator-coated metal is used, the substrate may comprise one or more insulator-coated metals selected from: insulator coated stainless-steel or any other suitable insulator-coated metal.

[0038] Additionally or alternatively, a flexible IC may not include the flexible substrate, which, for example, may be removed during a manufacturing step.

[0039] Figure 3 shows a graph of the variation in output voltage with respect to temperature of an example temperature sensor according to the present disclosure. The temperature sensor used in this case is as shown in Figure 1 and comprises an NTC thermistor and a PTC resistor in a potential divider. The voltage supply (VDD) used is a positive voltage supply. It will be appreciated that the output voltage of the temperature sensor 100 is the voltage of output node (OUT) relative to ground (GND). The graph shows that the temperature sensor exhibits a direct relationship between the temperature and output voltage (i.e. as the temperature increases, so does the output voltage). It will be appreciated that, if the voltage supply (VDD) used was instead a negative voltage supply, the temperature sensor would exhibit an inverse relationship between the temperature and output voltage (i.e. as the temperature increased, the output voltage would decrease).

[0040] Figure 4 shows a functional block diagram illustrating the steps of a method 400 of operating a temperature sensor in an integrated circuit according to the present disclosure.

[0041] A first step, represented by item 401, of method 400 comprises providing a negative temperature coefficient thermistor formed of doped metal oxide semiconductor material. The negative temperature coefficient thermistor may be coupled between a supply voltage and an output node of the temperature sensor. The negative temperature coefficient thermistor may be formed of one or more of: ZnO, SnO2, NiO, SnO, CU2O, ln2Os, LiZnO, ZnSnO, InSnO, InZnO, HflnZnO, InGaZnO, ZnxNy, ZnOxNx, and any other suitable metal oxide semiconductor material. The method may comprise providing a plurality of negative temperature coefficient thermistors (for example, each coupled between the supply voltage and the output node).

[0042] An optional second step, represented by item 403, of method 400 comprises providing a resistor coupled between the output node and ground. The resistor may be formed of (for example, consist of) a metal selected from one or more of: Titanium, Nickel, Palladium, Platinum, Iron, Osmium, Molybdenum, Tungsten, Aluminium, Copper, Silver, Palladium, Platinum, Gold, Rhodium, Iridium, Zinc, Steel, Nichrome, Nichrome V and any other suitable positive temperature coefficient metal or metal alloy. For example, the resistor may be formed of a metal selected from one or more of: Nickel, Iron, Molybdenum, Tungsten, Aluminium, Copper, Silver, Platinum, Gold, Zinc, Steel, Nichrome, Nichrome V, and any other suitable positive temperature coefficient metal or metal alloy. The forming of the thermistor and the resistor may be such that they together form a potential divider.

[0043] A third step, represented by item 405, of method 400 comprises determining, on the basis of a measured resistance of the thermistor, a temperature of the thermistor. The determining may comprise evaluating a voltage (for example, relative to ground) of the output node. Where the method comprises providing a plurality of negative temperature coefficient thermistors, it may be that the method comprises determining an average temperature of the plurality of thermistors. In such cases, it may be that the determining of the average temperature is performed on the basis of a measured combined equivalent resistance of the plurality of thermistors.

[0044] An optional fourth step, represented by item 407, of method 400 comprises operating the temperature sensor in a first mode of operation. In such cases, it may be that operating the temperature sensor in the first mode of operation comprises applying a positive supply voltage. Operating the temperature sensor in the first mode of operation may comprise configuring the temperature sensor such that an increase in a temperature of the temperature sensor causes an increase in a voltage of the output node.

[0045] An optional fifth step, represented by item 409, of method 400 comprises operating the temperature sensor in a second mode of operation. In such cases, it may be that operating the temperature sensor in the second mode of operation comprises applying a negative supply voltage. Operating the temperature sensor in the second mode of operation may comprise configuring the temperature sensor such that an increase in a temperature of the temperature sensor causes a decrease in a voltage of the output node.

[0046] Figure 5 shows a functional block diagram illustrating the steps of a method 500 of manufacturing an integrated circuit comprising a temperature sensor according to the present disclosure.

