Compensation circuit, operational amplifier circuit and electronic equipment

Abstract

The invention discloses a compensation circuit of an operational amplifier, an operational amplification circuit and electronic equipment, and the circuit comprises an error amplifier which is configured to obtain a sampling signal of an input voltage inputted to two input ends of the operational amplifier, and carries out the error amplification of the sampling signal, and obtains an amplification signal; the rectifying circuit is configured to rectify the amplified signal to obtain an enable signal; the current extraction circuit is electrically connected with the output end of the operational amplifier and electrically connected with the output end of the rectifying circuit, and is configured as follows: when a first enable signal output by the rectifying circuit is received, the current extraction circuit extracts a part of current output by the output end of the operational amplifier to obtain an extraction current so as to compensate the output voltage of the operational amplifier; and the extraction current is the current in direct proportion to the absolute temperature, and when the second enable signal output by the rectification circuit is received, the current extraction circuit is switched off, so that the full-temperature stability of the operational amplifier circuit is remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of integrated circuits, and in particular to a compensation circuit, an operational amplifier circuit and an electronic device. Background Art

[0002] Operational amplifier circuit (abbreviated as op amp) is a common circuit in integrated circuit design, widely used in various circuits such as amplification, following, and comparison. Input offset voltage VOS is an important indicator of op amp performance. It refers to the voltage difference between the input terminals when the output terminal is 0. It is roughly considered that the input offset voltage multiplied by the op amp gain is expressed as the deviation of the output voltage from the ideal value. When the op amp is used in a circuit with high voltage accuracy requirements, how to reduce the input offset voltage of the op amp is particularly important.

[0003] The size of the input offset voltage is related to the circuit structure, process manufacturing, temperature and other factors of the op amp itself. The offset caused by the first two can be corrected by adjusting parameters, but the offset caused by temperature will be different in different temperature ranges. The offset voltage tends to gradually increase with the increase of temperature, so it cannot be corrected only by adjusting parameters. Moreover, when the voltage offset in the high temperature range is corrected by adjusting parameters, the original low offset characteristics of the low temperature range will be destroyed, and the problem cannot be fundamentally solved. On the contrary, it may reduce the full temperature stability characteristics of the op amp. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] In order to solve the above problems, the present application provides, on one hand, a compensation circuit for an operational amplifier, comprising:

[0006] An error amplifier, wherein the error amplifier is configured to: obtain a first sampling signal of a first input voltage input to a non-inverting input terminal of the operational amplifier, and obtain a second sampling signal of a second input voltage input to an inverting input terminal of the operational amplifier, and perform error amplification on the first sampling signal and the second sampling signal to obtain an amplified signal, wherein when the difference between the first sampling signal and the second sampling signal is greater than or equal to a preset threshold, the amplified signal is a first amplified signal, and when the difference between the first sampling signal and the second sampling signal is less than the preset threshold, the amplified signal is a second amplified signal;

[0007] A rectifier circuit, whose input end is electrically connected to the output end of the error amplifier circuit, is configured to: rectify the amplified signal to obtain an enable signal, wherein the first enable signal is obtained when the rectifier circuit receives the first amplified signal, and the second enable signal is obtained when the rectifier circuit receives the second amplified signal;

[0008] The current extraction circuit is electrically connected to the output end of the operational amplifier and the output end of the rectifier circuit, and is configured as follows: when receiving a first enable signal output by the rectifier circuit, the current extraction circuit extracts part of the current output by the output end of the operational amplifier to obtain an extracted current to compensate for the output voltage of the operational amplifier, and the extracted current is a current proportional to the absolute temperature. When receiving a second enable signal output by the rectifier circuit, the current extraction circuit is turned off.

[0009] The above technical solution has the following advantages and beneficial effects: through the solution of the embodiment of the present application, it is possible to selectively extract part of the current output from the output end of the operational amplifier through the current extraction circuit in the high temperature range to obtain the extracted current, so as to compensate the output voltage of the operational amplifier, and it does not affect the low offset characteristics of the operational amplifier circuit in the low temperature range, so that the full temperature stability of the operational amplifier circuit is significantly improved.

[0010] Exemplarily, it also includes:

[0011] A first sampling circuit, wherein the output end of the first sampling circuit is connected to the first input end of the error amplifier, and is used for sampling the first input voltage of the non-inverting input end of the operational amplifier to obtain a first sampling signal and output it;

[0012] A second sampling circuit, wherein the output end of the second sampling circuit is connected to the second input end of the error amplifier, and is used for sampling the second input voltage of the inverting input end of the operational amplifier to obtain a second sampling signal and output it;

[0013] The first input end of the error amplifier is connected to the first sampling circuit, and the second input end of the error amplifier is connected to the second sampling circuit.

