INTEGRATED TEMPERATURE THRESHOLD DETECTION CIRCUIT AND CORRESPONDING METHOD

Abstract

Integrated circuit comprising a temperature-independent voltage generator (VIG) circuit configured to generate a constant temperature voltage (VIG) by summing a voltage proportional to the absolute temperature (VPTAT) and a voltage complementary to the absolute temperature (VCTAT), and a temperature threshold detection (TTD) circuit comprising a resistive voltage divider bridge (RS1, RS2) configured to generate a reference voltage (VREF) equal to a fraction of the constant temperature voltage (VIG) and a comparator circuit (COMP) configured to compare the voltage proportional to the absolute temperature (VPTAT) with the reference voltage (VREF). Figure for the abstract: Fig 1

Description

Title of the invention: INTEGRATED TEMPERATURE THRESHOLD DETECTION CIRCUIT AND CORRESPONDING METHOD

[0001] Embodiments and implementations relate to integrated circuits, in particular temperature threshold detection circuits.

[0002] The behavior of an electronic device is generally influenced by temperature. It is recognized, for example, that a laser operating at low temperature is capable of emitting a more powerful beam. However, when the temperature is too low, this beam can present a risk for a person exposed to it. It is therefore important to guard against this risk, in particular to comply with standardized constraints, and lowering the emission power can be disadvantageous at warmer temperatures. Conventional techniques for detecting a temperature threshold from which a malfunction of a device such as a laser can occur present difficulties either in terms of a lack of detection precision or in terms of the complexity and cost of the product.

[0003] Indeed, known circuits for detecting this temperature threshold are not always reliable and do not guarantee precise detection of the temperature threshold. This is particularly the case when these circuits generate a signal representative of the temperature which may have imperfections.

[0004] Indeed, a signal representative of the temperature from such circuits may undergo undesirable variations. These variations may have different origins, such as variations linked to the power supply of these circuits. At a given temperature, a variation in the signal representative of the temperature may result, for example, in a shift or drift of the signal generated to be representative of the temperature, compared to the actual temperature.

[0005] Therefore, a shift occurring at the detection threshold can result in a significant loss of accuracy in the temperature measurement and a lack of detection or incorrect detection of the temperature threshold. Although there are ways to reduce the drift of the generated signal, these typically require the addition of complex and expensive circuits.

[0006] There is thus a need to propose a simple solution making it possible to improve the reliability of temperature threshold detections, with low complexity and low cost.

[0007] According to one aspect, there is provided an integrated circuit comprising a temperature-independent voltage generator circuit configured to generate a voltage constant with temperature by the sum of a voltage proportional to the absolute temperature and a voltage complementary to the absolute temperature.

[0008] The integrated circuit also includes a temperature threshold detection circuit comprising a resistive voltage divider bridge configured to generate a reference voltage equal to a fraction of the constant voltage with temperature and a comparator circuit configured to compare the voltage proportional to the absolute temperature with the reference voltage.

[0009] On the one hand, since the reference voltage is obtained from the constant voltage with temperature, the reference voltage supports, at least in part, any undesirable variations of the constant voltage with temperature. On the other hand, the voltage proportional to the absolute temperature also supports, at least in part, any undesirable variations of the constant voltage with temperature. Consequently, any undesirable variations contained in the reference voltage and in the voltage proportional to the absolute temperature compensate each other "intrinsically", by construction, during the comparison. Thus, precise and reliable detection is obtained with a temperature-independent voltage generator circuit which can be of conventional, simple and economical design.

[0010] According to one embodiment, the temperature-independent voltage generator circuit is configured to generate a voltage constant with temperature on a base node and wherein the voltage divider resistive bridge comprises a first resistive element coupled between the base node and a reference node and a second resistive element coupled between the reference node and a ground terminal.

[0011] According to one embodiment, the voltage divider resistive bridge is capable of modifying the ratio of the resistive values ​​of the resistive elements while maintaining a total resistive value of the resistive elements in series, in a manner controlled by a control signal.

[0012] The ratio of the resistive values ​​of the resistive elements makes it possible to obtain the desired reference voltage, i.e. the voltage corresponding to a temperature threshold adapted to a given application of the integrated circuit.