[0047] A first step, represented by item 501, of method 500 comprises forming a negative temperature coefficient thermistor of doped metal oxide semiconductor material coupled between a supply voltage and an output node of the temperature sensor. The negative temperature coefficient thermistor is formed of semiconductor materials selected from one or more of: ZnO, SnO2, NiO, SnO, CU2O, ln2O3, LiZnO, ZnSnO, InSnO, InZnO, HflnZnO, InGaZnO, ZnxNy, ZnOxNx, and any other suitable metal oxide semiconductor material.

[0048] An optional second step, represented by item 503, of method 500 comprises forming a plurality of negative temperature coefficient thermistors. In such cases, it may be that each of the thermistors in the plurality is coupled between the supply voltage and the output node. It may be that the forming of the plurality of thermistors is such that two or more of the thermistors are connected in series. It may be that the forming of the plurality of thermistors is such that two or more of the thermistors are connected in parallel.

[0049] A third step, represented by item 505, of method 500 comprises forming a resistor coupled between the output node and ground. The resistor may be formed of (for example, consist of) a metal selected from one or more of: Titanium, Nickel, Palladium, Platinum, Iron, Osmium, Molybdenum, Tungsten, Aluminium, Copper, Silver, Palladium, Platinum, Gold, Rhodium, Iridium, Zinc, Steel, Nichrome, Nichrome V and any other suitable positive temperature coefficient metal or metal alloy. For example, the resistor may be formed of a metal selected from one or more of: Nickel, Iron, Molybdenum, Tungsten, Aluminium, Copper, Silver, Platinum, Gold, Zinc, Steel, Nichrome, Nichrome V, and any other suitable positive temperature coefficient metal or metal alloy. The forming of the thermistor (or plurality of thermistors) and the resistor may be such that they together form a potential divider. Forming the resistor may comprise forming a metal track. Forming the resistor may comprise forming a metal track with dimensions which provide one or more predetermined resistance characteristics. The one or more predetermined resistance characteristics may comprise a predetermined resistance at a specified temperature. Thus, it may be that the resistor may be formed to provide a predetermined resistance at a specified temperature. The forming of the plurality of negative temperature coefficient thermistors and the forming of the resistor may be such that the plurality of thermistors are distributed (for example, spread evenly or symmetrically) across a footprint of the resistor.

[0050] Whilst the present disclosure has been described and illustrated with reference to particular examples, it will be appreciated by those of ordinary skill in the art that the present disclosure lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

[0051] Whilst the illustrated examples show temperature sensors including ten thermistors, it will be appreciated that other embodiments include other numbers of thermistors. Similarly, whilst the illustrated examples show temperature sensors including only one resistor, it will be appreciated that, in other embodiments, more than one resistor may be present.

[0052] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the present disclosure that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the present disclosure, may not be desirable, and may therefore be absent, in other embodiments.

Claims

1. An integrated circuit comprising a temperature sensor, the temperature sensor comprising:a negative temperature coefficient thermistor comprising doped metal oxide semiconductor material and coupled between a supply voltage and an output node of the temperature sensor; anda resistor coupled between the output node and ground.

2. An integrated circuit according to claim 1, wherein the doped metal oxide semiconductor material comprises a semiconductor material selected from one or more of: ZnO, SnO?, NiO, SnO, CU2O, InaOa, LiZnO, ZnSnO, InSnO, InZnO, HflnZnO, InGaZnO, ZnxNy, and ZnOxNx.

3. An integrated circuit according to claim 1 or 2, wherein the resistor comprises a positive temperature coefficient resistance temperature detector.

4. An integrated circuit according to claim 3, wherein the resistance temperature detector comprises a length of metal track.

5. An integrated circuit according to claim 3 or 4, wherein the resistance temperature detector comprises one or more of: Titanium, Nickel, Palladium, Platinum, Iron, Osmium, Molybdenum, Tungsten, Aluminium, Copper, Silver, Palladium, Platinum, Gold, Rhodium, Iridium, Zinc, Steel, Nichrome, and Nichrome V.

6. An integrated circuit according to any preceding claim, wherein a footprint of the thermistor is located at least partially within a footprint of the resistor.