[0014] The above technical solution has the following advantages and beneficial effects:

[0015] Exemplarily, the first amplified signal is a low-level signal, and the second amplified signal is a high-level signal. The rectifier circuit includes a rectifier and an odd number of inverters connected in sequence, which are used to rectify and invert the first amplified signal and the second amplified signal to obtain the first enable signal and the second enable signal respectively.

[0016] The above technical solution has the following advantages and beneficial effects: the amplified signal is rectified by the rectifier so that the voltage output to the inverter becomes smoother and more stable, and the signal can be inverted by the inverter, thereby controlling the output of the enable signal that controls the first switch tube to turn on or off.

[0017] Exemplarily, the current extraction circuit includes a first switching tube, and the output end of the rectifier circuit is connected to the gate of the first switching tube, and is used to: when a first enable signal is output, control the first switching tube to be turned on, so that the current extraction circuit extracts part of the current output by the output end of the operational amplifier to obtain the extracted current; when a second enable signal is output, control the first switching tube to be turned off, so that the current extraction circuit is turned off.

[0018] The above technical solution has the following advantages and beneficial effects: the on and off of the first switch tube is controlled based on the enable signal, so that in the high temperature range, part of the current output by the output end of the operational amplifier can be selectively extracted through the current extraction circuit to obtain the extracted current, so as to compensate the output voltage of the operational amplifier, and the low offset characteristics of the operational amplifier circuit in the low temperature range are not affected, so that the full temperature stability of the operational amplifier circuit is significantly improved.

[0019] Exemplarily, the current extraction circuit further includes:

[0020] The current generating branch is connected between the power supply terminal and the ground terminal and comprises a first switch tube, which is used to generate a first current proportional to the absolute temperature when the first switch tube is turned on;

[0021] A current mirror circuit, one end of which is connected to a current generating branch;

[0022] A current extraction branch, one end of which is connected to the output end of the operational amplifier and the other end is grounded, and the current extraction branch is also electrically connected to the other end of the current mirror circuit, wherein the current mirror circuit copies the first current generated by the current generating branch and proportional to the absolute temperature to the current extraction branch at a predetermined multiple, so that the current extraction branch extracts a second current proportional to the absolute temperature from the output end of the operational amplifier, and the second current is a predetermined multiple of the first current.

[0023] The above technical solution has the following advantages and beneficial effects: when the first switch tube is turned on, the circuit can extract a current proportional to the absolute temperature from the output end of the operational amplifier through the current extraction circuit, thereby selectively compensating the operational amplifier in the high temperature range without affecting the low offset characteristics of the operational amplifier in the low temperature range, thereby significantly improving the full temperature stability of the operational amplifier.

[0024] Exemplarily, the current generating branch includes:

[0025] A first PMOS tube, whose source is connected to the power supply terminal and whose drain is connected to the source of the first switch tube;

[0026] A first triode, wherein the collector of the first triode is connected to the drain of the first switch tube;

[0027] A resistor, one end of which is connected to the emitter of the first transistor, and the other end of which is connected to the ground;

[0028] a second PMOS tube, wherein the gate of the second PMOS tube is connected to the drain of the first PMOS tube, and the source of the second PMOS tube is connected to the power supply end;

[0029] The second transistor, the base of the second transistor is connected to the emitter of the first transistor, the collector of the second transistor is connected to the base of the first transistor and the drain of the second PMOS tube, and the negative temperature characteristic of the second transistor is utilized to make the current flowing through the first transistor a first current proportional to the absolute temperature.

[0030] The above technical solution has the following advantages or beneficial effects: the negative temperature characteristic of the second transistor is utilized to make the current flowing through the first transistor a first current that is proportional to the absolute temperature, and based on the first current control, an extraction current that is positively correlated with the temperature is extracted from the operational amplifier, effectively suppressing the voltage change of the operational amplifier caused by high temperature, thereby improving the stability of the entire circuit.

[0031] Exemplarily, the current mirror circuit includes:

[0032] a third PMOS tube, wherein the gate of the third PMOS tube is electrically connected to the gate and drain of the first PMOS tube, and the source of the third PMOS tube is connected to the power supply terminal;

[0033] A first NMOS tube, a drain of the first NMOS tube connected to the drain of the third PMOS tube, a gate of the first NMOS tube connected to the drain of the third PMOS tube, a source of the first NMOS tube connected to the ground terminal, and a gate of the first NMOS tube connected to a current extraction branch.

