Band-gap reference circuit, calibration method, chip and electronic equipment

Abstract

The embodiment of the invention provides a band-gap reference circuit, a calibration method, a chip and electronic equipment, and the band-gap reference circuit comprises a temperature drift calibration circuit which comprises a first current generation module which is used for generating a first current based on a first calibration code word; the second current generation module is used for generating a second current based on the first calibration code word; one of the first current and the second current is a positive temperature coefficient current and the other is a negative temperature coefficient current, and the first current and the second current change in equal proportion along with the change of the first calibration code word; the third current generation module is used for scaling the first current based on the second calibration code word to obtain a third current; the output end of the second current generation module is connected with the output end of the third current generation module and serves as an output node of the temperature drift calibration circuit, and the second current generation module is used for outputting temperature drift calibration current based on the difference between the second current and the third current so as to calibrate the temperature drift of the reference signal. According to the embodiment of the invention, the calibration effect is low in process sensitivity.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a bandgap reference circuit, a calibration method, a chip and an electronic device. Background Art

[0002] In the related art, the first-order temperature drift calibration adopts single-point calibration or two-point calibration. Single-point calibration is difficult to achieve low temperature drift. Two-point calibration uses a theoretical formula to calculate the required temperature drift first-order calibration value, but this calibration value depends on the process parameters, so changes in process parameters will cause changes in the calibration effect. Summary of the invention

[0003] In view of the above problems, the embodiments of the present application provide a bandgap reference circuit, a calibration method, a chip and an electronic device to solve the above technical problems.

[0004] In the first aspect, the embodiment of the present application provides a bandgap reference circuit, including: a first current generating module, used to generate a first current based on a first calibration codeword; a second current generating module, used to generate a second current based on the first calibration codeword; one of the first current and the second current is a positive temperature coefficient current and the other is a negative temperature coefficient current, and the first current and the second current change in proportion to the change of the first calibration codeword; a third current generating module, the input end of which is connected to the first current generating module, and is used to scale the first current based on the second calibration codeword to obtain a third current; wherein the output end of the second current generating module is connected to the output end of the third current generating module and serves as the output node of the temperature drift calibration circuit, and is used to output a first-order temperature drift calibration current based on the difference between the second current and the third current, and the temperature drift calibration current is used to calibrate the temperature drift of the reference signal. When calibrating the circuit of this embodiment, the second calibration codeword is adjusted at the first temperature so that the difference between the second current and the third current is substantially zero, and the first calibration codeword is adjusted at the second temperature so that the reference signal is equal to the reference signal at the first temperature, the calibration depends on the signal measurement and has nothing to do with the process parameters, and the calibration effect has low process sensitivity.

[0005] Optionally, the first current generating module includes: a first current source array for receiving a first calibration codeword and generating a first current based on the first calibration codeword; the second current generating module includes: a second current source array for receiving the first calibration codeword and generating a second current based on the first calibration codeword.

[0006] Optionally, the first current source array includes: N first mirror branches connected in parallel, N is an integer greater than or equal to 2, each first mirror branch includes: a first current mirror unit, used to copy a current with a temperature coefficient corresponding to the first current to generate a first branch current; and a first switch unit, connected in series with the first current mirror unit, each first switch unit is controlled by a digital bit in a first calibration codeword, and is used to turn on or off the first mirror branch; wherein the first current is the sum of the first branch currents of the turned-on first mirror branches.

[0007] Optionally, the first current generating module further includes: a first bias voltage unit, configured to generate a bias voltage of the first current source array.

[0008] Optionally, the second current source array includes: P second mirror branches connected in parallel, P is an integer greater than or equal to 2, each second mirror branch includes: a second current mirror unit, used to copy the current with a temperature coefficient corresponding to the second current to generate a second branch current; and a second switch unit, connected in series with the second current mirror unit, each second switch unit is controlled by a digital bit in the first calibration codeword, and is used to turn on or off the second mirror branch; wherein the second current is the sum of the second branch currents of the turned-on second mirror branches.

[0009] Optionally, the second current generating module further includes: a second bias voltage unit, configured to generate a bias voltage for the second current source array.

[0010] Optionally, the third current generating module includes: a current receiving unit and a third current source array; the current receiving unit is used to receive the first current and generate a bias voltage for the third current source array; the third current source array is connected to the current receiving unit, is used to receive a second calibration codeword, and based on the second calibration codeword, mirrors the first current to generate a second current.

[0011] Optionally, the third current source array includes: M third mirror branches connected in parallel, M is an integer greater than or equal to 2, each third mirror branch includes: a third current mirror unit, used to mirror the first current to generate a third branch current; and a third switch unit, connected in series with the third current mirror unit, each third switch unit is controlled by a digital bit in the second calibration codeword, and is used to turn on or off the third mirror branch; wherein the third current is the sum of the third branch currents of the turned-on third mirror branches.

[0012] Optionally, the bandgap reference circuit further includes: a first calibration module, configured to adjust the second calibration codeword at the first temperature so that the difference between the second current and the third current is zero; and adjust the first calibration codeword at the second temperature so that the reference signal is equal to the reference signal at the first temperature.

[0013] Optionally, the first calibration module includes: a comparison unit, used to compare the calibration reference voltage and the voltage of the output node and generate a comparison output; and a control unit, used to adjust the second calibration codeword based on the comparison output until the comparison output jumps.

[0014] Optionally, the bandgap reference circuit also includes: a first switch connected between the output node and the first comparison input terminal of the comparison unit; a second switch connected between the calibration reference voltage terminal and the second comparison input terminal of the comparison unit, wherein the calibration reference voltage terminal is used to output the calibration reference voltage; wherein the first switch and the second switch are turned on when calibration of the first temperature is performed.

