Microcontroller including reference voltage generator circuit

Abstract

The utility model relates to a microcontroller comprising a reference voltage generator circuit. The reference voltage generator circuit has a first transistor coupled as a diode, a second transistor coupled as a diode, a first variable resistor, an operational amplifier having a first input connected to the first transistor via the first variable resistor and a second input connected to the second transistor, and a second variable resistor having a first terminal connected to the second transistor and to the second input terminal of the operational amplifier. A current mirror is controlled by an output of the operational amplifier and is configured to replicate a current proportional to an absolute temperature of the second variable resistor. A current replicator branch is connected to the second transistor via a switch, the current replicator branch configured to replicate a current proportional to an absolute temperature of the second variable resistor and inject the current through the second transistor. The control unit is used for controlling the switching of the current replicator branch and adapting the resistance values of the first and second variable resistors.

Description

Technical Field

[0001] Embodiments relate to microcontrollers, and more particularly to microcontrollers including temperature independent reference voltage generator circuits. Background Art

[0002] Generally speaking, a microcontroller is configured to process a dedicated application. A microcontroller comprises several electronic modules that are configured to implement functions in the context of the application processed by this microcontroller.

[0003] The microcontroller may include a reference voltage generator circuit. In general, this circuit is referred to by the expression "bandgap voltage reference". Such a circuit is configured to generate a reference voltage that is independent of absolute temperature. This reference voltage can then be used by different electronic modules of the microcontroller. Moreover, this circuit may also generate polarization currents, currents that depend on absolute temperature and reference currents.

[0004] A microcontroller may have several operating modes in order to adapt its power consumption according to its needs.

[0005] For example, a microcontroller includes an operating mode called a normal operating mode and another operating mode called a low power operating mode.

[0006] The normal operation mode corresponds to a mode in which the modules of the microcontroller are powered by electricity to realize their functions for processing the application dedicated to the microcontroller. For example, in the normal operation mode, the electronic modules powered may consist of a digital processing module, a flash memory, or an analog peripheral module (such as an analog-to-digital converter, a digital-to-analog converter, and a power management unit).

[0007] The low power mode corresponds to a mode in which most modules of the microcontroller are not powered by electricity. This low power mode is used when the application dedicated to the microcontroller does not require the implementation of the functions of the modules of the microcontroller within a given period of time. For example, in the low power mode, only the reference voltage generator circuit and the power supply monitoring circuit are powered. Then, this power supply monitoring circuit uses the reference voltage to compare it with the power supply voltage. The low power mode is intended to minimize the power consumption of the microcontroller when the functions of the microcontroller are not implemented.

[0008] In normal operating mode, at least some of the electronic modules powered generally require receiving a more accurate reference voltage than required by the few modules powered in low power mode. Low power mode generally requires minimizing power consumption of the reference voltage generator circuit.

[0009] Therefore, the operating modes of the microcontroller may have opposing requirements with respect to the accuracy of the reference voltage and the power consumption of the reference voltage generator circuit.

[0010] To address these opposing needs, the microcontroller may include two reference voltage generator circuits. The first reference voltage generator circuit may then be optimized to supply an accurate reference voltage for the normal operating mode, and the second reference voltage generator circuit may be optimized to consume relatively less power for the low power mode. The disadvantage of this solution is the use of two reference voltage generator circuits, which can clutter the microcontroller and be expensive to manufacture.

[0011] Alternatively, a unique reference voltage generator circuit can be provided that can intermittently operate according to different duty cycles depending on the operating mode of the microcontroller. The disadvantage of such a reference voltage generator circuit is that the structure is complex and uses many electronic components to adapt its operating duty cycle. Utility Model Content

[0012] Embodiments relate to a microcontroller, for example, a microcontroller including a temperature-independent reference voltage generator circuit.

[0013] Embodiments may provide a reference voltage generator circuit having a simple structure, which is suitable for generating an accurate reference voltage when a microcontroller is in its normal operation mode and reducing its power consumption when the microcontroller is in its low power consumption mode.

[0014] According to one aspect of the present disclosure, there is provided a microcontroller including a reference voltage generator circuit, wherein the reference voltage generator circuit includes: a first transistor coupled as a diode; a second transistor coupled as a diode; a first variable resistor, the first transistor and the second transistor being configured to generate a current proportional to the absolute temperature of the first variable resistor; an operational amplifier having a first input connected to the first transistor via the first variable resistor, and a second input connected to the second transistor; a second variable resistor having a first terminal connected to the second transistor and to the second input of the operational amplifier, and a second terminal connected to a reference voltage node; a current mirror controlled by the output of the operational amplifier and configured to replicate a current proportional to the absolute temperature of the second variable resistor; a current replicator branch connected to the second transistor via a switch, the current replicator branch being configured to replicate a current proportional to the absolute temperature of the second variable resistor and inject the current through the second transistor; and a control unit configured to control the switch of the current replicator branch and adapt the resistance values ​​of the first variable resistor and the second variable resistor so as to keep the reference voltage carried on the reference voltage node independent of temperature.