[0013] According to one embodiment, the temperature-independent voltage generator circuit comprises a first bipolar transistor having a base coupled to the base node, an emitter coupled to an intermediate node of a resistive constant voltage adjustment circuit, and a collector coupled to a first branch.

[0014] The temperature-independent voltage generator circuit further comprises a second bipolar transistor having a base coupled to the base node, an emitter coupled to the intermediate node of the constant voltage adjustment resistive circuit, and a collector coupled to a second branch.

[0015] The temperature-independent voltage generator circuit also includes a current generator circuit configured to generate a first current in the first branch and a second current in the second branch, the first bipolar transistor, the second bipolar transistor, and the constant voltage adjustment resistive circuit being jointly configured to generate the voltage proportional to the absolute temperature between the intermediate node and the ground terminal, and to generate the complementary voltage to the absolute temperature between the base node and the intermediate node.

[0016] Such a temperature-independent voltage generator circuit, usually referred to by the English term “band-gap structure”, makes it possible to produce all the voltages useful for detecting the temperature threshold, in particular the voltage proportional to the absolute temperature and the voltage constant with the temperature from which the reference voltage is obtained.

[0017] According to one embodiment, the current generator circuit comprises an amplifier having a first input coupled to the first branch and a second input coupled to the second branch, the amplifier being configured to generate a control signal on the base node adapted to control a control of the intensity of the currents flowing in the first branch and in the second branch, by the first bipolar transistor and the second bipolar transistor.

[0018] By "control of the intensity of the currents", it is meant that from the control signal generated on the bases of two bipolar transistors having different surface areas, the conductivity in the two respective branches is simultaneously adjusted as a function of the difference in intensity of the currents in these branches. Indeed, for example, for the same base-emitter voltage of the bipolar transistors, the bipolar transistor having the largest surface area is capable of increasing the intensity of the current flowing in its branch more amply than the other bipolar transistor, until an identical current is obtained in the two branches.

[0019] According to one embodiment, the current generator circuit comprises a current mirror assembly configured to generate said first current in the first branch and said second current in the second branch.

[0020] A current mirror assembly, conventional and known per se, makes it possible to duplicate the current flowing in the first branch to generate a current of the same intensity in the second branch.

[0021] According to one embodiment, the current generation circuit comprises a first MOS transistor having conduction terminals coupled on the first branch between the current mirror and the collector of the first bipolar transistor and a control terminal coupled to a node of the second branch, and a second MOS transistor having conduction terminals coupled on the second branch between the node of the second branch and the collector of the second bipolar transistor and a control terminal coupled to the node of the second branch.

[0022] The current generation circuit also includes a third MOS transistor having conduction terminals respectively coupled to a supply voltage terminal and the base node and a control terminal coupled to the node of the second branch.

[0023] On the one hand, the first MOS transistor makes it possible to reduce the influence of variations in the supply voltage on the constant voltage with temperature, and therefore on the reference voltage.

[0024] On the other hand, the second MOS transistor makes it possible to reduce the influence of the Early effect linked to the operation of the bipolar transistors on the current of the second branch. The current of the second branch therefore becomes independent of the collector-emitter voltage of the second bipolar transistor. Similarly, this also allows the duplicated current in the first branch to become independent of the collector-emitter voltage of the first bipolar transistor.

[0025] Finally, the third MOS transistor makes it possible to supply sufficient current to the base node to power the resistive voltage divider bridge. In addition, the third MOS transistor makes it possible to produce a current control in the branches by control on the bases of the bipolar transistors, in a manner comparable to the control signal defined previously.

[0026] According to another aspect, there is provided a system comprising the integrated circuit as defined above, in which the comparator circuit is configured to generate a detection signal when the voltage proportional to the absolute temperature is lower than the reference voltage, or when the voltage proportional to the absolute temperature is higher than the reference voltage and a control circuit connected to the temperature threshold detection circuit and to an element having temperature varying characteristics, the control circuit being configured to deactivate the element when the detection signal is generated.

[0027] There are systems integrating elements which may have characteristics which vary with temperature and which may represent a risk when they are exposed to temperatures which are too high or too low. Thus, by using a temperature threshold detection circuit as defined above within these systems, these devices can be deactivated autonomously and automatically in order to effectively protect the user against these risks.