[0015] Optionally, the bandgap reference circuit further includes: a second calibration module, configured to adjust the reference signal to a target value at the first temperature after adjusting the second calibration codeword so that the difference between the second current and the third current is zero.

[0016] Optionally, the second calibration module includes: an adjustable resistor array.

[0017] Optionally, the bandgap reference circuit further includes: a reference circuit; wherein the output node is connected to a first calibration node of the reference circuit, and is used to inject the above-mentioned temperature drift calibration current into the first calibration node.

[0018] Optionally, the reference circuit includes at least two transistors, and the first calibration node is on a common branch of the at least two transistors.

[0019] Optionally, the first calibration node is at any resistance node in the output path of the reference signal.

[0020] Optionally, the bandgap reference circuit further includes: a high-order temperature drift calibration circuit connected to the second calibration node of the reference circuit, configured to generate a high-order temperature drift calibration current and inject the high-order temperature drift calibration current into the second calibration node.

[0021] Optionally, the bandgap reference circuit also includes a reference circuit, which includes: an operational amplifier module; a chopping module, used to alternately switch the positive and negative directions of the operational amplifier input and the operational amplifier output to modulate the mismatch voltage of the operational amplifier module to a high frequency; and a notch filter module, used to filter the operational amplifier output.

[0022] In a second aspect, an embodiment of the present application provides a calibration method for a bandgap reference circuit, the method comprising: generating a first current based on a first calibration codeword; generating a second current based on the first calibration codeword; one of the first current and the second current is a positive temperature coefficient current and the other is a negative temperature coefficient current, and the first current and the second current change proportionally with the first calibration codeword; scaling the first current based on the second calibration codeword to obtain a third current; and outputting a temperature drift calibration current to the reference circuit based on the difference between the second current and the third current to calibrate the temperature drift of the reference signal.

[0023] Optionally, the calibration method further includes: adjusting the second calibration code at the first temperature so that the difference between the second current and the third current is zero; and adjusting the first calibration code at the second temperature so that the reference signal is equal to the reference signal at the first temperature.

[0024] Optionally, the calibration method further comprises: after adjusting the second calibration codeword so that the difference between the second current and the third current is zero, adjusting the reference signal to a target value at the first temperature.

[0025] In a third aspect, an embodiment of the present application further provides a chip comprising the above-mentioned circuit.

[0026] In a fourth aspect, an embodiment of the present application further provides an electronic device, comprising the above-mentioned chip or circuit.

[0027] The bandgap reference circuit, calibration method, chip and electronic device provided by the embodiments of the present application have a two-point calibration that depends on signal measurement and is independent of process parameters, and the calibration effect has low process sensitivity.

[0028] These and other aspects of the present application will become more clearly understood in the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 A schematic diagram of the structure of a temperature drift calibration circuit provided in an embodiment of the present application is shown.

[0031] Figure 2 A schematic structural diagram of the first current generating module 11 provided in an embodiment of the present application is shown.

[0032] Figure 3 A schematic structural diagram of the second current generating module 12 provided in an embodiment of the present application is shown.

[0033] Figure 4 A schematic structural diagram of the third current generating module 13 provided in an embodiment of the present application is shown.

[0034] Figure 5 A schematic diagram of the structure of a temperature drift calibration circuit provided in an embodiment of the present application is shown.

[0035] Figure 6 A schematic structural diagram of a bandgap reference circuit provided in an embodiment of the present application is shown.

[0036] Figure 7 A circuit diagram of a calibration node provided in an embodiment of the present application is shown.

[0037] Figure 8 A circuit diagram of another calibration node provided in an embodiment of the present application is shown.

[0038] Fig. 9 A circuit diagram of another calibration node provided in an embodiment of the present application is shown.

[0039] Fig.10 A circuit diagram of a bandgap reference circuit provided in an embodiment of the present application is shown.

[0040] Fig.11 A flow chart of a calibration method provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0041] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0042] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0043] In the embodiments of the present application, at least one refers to one or more; multiple refers to two or more. In the description of the present application, the words "first", "second", "third", etc. are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order.

[0044] References to "one embodiment" or "some embodiments" etc. described in this specification mean that one or more embodiments of the present application include a particular feature, structure or characteristic described in conjunction with the embodiment. Thus, in this specification, the terms "include", "comprises", "has" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0045] It should be noted that in the embodiments of the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0046] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0047] The first pole / first end of each transistor used in the embodiments of the present application is one of the source and the drain, and the second pole / second end of each transistor is the other of the source and the drain. Since the source and drain of the transistor can be symmetrical in structure, the source and drain thereof can be structurally indistinguishable, that is, the first pole / first end and the second pole / second end of the transistor in the embodiments of the present application can be structurally indistinguishable. Exemplarily, in the case where the transistor is a P-type transistor, the first pole / first end of the transistor is the source, and the second pole / second end is the drain; exemplarily, in the case where the transistor is an N-type transistor, the first pole / first end of the transistor is the drain, and the second pole / second end is the source.

[0048] In the circuit structure provided in the embodiments of the present application, the first node, the second node and other nodes do not represent actual existing components, but represent the junction points of related couplings in the circuit diagram, that is, these nodes are nodes formed by the equivalent junction points of related couplings in the circuit diagram.

[0049] The embodiment of the present application provides a bandgap reference circuit, which is used to output a reference signal. In the implementation of the present application, the bandgap reference circuit may include a temperature drift calibration circuit, which may generate a temperature drift calibration current to calibrate the temperature drift of the reference signal. The reference signal may include a reference voltage signal and a reference current signal.