[0015] In some embodiments, the microcontroller further comprises a plurality of electronic modules, wherein the microcontroller has a plurality of operating modes to selectively power the electronic modules, and the control unit is configured to control the switch of the current replicator branch according to an active operating mode in the operating mode of the microcontroller to inject more or less current through the second transistor according to the active operating mode in the operating mode.

[0016] In some embodiments, the control unit is configured to control a switch of the current replicator branch to increase the current injected through the second transistor when an active one of the operating modes of the microcontroller requests an increased accuracy of the reference voltage.

[0017] In some embodiments, the control unit is configured to control a switch of the current replicator branch to reduce a current injected through the second transistor when an active one of the operating modes of the microcontroller requests a reduction in power consumption of the microcontroller.

[0018] In some embodiments, based on a lookup table that associates multiple operating modes of the microcontroller to control of the switch and the resistance values ​​of the first variable resistor and the second variable resistor, the control unit is configured to control the switch and adapt the resistance values ​​of the first variable resistor and the second variable resistor according to the operating mode of the microcontroller.

[0019] In some embodiments, the first transistor is a bipolar transistor having an emitter connected to the first variable resistor, a base and a collector both connected to the first cold point; wherein the second transistor is a bipolar transistor having an emitter connected to the second input of the operational amplifier and the first terminal of the second variable resistor, and also having a base and a collector both connected to the second cold point; and wherein the first transistor and the second transistor have different sizes.

[0020] In some embodiments, a size of the first transistor is N times a size of the second transistor, where N is an integer greater than or equal to 2.

[0021] In some embodiments, the first cold point and the second cold point are connected to a ground node.

[0022] In some embodiments, the current mirror includes a first p-channel insulated gate field effect transistor and a second p-channel insulated gate field effect transistor; wherein the first p-channel insulated gate field effect transistor includes a gate connected to the output terminal of the operational amplifier, a source configured to receive a power supply voltage, and a drain connected to the first input terminal of the operational amplifier and connected to the first variable resistor; wherein the second p-channel insulated gate field effect transistor includes a gate connected to the output terminal of the operational amplifier, a source configured to receive a voltage, and a drain connected to the second variable resistor; and wherein the first p-channel insulated gate field effect transistor is substantially identical to the second p-channel insulated gate field effect transistor.

[0023] In some embodiments, the current replicator branch includes a third p-channel insulated gate field effect transistor, the third p-channel insulated gate field effect transistor including a gate connected to the output of the operational amplifier, a source configured to receive a voltage, and a drain connected to the first terminal of the second variable resistor via a switch, the third p-channel insulated gate field effect transistor being substantially identical to the first p-channel insulated gate field effect transistor and the second p-channel insulated gate field effect transistor.

[0024] In some embodiments, the first input terminal of the operational amplifier is an inverting input terminal, and the second input terminal of the operational amplifier is a non-inverting input terminal.

[0025] In some embodiments, the microcontroller further comprises a capacitive element having a first terminal connected to the output of the operational amplifier and a second terminal connected to the supply voltage node.

[0026] In some embodiments, the microcontroller also includes a temperature sensor, which includes: a p-channel insulated gate field effect transistor, which includes a gate connected to the output of the operational amplifier, a source connected to a power supply voltage node, and a drain; and a resistor having a first terminal connected to the drain of the p-channel insulated gate field effect transistor and a second terminal connected to the cold point.

[0027] According to one aspect of the present disclosure, there is provided a microcontroller including a reference voltage generator circuit, wherein the reference voltage generator circuit includes: a first transistor coupled as a diode, the first transistor having a first terminal and a second terminal, the second terminal being connected to a ground node; a second transistor coupled as a diode, the second transistor having a first terminal and a second terminal, the second terminal being connected to the ground node; a first variable resistor having a first terminal connected to the first terminal of the first transistor; an operational amplifier having a first input terminal connected to the second terminal of the first variable resistor and a second input terminal connected to the first terminal of the second transistor; a second variable resistor having a first terminal connected to the first terminal of the second transistor and the second input terminal of the operational amplifier, the second variable resistor also having a second terminal connected to a reference voltage node; a third transistor having a control terminal connected to the output terminal of the operational amplifier and a current path connected between the second terminal of the first variable resistor and a power supply voltage node; a fourth transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the second terminal of the first variable resistor and the power supply voltage node; a fifth transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the first node and the power supply voltage node; a first switch connected between the first node and the second input of the operational amplifier; a sixth transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the second node and the power supply voltage node; a second switch connected between the second node and the second input of the operational amplifier; a seventh transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the third node and the power supply voltage node; a third switch connected between the third node and the second input of the operational amplifier; and a control unit having a first output coupled to the first switch, a second output coupled to the second switch, and a third output coupled to the third switch.

