Reference current generating device and calibration method thereof, control chip, and electronic equipment

Abstract

The present disclosure relates to a reference current generating device and a calibration method thereof, a control chip, and an electronic device. In the device, the output end of a bandgap voltage generating circuit is connected to the first end of a first voltage-dividing resistor, the second end of the first voltage-dividing resistor is connected to the first end of a second voltage-dividing resistor and the negative input end of an operational amplifier, the output end of the operational amplifier is connected to the first end of a current mirror, the positive input end of the operational amplifier is connected to the second end of the current mirror and the first end of a positive temperature coefficient resistor, the second end of the positive temperature coefficient resistor is connected to the first end of a negative temperature coefficient resistor and the first end of an adjustment switch, the second end of the negative temperature coefficient resistor and the second end of the adjustment switch are grounded. The embodiment of the present disclosure realizes a simple circuit structure, and only needs to be calibrated at room temperature to realize a reference current generating device with high absolute accuracy and low temperature coefficient, and has the characteristics of low cost, low temperature coefficient, and high precision.

Description

Technical Field

[0001] The present disclosure relates to the technical field of integrated circuits, and in particular to a reference current generating device and a calibration method thereof, a control chip, and an electronic device. Background Art

[0002] The reference current generation circuit is an important bias circuit. It needs to be independent of the power supply voltage and have a low temperature coefficient to provide a reference for other circuit modules in the chip. Usually, the on-chip reference current can be obtained by dividing the reference voltage that does not change with temperature by the resistance that does not change with temperature. The zero temperature coefficient resistor is usually composed of two types of resistors with different temperature coefficients.

[0003] However, the process fluctuation and mismatch of resistors will affect the temperature coefficient and absolute value of the current. The temperature coefficient of the current can be calibrated by scanning the temperature curve of the current and adjusting the resistors; the absolute value of the current can also be calibrated by adjusting the current mirror ratio, but this requires higher costs and a larger chip area. Summary of the invention

[0004] According to one aspect of the present disclosure, a reference current generating device is provided, the device comprising a bandgap voltage generating circuit, a first voltage dividing resistor, a second voltage dividing resistor, a positive temperature coefficient resistor, a negative temperature coefficient resistor, an operational amplifier, a current mirror, and an adjustment switch, wherein:

[0005] The output end of the bandgap voltage generating circuit is connected to the first end of the first voltage-dividing resistor, and the output end of the bandgap voltage generating circuit is used to output a bandgap voltage.

[0006] The second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor and the negative input end of the operational amplifier.

[0007] The output terminal of the operational amplifier is connected to the first terminal of the current mirror,

[0008] The positive input terminal of the operational amplifier is connected to the second terminal of the current mirror and the first terminal of the positive temperature coefficient resistor.

[0009] The second end of the positive temperature coefficient resistor is connected to the first end of the negative temperature coefficient resistor and the first end of the regulating switch.

[0010] The second end of the negative temperature coefficient resistor and the second end of the regulating switch are grounded,

[0011] The output end of the current mirror is used to output a reference current.

[0012] In a possible implementation, the current mirror includes a first PMOS transistor and a second PMOS transistor, wherein:

[0013] The gate of the first PMOS transistor and the gate of the second PMOS transistor serve as the first end of the current mirror,

[0014] The source of the first PMOS transistor and the source of the second PMOS transistor are used to receive a power supply voltage,

[0015] The drain of the first PMOS transistor serves as the second end of the current mirror.

[0016] The drain of the second PMOS transistor serves as the output end of the current mirror.

[0017] In a possible implementation manner, the reference current is determined by the following formula:

[0018] IREF=VBG*R1 / (R1+R2) / (Rp0+Rn0+Rp0*(kp-kn*Rn0 / Rp0)(T-T0)),

[0019] Among them, IREF represents the reference current, VBG represents the bandgap voltage, kp represents the first-order temperature coefficient of the unit resistance of the positive temperature coefficient resistor, kn represents the first-order temperature coefficient of the unit resistance of the negative temperature coefficient resistor, Rp0 represents the resistance value of the positive temperature coefficient resistor at room temperature, Rn0 represents the resistance value of the negative temperature coefficient resistor at room temperature, R1 represents the resistance value of the first voltage divider resistor, R2 represents the resistance value of the second voltage divider resistor, T represents the operating temperature, and T0 represents the room temperature.

