A reference voltage circuit and an electronic device

Abstract

This application discloses a reference voltage circuit and an electronic device. The reference voltage circuit includes: a bandgap reference source, a bandgap amplifier, a first switch, a first resistor, a second resistor, a first switch, a first capacitor, a filter circuit, a first amplifier, and a controller. The controller is connected to the bandgap reference source, the bandgap amplifier, the first switch, and the filter circuit. The controller is used to control the bandgap reference source and the bandgap amplifier to operate for a first operating time in each cycle, and to sequentially control the first switch and the filter circuit during the first operating time. The ratio of the first operating time to the cycle is less than or equal to 1 / 100. Through this method, the bandgap reference source and the bandgap amplifier can operate intermittently, thereby reducing the power consumption of the bandgap reference source and the bandgap amplifier.

Description

Technical Field

[0001] This application relates to the field of power supply circuit technology, and in particular to a reference voltage circuit and electronic device. Background Technology

[0002] With the development of electronic devices, reference voltage circuits are used to output a reference voltage to provide a stable reference voltage for analog-to-digital converters (ADCs) or digital-to-analog converters (DACs). To reduce the power consumption of the reference voltage circuit, existing technologies reduce its operating current, which leads to increased noise in the circuit. Summary of the Invention

[0003] This application mainly provides a reference voltage circuit and electronic device to solve the problem of increased noise.

[0004] This application provides a reference voltage circuit, including: Bandgap reference source; The bandgap amplifier comprises a first switching transistor, a first resistor, and a second resistor. The first input terminal of the bandgap amplifier is connected to the bandgap reference source, and the output terminal of the bandgap amplifier is connected to the control terminal of the first switching transistor. The first terminal of the first switching transistor receives a first voltage, and the second terminal of the first switching transistor is grounded through the first resistor and the second resistor. The second input terminal of the bandgap amplifier is connected between the first resistor and the second resistor. The system comprises a first switch, a first capacitor, a filter circuit, and a first amplifier. One end of the first switch is connected to the second end of the first switching transistor, and the other end of the first switch is connected to one end of the first capacitor and the filter circuit. The other end of the first capacitor is grounded, and the filter circuit is connected to the first amplifier. The controller is connected to the bandgap reference source, the bandgap amplifier, the first switch, and the filter circuit respectively. The controller is used to control the bandgap reference source and the bandgap amplifier to work for a first working time in each cycle, and to control the first switch and the filter circuit in sequence during the first working time. The ratio of the first working time to the cycle is less than or equal to 1 / 100.

[0005] In some embodiments, the filter circuit includes a second switch, a third resistor, and a second capacitor. One end of the second switch is connected to the other end of the first switch, the other end of the second switch is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the first amplifier and one end of the second capacitor, and the other end of the second capacitor is grounded.

[0006] In some embodiments, the controller is connected to the second switch, and the controller is configured to control the first switch to turn on at a first preset time interval and control the second switch to turn on at a second preset time interval when controlling the bandgap reference source and the bandgap amplifier to start working, wherein the second preset time is greater than the first preset time.

[0007] In some embodiments, the controller is configured to control the second switch to open when the voltage between the third resistor and the second capacitor reaches a stable state, control the first switch to open at a third preset time interval, and control the bandgap reference source and the bandgap amplifier to stop working at a fourth preset time interval, wherein the third preset time is less than the difference between the second preset time and the first preset time, and the fourth preset time is greater than the third preset time.

[0008] In some embodiments, the first preset time is between 5 and 40 μs, and the difference between the second preset time and the first preset time is between 5 and 40 μs.

[0009] In some embodiments, the output voltage of the filter circuit satisfies the following formula:

[0010] in, , R3 is the conduction time of the second switch, R3 is the resistance value of the third resistor, and C2 is the capacitance value of the second capacitor. The output voltage of the filter circuit is [value]. The input voltage of the filter circuit is n, where n is a positive integer greater than or equal to 1. The cutoff frequency of the filter circuit satisfies the following formula:

[0011] in, T1 is the cutoff frequency of the filter circuit and T2 is the period.