[0028] In some embodiments, the first transistor is a bipolar transistor having a first size; the second transistor is a bipolar transistor having a second size; and wherein the first size is N times the second size, N being an integer greater than or equal to 2.

[0029] In some embodiments, the third transistor is a p-channel insulated gate field effect transistor; the fourth transistor is a p-channel insulated gate field effect transistor; and wherein the third transistor is substantially identical to the fourth transistor.

[0030] In some embodiments, the fifth transistor is a p-channel insulated gate field effect transistor; the sixth transistor is a p-channel insulated gate field effect transistor; the seventh transistor is a p-channel insulated gate field effect transistor; and wherein the third transistor, the fourth transistor, the fifth transistor, the sixth transistor and the seventh transistor are substantially the same.

[0031] In some embodiments, the microcontroller further comprises a capacitive element having a first terminal connected to the output of the operational amplifier and a second terminal connected to the supply voltage node.

[0032] In some embodiments, the microcontroller also includes a temperature sensor, which includes: a p-channel insulated gate field effect transistor, including a gate connected to the output of the operational amplifier, a source connected to a power supply voltage node, and a drain; and a resistor having a first terminal connected to the drain of the p-channel insulated gate field effect transistor and a second terminal connected to a ground node.

[0033] In one aspect, a microcontroller includes a reference voltage generator circuit. The reference voltage generator circuit includes a first transistor coupled as a diode, a second transistor coupled as a diode, and a first variable resistor. The first transistor and the second transistor are configured to generate a current proportional to the absolute temperature of the first variable resistor. The operational amplifier has a first input terminal connected to the first transistor via the first variable resistor and a second input terminal connected to the second transistor. The second variable resistor has a first terminal connected to the second transistor and connected to the second input terminal of the operational amplifier and a second terminal connected to a reference voltage node. The current mirror is controlled by the output of the operational amplifier and is configured to replicate a current proportional to the absolute temperature of the second variable resistor. The current replicator branch is connected to the second transistor via a switch. The current replicator branch is configured to replicate a current proportional to the absolute temperature of the second variable resistor and inject the current through the second transistor. The control unit is configured to control the switch of the current replicator branch and adapt the resistance values ​​of the first variable resistor and the second variable resistor so as to keep the reference voltage carried on the reference voltage node independent of temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other advantages and features of the invention will become clear by studying the detailed description of embodiments which are by no means limiting and the accompanying drawings, in which:

[0035] Figure 1 A microcontroller according to an embodiment is illustrated;

[0036] Figure 2 An embodiment of a reference voltage generator circuit is illustrated; and

[0037] Figure 3 A temperature sensor that can be used with a microcontroller is illustrated. DETAILED DESCRIPTION

[0038] This application claims the benefit of French Patent Application No. 2214369, filed on December 23, 2022, which is incorporated herein by reference.

[0039] According to one aspect, a microcontroller includes a reference voltage generator circuit, which includes a first transistor and a second transistor installed as a diode and a first variable resistor. The first transistor and the second transistor are configured to generate a current proportional to the absolute temperature in the first resistor. The operational amplifier has a first input terminal connected to the first transistor via the first variable resistor, and a second input terminal connected to the second transistor. The second variable resistor has a first terminal connected to the second transistor and connected to the second input terminal of the operational amplifier and a second terminal configured to deliver a reference voltage. The current mirror is controlled by the output of the operational amplifier and is configured to replicate a current proportional to the absolute temperature in the second resistor. At least one additional current replicator branch is connected to the second transistor via at least one switch and is configured to replicate a current proportional to the absolute temperature and inject it through the second transistor. The control unit is configured to control at least one switch of at least one additional branch and adapt the resistance values ​​of the first resistor and the second resistor so as to keep the reference voltage independent of temperature.

[0040] Then, the control unit allows injecting more or less current through the second transistor. Injecting a larger amount of current through the second transistor allows having a more accurate current and allows reducing the influence of the offset voltage of the operational amplifier on the reference voltage generated by the reference voltage generator circuit. Injecting a smaller amount of current through the second transistor allows reducing the power consumption of the reference voltage generator circuit.

[0041] This reference voltage generator circuit is configured to reduce the influence of the offset voltage of the operational amplifier to improve the accuracy of the reference voltage, or to reduce the power consumption of the microcontroller according to the needs thereof.

[0042] The reference voltage generator circuit has a simple structure and low manufacturing cost.

[0043] Furthermore, since the influence of the offset voltage can be limited, an operational amplifier with reduced size and with a higher offset voltage can be used. In this way, the size of the reference voltage generator circuit can be reduced. Such a reference voltage generator circuit then occupies less space in the microcontroller.