[0020] In a possible implementation manner, the positive temperature coefficient resistor and the negative temperature coefficient resistor are adjustable resistors, wherein the device further includes:

[0021] A control module is connected to the output end of the current mirror, the control end of the regulating switch, and the resistance adjustment ends of the positive temperature coefficient resistor and the negative temperature coefficient resistor, and is used for:

[0022] Using a switch control signal to control the switch state of the regulating switch and obtain reference currents in different switch states, wherein the switch control signal acts on the control end of the regulating switch to control the switch state between the first end and the second end of the regulating switch, wherein the switch state includes an on state and an off state;

[0023] The size of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor is adjusted according to the reference current in different switching states.

[0024] In a possible implementation manner, the using a switch control signal to control the switch state of the regulating switch and obtaining a reference current in different switch states includes:

[0025] Using a switch control signal to control the regulating switch to be turned on, and obtaining a first reference current when the regulating switch is in a turned-on state;

[0026] Using a switch control signal to control the regulating switch to turn off, and obtaining a second reference current when the regulating switch is in a turned-off state;

[0027] The adjusting the size of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor according to the reference current in different switch states includes:

[0028] The ratio of the first reference current to the second reference current is determined, and the resistance of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor is adjusted until the ratio reaches a preset range of a target ratio.

[0029] In a possible implementation manner, the first voltage-dividing resistor and the second voltage-dividing resistor are adjustable resistors, wherein the control device is also connected to the resistance adjustment ends of the first voltage-dividing resistor and the second voltage-dividing resistor, and the control device is further used to:

[0030] The first voltage-dividing resistor and / or the second voltage-dividing resistor are adjusted according to the magnitude of the reference current and the target reference current.

[0031] According to one aspect of the present disclosure, a calibration method for a reference current generating device is provided, and the method is applied to the reference current generating device, wherein the method comprises at least one of the following steps:

[0032] Calibrate the bandgap voltage generating circuit so that the temperature coefficient of the bandgap voltage output by the bandgap voltage generating circuit is reduced to a preset value;

[0033] Adjusting the resistance of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor to calibrate the temperature coefficient of the reference current output by the current mirror;

[0034] The size of the first voltage-dividing resistor and / or the second voltage-dividing resistor is adjusted to calibrate the size of the reference current output by the current mirror.

[0035] According to one aspect of the present disclosure, a control chip is provided, wherein the control chip includes the reference current generating device.

[0036] According to one aspect of the present disclosure, an electronic device is provided, and the electronic device includes the control chip.

[0037] In a possible implementation, the electronic device includes any one of a display, a smart phone, a smart watch, a smart bracelet, a tablet computer, a laptop computer, an all-in-one computer, an access control device, and an electronic door lock.

[0038] According to one aspect of the present disclosure, an electronic device is provided, comprising: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to call the instructions stored in the memory to execute the above method.

[0039] According to one aspect of the present disclosure, a computer-readable storage medium is provided, on which computer program instructions are stored, and the computer program instructions implement the above method when executed by a processor.

[0040] The reference current generating device of the embodiment of the present disclosure includes a bandgap voltage generating circuit, a first voltage-dividing resistor, a second voltage-dividing resistor, a positive temperature coefficient resistor, a negative temperature coefficient resistor, an operational amplifier, a current mirror, and an adjustment switch, wherein the output end of the bandgap voltage generating circuit is connected to the first end of the first voltage-dividing resistor, the output end of the bandgap voltage generating circuit is used to output the bandgap voltage, the second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor and the negative input end of the operational amplifier, the output end of the operational amplifier is connected to the first end of the current mirror, the positive input end of the operational amplifier is connected to the second end of the current mirror and the first end of the positive temperature coefficient resistor, the second end of the positive temperature coefficient resistor is connected to the first end of the negative temperature coefficient resistor and the first end of the adjustment switch, the second end of the negative temperature coefficient resistor and the second end of the adjustment switch are grounded, and the output end of the current mirror is used to output the reference current. Through the above structure, the embodiment of the present disclosure realizes a simple circuit structure, and only needs to be calibrated at room temperature to realize a reference current generating device with high absolute accuracy and low temperature coefficient, and has the characteristics of low cost, low temperature coefficient, and high precision.

[0041] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and do not limit the present disclosure. Other features and aspects of the present disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used to illustrate the technical solutions of the present disclosure together with the specification.

[0043] Figure 1 A schematic diagram of a reference current generating device according to an embodiment of the present disclosure is shown.

[0044] Figure 2 A flow chart of a calibration method for a reference current generating device according to an embodiment of the present disclosure is shown.

[0045] Figure 3 FIG. 4 is a schematic diagram showing the Monte Carlo simulation results of the reference current IREF without calibration.