[0028] According to another aspect, there is provided a method for detecting a temperature threshold from a voltage constant with the temperature generated by the sum of a voltage proportional to the absolute temperature and a voltage complementary to the absolute temperature, comprising a generation of a reference voltage equal to a fraction of the voltage constant with the temperature, and a comparison of the voltage proportional to the absolute temperature with the reference voltage.

[0029] According to one embodiment, the generation of the constant voltage with the temperature is done on a base node and in which the generation of the reference voltage equal to a fraction of the constant voltage with the temperature is done with a resistive voltage divider bridge comprising a first resistive element coupled between the base node and a reference node and a second resistive element coupled between the reference node and a ground terminal.

[0030] According to one embodiment, the method comprises a modification by the voltage divider bridge of the ratio of the resistive values ​​of the resistive elements while maintaining a total resistive value of the resistive elements in series, controlled by a control signal.

[0031] According to one embodiment, the generation of the constant voltage with the temperature comprises a generation of a first current in a first branch coupled to the collector of a first bipolar transistor, and of a second current in a second branch coupled to the collector of a second bipolar transistor, and a generation of the voltage proportional to the absolute temperature at the terminals of a first resistive element coupled between an emitter of the first bipolar transistor and a ground terminal.

[0032] The generation of the constant voltage with the temperature also comprises a generation of the complementary voltage at the absolute temperature between a base of the second bipolar transistor and an intermediate node coupled to the emitter of the second bipolar transistor via a second resistive element.

[0033] According to one embodiment, the generation of said first current in the first branch and of said second current in the second branch comprises a control of the first bipolar transistor and of the second bipolar transistor, so as to reduce the difference in intensity between the currents flowing respectively in the first branch and in the second branch, as a function of the difference between the intensity of the first current flowing in the first branch and the intensity of the second current flowing in the second branch.

[0034] According to one embodiment, the generation of said first current in the first branch and of said second current in the second branch is done by a current mirror assembly.

[0035] According to another aspect, there is provided a method comprising the method of detecting a temperature threshold as defined above, comprising a generation of a detection signal by the comparator circuit when the voltage proportional to the absolute temperature is lower than the reference voltage, or when the voltage proportional to the absolute temperature is higher than the reference voltage, and deactivation of an element having temperature-varying characteristics by a control circuit connected to the threshold detection circuit when the detection signal is generated.

[0036] Other advantages and characteristics of the invention will appear on examining the detailed description of the embodiment and implementation, which is in no way limiting, and the appended drawings in which:

[0037] [Fig.l] ;

[0038] [Fig.2] ;

[0039] [Fig.3] schematically illustrate modes of implementation and embodiment of the invention.

[0040] [Fig.l] schematically illustrates an integrated circuit IC, comprising a temperature-independent voltage generator BG according to one embodiment.

[0041] The temperature-independent voltage generator circuit BG comprises a first bipolar transistor Q1 and a second bipolar transistor Q2. Such bipolar transistors used in a temperature-independent voltage generator circuit BG are known per se and have different emitter areas and base-emitter junction current densities. For example, the surface area of ​​the first bipolar transistor Q1, corresponding to the size of the first bipolar transistor Q1, may be eight times greater than the surface area of ​​the second bipolar transistor Q2. To obtain such a size ratio, the first bipolar transistor Q1 may comprise a parallel arrangement of N bipolar transistors, for example N=8, in which each of the bipolar transistors has a surface area identical to that of the second bipolar transistor Q2.Such a parallel arrangement can be achieved by coupling the collectors, emitters and bases of each transistor together respectively. An area N times larger allows the bipolar transistor to amplify the current intensity on its collector by a factor of N for the same voltage applied between its base and emitter.

[0042] The base of the first bipolar transistor Q1 and the base of the second bipolar transistor Q2 are connected together on a common base node NB. In particular, the first bipolar transistor Q1 has a collector connected to a first branch. The second bipolar transistor Q2 has a collector connected to a second branch.

[0043] The first bipolar transistor Q1 comprises an emitter coupled to an intermediate node NINT of a resistive constant voltage adjustment circuit, via a first resistor RCTAT. The second bipolar transistor Q2 comprises an emitter coupled to the intermediate node NINT of the resistive constant voltage adjustment circuit. The resistive constant voltage adjustment circuit comprises the first resistor RCTAT connected between the emitter of the first bipolar transistor Q1 and the intermediate node NINT and a second resistor RPTAT connected between the intermediate node NINT and a ground terminal GND.