[0012] In some embodiments, the bandgap reference source includes a second amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second switch, and a third switch. The first input terminal of the second amplifier is connected to the control terminal of the second switch, the first terminal of the third switch, and one end of the sixth resistor. The second input terminal of the second amplifier is connected to the first terminal of the second switch and one end of the fourth resistor. The output terminal of the second amplifier is connected to the other end of the fourth resistor, the other end of the fifth resistor, the other end of the sixth resistor, and the first input terminal of the bandgap amplifier. One end of the fifth resistor is connected to the control terminal of the third switch. The second terminals of the second and third switches are grounded through the seventh resistor. The fifth resistor is used to perform exponential curvature compensation on the voltage output by the second amplifier.

[0013] In some embodiments, the voltage output by the second amplifier satisfies the following formula:

[0014] in, The voltage output by the second amplifier. The voltage difference between the control terminal and the second terminal of the third switch is... The voltage difference between the control terminal and the second terminal of the second switch is [missing information]. for and The difference between them, where R4 is the resistance value of the fourth resistor, R5 is the resistance value of the fifth resistor, and R7 is the resistance value of the seventh resistor. The amplification factor of the third switching transistor is given by T, where T is the temperature.

[0015] In some embodiments, the reference voltage circuit further includes a fourth switch and a fifth switch. The control terminal of the fourth switch is connected to the first output terminal of the first amplifier, and the control terminal of the fifth switch is connected to the second output terminal of the first amplifier. The second terminals of the fourth and fifth switches are connected to the second input terminal of the first amplifier. The first terminal of the fourth switch receives a second voltage, and the first terminal of the fifth switch is grounded. The second terminals of the fourth and fifth switches are used to output a reference voltage.

[0016] This application also provides an electronic device including the above-described reference voltage circuit, which is used to output a reference voltage.

[0017] The beneficial effects of this application are as follows: The controller of this application is connected to the bandgap reference source, the bandgap amplifier, the first switch, and the filter circuit respectively. The controller is used to control the bandgap reference source and the bandgap amplifier to work for a first working time in each cycle, and to control the first switch and the filter circuit sequentially during the first working time. The ratio of the first working time to the cycle is less than or equal to 1 / 100. By controlling the bandgap reference source and the bandgap amplifier to work simultaneously for a first working time in each cycle, the bandgap reference source and the bandgap amplifier can achieve intermittent operation, thereby reducing the power consumption of the bandgap reference source and the bandgap amplifier. By ensuring that the ratio of the first working time to the cycle is less than or equal to 1 / 100, the bandgap reference source and the bandgap amplifier can achieve extremely short working times, further reducing the power consumption of the bandgap reference source and the bandgap amplifier. By filtering noise through the filter circuit, the noise of the reference voltage circuit can be reduced. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a circuit diagram of one embodiment of the reference voltage circuit provided in this application; Figure 2 yes Figure 1 A timing diagram illustrating the operation of an embodiment of a reference voltage circuit; Figure 3 yes Figure 1 A circuit diagram of one embodiment of a medium bandgap reference source. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0021] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] Please see Figure 1 As shown, Figure 1 This is a circuit diagram of one embodiment of the reference voltage circuit provided in this application. The reference voltage circuit 100 of this embodiment is applied to an electronic device, including but not limited to smart devices, wearable devices, or devices applied to the Internet of Things (IoT).

[0024] The reference voltage circuit 100 in this embodiment is used to output a reference voltage. The reference voltage circuit 100 includes a bandgap reference source 10, a bandgap amplifier 20, a first switch Q1, a first resistor R1, a second resistor R2, a first switch S1, a first capacitor C1, a filter circuit 30, a first amplifier 40, and a controller 50. The controller 50 includes, but is not limited to, an MCU (Microcontroller Unit).

[0025] The bandgap reference source 10 is an integrated circuit reference circuit. The first input terminal of the bandgap amplifier 20 is connected to the bandgap reference source 10, and the output terminal of the bandgap amplifier 20 is connected to the control terminal of the first switch Q1. The first terminal of the first switch Q1 receives the first voltage V1, and the second terminal of the first switch Q1 is grounded through the first resistor R1 and the second resistor R2. The second input terminal of the bandgap amplifier 20 is connected between the first resistor R1 and the second resistor R2.