[0046] Figure 4 A schematic diagram of Monte Carlo simulation results of a reference current of a reference current generating device according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0047] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0048] In the description of the present disclosure, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0050] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0051] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0052] The term "and / or" herein is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set consisting of A, B, and C.

[0053] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present disclosure.

[0054] See also Figure 1 , Figure 1 A schematic diagram of a reference current generating device according to an embodiment of the present disclosure is shown.

[0055] like Figure 1 As shown, the device includes a bandgap voltage generating circuit 10, a first voltage dividing resistor R1, a second voltage dividing resistor R2, a positive temperature coefficient resistor R p , Negative temperature coefficient resistor R n , operational amplifier Amp, current mirror 20, regulating switch M3, wherein,

[0056] The output end of the bandgap voltage generating circuit 10 is connected to the first end of the first voltage dividing resistor R1, and the output end of the bandgap voltage generating circuit 10 is used to output the bandgap voltage VBG.

[0057] The second end of the first voltage-dividing resistor R1 is connected to the first end of the second voltage-dividing resistor R2 and the negative input end (-) of the operational amplifier Amp.

[0058] The output end of the operational amplifier Amp is connected to the first end of the current mirror 20.

[0059] The positive input terminal (+) of the operational amplifier Amp is connected to the second terminal of the current mirror 20 and the positive temperature coefficient resistor R p The first end,

[0060] The positive temperature coefficient resistor R p The second end is connected to the negative temperature coefficient resistor R n and a first end of the regulating switch M3,

[0061] The negative temperature coefficient resistor R nThe second end of the regulating switch M3 and the second end of the regulating switch M3 are grounded,

[0062] The output terminal of the current mirror 20 is used to output a reference current IREF.

[0063] The reference current generating device of the embodiment of the present disclosure includes a bandgap voltage generating circuit 10, a first voltage dividing resistor R1, a second voltage dividing resistor R2, a positive temperature coefficient resistor R p , Negative temperature coefficient resistor R n , an operational amplifier Amp, a current mirror 20, and an adjustment switch M3, wherein the output end of the bandgap voltage generating circuit 10 is connected to the first end of the first voltage-dividing resistor R1, the output end of the bandgap voltage generating circuit 10 is used to output the bandgap voltage VBG, the second end of the first voltage-dividing resistor R1 is connected to the first end of the second voltage-dividing resistor R2 and the negative input end of the operational amplifier Amp, the output end of the operational amplifier Amp is connected to the first end of the current mirror 20, and the positive input end of the operational amplifier Amp is connected to the second end of the current mirror 20 and the positive temperature coefficient resistor R p The first end of the positive temperature coefficient resistor R p The second end is connected to the negative temperature coefficient resistor R n and the first end of the regulating switch M3, the negative temperature coefficient resistor R n The second end of the regulating switch M3 and the second end of the regulating switch M3 are grounded, and the output end of the current mirror 20 is used to output the reference current IREF. Through the above structure, the embodiment of the present disclosure realizes a simple circuit structure, and only needs to be calibrated at room temperature to realize a reference current generating device with high absolute accuracy and low temperature coefficient, which has the characteristics of low cost, low temperature coefficient and high accuracy.

[0064] The embodiments of the present disclosure do not limit the specific implementation of the bandgap voltage generating circuit 10 and the current mirror 20, and those skilled in the art may implement them using relevant technologies according to actual conditions and needs. The reference current generating device of the embodiments of the present disclosure may also be arranged in a negative voltage circuit, and an NMOS pull-down reference current may be generated by performing a dual operation on the circuit in the aforementioned reference current generating device. The dual operation may include replacing the PMOS tube with an NMOS tube, converting the connection method of components such as capacitors and inductors, and redefining the power supply, ground, etc. It should be understood that in a circuit, a dual operation refers to the existence of a transformation so that the characteristics under one circuit structure and parameters correspond to the characteristics under another circuit structure and parameters after the transformation. For example Figure 1In the invention, a first PMOS transistor M1 and a second PMOS transistor M2 form a current mirror, and an NMOS tube forms a regulating switch M3. Through a dual operation, another circuit corresponding in structure and component characteristics can be obtained to generate a reference current pulled down by an NMOS.

[0065] In a possible implementation, Figure 1 As shown, the current mirror 20 may include a first PMOS transistor M1 and a second PMOS transistor M2, wherein:

[0066] The gate of the first PMOS transistor M1 and the gate of the second PMOS transistor M2 serve as the first end of the current mirror 20.

[0067] The source of the first PMOS transistor M1 and the source of the second PMOS transistor M2 are used to receive a power supply voltage VDD.