[0044] The first bipolar transistor Q1, the second bipolar transistor Q2 and the constant voltage adjustment resistive circuit are jointly configured to generate a voltage proportional to the absolute temperature VPTAT between the intermediate node NINT and the ground terminal GND, and to generate a voltage complementary to the absolute temperature VCTAT between the base node NB and the intermediate node NINT. In particular, the voltage complementary to the absolute temperature VCTAT has a coefficient inversely proportional to the temperature, and the voltage proportional to the absolute temperature VPTAT has a coefficient proportional to the temperature, which are derived from the difference in current density of the base-emitter junction between the first bipolar transistor Q1 and the second bipolar transistor Q2 when the transistors Q1 and Q2 are crossed by a current of the same intensity.

[0045] Thus, we find on the base node NB a constant voltage with the temperature VBG equal to the sum of the voltage proportional to the absolute temperature VPTAT and the complementary voltage to the absolute temperature VCTAT.

[0046] Advantageously, the values ​​of the resistors RCTAT and RPTAT are adjusted in order to adjust the voltages VPTAT and VCTAT to obtain the constant voltage with the temperature VBG.

[0047] The temperature-independent voltage generator circuit BG further comprises a current generator circuit POL. The current generator circuit POL comprises a supply voltage terminal VDD and an operational amplifier OP.

[0048] The OP amplifier has a first input INL connected to the first branch, a second input INR connected to the second branch and an output connected to the base node NB. The first input INL and the second input INR correspond respectively to the inverting input and the non-inverting input of the OP amplifier.

[0049] Furthermore, the current generator circuit POL comprises a resistor RL on the first branch and a resistor RR on the second branch.

[0050] The resistor RL is connected between the supply voltage terminal VDD and the first input INL of the OP amplifier on the first branch. The resistor RR is connected between the supply voltage terminal VDD and the second input INR of the OP amplifier on the second branch.

[0051] The resistors RL and RR have equal resistive values ​​and make it possible to generate, on the inputs of the operational amplifier OP, voltage signals directly proportional to the currents flowing respectively in the first branch IL and in the second branch IR.

[0052] The OP amplifier is configured to generate a control signal VCOM on the base node NB, for example a control voltage, as a function of the potential difference between the first input INL and the second input INR. This potential difference is positive when the potential of the first input INL is greater than the potential of the second input INR, and negative otherwise.

[0053] In particular, the control signal VCOM makes it possible to control the base current of the first bipolar transistor Q1 and the second bipolar transistor Q2 until the first current IL and the second current IR are identical.

[0054] On the one hand, the control signal VCOM makes it possible to control an increase in the base current of the first bipolar transistor Q1 and of the second bipolar transistor Q2 when the potential difference between the inputs of the OP amplifier is negative.

[0055] On the other hand, the VCOM control signal makes it possible to control a reduction in the base current when the potential difference between the inputs of the OP amplifier is positive.

[0056] Consequently, the control signal VCOM is therefore adapted to control a control of the intensity of the first current IL flowing in the first branch and of the second current IR flowing in the second branch. The intensities of the currents IL and IR can thus be regulated throughout the operating period of the temperature-independent voltage generator circuit BG.

[0057] Alternatively, the POL current generator circuit can be produced with an assembly of MOS type transistors (acronym for the classic and well-known terms “Metal Oxide Semiconductor”) as described below in relation to [Fig.2].

[0058] The integrated circuit IC also comprises a temperature threshold detection circuit DET. The threshold detection circuit DET comprises a resistive voltage divider bridge. The resistive voltage divider bridge comprises a first resistor RS1 and a second resistor RS2. The first resistor RS1 is connected between the base node NB and a reference node NREF and the second resistor RS2 is connected between the reference node NREF and the ground terminal GND.

[0059] Thus, the resistive voltage divider bridge generates a reference voltage VREF between the reference node NREF and the ground terminal GND. The reference voltage VREF is equal to a fraction of the constant voltage with the temperature VBG and is in particular: VREF = x VBG = kx VBG

[0060] Furthermore, the resistive voltage divider bridge can receive a control signal CTRL from an external control circuit for example. Depending on the control signal CTRL received, the resistive voltage divider bridge can increase or decrease the ratio “k” of the resistive values ​​of the first resistor RS1 and the second resistor RS2 while maintaining a total resistive value of resistors RS 1 and RS2 in series.