[0026] In some embodiments, the first switch Q1 can be a P-channel MOSFET, the control terminal of the first switch Q1 is the gate of the P-channel MOSFET, the first terminal of the first switch Q1 is the source of the P-channel MOSFET, and the second terminal of the first switch Q1 is the drain of the P-channel MOSFET. In other embodiments, the first switch Q1 can be other types of switches, which will not be described in detail here.

[0027] One end of the first switch S1 is connected to the second end of the first switching transistor Q1, and the other end of the first switch S1 is connected to one end of the first capacitor C1 and the filter circuit 30. The other end of the first capacitor C1 is grounded, and the filter circuit 30 is connected to the first amplifier 40. The first capacitor C1 is used for isolation to reduce the possibility of excessive drain current in the first switching transistor Q1.

[0028] In some implementations, the first amplifier 40 can be an error amplifier, which is a high-gain operational amplifier. Its input terminal receives the feedback signal and the voltage output by the filter circuit 30, amplifies the difference signal between the two and outputs a control signal. Through negative feedback adjustment, the error amplifier outputs a stable reference voltage.

[0029] The controller 50 is connected to the bandgap reference source 10, the bandgap amplifier 20, the first switch S1 and the filter circuit 30 respectively. The controller 50 is used to control the bandgap reference source 10, the bandgap amplifier 20, the first switch S1 and the filter circuit 30.

[0030] For example, an external power supply (not shown) is connected to the bandgap reference source 10 via a switching transistor (not shown), and the external power supply (not shown) is also connected to the bandgap amplifier 20 via a switching transistor (not shown). The controller 50 is connected to both the switching transistors of the bandgap reference source 10 and the bandgap amplifier 20. The controller 50 is used to turn on the switching transistors of the bandgap reference source 10 and the bandgap amplifier 20, thereby enabling the controller 50 to control the operation of the bandgap reference source 10 and the bandgap amplifier 20. The controller 50 is also used to turn off the switching transistors of the bandgap reference source 10 and the bandgap amplifier 20, thereby enabling the controller 50 to control the bandgap reference source 10 and the bandgap amplifier 20 to stop operating. In other embodiments, the controller 50 can also control the operation or shutdown of the bandgap reference source 10 and the bandgap amplifier 20 in other ways.

[0031] For example, the control terminal of the first switch S1 and the control terminal of the filter circuit 30 are both connected to the controller 50. The controller 50 is used to control the first switch S1 to be turned on or off, and to control the filter circuit 30 to be turned on or off.

[0032] The controller 50 is used to control the bandgap reference source 10 and the bandgap amplifier 20 to operate for a first operating time in each cycle, and to sequentially control the first switch S1 and the filter circuit 30 during the first operating time. The ratio of the first operating time to the cycle is less than or equal to 1 / 100. That is, in each cycle, the controller 50 controls the bandgap reference source 10 and the bandgap amplifier 20 to operate simultaneously for a first operating time, and sequentially controls the first switch S1 to turn on or off, and controls the filter circuit 30 to operate or not operate, wherein the ratio of the first operating time to the cycle is less than or equal to 1 / 100.

[0033] In some embodiments, each cycle is 33ms and the first operating time is 100μs. Therefore, the ratio of the first operating time to the cycle is 1 / 330 (less than 1 / 100), meaning the first operating time is much shorter than the cycle. For example, the actual current of the bandgap reference 10 is 5.5μA, and the actual current of the bandgap amplifier 20 is 17μA. The average current of the bandgap reference 10 and the bandgap amplifier 20 is 22.5μA multiplied by 1 / 330, which equals approximately 68nA. At this point, the power consumption of the bandgap reference 10 and the bandgap amplifier 20 can be ignored, thereby reducing their power consumption.