[0068] The drain of the first PMOS transistor M1 serves as the second end of the current mirror 20.

[0069] The drain of the second PMOS transistor M2 serves as the output terminal of the current mirror 20 .

[0070] In a possible implementation, Figure 1 As shown, the regulating switch M3 may be an NMOS transistor, wherein the source of the regulating switch M3 (the second end of the regulating switch M3) is grounded, and the drain of the regulating switch M3 (the first end of the regulating switch M3) is connected to the positive temperature coefficient resistor R p , Negative temperature coefficient resistor R n The gate of the regulating switch M3 (the control end of the regulating switch M3) is used to receive a switch control signal.

[0071] In a possible implementation manner, the reference current IREF may be determined by the following formula 1:

[0072] IREF=VBG*R1 / (R1+R2) / (Rp0+Rn0+Rp0*(kp-kn*Rn0 / Rp0)(T-T0)) Formula 1

[0073] Wherein, IREF represents the reference current, VBG represents the bandgap voltage, and kp represents the positive temperature coefficient resistor R p The first-order temperature coefficient of unit resistance, kn represents the negative temperature coefficient resistor R n The first-order temperature coefficient of the unit resistance, Rp0 represents the positive temperature coefficient resistor R p Resistance value at room temperature, Rn0 represents negative temperature coefficient resistance R nThe resistance value at room temperature, R1 represents the resistance value of the first voltage-dividing resistor R1, R2 represents the resistance value of the second voltage-dividing resistor R2, T represents the operating temperature, and T0 represents the room temperature.

[0074] For example, Figure 1 In the reference current generating device shown in FIG. 1 , the positive temperature coefficient resistor R p , Negative temperature coefficient resistor R n The relationship between Rp(T) and Rn(T) with temperature can be expressed by equation 2 and equation 3:

[0075] Rp(T)=Rp0*[1+kp(T-T0)] Formula 2

[0076] Rn(T)=Rn0*[1-kn(T-T0)] Formula 3

[0077] According to equation 2 and equation 3, the expression of reference current IREF can be derived as equation 4:

[0078] IREF=VBG*R1 / (R1+R2) / (Rp0+Rn0+(kp*Rp0-kn*Rn0)(T-T0)) Equation 4

[0079] When kp*Rp0-kn*Rn0=0, the reference current IREF is independent of temperature. It should be understood that process corners, mismatches, etc. may cause changes in Rp0 and Rn0.

[0080] Formula 1 can be obtained through formula 4.

[0081] In a possible implementation manner, the positive temperature coefficient resistor R p and / or the negative temperature coefficient resistor R n It is an adjustable resistor.

[0082] In a possible implementation, the device may further include:

[0083] A control module (not shown) is connected to the output end of the current mirror 20, the control end of the regulating switch M3 and the positive temperature coefficient resistor R p , the resistance adjustment end of the negative temperature coefficient resistor Rn is used for:

[0084] Using a switch control signal to control the switch state of the regulating switch M3, and obtaining a reference current IREF in different switch states, wherein the switch control signal acts on the control end of the regulating switch M3 to control the switch state between the first end and the second end of the regulating switch M3, wherein the switch state includes an on state and an off state;

[0085] According to the reference current IREF in different switching states, the positive temperature coefficient resistor Rp and / or the negative temperature coefficient resistor R n to adjust the size.

[0086] The embodiments of the present disclosure do not limit the specific implementation of the control module, and those skilled in the art can set it according to actual conditions and needs. For example, in one example, the control module may include a processing component, and the processing component includes but is not limited to a separate processor, or a discrete component, or a combination of a processor and a discrete component. The processor may include a controller having an execution instruction function in an electronic device, and the processor may be implemented in any appropriate manner, for example, by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors or other electronic components. Inside the processor, the executable instructions may be executed by hardware circuits such as logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers.

[0087] The embodiment of the present disclosure does not limit the specific implementation method of using the switch control signal to control the switch state of the regulating switch M3 and obtain the reference current IREF in different switch states, but only limits the specific implementation method of controlling the positive temperature coefficient resistor R according to the reference current IREF in different switch states. p and / or the negative temperature coefficient resistor R n The specific implementation method of adjusting the size is not limited, and technical personnel in this field can set it according to actual conditions and needs.

[0088] For example, in a possible implementation, the using of the switch control signal to control the switch state of the regulating switch M3 and obtaining the reference current IREF in different switch states may include:

[0089] Using a switch control signal to control the regulating switch M3 to be turned on, and obtaining a first reference current (IREF1) of the regulating switch M3 in a turned-on state;

[0090] The regulating switch M3 is controlled to be turned off by using a switch control signal, and a second reference current (IREF2) of the regulating switch M3 in the turned-off state is obtained.