[0061] A user can then define the resistive ratio of the voltage divider resistive bridge using the control signal CTRL and consequently modify the value of the reference voltage VREF. The reference voltage VREF can be modified so that it can correspond to a desired temperature threshold for a given application, for example at a temperature of -15°C.

[0062] The temperature threshold detection circuit DET further comprises a comparator circuit COMP which may be an operational amplifier mounted as a comparator for example.

[0063] The comparator circuit COMP comprises an inverting input connected to the reference node NREF and a non-inverting input connected to the intermediate node NINT. This makes it possible to detect a drop in temperature below the temperature threshold determined by the reference voltage VREF.

[0064] By interchanging the connections of the inputs of the comparator circuit COMP, i.e. by connecting the inverting input to the intermediate node NINT and the non-inverting input to the reference node NREF, the comparator circuit COMP is configured to detect a rise in temperature above the temperature threshold determined by the reference voltage VREF.

[0065] At the end of the comparison, the comparator circuit COMP generates at output a detection signal VOUT when the voltage proportional to the absolute temperature VPTAT is greater than the reference voltage VREF or when the voltage proportional to the absolute temperature VPTAT is less than the reference voltage VREF.

[0066] Thus, the comparator circuit COMP makes it possible to detect when the measured temperature reaches a high temperature threshold or a low temperature threshold.

[0067] On the one hand, if a parasitic variation of the constant voltage with the temperature VBG occurs, then a parasitic variation is also found in the complementary voltage at the absolute temperature VPTAT and in the voltage proportional to the absolute temperature VPTAT which define the constant voltage with the temperature VBG. In other words, the voltage proportional to the absolute temperature VPTAT undergoes variations similar to those of the constant voltage with the temperature VBG.

[0068] On the other hand, the reference voltage VREF presents a parasitic variation corresponding to the variation of the voltage VBG proportionally to the resistive ratio “k” of the resistive voltage divider bridge.

[0069] By comparing the voltage proportional to the absolute temperature VPTAT with the reference voltage VREF, the parasitic variations in each of these voltages compensate each other to the first order.

[0070] Compensation for parasitic variations makes it possible to significantly reduce the disparity between the signal proportional to the temperature VPTAT and the reference voltage VREF in order to guarantee reliable detection of the temperature threshold.

[0071] For example, experimental measurements carried out for the detection of a temperature threshold of -15°C were obtained with an inaccuracy of only 2.7°C for a maximum deviation from the mean corresponding to three standard deviations.

[0072] [Fig.2] illustrates a variant of the current generator circuit POL comprising, in this variant, an active current mirror assembly MIR.

[0073] The MIR current mirror circuit comprises a MOS transistor ML on the first branch and a MOS transistor MR on the second branch. The MOS transistor ML of the first branch has a source connected to the supply voltage terminal VDD, a gate and a drain connected to a node NL of the first branch. The MOS transistor MR of the second branch has a source connected to the supply voltage terminal VDD, a gate coupled to the gate of the MOS transistor ML of the first branch and a drain connected to a node NR of the second branch.

[0074] Such a current mirror assembly MIR conventionally makes it possible to generate the first current IL on the first branch and the second current IR of the same intensity as the first current IL on the second branch.

[0075] The current generator circuit POL further comprises a first MOS transistor M1, a second MOS transistor M2 and a third MOS transistor M3.

[0076] The first MOS transistor Ml has a source connected to the drain of the MOS transistor ML of the first branch, a gate connected to the node NR of the second branch and a drain connected to the collector of the first bipolar transistor Ql.

[0077] The first MOS transistor M1 makes it possible to reduce the influence of variations in the supply voltage VDD on the constant voltage with the temperature VBG, and therefore on the reference voltage VREF.

[0078] The second MOS transistor M2 has a source and a gate connected to the NR node of the second branch and a drain connected to the collector of the second bipolar transistor Q2.

[0079] The second MOS transistor M2 makes it possible to reduce the influence of the Early effect linked to the operation of the bipolar transistors Q1 and Q2 on the second current IR of the second branch. The current IR of the second branch therefore becomes independent of the collector-emitter voltage of the second bipolar transistor Q2. Similarly, this also allows the first current IL duplicated in the first branch to become independent of the collector-emitter voltage of the first bipolar transistor QL

[0080] The third MOS transistor M3 has a source connected to the supply voltage terminal VDD, a gate connected to the node NR of the second branch and a drain connected to the base node NB.