[0034] In this embodiment, the controller 50 is connected to the bandgap reference source 10, the bandgap amplifier 20, the first switch S1, and the filter circuit 30. The controller 50 controls the bandgap reference source 10 and the bandgap amplifier 20 to operate for a first operating time in each cycle, and sequentially controls the first switch S1 and the filter circuit 30 during the first operating time. The ratio of the first operating time to the cycle is less than or equal to 1 / 100. By controlling the bandgap reference source 10 and the bandgap amplifier 20 to operate simultaneously for a first operating time in each cycle, the bandgap reference source 10 and the bandgap amplifier 20 can achieve intermittent operation, thereby reducing the power consumption of the bandgap reference source 10 and the bandgap amplifier 20. By ensuring that the ratio of the first operating time to the cycle is less than or equal to 1 / 100, the bandgap reference source 10 and the bandgap amplifier 20 can achieve extremely short operating times, further reducing the power consumption of the bandgap reference source 10 and the bandgap amplifier 20. By filtering noise through the filter circuit 30, the noise of the reference voltage circuit 100 can be reduced.

[0035] Please see Figure 1 As shown, the filter circuit 30 in this embodiment includes a second switch S2, a third resistor R3, and a second capacitor C2.

[0036] One end of the second switch S2 is connected to the other end of the first switch S1. The other end of the second switch S2 is connected to one end of the third resistor R3. The other end of the third resistor R3 is connected to one end of the first amplifier 40 and one end of the second capacitor C2. The other end of the second capacitor C2 is grounded.

[0037] In some embodiments, the controller 50 is connected to the second switch S2; for example, the controller 50 is connected to the control terminal of the second switch S2. The controller 50 is used to control the second switch S2 to be turned on or off; when the controller 50 controls the second switch S2 to be turned on, the controller 50 controls the filter circuit 30 to work; when the controller 50 controls the second switch S2 to be turned off, the controller 50 controls the filter circuit 30 to stop working.

[0038] Please see Figure 1 and Figure 2 As shown, Figure 2 yes Figure 1 A schematic diagram of the operating timing of an embodiment of the intermediate reference voltage circuit. In this embodiment, the controller 50 is used to control the first switch S1 to turn on at a first preset time t1 and the second switch S2 to turn on at a second preset time t2 when the bandgap reference source 10 and the bandgap amplifier 20 start to operate, wherein the second preset time t2 is greater than the first preset time t1.

[0039] Figure 2 The signal EN1 is the control signal output by the controller 50 to the bandgap reference source 10 and the bandgap amplifier 20. Figure 2 The signal EN2 is the control signal output by the controller 50 to the first switch S1. Figure 2 The signal EN3 in the diagram is the control signal output by the controller 50 to the second switch.

[0040] Figure 2 When signal EN1 changes from low to high, controller 50 controls bandgap reference source 10 and bandgap amplifier 20 to start working. After a first preset time t1, signal EN2 changes from low to high, controller 50 controls first switch S1 to turn on, and the voltage output by bandgap amplifier 20 replenishes the charge of first capacitor C1. After a second preset time t2, signal EN3 changes from low to high, controller 50 controls second switch S2 to turn on, and the second preset time t2 is greater than the first preset time t1. In this way, controller 50 sequentially controls first switch S1 and filter circuit 30 during the first working time.

[0041] Specifically, when the signal EN1 changes from low level to high level, after a first preset time t1, the voltage output by the bandgap amplifier 20 is stable; when the signal EN1 changes from low level to high level, after a second preset time t2, the voltage Vref between the first switch S1 and the first capacitor C1 is stable; when the controller 50 controls the second switch S2 to be turned on, the second capacitor C2 samples the voltage Vref between the first switch S1 and the first capacitor C1.

[0042] In some embodiments, the capacitance value of the first capacitor C1 is less than the capacitance value of the second capacitor C2, and the voltage Vhold between the third resistor R3 and the second capacitor C2 remains constant through the second capacitor C2.

[0043] In this embodiment, the controller 50 is used to control the second switch S2 to open when the voltage Vhold between the third resistor R3 and the second capacitor C2 reaches a stable value, control the first switch S1 to open at a third preset time interval t3, and control the bandgap reference source 10 and the bandgap amplifier 20 to stop working at a fourth preset time interval t4. The third preset time t3 is less than the difference between the second preset time t2 and the first preset time t1, and the fourth preset time t4 is greater than the third preset time t3.