[0091] For example, in a possible implementation manner, the reference current IREF under different switching states is used to adjust the positive temperature coefficient resistor R p and / or the negative temperature coefficient resistor R n The size of the adjustment includes:

[0092] Determine the ratio of the first reference current (IREF1) to the second reference current (IREF2), and adjust the positive temperature coefficient resistor R p and / or the negative temperature coefficient resistor R n until the ratio reaches a preset range of the target ratio.

[0093] Exemplary, to adjust the negative temperature coefficient resistor R n For example, the embodiment of the present disclosure can use the switch control signal to control the regulating switch M3 to turn on the negative temperature coefficient resistor R n The regulating switch M3 is short-circuited, and the first reference current (IREF1) of the regulating switch M3 in the on state is obtained, wherein the first reference current (IREF1)1=VBG*R1 / (R1+R2) / Rp0; then the regulating switch M3 is turned off by using the switch control signal, and the negative temperature coefficient resistor R n The circuit is connected, and the second reference current (IREF2) 2 = VBG * R1 / (R1 + R2) / (Rp0 + Rn0) of the regulating switch M3 in the off state is obtained, and the ratio of the first reference current (IREF1) to the second reference current (IREF2) IREF1 / IREF2 = 1 + Rn0 / Rp0 is determined, and then the size of the ratio IREF1 / IREF2 1 + Rn0 / Rp0 is compared with the target ratio, and the negative temperature coefficient resistor R is adjusted. n Of course, the embodiment of the present disclosure does not limit the specific size of the target ratio. Those skilled in the art can set it according to actual conditions and needs, and repeat the above process. The embodiment of the present disclosure can make Rn0 / Rp0 equal to the design value. On this basis, even if Rp0 and Rn0 are not equal to the original design values, it will only affect the absolute value of the current and will not affect the temperature characteristics.

[0094] In a possible implementation manner, the first voltage-dividing resistor R1 and / or the second voltage-dividing resistor R2 may also be an adjustable resistor, wherein the control device is further connected to the resistance adjustment end of the first voltage-dividing resistor R1 and / or the second voltage-dividing resistor R2, and the control device may also be used to:

[0095] The first voltage-dividing resistor R1 and / or the second voltage-dividing resistor R2 are adjusted according to the magnitudes of the reference current IREF and the target reference current IREF.

[0096] Exemplarily, taking the adjustment of the second voltage-dividing resistor R2 as an example, the embodiment of the present disclosure can obtain the reference current IREF in real time, and compare the reference current IREF with the target reference current IREF, and adjust the size of the second voltage-dividing resistor R2 according to the comparison result so that the reference current IREF output by the reference current generating device reaches the target reference current IREF. Of course, the disclosed embodiment does not limit the specific implementation method of adjusting the second voltage-dividing resistor R2 according to the magnitude of the reference current IREF and the target reference current IREF. Those skilled in the art can set it according to actual conditions and needs. For example, a first adjustment step and a second adjustment step can be set, and the first adjustment step is larger than the second adjustment step. If the reference current IREF and the target reference current IREF have a large difference, the first adjustment step can be used to adjust the magnitude of the second voltage-dividing resistor R2 for rough adjustment. If the difference between the reference current IREF and the target reference current IREF is reduced to a preset range, the second adjustment step can be used to fine-tune the resistance of the second voltage-dividing resistor R2, thereby improving the accuracy of the adjustment. Of course, in order to further improve the accuracy of the reference current IREF output by the reference current generating device, that is, to approach the target reference current IREF, the second adjustment step can be further adjusted, for example, the adjustment step can be further reduced based on the second adjustment step to adjust the resistance of the second voltage-dividing resistor R2. It is worth mentioning that this adjustment method can also be used for the negative temperature coefficient resistor R n The adjustment of the resistance value will not be described in detail here.

[0097] Of course, the control module of the embodiment of the present disclosure can also calibrate the bandgap voltage VBG generated by the bandgap voltage generating circuit 10 to improve the accuracy and stability of the bandgap voltage VBG. The embodiment of the present disclosure does not limit the calibration method generated by the bandgap voltage generating circuit 10, and those skilled in the art can adopt relevant technologies to implement it according to actual conditions and needs.

[0098] See also Figure 2 , Figure 2 A flow chart of a calibration method for a reference current generating device according to an embodiment of the present disclosure is shown.