[0050] Figure 1 FIG. 4 shows a schematic diagram of the structure of the temperature drift calibration circuit provided in an embodiment of the present application. Figure 1As shown, the temperature drift calibration circuit 100 includes: a first current generating module 11, used to generate a first current based on a first calibration codeword; a second current generating module 12, used to generate a second current based on the first calibration codeword; a third current generating module 13, connected to the output end of the first current generating module 11, used to scale the first current based on the second calibration codeword to obtain a third current; wherein the output end of the second current generating module 12 is connected to the output end of the third current generating module 13 and serves as an output node 14 of the temperature drift calibration circuit 100, and the output node 14 is used to output a temperature drift calibration current based on the difference between the second current and the third current, and the temperature drift calibration current is used to calibrate the temperature drift of the reference signal.

[0051] Among them, one of the first current and the second current is a positive temperature coefficient current and the other is a negative temperature coefficient current. Specifically, the first current generating module 11 generates a first current with a positive temperature coefficient, and the second current generating module 12 generates a second current with a negative temperature coefficient; or the first current generating module 11 generates a first current with a negative temperature coefficient, and the second current generating module 12 generates a second current with a positive temperature coefficient.

[0052] The first current and the second current change in equal proportion to the first calibration codeword. Specifically, when the first calibration codeword changes from D1 to D2, the first current and the second current are scaled in the same proportion.

[0053] In this embodiment, the third current is obtained by scaling the first current, and the temperature coefficient of the third current is consistent with that of the first current. Specifically, if the first current is a positive temperature coefficient current, the third current is also a positive temperature coefficient current; or if the first current is a negative temperature coefficient current, the third current is also a negative temperature coefficient current. The difference between the third current and the second current is equivalent to the difference between the negative temperature coefficient current and the positive temperature coefficient current.

[0054] When calibrating the circuit of this embodiment, the second calibration code is adjusted at the first temperature so that the difference between the second current and the third current is substantially zero, and the first calibration code is adjusted at the second temperature so that the reference signal is substantially equal to the reference signal at the first temperature.

[0055] At the first temperature, the difference between the second current and the third current after the calibration of the first temperature is recorded as Ix1. At the second temperature, the difference between the second current and the third current after the calibration of the second temperature is recorded as Ix2. Since the first current and the second current change in proportion to the first calibration codeword, and the third current is obtained by scaling based on the first current, when the first calibration codeword is adjusted so that the second current is scaled n times, the first current is scaled n times, and the third current is scaled n times, then Ix2 = n*Ix1, wherein when the first calibration codeword is adjusted so that the second current is amplified, n is greater than 1, and when the first calibration codeword is adjusted so that the second current is reduced, n is less than 1. Since Ix2 is in an n-fold relationship with Ix1, after Ix1 is calibrated to be close to 0 at the first temperature, when the calibration of the second temperature is performed, Ix2 is still close to 0. Therefore, after calibration, at the first temperature and the second temperature, the difference between the second current and the third current is substantially zero, and the reference signal is substantially equal, so that calibration at two temperature points can be achieved. Furthermore, the two-point calibration depends on signal measurement (ie, measurement of the difference between the second current and the third current, measurement of the reference signal) and has nothing to do with process parameters, and the calibration effect has low process sensitivity.

[0056] In some possible implementations, the first current, the second current, and the third current are proportional to the temperature, and the temperature drift calibration current is used to perform first-order temperature compensation on the reference signal. The temperature drift calibration current is called a first-order temperature drift calibration current.

[0057] In some possible implementations, the first current, the second current and the third current are proportional to the square of the temperature, and the above-mentioned temperature drift calibration current includes first-order temperature drift and high-order temperature drift, which can be used to perform first-order temperature compensation and high-order temperature compensation on the reference signal.

[0058] As an implementation manner, the first current generating module 11 includes a first current source array, and the first current source array is used to receive a first calibration codeword and generate a first current based on the first calibration codeword. Figure 2 An exemplary first current generating module 11 is described.

[0059] Figure 2 FIG. 1 shows a schematic diagram of the structure of the first current generating module 11 provided in an embodiment of the present application. Figure 2As shown, the first current generating module 11 includes a first current source array 111. The first current source array 111 includes: N first mirror branches connected in parallel, respectively marked as first mirror branches 111-1, first mirror branches 111-2 to first mirror branches 111-N, each first mirror branch may include: a first current mirror unit 1111, used to copy the current with a temperature coefficient corresponding to the first current to generate a first branch current; and a first switch unit 1112, connected in series with the first current mirror unit 1111, each first switch unit 1112 is controlled by a digital bit in the first calibration codeword, and is used to turn on or off the corresponding first mirror branch. Wherein, the first current is the sum of the first branch currents of the first mirror branches that are turned on. Wherein, if the first current generating module 11 is used to generate a first current with a positive temperature coefficient, the first current source array 111 copies the current with a positive temperature coefficient; if the first current generating module 11 is used to generate a first current with a negative temperature coefficient, the first current source array 111 copies the current with a negative temperature coefficient.

[0060] As an implementation, the first switch unit 1112 may include at least one transistor, and the at least one transistor receives a digital bit in the first calibration codeword and serves as a switch tube controlled by the digital bit.

[0061] As an implementation method, Figure 2 As shown, the first current generating module 11 further includes: a first bias voltage unit 112 for generating a bias voltage of the first current source array 111 .