[0044] Figure 2 When the signal EN3 changes from high level to low level, the controller 50 controls the second switch S2 to open. For example, when the voltage Vhold between the third resistor R3 and the second capacitor C2 reaches a stable value, the second capacitor C2 samples the voltage Vref between the first switch S1 and the first capacitor C1 for 2μs. That is, when the signal EN3 changes from low level to high level, the controller 50 controls the signal EN3 to change from high level to low level.

[0045] When signal EN3 changes from high to low, after a third preset time t3, signal EN2 changes from high to low, meaning controller 50 controls the first switch S1 to open. When signal EN3 changes from high to low, after a fourth preset time t4, signal EN1 changes from high to low, meaning controller 50 controls the bandgap reference source 10 and bandgap amplifier 20 to stop working; thus, it is possible to sequentially control the second switch S2, the first switch S1, and the bandgap reference source 10 and bandgap amplifier 20.

[0046] In some embodiments, the first preset time t1 is between 5 and 40 μs, and the first preset time t1 includes, but is not limited to, 5 μs, 10 μs, 15 μs, 20 μs, 25 μs, 30 μs, 35 μs, or 40 μs. The difference between the second preset time t2 and the first preset time t1 is between 5 and 40 μs, and the difference between the second preset time t2 and the first preset time t1 includes, but is not limited to, 5 μs, 10 μs, 15 μs, 20 μs, 25 μs, 30 μs, 35 μs, or 40 μs; for example, if the difference between the second preset time t2 and the first preset time t1 is 40 μs, then when the controller 50 control signal EN2 changes from low level to high level, the control signal EN3 changes from low level to high level at intervals of 40 μs.

[0047] For example, the first preset time t1 is 40μs, the third preset time t3 is 1μs, and the fourth preset time t4 is 2μs. Starting from the transition of signal EN1 from low to high, signal EN2 transitions from low to high after a 40μs interval; signal EN3 transitions from low to high after an 80μs interval; and the voltage Vhold between the third resistor R3 and the second capacitor C2 stabilizes after an 82μs interval. Starting from the transition of signal EN3 from high to low, signal EN2 transitions from high to low after a 1μs interval, and signal EN1 transitions from high to low after a 2μs interval. Therefore, the first operating time of the bandgap reference source 10 and the bandgap amplifier 20 is 84μs, with a period of 33ms. The ratio of the first operating time to the period is 7 / 2750, enabling intermittent operation of the bandgap reference source 10 and the bandgap amplifier 20, achieving extremely short operating times, and reducing the power consumption of the bandgap reference source 10 and the bandgap amplifier 20.

[0048] In this embodiment, the controller 50 is used to control the first switch S1 to turn on at a first preset time t1 interval and the second switch S2 to turn on at a second preset time t2 interval when the bandgap reference source 10 and the bandgap amplifier 20 start working, wherein the second preset time t2 is greater than the first preset time t1; the controller 50 is used to control the second switch S2 to turn off when the voltage Vhold between the third resistor R3 and the second capacitor C2 reaches stability, control the first switch S1 to turn off at a third preset time t3 interval, and control the bandgap reference source 10 and the bandgap amplifier 20 to stop working at a fourth preset time t4 interval. Through the above method, the bandgap reference source 10 and the bandgap amplifier 20 can operate intermittently and for extremely short periods, reducing the power consumption of the bandgap reference source 10 and the bandgap amplifier 20.

[0049] Please see Figure 1 As shown, the output voltage of the filter circuit 30 in this embodiment satisfies the following formula: (1); in, , R3 is the conduction time of the second switch S2, R3 is the resistance value of the third resistor R3, and C2 is the capacitance value of the second capacitor C2. This is the output voltage of the filter circuit 30. Let n be the input voltage of filter circuit 30, where n is a positive integer greater than or equal to 1. Vhold is the voltage Vhold between the third resistor R3 and the second capacitor C2 in the above embodiment. Vref is the voltage Vref between the first switch S1 and the first capacitor C1 in the above embodiment.