[0099] The method is applied to the reference current generating device, wherein: Figure 2 and Figure 1 As shown, the method includes at least one of the following steps:

[0100] Step S10, calibrating the bandgap voltage generating circuit 10 so that the temperature coefficient of the bandgap voltage VBG output by the bandgap voltage generating circuit 10 is reduced to a preset value;

[0101] Step S11, adjusting the positive temperature coefficient resistor Rp and / or the negative temperature coefficient resistor R n The resistance value is used to calibrate the temperature coefficient of the reference current IREF output by the current mirror 20;

[0102] Step S12 , adjusting the size of the first voltage-dividing resistor R1 and / or the second voltage-dividing resistor R2 to calibrate the size of the reference current IREF output by the current mirror 20 .

[0103] As mentioned above, Figure 1 As shown, the reference current generating device of the embodiment of the present disclosure includes a bandgap voltage generating circuit 10, a first voltage dividing resistor R1, a second voltage dividing resistor R2, a positive temperature coefficient resistor R p , Negative temperature coefficient resistor R n , an operational amplifier Amp, a current mirror 20, and an adjustment switch M3, wherein the output end of the bandgap voltage generating circuit 10 is connected to the first end of the first voltage-dividing resistor R1, the output end of the bandgap voltage generating circuit 10 is used to output the bandgap voltage VBG, the second end of the first voltage-dividing resistor R1 is connected to the first end of the second voltage-dividing resistor R2 and the negative input end of the operational amplifier Amp, the output end of the operational amplifier Amp is connected to the first end of the current mirror 20, and the positive input end of the operational amplifier Amp is connected to the second end of the current mirror 20 and the positive temperature coefficient resistor R p The first end of the positive temperature coefficient resistor R p The second end is connected to the negative temperature coefficient resistor R n and the first end of the regulating switch M3, the negative temperature coefficient resistor R n The second end of and the second end of the regulating switch M3 are grounded, and the output end of the current mirror 20 is used to output the reference current IREF. Through the above structure, the disclosed embodiment realizes a simple circuit structure, and only needs to be calibrated at room temperature to realize a reference current generating device with high absolute accuracy and low temperature coefficient, which has the characteristics of low cost, low temperature coefficient and high accuracy. For the specific introduction of the reference current generating device, please refer to the above description, which will not be repeated here.

[0104] The embodiment of the present disclosure calibrates the bandgap voltage generating circuit 10 so that the temperature coefficient of the bandgap voltage VBG output by the bandgap voltage generating circuit 10 is reduced to a preset value, and adjusts the negative temperature coefficient resistor R nThe resistance size is adjusted to calibrate the temperature coefficient of the reference current IREF output by the current mirror 20, and the size of the second voltage-dividing resistor R2 is adjusted to calibrate the size of the reference current IREF output by the current mirror 20, so that the reference current generating device can output a more accurate reference current IREF with a lower temperature coefficient.

[0105] In some possible implementations, the method can be implemented by a processing component calling a computer-readable instruction stored in a memory. In one example, the processing component includes but is not limited to a separate processor, or a discrete component, or a combination of a processor and a discrete component. The processor may include a controller having an execution instruction function in an electronic device, and the processor may be implemented in any appropriate manner, for example, by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors or other electronic components. Inside the processor, the executable instructions may be executed by hardware circuits such as logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers.

[0106] As an example, calibration of the reference current generating device may include:

[0107] 1. Calibrate the bandgap voltage generating circuit 10 at room temperature to obtain a bandgap voltage VBG with a low temperature coefficient. The specific implementation method of the bandgap voltage generating circuit 10 and the calibration method of generating the bandgap voltage VBG are not limited in the embodiments of the present disclosure, and those skilled in the art can adopt relevant technologies to implement them according to actual conditions and needs.

[0108] 2. Calibrate the temperature coefficient of IREF at room temperature.

[0109] ① Close the regulating switch M3 and set the negative temperature coefficient resistor R n Short circuit, the output current IREF1 = VBG*R1 / (R1+R2) / Rp0 at room temperature is measured;

[0110] ②Disconnect the adjustment switch M3 and connect the negative temperature coefficient resistor R n Connect to the circuit and measure the output current IREF2 = VBG*R1 / (R1+R2) / (Rp0+Rn0) at room temperature;

[0111] Calculation shows that IREF1 / IREF2=1+Rn0 / Rp0.

[0112] ③Calibrate negative temperature coefficient resistor Rn , repeat ①②, so that Rn0 / Rp0 is equal to the design value. On this basis, even if Rp0 and Rn0 are not equal to the original design value, it will only affect the absolute value of the current and will not affect the temperature characteristics.