[0062] As an implementation manner, the second current generating module 12 includes a second current source array, and the second current source array is used to receive the first calibration codeword and generate the second current based on the first calibration codeword. Figure 3 An exemplary second current generating module 12 is described.

[0063] Figure 3 FIG. 1 shows a schematic diagram of the structure of the second current generating module 12 provided in an embodiment of the present application. Figure 3As shown, the second current generating module 12 includes a second current source array 121. The second current source array 121 includes: P second mirror branches connected in parallel, respectively marked as second mirror branches 121-1, second mirror branches 121-2 to second mirror branches 121-P, each second mirror branch includes: a second current mirror unit 1211, used to copy the current with a temperature coefficient corresponding to the second current to generate a second branch current; and a second switch unit 1212, connected in series with the second current mirror unit 1211, each second switch unit 1212 is controlled by a digital bit in the first calibration codeword, and is used to turn on or off the corresponding second mirror branch. Wherein, the second current is the sum of the second branch currents of the turned-on second mirror branches. Wherein, if the second current generating module 12 is used to generate a second current with a positive temperature coefficient, the second current source array 121 is used to copy the current with a positive temperature coefficient; if the second current generating module 12 is used to generate a second current with a negative temperature coefficient, the second current source array 121 is used to copy the current with a negative temperature coefficient.

[0064] As an implementation method, Figure 3 As shown, the second current generating module 12 further includes: a second bias voltage unit 122 for generating a bias voltage for the second current source array 121 .

[0065] In some embodiments, the first current source array 111 and the second current source array 121 may have the same number of mirror branches, for example, the first current source array 111 and the second current source array 121 may each include N mirror branches. The N mirror branches receive an N-bit first calibration codeword.

[0066] In some embodiments, the number of mirror branches of the first current source array 111 and the second current source array 121 may be different. That is, the number P of the second mirror branches is not equal to the number N of the first mirror branches, that is, P is not equal to N. Among them, the first current source array 111 and the second current source array 121 both generate corresponding currents based on the first calibration codeword, and when the number of mirror branches of the two is different, the two share the high-order digital bits of the first calibration codeword. For example, when P is greater than N, the number of bits of the first calibration codeword is greater than or equal to P, wherein the first current source array 111 generates a first branch current based on the high N bits of the first calibration codeword, and the second current source array 111 generates a second branch current based on the high P bits of the first calibration codeword. Since the weight corresponding to the high bit is much greater than the low bit, the first current and the second current are generally proportional.

[0067] Figure 4 FIG. 1 shows a schematic diagram of the structure of the third current generating module 13 provided in an embodiment of the present application. Figure 4As shown, the third current generating module 13 includes: a current receiving unit 131 and a third current source array 132. The current receiving unit 131 is used to receive the first current and generate a bias voltage of the third current source array 132; the third current source array 132 is connected to the current receiving unit 131, and is used to receive the second calibration codeword, and based on the second calibration codeword, the first current is mirrored to generate the second current. As an example, the current receiving unit 131 may include a current mirror.

[0068] As an example, as shown in FIG. 4 , the third current source array 132 includes: M third mirror branches connected in parallel, respectively marked as third mirror branches 132-1, third mirror branches 132-2 to third mirror branches 132-M, each third mirror branch includes: a third current mirror unit 1321, used to mirror the first current to generate a third branch current; and a third switch unit 1322, connected in series with the third current mirror unit 1321, each third switch unit 1312 is controlled by a digital bit in the second calibration codeword, and is used to turn on or off the corresponding third mirror branch. The third current is the sum of the third branch currents of the turned-on third mirror branches.

[0069] Figure 5 FIG. 1 shows a schematic diagram of the structure of a temperature drift calibration circuit 100 provided in an embodiment of the present application. Figure 5 As shown, the temperature drift calibration circuit 100 may further include: a first calibration module 15, used to adjust the second calibration code at the first temperature so that the difference between the second current and the third current is zero; and adjust the first calibration code at the second temperature so that the reference signal is substantially equal to the reference signal at the first temperature.

[0070] As an implementation method, Figure 5 As shown, the first calibration module 15 includes: a comparison unit 151, used to compare the calibration reference voltage and the voltage of the output node 14 and generate a comparison output; a control unit 152, used to adjust the second calibration code word based on the comparison output until the comparison output jumps.

[0071] In some embodiments, the temperature drift calibration circuit 100 may further include: a second calibration module 16, which is used to adjust the reference signal to the target value at the first temperature after adjusting the second calibration codeword so that the difference between the second current and the third current is zero. Further, a first calibration module 15 is used to adjust the first calibration codeword at the second temperature to adjust the reference signal to the target value after adjusting the reference signal to the target value at the first temperature, and at this time, the reference signal is the target value at both the first temperature and the second temperature.

[0072] As an implementation method, Figure 5As shown, the temperature drift calibration circuit 100 further includes: a first switch 17 connected between the output node 14 and the first comparison input terminal 1511 of the comparison unit 151; a second switch 18 connected between the calibration reference voltage terminal and the second comparison input terminal 1512 of the comparison unit 151, wherein the calibration reference voltage terminal is used to receive the calibration reference voltage. The first switch 17 and the second switch 18 are turned on when the first temperature calibration is performed.

[0073] Figure 5 The first current generating module 11, the second current generating module 12 and the third current generating module 13 can be seen in Figures 2 to 4 As shown, this manual will not go into details here.

[0074] The embodiment of the present application also provides a bandgap reference circuit.