[0044] In a preferred embodiment, the microcontroller further comprises several electronic modules, the microcontroller having several operating modes allowing selective powering of the electronic modules, the control unit being configured to control at least one switch of at least one additional current copier branch depending on the active operating mode of the microcontroller so as to inject more or less current through the second transistor depending on this operating mode.

[0045] Thus, such a voltage generator circuit is configured to adapt its operation depending on the operating mode of the microcontroller.Thus, such a microcontroller has the advantage of using the same reference voltage generating circuit to generate reference voltages for different operating modes of the microcontroller.

[0046] Preferably, the control unit is configured to control at least one switch of the at least one additional current replicator branch to increase the current injected through the second transistor when an active operating mode of the microcontroller requests increased accuracy of the reference voltage. Such active operating mode of the microcontroller may be a normal operating mode.

[0047] Advantageously, the control unit is configured to control at least one switch of the at least one additional current replicator branch so as to reduce the current injected through the second transistor when an active operating mode of the microcontroller requests a reduction in power consumption of the microcontroller. Such an active operating mode of the microcontroller may be a low power mode.

[0048] In an advantageous embodiment, the control unit is configured to control the at least one switch according to the operating mode of the microcontroller and to adapt the resistance values ​​of the first resistor and the second resistor based on a lookup table associating different operating modes of the microcontroller to control of the at least one switch and the resistance values ​​of the first resistor and the second resistor.

[0049] Preferably, the first transistor is a bipolar transistor, the emitter of which is connected to the first resistor, and the base and collector are connected to the cold point. In addition, the second transistor is a bipolar transistor, the emitter of which is connected to the second input of the operational amplifier and the first terminal of the second resistor, and the base and collector are connected to the cold point, and the first transistor and the second transistor have different sizes.

[0050] Advantageously, the size of the first transistor is N times the size of the second transistor, N being an integer greater than or equal to 2, for example equal to 8.

[0051] In an advantageous embodiment, the current mirror comprises a first p-channel insulated gate field effect transistor and a second p-channel insulated gate field effect transistor, the first transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a supply voltage, and a drain connected to the first input of the operational amplifier and to the first resistor, the second transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a voltage, and a drain connected to the second resistor, the first transistor and the second transistor being identical.

[0052] Preferably, at least one current replicator branch comprises a p-channel insulated gate field effect transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a voltage and a drain connected to the first terminal of the second resistor via at least one switch, this transistor being identical to the first transistor and the second transistor of the current mirror.

[0053] Advantageously, the first input terminal of the operational amplifier is an inverting input terminal and the second input terminal of the operational amplifier is a non-inverting input terminal.

[0054] In an advantageous embodiment, the microcontroller further comprises a capacitive element having a first terminal connected to the output of the operational amplifier and a second terminal configured to receive a supply voltage.

[0055] Advantageously, the microcontroller further comprises a temperature sensor comprising a p-channel insulated gate field effect transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a supply voltage, a drain, and a resistor having a first terminal connected to the drain of this transistor and a second terminal connected to the cold point.

[0056] Now referring to the accompanying drawings, Figure 1 A microcontroller MCU comprising different electronic modules MD1, MD2, MD3 and a reference voltage generator circuit BDGP is illustrated. In this case, only three electronic modules MD1, MD2, MD3 are represented. However, more electronic modules may be provided.

[0057] For example, the electronic modules MD1 , MD2 , MD3 may include electronic modules such as an analog-to-digital converter, a power management unit, a voltage regulator, and a reset circuit.

[0058] The reference voltage generator circuit BDGP is configured to generate a temperature-independent reference voltage VREF (the reference voltage generator circuit is referred to by the expression "bandgap voltage reference"). This reference voltage can then be used by some electronic modules MD2, MD3 of the microcontroller MCU. In particular, the reference voltage is temperature-independent within a temperature range that may be comprised between -40°C and 140°C. The reference voltage may be 1.2 Volts.

[0059] Furthermore, the microcontroller MCU has several operating modes, allowing the electronic modules MD1 , MD2 , MD3 to be powered in a selective manner.

[0060] For example, the microcontroller MCU includes an operating mode called a normal operating mode and another operating mode called a low power consumption mode. The normal operating mode corresponds to a mode in which at least most of the electronic modules MD1, MD2, MD3 of the microcontroller MCU are powered by electricity. The low power consumption mode corresponds to a mode in which most of the electronic modules MD1, MD2, MD3 of the microcontroller MCU are not powered by electricity.

[0061] In particular, the normal operation mode corresponds to a mode in which the electronic modules of the microcontroller MCU are powered by electricity to realize their functions of processing applications dedicated to the microcontroller MCU. For example, in the normal operation mode, the powered electronic modules may consist of digital processing modules, flash memory or analog peripheral modules (such as analog-to-digital converters, digital-to-analog converters and power management units).