[0113] 3. Calibrate the absolute value of IREF at room temperature.

[0114] The second voltage-dividing resistor R2 is calibrated so that the absolute value of the reference current IREF meets the design requirements.

[0115] It can be understood that the above-mentioned various method embodiments mentioned in the present disclosure can be combined with each other to form a combined embodiment without violating the principle logic. Due to space limitations, the present disclosure will not repeat them. It can be understood by those skilled in the art that in the above-mentioned method of the specific implementation method, the specific execution order of each step should be determined according to its function and possible internal logic.

[0116] In addition, for a specific introduction on calibrating the bandgap voltage generating circuit 10, calibrating the temperature coefficient of the reference current IREF output by the current mirror 20, and calibrating the magnitude of the reference current IREF output by the current mirror 20, please refer to the aforementioned description of the reference current generating device, which will not be repeated here.

[0117] See also Figure 3 , Figure 4 , Figure 3 FIG. 1 shows a schematic diagram of Monte Carlo simulation results of the reference current IREF without calibration. Figure 4 A schematic diagram of Monte Carlo simulation results of a reference current IREF of a reference current generating device according to an embodiment of the present disclosure is shown.

[0118] from Figure 3 It can be seen that without calibration, at room temperature (27°C), the current absolute value is 113uA at maximum and 93uA at minimum, with an error of about 20%. The error is mainly caused by the process fluctuation of the resistor.

[0119] from Figure 3 It can also be seen that the single Monte Carlo simulation current curve can change up to 1uA (113uA at room temperature) in the range of -40℃~125℃, and the temperature drift is about 52ppm. It should be noted that the resistance change trend of the two temperature coefficient resistor models is synchronized during Monte Carlo simulation, that is, they will increase or decrease at the same time, so the temperature coefficient is relatively good. The actual situation may be different, and the temperature coefficient will be worse than the simulation.

[0120] like Figure 4 The following is the result after calibration of the reference current IREF of 100uA. Figure 4It can be seen that the curve of current changing with temperature is in the shape of a quadratic function, opening downward, and does not increase or decrease linearly with temperature. Therefore, the reference current IREF of the reference current generating device only contains a second-order temperature coefficient.

[0121] from Figure 4 It can also be seen that at room temperature (27°C), the change in the absolute value of the calibrated current is less than 0.4uA, that is, the error is less than 0.4%. The absolute accuracy is related to the LSB of the voltage divider resistor R2. The smaller this value is, the higher the absolute accuracy at room temperature, but the greater the hardware overhead required.

[0122] In addition from Figure 4 It can also be seen that the single Monte Carlo simulation current curve changes less than 0.7uA in the range of -40℃~125℃, that is, the temperature drift is less than 42ppm. This value depends on the second-order temperature characteristics of the resistor itself and is related to the process. A better process can achieve a lower temperature coefficient under the same architecture.

[0123] It can be seen that compared with the prior art (which does not adopt the calibration technology of the embodiment of the present disclosure), the circuit structure of the reference current generating device of the embodiment of the present disclosure is simple, and only needs to be calibrated at room temperature to achieve a reference current IREF with high absolute accuracy and low temperature coefficient, and the cost is low.

[0124] According to one aspect of the present disclosure, a control chip is provided, wherein the control chip includes the reference current generating device.

[0125] According to one aspect of the present disclosure, an electronic device is provided, and the electronic device includes the control chip.

[0126] In a possible implementation, the electronic device includes any one of a display, a smart phone, a smart watch, a smart bracelet, a tablet computer, a laptop computer, an all-in-one computer, an access control device, and an electronic door lock.

[0127] Of course, the electronic device may also include other terminal devices, and the terminal device may be a user equipment (UE), a mobile device, a user terminal, a terminal, a handheld device, a computing device or a vehicle-mounted device, etc. For example, some examples of terminals are: mobile phones, tablet computers, laptop computers, PDAs, mobile Internet devices (MID), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control (Industrial Control), wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids (Smart Grid), wireless terminals in transportation safety (Transportation Safety), wireless terminals in smart cities (Smart City), wireless terminals in smart homes (Smart Home), wireless terminals in Internet of Vehicles, etc. For example, the server may be a local server or a cloud server.