[0050] Controller 50 is used to perform z-transform on formula (1) to obtain the complex frequency domain expression of the output voltage of filter circuit 30 in discrete time as follows: (2); Where z is the complex frequency variable. Equation (2) can be transformed into: (3); Where f is the noise frequency of the bandgap reference source 10 and the bandgap amplifier 20, T1 is the aforementioned period, j is the imaginary unit, and the square of j equals -1.

[0051] The output voltage of filter circuit 30 is obtained based on formula (3). The input voltage of the filter circuit 30 The ratio of the modulus: (4); When the noise frequency f of the bandgap reference source 10 and the bandgap amplifier 20 is very small, the following formula is satisfied: (5); Substituting formula (5) into formula (4) yields: (6); The noise frequency f of the bandgap reference source 10 and the bandgap amplifier 20 is equal to the cutoff frequency of the filter circuit 30. When the following formula is satisfied: (7); Substituting formula (7) into formula (6) yields: (8); Therefore, the cutoff frequency of filter circuit 30 Satisfy the following formula: (9); in, T1 is the cutoff frequency of filter circuit 30, and T1 is the period.

[0052] In some embodiments, the resistance of the third resistor R3 is 1MΩ, the capacitance of the second capacitor C2 is 100pF, and the conduction time of the second switch S2 is... For 2μs, based on We can obtain k as 0.02. The period T1 is 33ms. Substituting into formula (9), we obtain the cutoff frequency of filter circuit 30. The frequency is 0.069Hz, meaning that the filter circuit 30 can filter out noise with a frequency higher than 0.069Hz in the voltage Vref between the first switch S1 and the first capacitor C1.

[0053] The cutoff frequency of the filter circuit 30 in this embodiment Satisfy the following formula To enable the filter circuit 30 to achieve a lower cutoff frequency. For example, cutoff frequency The frequency is 0.069Hz, and thus the filter circuit 30 filters out low noise from the bandgap reference source 10 and the bandgap amplifier 20.

[0054] Please see Figure 1 and Figure 3 As shown, Figure 3 yes Figure 1 A circuit diagram of one embodiment of a mid-bandgap reference source. The bandgap reference source 10 in this embodiment includes a second amplifier 11, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a second switch Q2, and a third switch Q3.

[0055] The first input terminal of the second amplifier 11 is connected to the control terminal of the second switch Q2, the first terminal of the third switch Q3, and one end of the sixth resistor R6. The second input terminal of the second amplifier 11 is connected to the first terminal of the second switch Q2 and one end of the fourth resistor R4. The output terminal of the second amplifier 11 is connected to the other end of the fourth resistor R4, the other end of the fifth resistor R5, the other end of the sixth resistor R6, and the first input terminal of the bandgap amplifier 20. One end of the fifth resistor R5 is connected to the control terminal of the third switch Q3. The second terminals of the second switch Q2 and the second terminals of the third switch Q3 are grounded through the seventh resistor R7. The fifth resistor R5 is used to perform exponential curvature compensation on the voltage output by the second amplifier 11.

[0056] In some implementations, both the second switch Q2 and the third switch Q3 are NPN transistors. The first terminal of the second switch Q2 is the collector of the NPN transistor, the second terminal is the emitter of the NPN transistor, and the control terminal of the second switch Q2 is the base of the NPN transistor. Similarly, the first terminal of the third switch Q3 is the collector of the NPN transistor, the second terminal is the emitter of the NPN transistor, and the control terminal of the third switch Q3 is the base of the NPN transistor. In other embodiments, the second switch Q2 and the third switch Q3 can be other types of switches, which will not be elaborated here.

[0057] The bandgap reference source 10 in this embodiment includes a second amplifier 11, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a second switch Q2, and a third switch Q3; by performing exponential curvature compensation on the voltage output of the second amplifier 11 through the fifth resistor R5, the high-order temperature nonlinearity error of the bandgap reference source 10 can be reduced.

[0058] In some implementations, the voltage output by the second amplifier 11 satisfies the following formula: (10); in, The voltage output by the second amplifier 11 The voltage difference between the control terminal and the second terminal of the third switch Q3. The voltage difference between the control terminal and the second terminal of the second switch Q2. for and The difference between them, R4 is the resistance value of the fourth resistor R4, R5 is the resistance value of the fifth resistor R5, and R7 is the resistance value of the seventh resistor R7. T represents the amplification factor of the third switching transistor Q3, and T represents the temperature.