[0062] The low power consumption mode corresponds to a mode in which most of the electronic modules of the microcontroller MCU are not powered by electricity. This low power consumption mode is used when the application dedicated to the microcontroller MCU does not require the implementation of the functions of the modules of the microcontroller MCU within a given period of time. For example, in the low power consumption mode, only the reference voltage generator circuit and the power supply monitoring circuit are powered. Then, this power supply monitoring circuit uses the reference voltage to compare it with the power supply voltage. The low power consumption mode is intended to minimize the power consumption of the microcontroller MCU when the functions of the microcontroller MCU are not implemented.

[0063] In normal operating mode, at least some of the electronic modules powered generally require receiving a more accurate reference voltage than required by the few modules powered in low power mode. Low power mode generally requires minimizing power consumption of the reference voltage generator circuit.

[0064] The reference voltage generator circuit is configured to adapt its operation to the active operating mode of the microcontroller, thereby improving the accuracy of the reference voltage when the microcontroller is in its normal operating mode and reducing its power consumption when the microcontroller is in its low power mode.

[0065] Figure 2 An embodiment of the reference voltage generator circuit BDGP is illustrated.

[0066] The reference voltage generator circuit BDGP includes an operational amplifier AOP, two bipolar transistors Q1, Q2, and a current mirror CMR including two PMOS-type transistors M1 and M2 (i.e., p-channel metal oxide semiconductor field effect transistors ("MOSFET")). The reference voltage generator circuit BDGP also includes two variable resistors R1, R2. The reference voltage generator circuit BDGP also includes a control unit UC, which is configured to control the resistance value of each variable resistor R1, R2 via a control RV, as described below. In this case, the reference voltage generator circuit BDGP includes the control unit, however, alternatively, a control unit located outside this reference voltage generator circuit BDGP may be provided.

[0067] Each of transistors Q1 and Q2 has a base, an emitter and a collector. Each transistor Q1 and Q2 is installed as a diode. In particular, the base of each transistor Q1 and Q2 is connected to its collector and a cold point (e.g., grounded GND). Transistor Q1 and transistor Q2 may have different sizes. The size of bipolar transistors Q1 and Q2 corresponds to the surface of the emitter of the bipolar transistor. In particular, the size ratio between transistor Q1 and transistor Q2 is equal to N. Thus, the size of transistor Q1 is N times the size of transistor Q2. For example, N may be greater than or equal to 2, for example, equal to 8.

[0068] The operational amplifier AOP has an inverting input terminal connected to the emitter of the transistor Q1 via the variable resistor R1. The operational amplifier AOP also has a non-inverting input terminal connected to the emitter of the transistor Q2.

[0069] The transistor M1 has a gate connected to the output terminal of the operational amplifier AOP to receive the signal Pg generated by the operational amplifier AOP, a source configured to receive the voltage VDD, and a drain connected to the inverting input terminal of the operational amplifier AOP and to the variable resistor R1.

[0070] Transistor M2 has a gate connected to the output terminal of the operational amplifier AOP to receive the signal Pg generated by the operational amplifier AOP, a source configured to receive the voltage VDD, and a drain connected to the non-inverting input terminal of the operational amplifier AOP and connected to the emitter of the second bipolar transistor Q2 via the variable resistor R2.

[0071] Each variable resistor R1, R2 comprises several resistive elements that can be activated or deactivated to adjust the resistance value of this variable resistor R1, R2. In particular, each variable resistor R1, R2 can be controlled digitally by a control unit UC. In particular, each variable resistor R1, R2 can comprise a MOSFET type transistor controlled by the control unit UC in order to individually activate or deactivate the resistive elements of this variable resistor R1, R2.

[0072] The reference voltage generator circuit BDGP has an output connected to the node between the drain of the transistor M2 and the variable resistor R2. This output allows the generation of a temperature-independent voltage VREF.

[0073] The operational amplifier AOP has a direct offset voltage Vos (“offset”). This offset voltage Vos influences the reference voltage VREF generated at the output of the reference voltage generator circuit BDGP.

[0074] The reference voltage generator circuit BDGP is configured to adjust the current injected into the bipolar transistor Q2 to limit the influence of the offset voltage Vos of the operational amplifier AOP on the reference voltage VREF.

[0075] In particular, the reference voltage generator circuit BDGP comprises several current replicator branches BRCH1, BRCH2, BRCH3. These current replicator branches BRCH1, BRCH2, BRCH3 are connected in parallel with each other between the power supply and the emitter of the bipolar transistor Q2. Figure 1 In the embodiment shown in , the reference voltage generator circuit BDGP includes three current replicator branches BRCH1, BRCH2, BRCH3. However, a reference voltage generator circuit including more or fewer current replicator branches may be provided. In particular, the reference voltage generator circuit BDGP includes a number of current replicator branches corresponding to the number of operating modes of the microcontroller MCU.