7. An integrated circuit according to claim 6, wherein the footprint of the thermistor is located entirely within the footprint of the resistor.

8. An integrated circuit according to any preceding claim, wherein the temperature sensor comprises a plurality of negative temperature coefficient thermistors, each of the thermistors in the plurality being coupled between the supply voltage and the output node.

9. An integrated circuit according to claims 7 and 8, wherein each negative temperature coefficient thermistor in the plurality is located entirely within the footprint of the resistor.

10. An integrated circuit according to claim 9, wherein the plurality of negative temperature coefficient thermistors are distributed across the footprint of the resistor.

11. An integrated circuit according to any preceding claim, wherein:the supply voltage is a positive supply voltage; andan increase in a temperature of the temperature sensor causes an increase in a voltage of the output node.

12. An integrated circuit according to any of claims 1 to 10, wherein:the supply voltage is a negative supply voltage; andan increase in a temperature of the temperature sensor causes a decrease in a voltage of the output node.

13. An integrated circuit according to any of claims 1 to 10, wherein the supply voltage is configurable to be either a positive supply voltage or a negative supply voltage.

14. An integrated circuit according to claim 13, wherein the temperature sensor is configurable to operate in:a first mode of operation in which the supply voltage is configured to be a positive supply voltage and an increase in a temperature of the temperature sensor causes an increase in a voltage of the output node; anda second mode of operation in which the supply voltage is configured to be a negative supply voltage and an increase in a temperature of the temperature sensor causes a decrease in a voltage of the output node.

15. An integrated circuit according to any preceding claim, wherein the integrated circuit is a flexible integrated circuit.

16. A method of operating a temperature sensor in an integrated circuit, the method comprising:providing a negative temperature coefficient thermistor formed of doped metal oxide semiconductor material; anddetermining, on the basis of a measured resistance of the thermistor, a temperature of the thermistor.

17. A method of operating a temperature sensor according to claim 16, wherein:the negative temperature coefficient thermistor is coupled between a supply voltage and an output node of the temperature sensor; andthe method further comprises providing a resistor coupled between the outputnode and ground.

18. A method of operating a temperature sensor according to claim 17, wherein the method further comprises:operating the temperature sensor in a first mode of operation by applying a positive supply voltage, such that an increase in a temperature of the temperature sensor causes an increase in a voltage of the output node; andoperating the temperature sensor in a second mode of operation by applying a negative supply voltage, such that an increase in a temperature of the temperature sensor causes a decrease in a voltage of the output node.

19. A method of manufacturing an integrated circuit comprising a temperature sensor, the method comprising:forming a negative temperature coefficient thermistor of doped metal oxide semiconductor material coupled between a supply voltage and an output node of the temperature sensor; andforming a resistor coupled between the output node and ground.

20. A method according to claim 19, wherein the forming of the resistor comprises forming a metal track with dimensions which provide one or more predetermined resistance characteristics.

21. A method according to claim 19 or 20, the method further comprising forming a plurality of negative temperature coefficient thermistors, each of the thermistors in the plurality being coupled between the supply voltage and the output node.

22. A method according to claim 21, wherein the forming of the plurality of negative temperature coefficient thermistors and the forming of the resistor are such that the plurality of thermistors are distributed across a footprint of the resistor.Application No: GB2408580.5Examiner:Ms Danielle JonesClaims searched: 1-22Date of search: 16 December 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 16 JPH01276602 A (K0AC0RP) See fig.

1. A - US 5795069 A (MATTES et al.) A - RU 2374709 Cl (G OBRAZOVATEL NOE UCHREZHDENIE) A - US 5835553 A (SUZUKI) A - US 9559162 B2 (DALEY et al.)Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if p Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP. WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPC____________GO IK_____________________________________________________The following online and other databases have been used in the preparation of this search reportSEARCH-PATENTInternational Classification:Subclass Subgroup Valid From GO IK 0007 / 16 01 / 01 / 2006 GO IK 0007 / 18 01 / 01 / 2006 GO IK 0007 / 20 01 / 01 / 2006 GO IK 0007 / 22 01 / 01 / 2006 GO IK 0007 / 24 01 / 01 / 2006

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