[0059] In some embodiments, the current flowing through the fifth resistor R5 is The current flowing through the sixth resistor R6 is Then the voltage drop across the sixth resistor R6 satisfies the following formula: (11); Where R6 is the resistance value of the sixth resistor R6, and the resistance value of the sixth resistor R6 is equal to the resistance value of the fourth resistor R4. for and The difference between them The voltage difference between the control terminal and the second terminal of the third switch Q3. This is the voltage difference between the control terminal and the second terminal of the second switch Q2.

[0060] Current flowing through the fifth resistor R5 With the current flowing through the sixth resistor R6 Satisfy the following formula: (12); in, This refers to the amplification factor of the third switch Q3. For example, the amplification factor of the second switch Q2 is equal to the amplification factor of the third switch Q3. The voltage output of the second amplifier 11... Satisfy the following formula: (13); Combining formulas (11), (12) and (13), we obtain the above formula (10).

[0061] In some embodiments, see Figure 1 As shown, the reference voltage circuit 100 in this embodiment also includes a fourth switch Q4 and a fifth switch Q5.

[0062] In this configuration, the control terminal of the fourth switch Q4 is connected to the first output terminal of the first amplifier 40, the control terminal of the fifth switch Q5 is connected to the second output terminal of the first amplifier 40, the second terminals of the fourth switch Q4 and the fifth switch Q5 are connected to the second input terminal of the first amplifier 40, the first terminal of the fourth switch Q4 receives the second voltage V2, the first terminal of the fifth switch Q5 is grounded, and the second terminals of the fourth switch Q4 and the fifth switch Q5 are used to output a reference voltage.

[0063] In some embodiments, the fourth switch Q4 can be a P-channel MOSFET, with its first terminal being the source and its second terminal being the drain, and its control terminal being the gate. The fifth switch Q5 can be an N-channel MOSFET, with its first terminal being the source and its second terminal being the drain, and its control terminal being the gate.

[0064] This application also provides an electronic device including the aforementioned reference voltage circuit 100, which is used to output a reference voltage. For example, the reference voltage circuit 100 is used to provide a stable reference voltage to the analog-to-digital converter or digital-to-analog converter of the electronic device.

[0065] The controller 50 of this application is connected to the bandgap reference source 10, the bandgap amplifier 20, the first switch S1, and the filter circuit 30, respectively. The controller 50 is used to control the bandgap reference source 10 and the bandgap amplifier 20 to operate for a first operating time in each cycle, and to control the first switch S1 and the filter circuit 30 sequentially during the first operating time. The ratio of the first operating time to the cycle is less than or equal to 1 / 100. By controlling the bandgap reference source 10 and the bandgap amplifier 20 to operate simultaneously for a first operating time in each cycle, the bandgap reference source 10 and the bandgap amplifier 20 can achieve intermittent operation, thereby reducing the power consumption of the bandgap reference source 10 and the bandgap amplifier 20. By ensuring that the ratio of the first operating time to the cycle is less than or equal to 1 / 100, the bandgap reference source 10 and the bandgap amplifier 20 can achieve extremely short operating times, further reducing the power consumption of the bandgap reference source 10 and the bandgap amplifier 20. By filtering noise through the filter circuit 30, the noise of the reference voltage circuit 100 can be reduced.

[0066] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A reference voltage circuit, characterized in that, include: Bandgap reference source; The bandgap amplifier comprises a first switching transistor, a first resistor, and a second resistor. The first input terminal of the bandgap amplifier is connected to the bandgap reference source, and the output terminal of the bandgap amplifier is connected to the control terminal of the first switching transistor. The first terminal of the first switching transistor receives a first voltage, and the second terminal of the first switching transistor is grounded through the first resistor and the second resistor. The second input terminal of the bandgap amplifier is connected between the first resistor and the second resistor. The system comprises a first switch, a first capacitor, a filter circuit, and a first amplifier. One end of the first switch is connected to the second end of the first switching transistor, and the other end of the first switch is connected to one end of the first capacitor and the filter circuit. The other end of the first capacitor is grounded, and the filter circuit is connected to the first amplifier. The controller is connected to the bandgap reference source, the bandgap amplifier, the first switch, and the filter circuit respectively. The controller is used to control the bandgap reference source and the bandgap amplifier to work for a first working time in each cycle, and to control the first switch and the filter circuit in sequence during the first working time. The ratio of the first working time to the cycle is less than or equal to 1 / 100.