[0076] Each current replicator branch BRCH1, BRCH2, BRCH3 comprises a PMOS type transistor M3, M4, M5. Thus, the first current replicator branch BRCH1 comprises a PMOS type transistor M3, the second current replicator branch BRCH2 comprises a PMOS type transistor M4, and the third current replicator branch BRCH3 comprises a PMOS type transistor M5.

[0077] Each of the transistors M3, M4, and M5 has a gate connected to the output terminal of the operational amplifier AOP to receive the signal Pg generated by the operational amplifier AOP, a source configured to receive the voltage VDD, and a drain connected to the non-inverting input terminal of the operational amplifier AOP and to the emitter of the second bipolar transistor Q2.

[0078] Preferably, transistors M1 , M2 , M3 , M4 and M5 are identical.

[0079] The reference voltage generator circuit BDGP further comprises a capacitive element CC between the power supply and the gates of the transistors M3, M4 and M5. The capacitive element CC allows ensuring the stability of the reference voltage generator circuit BDGP.

[0080] Furthermore, the current replicator branches BRCH1, BRCH2, BRCH3 are connected to the emitter of transistor Q2 via switches INT1, INT2, INT3. These switches are controlled by a control unit UC. The switches INT1, INT2, INT3 are controlled by the control unit UC to adjust the amount of current injected through the bipolar transistor Q2.

[0081] Specifically, the current injected through the bipolar transistor Q2 is expressed according to the following formula:

[0082]

[0083] Where ΔVbe is the voltage difference between the voltage across transistor Q1 and the voltage across transistor Q2, Vos is the offset voltage of the operational amplifier AOP, R1 is the resistance value of resistor R1, and k B is a constant (Boltzmann constant), q is the charge of the electron, T is the temperature, N corresponds to the ratio of the size of the bipolar transistor Q1 to the bipolar transistor Q2, and M is the number of parallel current replicator branches (according to the closed switches INT1, INT2, INT3) used to inject current through the bipolar transistor Q2. Figure 1 In the embodiment shown in , M is between 0 and 3.

[0084] The reference voltage VREF generated by the reference voltage generator circuit BDGP is expressed by the following equation:

[0085]

[0086]

[0087] Where Vd is the diode voltage of the bipolar transistor Q2 and R2 is the resistance value of the resistor R2.

[0088] The increase in the number M of current replicator branches connected to transistor Q2 allows more current to be injected through bipolar transistor Q2, thereby increasing the voltage difference ΔVbe to reduce the influence of the offset voltage Vos of the operational amplifier AOP.

[0089] The voltage difference is proportional to the absolute temperature (referred to by the abbreviation "PTAT" standing for "proportional to absolute temperature"), and the diode voltage is complementary to the absolute temperature (referred to by the abbreviation "CTAT" standing for "complementary to absolute temperature").

[0090] In order to keep the reference voltage independent of the absolute temperature when the number M of current replicator branches for injecting current through the bipolar transistor Q2 varies, the control unit is configured to adapt the ratio according to the number M of current replicator branches by adapting the resistance values ​​of the resistors R1 and R2. The value of .

[0091] In particular, the switches INT1, INT2, INT3 allow different configurations to be defined by varying the number M of current replicator branches BRCH1, BRCH2, BRCH3 for injecting current through the bipolar transistor Q2. Each of these configurations is associated with a pair of resistance values ​​of the resistor R1 and the resistor R2, allowing the reference voltage to be kept independent of the absolute temperature. The control unit UC is configured to adapt the resistance value RV of the resistor according to the configuration selected using the switches INT1, INT2, INT3.

[0092] Depending on the active operating mode of the microcontroller MCU, the configuration defined using switches INT1, INT2, INT3 is selected.

[0093] In particular, the control unit UC is configured to receive the active operation mode OPM of the microcontroller MCU and to generate a first control CMD for controlling the switches INT1 , INT2 , INT3 and a second control RV for adapting the resistance values ​​of the resistors R1 and R2 .

[0094] In particular, the processor of the microcontroller may be configured to generate a signal indicating the active operating mode OPM upon request of a user of the microcontroller and to transmit this signal to the control unit UC.

[0095] In order to improve this accuracy in the normal operation mode, the control unit UC is configured to control the switches INT1, INT2, INT3 to increase the number M of current replicator branches connected to the transistor Q2 to inject more current through the transistor Q2 to reduce the influence of the offset voltage Vos of the operational amplifier AOP on the reference voltage VREF. For example, the control unit UC can be configured to close the switches INT1, INT2, INT3 so as to use all the current replicator branches BRCH1, BRCH2, BRCH3 to inject current through the transistor Q2. Then, the control unit UC adapts the resistance values ​​of the resistors R1 and R2 according to the number M of current replicator branches used to inject more current through the transistor Q2 to keep the reference voltage VREF independent of temperature.