[0075] Figure 6 FIG. 4 shows a schematic diagram of the structure of a bandgap reference circuit provided in an embodiment of the present application. Figure 6 As shown, the bandgap reference circuit 600 includes: a reference circuit 61 for generating a reference signal; and a temperature drift calibration circuit 62 , wherein an output node of the temperature drift calibration circuit 62 is connected to a first calibration node 611 of the reference circuit 61 .

[0076] Temperature drift calibration circuit 62 refer to this manual Figures 1 to 5 The reference signal generated by the reference circuit 61 may include a reference current signal and / or a reference voltage signal.

[0077] When using the embodiment of the present application, during calibration, the second calibration code is adjusted at the first temperature until the difference between the second current and the third current is substantially zero, and the first calibration code is adjusted at the second temperature until the reference signal reaches the target value. The two-point calibration depends on signal measurement and is independent of process parameters, and the calibration effect has low process sensitivity.

[0078] As an implementation method, Figure 6 As shown, the bandgap reference circuit 600 may further include: a high-order temperature drift calibration circuit 63, connected to the second calibration node 612 of the reference circuit, for generating a high-order temperature drift calibration current to perform high-order temperature drift compensation on the reference signal. In some examples, the second calibration node 612 and the first calibration node 611 may be the same node. In some examples, the second calibration node 612 and the first calibration node 611 may be different nodes.

[0079] As an implementation method, Figure 6As shown, the reference circuit 61 includes: an operational amplifier module 613; a chopping module 614, which is used to alternately switch the positive and negative directions of the operational amplifier input and the operational amplifier output to modulate the mismatch voltage of the operational amplifier module 613 to a high frequency; a notch filter module (notch filter) 615, which is used to filter the output of the operational amplifier. The use of this embodiment can reduce the high-order temperature drift caused by the operational amplifier offset, and compared with the method of reducing the operational amplifier offset by increasing the operational amplifier area, the circuit area can be reduced. It should be understood that the embodiment of the present application does not exclude the method of increasing the operational amplifier area to reduce the operational amplifier offset. The purpose of this embodiment is to illustrate that a better calibration effect can be achieved by chopping and filtering under approximately the same operational amplifier area.

[0080] It should be understood that the first calibration node and / or the second calibration node are not limited in the present embodiment. Figures 7 to 9 , exemplary implementations of the first calibration node and the second calibration node are described.

[0081] As an implementation method, the reference circuit may include two transistors, and the first calibration node and / or the second calibration node are on a common branch of the two transistors. Figure 7 As shown, the reference circuit includes an operational amplifier OP, a first transistor Q1 and a second transistor Q2. The first calibration node and / or the second calibration node are located in a common branch of the first transistor Q1 and the second transistor Q2. For example, Figure 7 As shown, a resistor R4 is connected in series on the common branch of the first transistor Q1 and the second transistor Q2. The above-mentioned temperature drift calibration current is injected into R4, thereby changing the reference voltage Vbg. In the embodiment of the present application, the transistor may include a bipolar junction transistor (BJT) or a metal oxide semiconductor field effect transistor (MOS transistor), which is not limited in the present embodiment.

[0082] As an implementation method, the first calibration node and / or the second calibration node is any resistance node on the reference signal output path. Figure 8 and 9 As shown, the first calibration node and / or the second calibration node is between the resistor R4 and the resistor R5.

[0083] Fig.10 : shows a circuit diagram of a bandgap reference circuit provided by an embodiment of the present application, such as Fig.10 As shown, the bandgap reference circuit 1000 includes: a temperature drift calibration circuit 101 and a reference circuit 103. The reference circuit 103 is used to generate a reference voltage Vbg.

[0084] The temperature drift calibration circuit 101 includes IDAC1 (corresponding to the first current generating module mentioned above), IDAC2 (corresponding to the second current generating module mentioned above) and IDAC3 (corresponding to the third current generating module mentioned above). As an implementation mode, IDAC1 generates an IPTAT current (positive temperature coefficient current), IDAC2 generates an ICTAT current (negative temperature coefficient current), and the current generated by IDAC3 is a mirror image of the current generated by IDAC1. As another implementation mode, IDAC1 can generate an ICTAT current, and IDAC2 can generate an IPTAT current. IDAC1 and IDAC2 are controlled by the same calibration codeword (i.e., the first calibration codeword). IDAC3 is controlled by the second calibration codeword. The output end of IDAC2 is connected to the output end of IDAC3 and serves as an output node X.

[0085] As an implementation method, Fig.10 As shown, in the temperature drift calibration circuit 101, IDAC3 can be implemented with a PMOS current mirror, and IDAC1 and IDAC2 can be implemented with an NMOS current mirror. As another implementation, in the temperature drift calibration circuit 101, IDAC3 can be implemented with an NMOS current mirror, and IDAC1 and IDAC2 can be implemented with a PMOS current mirror. Accordingly, IDAC3 is adjusted to be grounded, and IDAC1 and IDAC2 are adjusted to be connected to the power supply.

[0086] In some embodiments, Fig.10 As shown, the temperature drift calibration circuit 101 may also include: a comparator COMP (corresponding to the above-mentioned comparison unit), a first switch k1, a second switch k2, a third switch k3, and R5 and R6. When the first switch k1 and the second switch k2 are turned on and the third switch k3 is turned off, R5 and R6 generate a reference voltage which is input to the negative terminal of the comparator COMP, and the output node X is connected to the positive terminal of the comparator COMP. The comparator compares the signal at its positive terminal and the signal at its negative terminal of the comparator COMP, and outputs a comparison output, that is, compares the reference voltage generated by R5 and R6 with the voltage of the output node X, and outputs a comparison output of the reference voltage and the voltage of the output node X. The temperature drift calibration circuit 101 may also include: a logic unit Logic (corresponding to the above-mentioned control unit), and the logic unit Logic can be used to adjust the calibration codeword of IDAC3 based on the comparison output of the comparator COMP.