2. The reference voltage circuit according to claim 1, characterized in that, The filter circuit includes a second switch, a third resistor, and a second capacitor. One end of the second switch is connected to the other end of the first switch, the other end of the second switch is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the first amplifier and one end of the second capacitor, and the other end of the second capacitor is grounded.

3. The reference voltage circuit according to claim 2, characterized in that, The controller is connected to the second switch. The controller is used to control the first switch to turn on at a first preset time interval and the second switch to turn on at a second preset time interval when controlling the bandgap reference source and the bandgap amplifier to start working. The second preset time is greater than the first preset time.

4. The reference voltage circuit according to claim 3, characterized in that, The controller is used to control the second switch to open when the voltage between the third resistor and the second capacitor reaches stability, control the first switch to open at a third preset time interval, and control the bandgap reference source and the bandgap amplifier to stop working at a fourth preset time interval. The third preset time is less than the difference between the second preset time and the first preset time, and the fourth preset time is greater than the third preset time.

5. The reference voltage circuit according to claim 3, characterized in that, The first preset time is between 5 and 40 μs, and the difference between the second preset time and the first preset time is between 5 and 40 μs.

6. The reference voltage circuit according to claim 2, characterized in that, The output voltage of the filter circuit satisfies the following formula: in, , R3 is the conduction time of the second switch, R3 is the resistance value of the third resistor, and C2 is the capacitance value of the second capacitor. The output voltage of the filter circuit is [value]. The input voltage of the filter circuit is n, where n is a positive integer greater than or equal to 1. The cutoff frequency of the filter circuit satisfies the following formula: in, T1 is the cutoff frequency of the filter circuit and T2 is the period.

7. The reference voltage circuit according to any one of claims 1-6, characterized in that, The bandgap reference source includes a second amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second switch, and a third switch. The first input terminal of the second amplifier is connected to the control terminal of the second switch, the first terminal of the third switch, and one end of the sixth resistor. The second input terminal of the second amplifier is connected to the first terminal of the second switch and one end of the fourth resistor. The output terminal of the second amplifier is connected to the other end of the fourth resistor, the other end of the fifth resistor, the other end of the sixth resistor, and the first input terminal of the bandgap amplifier. One end of the fifth resistor is connected to the control terminal of the third switch. The second terminals of the second and third switches are grounded through the seventh resistor. The fifth resistor is used to perform exponential curvature compensation on the voltage output by the second amplifier.

8. The reference voltage circuit according to claim 7, characterized in that, The voltage output by the second amplifier satisfies the following formula: in, The voltage output by the second amplifier. The voltage difference between the control terminal and the second terminal of the third switch is... The voltage difference between the control terminal and the second terminal of the second switch is [missing information]. for and The difference between them, where R4 is the resistance value of the fourth resistor, R5 is the resistance value of the fifth resistor, and R7 is the resistance value of the seventh resistor. The amplification factor of the third switching transistor is given by T, where T is the temperature.

9. The reference voltage circuit according to claim 8, characterized in that, The reference voltage circuit further includes a fourth switch and a fifth switch. The control terminal of the fourth switch is connected to the first output terminal of the first amplifier, and the control terminal of the fifth switch is connected to the second output terminal of the first amplifier. The second terminals of the fourth and fifth switches are connected to the second input terminal of the first amplifier. The first terminal of the fourth switch receives a second voltage, and the first terminal of the fifth switch is grounded. The second terminals of the fourth and fifth switches are used to output a reference voltage.

10. An electronic device, characterized in that, Includes a reference voltage circuit as described in any one of claims 1-9, wherein the reference voltage circuit is used to output a reference voltage.

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