[0096] In order to reduce the power consumption of the reference voltage generator circuit in the low power consumption mode, the control unit UC is configured to control the switches INT1, INT2, INT3 to reduce the current injected into the transistor Q2 by disconnecting at least a portion of the current replicator branches BRCH1, BRCH2, BRCH3. For example, the control unit UC can be configured to open all switches INT1, INT2, INT3 so as to disconnect all current replicator branches BRCH1, BRCH2, BRCH3 to reduce the current injected into the bipolar transistor Q2. The control unit US then adapts the resistance values ​​RV of the resistors R1 and R2 to keep the reference voltage VREF independent of temperature.

[0097] For example, the resistance values ​​of the resistors R1 and R2 suitable for different configurations that can be defined using the switches INT1, INT2 and INT3 are determined by simulation. In particular, the larger the number M of current replicator branches for injecting current in the bipolar transistor Q2, the more suitable it is to reduce the ratio The value of .

[0098] Therefore, the reference voltage generator circuit BDGP is configured to reduce the influence of the offset voltage Vos of the operational amplifier AOP to improve the accuracy of the reference voltage. Therefore, an operational amplifier AOP with a reduced size and a higher offset voltage Vos can be used. In this way, the size of the reference voltage generator circuit can be reduced. Thus, this reference voltage generator circuit occupies less space in the microcontroller.

[0099] Such a reference voltage generator circuit BDGP also allows adapting its power consumption according to the operating mode of the microcontroller.

[0100] Furthermore, this reference voltage generator circuit BDGP has an advantage of being simple in structure.

[0101] The microcontroller MCU may also include a temperature sensor TEMPS, such as Figure 3As shown in . The temperature sensor includes a p-channel insulated gate field effect transistor M6, which includes a gate connected to the output of an operational amplifier AOP of a reference voltage generator circuit BDGP to receive a signal Pg generated by the operational amplifier, a source configured to receive a voltage VDD, and a drain. The temperature sensor also includes a resistor Rs having a first terminal connected to the drain of this transistor M6 and a second terminal connected to ground GND. Then, a current proportional to the absolute temperature (PTAT) or independent of the absolute temperature (ZTAT) flows through the resistor Rs. Therefore, the voltage V_TEMPS across the resistor Rs is also proportional to the absolute temperature. Therefore, this temperature can be measured based on the voltage V_TEMPS. This temperature sensor is more accurate because the influence of the offset voltage Vos of the operational amplifier on the current flowing through the resistor Rs is limited due to the reference voltage generator circuit BDGP described above.

Claims

1. A microcontroller comprising a reference voltage generator circuit, characterized in that The reference voltage generator circuit comprises: a first transistor coupled as a diode; a second transistor coupled as a diode; a first variable resistor, the first transistor and the second transistor configured to generate a current proportional to an absolute temperature of the first variable resistor; an operational amplifier having a first input terminal connected to the first transistor via a first variable resistor, and a second input terminal connected to the second transistor; a second variable resistor having a first terminal connected to the second transistor and to the second input of the operational amplifier, and a second terminal connected to the reference voltage node; a current mirror controlled by the output of the operational amplifier and configured to replicate a current proportional to the absolute temperature of the second variable resistor; a current replicator branch connected to the second transistor via the switch, the current replicator branch configured to replicate a current proportional to the absolute temperature of the second variable resistor and to inject the current through the second transistor; and A control unit is configured to control the switches of the current replicator branch and to adapt the resistance values ​​of the first variable resistor and the second variable resistor so as to keep the reference voltage carried on the reference voltage node independent of temperature.

2. The microcontroller according to claim 1 further comprises a plurality of electronic modules, wherein the microcontroller has a plurality of operating modes to selectively power the electronic modules, and the control unit is configured to control the switch of the current replicator branch according to an active operating mode in the operating modes of the microcontroller to inject more or less current through the second transistor according to the active operating mode in the operating modes.

3. The microcontroller according to claim 2, wherein the control unit is configured to control the switch of the current replicator branch to increase the current injected through the second transistor when an active one of the operating modes of the microcontroller requests an increased accuracy of the reference voltage.

4. The microcontroller according to claim 2, wherein the control unit is configured to control the switch of the current replicator branch to reduce the current injected through the second transistor when an active one of the operating modes of the microcontroller requests a reduction in power consumption of the microcontroller.

5. The microcontroller according to claim 2, wherein: According to a lookup table associating various operation modes of the microcontroller to control of the switch and resistance values ​​of the first and second variable resistors, the control unit is configured to control the switch and adapt the resistance values ​​of the first and second variable resistors according to the operation mode of the microcontroller.