[0087] In some embodiments, Fig.10 As shown, the temperature drift calibration circuit 101 may further include: a second adjustable resistor array RT2. The reference voltage Vbg may be adjusted to a target value by adjusting the resistance value of the second adjustable resistor array RT2.

[0088] In some embodiments, Fig.10As shown, the temperature drift calibration circuit 101 may further include: a first adjustable resistor array RT1. The reference voltage Vbg may be adjusted to a target value by adjusting the resistance of the first adjustable resistor array RT1.

[0089] In some implementations, the reference voltage Vbg may be adjusted to a target value by adjusting the resistance of the second adjustable resistor array RT2 and the resistance of the first adjustable resistor array RT1 .

[0090] In some embodiments, Fig.10 As shown, it may also include: a high-order temperature drift calibration circuit 102, which is used to generate a high-order temperature drift calibration current to perform high-order temperature drift compensation on the reference voltage Vbg.

[0091] Calibration method 1

[0092] At the first temperature point (such as room temperature), the first switches k1 and k2 are turned on, and the third switch k3 is turned off. A reference voltage is generated through R5 and R6 and input to the negative terminal of the comparator COMP. At this time, the output node X is a high-resistance node, and the small current difference between IDAC2 and IDAC3 will pull the output node X to the power supply or ground. The comparator COMP compares the output node X with the reference voltage to obtain a judgment result. By controlling the calibration code word of IDAC3 (that is, the second calibration code word), the current difference between IDAC3 and IDAC2 (the current difference at the first temperature point is recorded as Ix1) is calibrated to 0 using the binary search method.

[0093] At the second temperature point (such as 85 degrees), the first switch k1 and the second switch k2 are turned off, the third switch k3 is turned on, and the current Ix of the output node X is injected into the reference circuit through the resistors R6 and R4. Since IDAC2 and IDAC3 generate positive temperature coefficient current and negative temperature coefficient current respectively, the current difference between the current generated by IDAC2 and the current generated by IDAC3 (the current difference at the second temperature point is recorded as Ix2) is no longer zero at this time. By controlling the calibration codeword shared by IDAC1 and IDAC2 (i.e., the first calibration codeword), the above current difference Ix2 is scaled, and Vbg is calibrated to the value near the first temperature point again, so as to achieve the calibration of the second temperature point.

[0094] When the calibration codeword shared by IDAC1 and IDAC2 is controlled, the current generated by IDAC2 is amplified or reduced by n times, and the current generated by IDAC1 and the current generated by IDAC3 are also amplified or reduced by n times, that is, the current difference becomes n*Ix2. Among them, when the current is amplified, n is greater than 1; when the current is reduced, n is less than 1. The changed current difference n*Ix2 is used to adjust the Vbg voltage. When the calibration codeword of IDAC2 is obtained at the second temperature point (the corresponding IPTAT and ICTAT current difference at this temperature is n*Ix2), when the temperature becomes room temperature during normal use, the IPTAT and ICTAT current difference at this temperature is n*Ix1, so the current difference at this temperature remains 0 and will not be affected by the calibration at the second temperature point. The Vbg voltage is basically equal at two temperature points, eliminating the influence of first-order temperature drift.

[0095] Calibration method 2

[0096] In the calibration method 2, Vbg is also calibrated to the target value at the first temperature point. The specific calibration process is as follows.

[0097] At the first temperature point (such as room temperature), the first switch k1 and the second switch k2 are turned on, and the third switch k3 is turned off. A reference voltage is generated through R5 and R6 and input to the negative terminal of the comparator COMP. At this time, the output node X is a high-resistance node, and the small current difference between IDAC2 and IDAC3 will pull the output node X to the power ground. Therefore, IDAC3 can be adjusted by binary division to calibrate the current difference to near 0.

[0098] After the first temperature point calibration is completed, the first switch k1 and the second switch k2 are turned off, the third switch k3 is turned on, and the current Ix of the output node X is injected into the reference circuit through the resistors R6 and R4. By adjusting at least one of RT1 and RT2, Vbg is calibrated to the target value.

[0099] At the second temperature point (such as 85 degrees), since the current difference Ix between IDAC2 and IDAC3 is no longer zero at this temperature, the current Ix of the output node X is adjusted by adjusting the current generated by IDAC1 and the current generated by IDAC2, and Vbg is calibrated to the vicinity of the target value again. Since the current Ix of the output node X is approximately equal to 0 at the first temperature, after the calibration at the second temperature point scales Ix, its current size remains zero near the first temperature point, so Vbg can be calibrated to the vicinity of the target value at both temperature points, that is, the influence of the first-order temperature drift of the reference voltage is eliminated.

[0100] The embodiment of the present application provides a calibration method for a bandgap reference circuit, which is applied to any of the bandgap reference circuits described above in the embodiment of the present application.

[0101] Fig.11 A flow chart of the calibration method provided in an embodiment of the present application is shown. Fig.11 As shown, the calibration method includes steps S1102 to S1108.

[0102] Step S1102, generating a first current based on a first calibration codeword;

[0103] Step S1104: generating a second current based on the first calibration codeword.

[0104] Among them, one of the first current and the second current is a positive temperature coefficient current and the other is a negative temperature coefficient current, and the first current and the second current change in proportion to the change of the first calibration codeword.

[0105] Step S1106 , scaling the first current based on the second calibration codeword to obtain a third current.