[0034] The above technical solution has the following advantages or beneficial effects: through such a circuit structure, the third PMOS tube is used to copy the current of the first PMOS tube, that is, the first current flowing through the first transistor and the resistor and proportional to the absolute temperature is copied, and then the first current is copied to the current extraction branch through the first NMOS tube, thereby controlling the extraction of the extraction current positively correlated with the temperature from the operational amplifier, effectively suppressing the voltage change of the operational amplifier caused by high temperature, thereby improving the stability of the entire circuit.

[0035] Exemplarily, the current extraction branch includes:

[0036] The second NMOS tube has a gate connected to the gate of the first NMOS tube, a drain connected to the output end of the operational amplifier, and a source connected to the ground end.

[0037] The above technical solution has the following advantages or beneficial effects: the second NMOS tube and the first NMOS tube form a current mirror to copy the current proportional to the absolute temperature to the branch where the first NMOS tube is located, thereby controlling the extraction of the current positively correlated with the temperature from the operational amplifier, effectively suppressing the voltage change of the operational amplifier caused by high temperature, thereby improving the stability of the entire circuit.

[0038] On one hand, the present application provides an operational amplifier circuit, which includes an operational amplifier; and the aforementioned compensation circuit, wherein the compensation circuit is electrically connected to the operational amplifier.

[0039] The above technical solution has the following advantages or beneficial effects: since the operational amplifier circuit of the present application includes the aforementioned compensation circuit, the operational amplifier can be selectively compensated in the high temperature range without affecting the low offset characteristics of the operational amplifier in the low temperature range, thereby significantly improving the full temperature stability of the operational amplifier.

[0040] On one hand, the present application provides an electronic device, which includes the compensation circuit or operational amplifier circuit as described above.

[0041] The above technical solution has the following advantages or beneficial effects: the above operational amplifier circuit is included in the electronic device, and thus has advantages similar to those of the above operational amplifier circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The following drawings of the present application are hereby used as part of the present application for understanding the present application. The drawings show the embodiments of the present application and their descriptions, and are used to explain the device and principle of the present application. In the drawings,

[0043] Figure 1 A schematic diagram of a temperature characteristic curve of an operational amplifier for replicating a constant voltage source in the related art is shown;

[0044] Figure 2 A schematic diagram of a compensation circuit in one embodiment of the present application is shown;

[0045] Figure 3 A circuit diagram of a voltage follower replicating a bandgap reference in one embodiment of the present application is shown;

[0046] Figure 4 A schematic diagram showing the misalignment phenomenon of a bandgap reference replica;

[0047] Figure 5A schematic diagram of the circuit structure of an error amplifier in one embodiment of the present application is shown;

[0048] Figure 6 A schematic diagram showing the control of the establishment of the PTAT current by the enable signal output by the rectifier circuit in one embodiment of the present application;

[0049] Figure 7 A schematic diagram of a current extraction circuit in one embodiment of the present application is shown;

[0050] Figure 8 A schematic diagram showing a bandgap reference replica voltage temperature characteristic curve before and after compensation in one embodiment of the present application;

[0051] Fig. 9 A schematic diagram showing a temperature characteristic curve of a constant pressure source before and after compensation in one embodiment of the present application;

[0052] Fig.10 A schematic block diagram of an electronic device in one embodiment of the present application is shown. DETAILED DESCRIPTION

[0053] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0054] It should be understood that the present application can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0055] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.

[0056] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures.

[0057] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "a", "an" and " / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0058] Embodiments of the invention are described herein with reference to cross-sectional views as schematic diagrams of ideal embodiments (and intermediate structures) of the present application. Thus, variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the present application should not be limited to the specific shapes shown herein, but include shape deviations due to, for example, manufacturing. Therefore, what is shown in the figures is schematic in nature, and their shapes are not intended to display the actual shape of the device and are not intended to limit the scope of the present application.

[0059] In order to thoroughly understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present application. The preferred embodiments of the present application are described in detail as follows, but in addition to these detailed descriptions, the present application may also have other implementations.

[0060] The operational amplifier is a common circuit in integrated circuit design, and is widely used in various circuits such as amplification, following, and comparison. The input offset voltage VOS is an important indicator of the performance of the operational amplifier. It refers to the voltage difference between the input terminals when the output terminal is 0. It is roughly considered that the input offset voltage multiplied by the operational amplifier gain is the deviation of the output voltage from the ideal value. When the operational amplifier is used in a circuit with high voltage accuracy requirements, it is particularly important to reduce the input offset voltage of the operational amplifier.