[0081] Finally, the third MOS transistor M3 makes it possible to supply sufficient current to the base node NB to power the voltage divider resistive bridge. In addition, the third MOS transistor M3 makes it possible to produce a current control in the branches by control on the bases of the bipolar transistors Q1 and Q2, in a manner comparable to the VCOM control signal defined previously.

[0082] [Fig.3] illustrates a system SYS comprising the integrated circuit IC as previously described in relation to [Fig.1] or in relation to [Fig.2].

[0083] The system SYS comprises a control circuit DRIVER and an element ELEM having characteristics varying with temperature. The control circuit DRIVER is connected to the temperature threshold detection circuit DET and to the element ELEM. The element ELEM may be an electronic device such as a vertical cavity laser diode capable of emitting relatively powerful radiation when the temperature is below a threshold, for example when the temperature is below -15°C. The control circuit DRIVER may typically be a circuit for controlling the laser diode.

[0084] The DRIVER control circuit is configured to deactivate the element ELEM when the detection signal VOUT is generated. Deactivating the element ELEM, such as the laser diode, at the temperature threshold can, for example, prevent the diode from emitting radiation that could present a danger to a user, and / or meet a standard.

Claims

Claims

1. Integrated circuit comprising a temperature-independent voltage generator circuit (BG) configured to generate a constant voltage with temperature (VBG) by summing a voltage proportional to the absolute temperature (VPTAT) and a complementary voltage to the absolute temperature (VCTAT), characterized in that the integrated circuit further comprises a temperature threshold detection circuit (DET) configured to generate a reference voltage (VREF) equal to a fraction of the constant voltage with temperature (VBG) and a comparator circuit (COMP) configured to compare the voltage proportional to the absolute temperature (VPTAT) with the reference voltage (VREF).

2. An integrated circuit according to claim 1, wherein the temperature-independent voltage generator circuit (BG) is configured to generate a temperature-constant voltage (VBG) on a base node (NB) and wherein the threshold detection circuit comprises a voltage divider resistive bridge having a first resistive element (RS1) coupled between the base node (NB) and a reference node (NREF) and a second resistive element (RS2) coupled between the reference node (NREF) and a ground terminal (GND).

3. Integrated circuit according to claim 2, in which the voltage divider resistive bridge (RS1, RS2) is capable of modifying the ratio of the resistive values ​​of the resistive elements (RS1, RS2) while maintaining a total resistive value of the resistive elements in series, in a manner controlled by a control signal (CTRL).

4. Integrated circuit according to one of claims 2 or 3, wherein the temperature-independent voltage generator circuit (BG) comprises: - a first bipolar transistor (Q1) having a base coupled to the base node (NB), an emitter coupled to an intermediate node (NINT) of a resistive constant voltage adjustment circuit (RCTAT, RPTAT), and a collector coupled to a first branch, - a second bipolar transistor (Q2) having a base coupled to the base node (NB), an emitter coupled to the intermediate node (NINT) of the resistive constant voltage adjustment circuit (RCTAT, RPTAT), and a collector coupled to a second branch, - a current generator circuit (POL) configured to generate a first current (IL) in the first branch and a second current (IR) in the second branch, - the first bipolar transistor (Ql), the second bipolar transistor (Q2), and the constant voltage adjustment resistive circuit (RCTAT, RPTAT) being jointly configured to generate the voltage proportional to the absolute temperature (VPTAT) between the intermediate node (NINT) and the ground voltage terminal (GND), and to generate the complementary voltage to the absolute temperature (VCTAT) between the base node (NB) and the intermediate node (NINT).

5. Integrated circuit according to claim 4, in which the current generator circuit (POL) comprises an amplifier (OP) having a first input (INR) coupled to the first branch and a second input (INL) coupled to the second branch, the amplifier (OP) being configured to generate a control signal (VCOM) on the base node (NB) adapted to control a control of the intensity of the currents (IR, IL) flowing in the first branch and in the second branch, by the first bipolar transistor (Ql) and the second bipolar transistor (Q2).