[0106] Step S1108 , outputting a temperature drift calibration current to the reference circuit based on the difference between the second current and the third current to calibrate the temperature drift of the reference signal.

[0107] With the method of this embodiment, the two-point calibration depends on signal measurement (ie, measurement of the difference between the second current and the third current, measurement of the reference signal) and has nothing to do with process parameters, and the calibration effect has low process sensitivity.

[0108] In some possible implementations, the calibration method further includes: adjusting the second calibration code at the first temperature so that the difference between the second current and the third current is zero; and adjusting the first calibration code at the second temperature so that the reference signal is equal to the reference signal at the first temperature.

[0109] In some possible implementations, the calibration method further includes: after adjusting the second calibration codeword so that the difference between the second current and the third current is zero, adjusting the reference signal to a target value at the first temperature. Accordingly, after adjusting the reference signal to the target value at the first temperature, adjusting the first calibration codeword at the second temperature to adjust the reference signal to the target value.

[0110] In some implementations, the temperature drift calibration current is injected into the first calibration node of the reference circuit.

[0111] As an implementation manner, the reference circuit includes at least two transistors, and the first calibration node is on a common branch of the at least two transistors.

[0112] As an implementation manner, the first calibration node is at any resistance node of the output path of the reference signal, that is, injects the above-mentioned temperature drift calibration current into any resistance node of the output path of the reference signal.

[0113] In some embodiments, the calibration method may further include: generating a high-order temperature drift calibration current and injecting the high-order temperature drift calibration current into the second calibration node.

[0114] In some examples, the second calibration node and the first calibration node may be the same node. In some examples, the second calibration node and the first calibration node may be different nodes.

[0115] For example, the temperature drift calibration current and the high-order temperature drift calibration current are injected into any resistance node of the output path of the reference signal, that is, the first-order temperature compensation and the high-order temperature compensation are injected into the same node.

[0116] For another example, a high-order temperature drift calibration current and the above-mentioned temperature drift calibration current are injected into a common branch of at least two transistors of the reference circuit, that is, the first-order temperature compensation and the high-order temperature compensation are injected into the same node.

[0117] For another example, the temperature drift calibration current is injected into any resistance node of the output path of the reference signal, and a high-order temperature drift calibration current is injected into the common branch of at least two transistors of the reference circuit, that is, the first-order temperature compensation and the high-order temperature compensation are injected into different nodes.

[0118] The embodiment of the present application also provides a chip, which includes the above-mentioned circuit. An integrated circuit (IC) is also called a chip, and the chip can be, but is not limited to, a SOC (System on Chip) chip or a SIP (system in package) chip. The reference signal calibration of the chip depends on the signal measurement and has nothing to do with the process parameters, and the calibration effect has low process sensitivity.

[0119] The embodiment of the present application also provides an electronic device, which includes a device body and a chip as described above provided in the device body. The electronic device may be, but is not limited to, a weight scale, a body fat scale, a nutrition scale, an infrared electronic thermometer, a pulse oximeter, a human body composition analyzer, a mobile power supply, a wireless charger, a fast charging charger, a car charger, an adapter, a display, a USB (Universal Serial Bus) docking station, a stylus, a true wireless headset, a car central control screen, a car, a smart wearable device, a mobile terminal, and a smart home device. Smart wearable devices include, but are not limited to, smart watches, smart bracelets, and cervical massagers. Mobile terminals include, but are not limited to, smart phones, laptops, tablet computers, and POS (point of sales terminal). Smart home devices include, but are not limited to, smart sockets, smart rice cookers, smart sweepers, and smart lights. The reference signal calibration of the electronic device depends on the signal measurement and has nothing to do with the process parameters, and the calibration effect has low process sensitivity.

[0120] The above are only preferred embodiments of the present application, and are not intended to limit the present application in any form. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technical personnel in the field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present application. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A bandgap reference circuit, It is characterized in that A temperature drift calibration circuit is included, wherein the temperature drift calibration circuit includes: A first current generating module, configured to generate a first current based on a first calibration codeword; A second current generating module, configured to generate a second current based on the first calibration codeword; one of the first current and the second current is a positive temperature coefficient current and the other is a negative temperature coefficient current, and the first current and the second current change in proportion to the change of the first calibration codeword; a third current generating module, whose input terminal is connected to the first current generating module, and is used for scaling the first current based on a second calibration codeword to obtain a third current; Among them, the output end of the second current generating module is connected to the output end of the third current generating module and serves as the output node of the temperature drift calibration circuit, which is used to output a temperature drift calibration current based on the difference between the second current and the third current, and the temperature drift calibration current is used to calibrate the temperature drift of the reference signal.

2. The bandgap reference circuit according to claim 1, It is characterized in that The first current generating module includes: a first current source array, configured to receive the first calibration codeword and generate the first current based on the first calibration codeword; The second current generating module includes: a second current source array, configured to receive the first calibration codeword and generate the second current based on the first calibration codeword.

3. The bandgap reference circuit as claimed in claim 2, It is characterized in that The first current source array comprises: N first mirror branches connected in parallel, where N is an integer greater than or equal to 2, and each first mirror branch comprises: a first current mirror unit, configured to replicate a current having a temperature coefficient corresponding to the first current to generate a first branch current; and A first switch unit, connected in series with the first current mirror unit, each first switch unit being controlled by a digital bit in the first calibration codeword to turn on or off the first mirror branch; The first current is the sum of the first branch currents of the first mirror branches that are turned on.