6. The microcontroller according to claim 1, wherein the first transistor is a bipolar transistor having an emitter connected to the first variable resistor, a base and a collector both connected to the first cold spot; wherein the second transistor is a bipolar transistor having an emitter connected to the second input of the operational amplifier and the first terminal of the second variable resistor, and further having a base and a collector both connected to the second cold point; and The first transistor and the second transistor have different sizes. 7 . The microcontroller according to claim 6 , wherein a size of the first transistor is N times a size of the second transistor, N being an integer greater than or equal to 2.

8. The microcontroller according to claim 6, wherein the first cold point and the second cold point are connected to a ground node.

9. The microcontroller of claim 1, wherein the current mirror comprises a first p-channel insulated gate field effect transistor and a second p-channel insulated gate field effect transistor; wherein the first p-channel insulated gate field effect transistor includes a gate connected to an output terminal of the operational amplifier, a source configured to receive a power supply voltage, and a drain connected to a first input terminal of the operational amplifier and to the first variable resistor; wherein the second p-channel insulated gate field effect transistor includes a gate connected to the output terminal of the operational amplifier, a source configured to receive a voltage, and a drain connected to the second variable resistor; and The first p-channel insulated gate field effect transistor is the same as the second p-channel insulated gate field effect transistor.

10. The microcontroller of claim 9, wherein the current replicator branch comprises a third p-channel insulated gate field effect transistor, the third p-channel insulated gate field effect transistor comprising a gate connected to the output of the operational amplifier, a source configured to receive a voltage, and a drain connected to the first terminal of the second variable resistor via a switch, the third p-channel insulated gate field effect transistor being identical to the first p-channel insulated gate field effect transistor and the second p-channel insulated gate field effect transistor.

11. The microcontroller according to claim 1, wherein the first input terminal of the operational amplifier is an inverting input terminal, and the second input terminal of the operational amplifier is a non-inverting input terminal.

12. The microcontroller of claim 1, further comprising a capacitive element having a first terminal connected to the output of the operational amplifier and a second terminal connected to a supply voltage node.

13. The microcontroller according to claim 1, further comprising a temperature sensor, the temperature sensor comprising: a p-channel insulated gate field effect transistor including a gate connected to the output of the operational amplifier, a source connected to a power supply voltage node, and a drain; as well as A resistor having a first terminal connected to the drain of the p-channel insulated gate field effect transistor and a second terminal connected to the cold point.

14. A microcontroller comprising a reference voltage generator circuit, characterized in that The reference voltage generator circuit comprises: a first transistor coupled as a diode, the first transistor having a first terminal and a second terminal, the second terminal being connected to a ground node; a second transistor coupled as a diode, the second transistor having a first terminal and a second terminal, the second terminal being connected to a ground node; a first variable resistor having a first terminal connected to the first terminal of the first transistor; an operational amplifier having a first input connected to the second terminal of the first variable resistor and a second input connected to the first terminal of the second transistor; a second variable resistor having a first terminal connected to the first terminal of the second transistor and the second input terminal of the operational amplifier, the second variable resistor also having a second terminal connected to a reference voltage node; a third transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the second terminal of the first variable resistor and a power supply voltage node; a fourth transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the second terminal of the first variable resistor and a power supply voltage node; a fifth transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the first node and a power supply voltage node; A first switch connected between the first node and the second input terminal of the operational amplifier; a sixth transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the second node and a power supply voltage node; a second switch connected between the second node and the second input terminal of the operational amplifier; a seventh transistor having a control terminal connected to the output of the operational amplifier and a current path connected between the third node and the power supply voltage node; A third switch connected between the third node and the second input terminal of the operational amplifier; and The control unit has a first output terminal coupled to the first switch, a second output terminal coupled to the second switch, and a third output terminal coupled to the third switch.

15. The microcontroller according to claim 14, wherein the first transistor is a bipolar transistor having a first size; wherein the second transistor is a bipolar transistor having a second size; and The first size is N times the second size, and N is an integer greater than or equal to 2.

16. The microcontroller according to claim 14, wherein the third transistor is a p-channel insulated gate field effect transistor; wherein the fourth transistor is a p-channel insulated gate field effect transistor; and The third transistor is the same as the fourth transistor.

17. The microcontroller according to claim 16, wherein the fifth transistor is a p-channel insulated gate field effect transistor; wherein the sixth transistor is a p-channel insulated gate field effect transistor; wherein the seventh transistor is a p-channel insulated gate field effect transistor; and The third transistor, the fourth transistor, the fifth transistor, the sixth transistor and the seventh transistor are the same.

18. The microcontroller of claim 14, further comprising a capacitive element having a first terminal connected to the output of the operational amplifier and a second terminal connected to a supply voltage node.

19. The microcontroller according to claim 14, further comprising a temperature sensor, the temperature sensor comprising: a p-channel insulated gate field effect transistor including a gate connected to the output of the operational amplifier, a source connected to a power supply voltage node, and a drain; as well as A resistor has a first terminal connected to the drain of the p-channel insulated gate field effect transistor and a second terminal connected to a ground node.

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