[0128] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A reference current generating device, characterized in that: The device includes a bandgap voltage generating circuit, a first voltage dividing resistor, a second voltage dividing resistor, a positive temperature coefficient resistor, a negative temperature coefficient resistor, an operational amplifier, a current mirror, and an adjustment switch, wherein: The output end of the bandgap voltage generating circuit is connected to the first end of the first voltage-dividing resistor, and the output end of the bandgap voltage generating circuit is used to output a bandgap voltage. The second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor and the negative input end of the operational amplifier. The output terminal of the operational amplifier is connected to the first terminal of the current mirror, The positive input terminal of the operational amplifier is connected to the second terminal of the current mirror and the first terminal of the positive temperature coefficient resistor. The second end of the positive temperature coefficient resistor is connected to the first end of the negative temperature coefficient resistor and the first end of the regulating switch. The second end of the negative temperature coefficient resistor and the second end of the regulating switch are grounded, The output end of the current mirror is used to output a reference current.

2. The device according to claim 1, characterized in that The current mirror includes a first PMOS transistor and a second PMOS transistor, wherein: The gate of the first PMOS transistor and the gate of the second PMOS transistor serve as the first end of the current mirror, The source of the first PMOS transistor and the source of the second PMOS transistor are used to receive a power supply voltage, The drain of the first PMOS transistor serves as the second end of the current mirror. The drain of the second PMOS transistor serves as the output end of the current mirror.

3. The device according to claim 1, characterized in that The reference current is determined by the following formula: IREF=VBG*R1 / (R1+R2) / (Rp0+Rn0+Rp0*(kp-kn*Rn0 / Rp0)(T-T0)), Among them, IREF represents the reference current, VBG represents the bandgap voltage, kp represents the first-order temperature coefficient of the unit resistance of the positive temperature coefficient resistor, kn represents the first-order temperature coefficient of the unit resistance of the negative temperature coefficient resistor, Rp0 represents the resistance value of the positive temperature coefficient resistor at room temperature, Rn0 represents the resistance value of the negative temperature coefficient resistor at room temperature, R1 represents the resistance value of the first voltage divider resistor, R2 represents the resistance value of the second voltage divider resistor, T represents the operating temperature, and T0 represents the room temperature.

4. The device according to claim 1, characterized in that The positive temperature coefficient resistor and the negative temperature coefficient resistor are adjustable resistors, wherein the device further comprises: A control module is connected to the output end of the current mirror, the control end of the regulating switch, and the resistance adjustment ends of the positive temperature coefficient resistor and the negative temperature coefficient resistor, and is used for: Using a switch control signal to control the switch state of the regulating switch and obtain reference currents in different switch states, wherein the switch control signal acts on the control end of the regulating switch to control the switch state between the first end and the second end of the regulating switch, wherein the switch state includes an on state and an off state; The size of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor is adjusted according to the reference current in different switching states.

5. The device according to claim 4, characterized in that The method of controlling the switch state of the regulating switch by using the switch control signal and obtaining the reference current under different switch states includes: Using a switch control signal to control the regulating switch to be turned on, and obtaining a first reference current when the regulating switch is in a turned-on state; Using a switch control signal to control the regulating switch to turn off, and obtaining a second reference current when the regulating switch is in a turned-off state; The adjusting the size of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor according to the reference current in different switch states includes: The ratio of the first reference current to the second reference current is determined, and the resistance of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor is adjusted until the ratio reaches a preset range of a target ratio.

6. The device according to claim 4, characterized in that The first voltage-dividing resistor and the second voltage-dividing resistor are adjustable resistors, wherein the control device is also connected to the resistance adjustment ends of the first voltage-dividing resistor and the second voltage-dividing resistor, and the control device is also used for: The first voltage-dividing resistor and / or the second voltage-dividing resistor are adjusted according to the magnitude of the reference current and the target reference current.

7. A calibration method for a reference current generating device, characterized in that: The method is applied to the reference current generating device according to any one of claims 1 to 6, wherein the method comprises at least one of the following steps: Calibrate the bandgap voltage generating circuit so that the temperature coefficient of the bandgap voltage output by the bandgap voltage generating circuit is reduced to a preset value; Adjusting the resistance of the positive temperature coefficient resistor and / or the negative temperature coefficient resistor to calibrate the temperature coefficient of the reference current output by the current mirror; The size of the first voltage-dividing resistor and / or the second voltage-dividing resistor is adjusted to calibrate the size of the reference current output by the current mirror.

8. A control chip, characterized in that: The control chip includes the reference current generating device according to any one of claims 1 to 6.

9. An electronic device, characterized in that: The electronic device comprises the control chip as claimed in claim 8.

10. The electronic device according to claim 9, characterized in that: The electronic device includes any one of a display, a smart phone, a smart watch, a smart bracelet, a tablet computer, a laptop computer, an all-in-one computer, an access control device, and an electronic door lock.

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