4. The bandgap reference circuit as claimed in claim 3, It is characterized in that The first current generating module further includes: a first bias voltage unit, configured to generate a bias voltage for the first current source array.

5. The bandgap reference circuit as claimed in claim 2, It is characterized in that The second current source array comprises: P second mirror branches connected in parallel, where P is an integer greater than or equal to 2, each second mirror branch comprises: a second current mirror unit, configured to replicate a current having a temperature coefficient corresponding to the second current to generate a second branch current; and A second switch unit, connected in series with the second current mirror unit, each second switch unit being controlled by a digital bit in the first calibration codeword to turn on or off the second mirror branch; The second current is the sum of the second branch currents of the turned-on second mirror branches.

6. The bandgap reference circuit as claimed in claim 5, It is characterized in that The second current generating module further includes: a second bias voltage unit, configured to generate a bias voltage for the second current source array.

7. The bandgap reference circuit according to claim 1, It is characterized in that The third current generating module comprises: a current receiving unit and a third current source array; The current receiving unit is used to receive the first current and generate a bias voltage of the third current source array; The third current source array is connected to the current receiving unit, and is configured to receive the second calibration codeword, and mirror the first current based on the second calibration codeword to generate the second current.

8. The bandgap reference circuit as claimed in claim 7, It is characterized in that The third current source array comprises: M third mirror branches connected in parallel, where M is an integer greater than or equal to 2, and each third mirror branch comprises: A third current mirror unit, configured to mirror the first current to generate a third branch current; and A third switch unit is connected in series with the third current mirror unit, each of the third switch units is controlled by a digital bit in the second calibration codeword to turn on or off the third mirror branch; The third current is the sum of the third branch currents of the turned-on third mirror branches.

9. The bandgap reference circuit according to any one of claims 1 to 8, It is characterized in that The temperature drift calibration circuit also includes: The first calibration module is used to adjust the second calibration codeword at a first temperature so that the difference between the second current and the third current is zero; and adjust the first calibration codeword at a second temperature so that the reference signal is equal to the reference signal at the first temperature.

10. The bandgap reference circuit as claimed in claim 9, It is characterized in that The first calibration module comprises: A comparison unit, used for comparing the calibration reference voltage with the voltage of the output node and generating a comparison output; A control unit is used to adjust the second calibration codeword based on the comparison output until the comparison output jumps.

11. The bandgap reference circuit according to claim 10, It is characterized in that The temperature drift calibration circuit also includes: A first switch connected between the output node and a first comparison input terminal of the comparison unit; A second switch connected between a calibration reference voltage terminal and a second comparison input terminal of the comparison unit, wherein the calibration reference voltage terminal is used to receive the calibration reference voltage; The first switch and the second switch are turned on when the first temperature is calibrated.

12. The bandgap reference circuit according to claim 9, It is characterized in that The temperature drift calibration circuit also includes: a second calibration module, configured to adjust the reference signal to a target value at the first temperature after adjusting the second calibration codeword so that a difference between the second current and the third current is zero; The first calibration module is used for adjusting the first calibration codeword at the second temperature to adjust the reference signal to the target value after adjusting the reference signal to the target value at the first temperature.

13. The bandgap reference circuit as claimed in claim 12, It is characterized in that The second calibration module includes: an adjustable resistor array.

14. The bandgap reference circuit according to any one of claims 1 to 8, It is characterized in that Also includes: Reference circuit; The output node is connected to a first calibration node of the reference circuit and is used to inject the temperature drift calibration current into the first calibration node.

15. The bandgap reference circuit as claimed in claim 14, It is characterized in that The reference circuit includes at least two transistors, and the first calibration node is on a common branch of the at least two transistors.

16. The bandgap reference circuit according to claim 14, It is characterized in that The first calibration node is any resistance node in the output path of the reference signal.

17. The bandgap reference circuit according to claim 14, It is characterized in that Also includes: A high-order temperature drift calibration circuit is connected to the second calibration node of the reference circuit and is used to generate a high-order temperature drift calibration current and inject the high-order temperature drift calibration current into the second calibration node.

18. The bandgap reference circuit according to any one of claims 1 to 8, It is characterized in that Also included is a reference circuit, the reference circuit comprising: Operational amplifier module; A chopper module is used to alternately switch the positive and negative directions of the operational amplifier input and the operational amplifier output to modulate the mismatch voltage of the operational amplifier module to a high frequency; The notch filter module is used to filter the output of the operational amplifier.

19. A method for calibrating a bandgap reference circuit, It is characterized in that The method comprises: generating a first current based on a first calibration codeword; generating a second current based on the first calibration codeword; one of the first current and the second current is a positive temperature coefficient current and the other is a negative temperature coefficient current, and the first current and the second current change in proportion to the change of the first calibration codeword; scaling the first current based on a second calibration codeword to obtain a third current; Based on the difference between the second current and the third current, a temperature drift calibration current is output to the reference circuit to calibrate the temperature drift of the reference signal.

20. The calibration method according to claim 19, It is characterized in that The calibration method further comprises: adjusting the second calibration codeword at a first temperature so that a difference between the second current and the third current is zero; The first calibration codeword is adjusted at a second temperature to make the reference signal equal to the reference signal at the first temperature.

21. The calibration method according to claim 20, It is characterized in that The calibration method further comprises: After adjusting the second calibration codeword to make the difference between the second current and the third current zero, the reference signal is adjusted to a target value at a first temperature.

22. A chip, It is characterized in that The circuit comprises the circuit described in any one of claims 1 to 18.

23. An electronic device, It is characterized in that The invention comprises a device body and the chip as claimed in claim 22 arranged in the device body.

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