6. Circuit according to claim 4, wherein the current generator circuit (POL) comprises a current mirror assembly (MIR) configured to generate said first current (IL) in the first branch and said second current (IR) in the second branch.

7. Integrated circuit according to claim 6, wherein the current generation circuit (POL) comprises: - a first MOS transistor (Ml) having conduction terminals coupled on the first branch between the current mirror (MIR) and the collector of the first bipolar transistor (Ql) and a control terminal coupled to a node (NR) of the second branch, and - a second MOS transistor (M2) having conduction terminals coupled on the second branch between the node (NR) of the second branch and the collector of the second bipolar transistor (Q2) and a control terminal coupled to the node (NR) of the second branch, - a third MOS transistor (M3) having conduction terminals respectively coupled to a supply voltage terminal (VDD) and to the base node (NB) and a control terminal coupled to the node (NR) of the second branch.

8. Temperature measurement system, comprising: - the integrated circuit according to one of claims 1 to 7, wherein the comparator circuit (COMP) is configured to generate a detection signal (VOUT) when the voltage proportional to the absolute temperature (VPTAT) is lower than the reference voltage (VREF), or when the voltage proportional to the absolute temperature (VPTAT) is higher than the reference voltage (VREF) - a control circuit (DRIVER) connected to the temperature threshold detection circuit (DET) and to an element (ELEM) having temperature-varying characteristics, the control circuit (DRIVER) being configured to deactivate the element (ELEM) when the detection signal is generated.

9. Method for detecting a temperature threshold from a voltage constant with the temperature (VBG) generated by the sum of a voltage proportional to the absolute temperature (VPTAT) and a voltage complementary to the absolute temperature (VCTAT), characterized in that the method comprises a generation of a reference voltage (VREF) equal to a fraction of the voltage constant with the temperature (VBG), and a comparison of the voltage proportional to the absolute temperature (VPTAT) with the reference voltage (VREF).

10. Method according to claim 9, wherein the generation of the constant voltage with the temperature (VBG) is made on a base node (NB) and wherein the generation of the reference voltage (VREF) equal to a fraction of the constant voltage with the temperature (VBG) is made with a resistive voltage divider bridge comprising a first resistive element (RS1) coupled between the base node (NB) and a reference node (NREF) and a second resistive element (RS2) coupled between the reference node (NREF) and a ground terminal (GND).

11. Method according to claim 10, comprising a modification by the voltage divider bridge (RS1, RS2) of the ratio of the resistive values ​​of the resistive elements (RS1, RS2) while maintaining a total resistive value of the resistive elements in series, controlled by a control signal (CTRL).

12. Method according to one of claims 10 or 11, wherein the generation of the constant voltage with the temperature (VBG) comprises: - a generation of a first current (IL) in a first branch coupled to the collector of a first bipolar transistor (Ql), and of a second current (IR) in a second branch coupled to the collector of a second bipolar transistor (Q2), - a generation of the voltage proportional to the absolute temperature (VPTAT) at the terminals of a first resistive element (RPTAT) coupled between an emitter of the second bipolar transistor (Q2) a ground terminal (GND), - a generation of the complementary voltage at the absolute temperature (VCTAT) between a base of the first bipolar transistor (Ql) and an intermediate node (NINT) coupled to the emitter of the first bipolar transistor (Ql) via a second resistive element (RCTAT).

13. The method of claim 12, wherein generating said first current (IL) in the first branch and said second current (IR) in the second branch comprises controlling the first bipolar transistor (Q1) and the second bipolar transistor (Q2) so as to reduce the difference in intensity between the currents (IR, IL) flowing in the first branch and in the second branch respectively, depending on the difference between the intensity of the first current (IL) flowing in the first branch and the intensity of the second current (IR) flowing in the second branch.

14. Method according to claim 12, wherein the generation of said first current (IL) in the first branch and of said second current (IR) in the second branch is done by a current mirror assembly (MIR).

15. A method of measuring temperature comprising: - the method of detecting a temperature threshold according to claim 9 to 14 further comprising generating a detection signal (VOUT) when the voltage proportional to the absolute temperature (VPTAT) is lower than the reference voltage (VREF), or when the voltage proportional to the absolute temperature (VPTAT) is higher than the reference voltage (VREF), - deactivation of an element (ELEM) having temperature-varying characteristics by a control circuit (DRIVER) when the detection signal is generated.

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