[0061] The size of the input offset voltage is related to the circuit structure, manufacturing process, temperature and other factors of the op amp itself. The offset caused by the first two can be corrected by adjusting parameters, but the offset caused by temperature will vary in different temperature ranges. The offset voltage tends to increase gradually with the increase of temperature, so it cannot be corrected only by adjusting parameters.

[0062] The input offset voltage changes with temperature, and its temperature coefficient is called TCVOS, which is the temperature drift of the offset voltage. For circuits that have extremely high requirements for temperature stability, such as bandgap references, when using op amps to replicate or amplify them, the input offset voltage caused by the op amp due to temperature will directly affect the performance of the circuit and the accuracy of the subsequent circuits. Figure 1 As shown in the figure, the constant voltage source is copied using an op amp, where Vref is the constant voltage source and Vref_copy is the copy voltage generated by the op amp. Observing the temperature characteristic curves of the two, it can be seen that when the temperature is below 100°C, the voltage values ​​of the two are similar, and the input offset voltage of the op amp is low; when the temperature is above 100°C, Vref_copy gradually deviates from Vref, and the input offset voltage increases. As the operating temperature of the op amp continues to rise, the input offset voltage increases sharply in the high temperature section, and the circuit performance drops sharply.

[0063] Improving the sudden drop of the op amp input offset voltage in the high temperature range is crucial to improving the reliability of the op amp. When the offset voltage of the op amp is improved by adjusting the parameters to correct the voltage offset in the high temperature range, the original low offset characteristics in the low temperature range will be destroyed, which cannot fundamentally solve the problem. Instead, it may reduce the full temperature stability characteristics of the op amp.

[0064] The compensation circuit in the embodiments of the present application will be described below in conjunction with the accompanying drawings. Under the premise of no conflict, the features in the various embodiments of the present application can be combined with each other.

[0065] In order to solve the above technical problems, an embodiment of the present application provides a compensation circuit 200 of an operational amplifier 100, such as Figure 2As shown, it includes: an error amplifier 210, a rectifier circuit 220, and a current extraction circuit 230, wherein the error amplifier 210 is configured to: obtain a first sampling signal of a first input voltage input to the non-inverting input terminal of the operational amplifier 100, and obtain a second sampling signal of a second input voltage of the inverting input terminal of the operational amplifier 100, perform error amplification on the first sampling signal and the second sampling signal to obtain an amplified signal, wherein when the difference between the first sampling signal and the second sampling signal is greater than a preset threshold, the amplified signal is a first amplified signal, and when the difference between the first sampling signal and the second sampling signal is less than the preset threshold, the amplified signal is a second amplified signal; the input terminal of the rectifier circuit 220 is electrically connected to the output terminal of the error amplifier circuit, and is configured to : rectifying the amplified signal to obtain an enable signal, wherein the first enable signal is obtained when the rectifier circuit 220 receives the first amplified signal, and the second enable signal is obtained when the rectifier circuit 220 receives the second amplified signal; the current extraction circuit 230 is electrically connected to the output end of the operational amplifier 100, and is electrically connected to the output end of the rectifier circuit 220, and is configured as follows: when receiving the first enable signal output by the rectifier circuit 220, the current extraction circuit 230 extracts part of the current output by the output end of the operational amplifier 100 to obtain an extracted current to compensate for the output voltage of the operational amplifier 100, and the extracted current is a current proportional to the absolute temperature, and when receiving the second enable signal output by the rectifier circuit 220, the current extraction circuit 230 is turned off.

[0066] In the embodiment of the present application, the voltage of the two input terminals of the operational amplifier 100 is obtained and amplified by the error amplifier 210, and then rectified by the rectifier circuit 220 to generate an enable signal, and the enable signal is used to control the current extraction circuit 230 to extract part of the current output by the output end of the operational amplifier 100 to obtain the extracted current or shut down the current extraction circuit 230, thereby selectively compensating the operational amplifier in the high temperature range without affecting the low offset characteristics of the operational amplifier in the low temperature range, thereby significantly improving the full temperature stability of the operational amplifier.

[0067] The structures of various parts of the operational amplifier 100 and the compensation circuit 200 in the embodiment of the present application are described below by way of example.

[0068] First, if Figure 2As shown, the compensation circuit 200 also includes a first sampling circuit (i.e., a VP sampling circuit) and a second sampling circuit (i.e., a VN sampling circuit). The first sampling circuit is used to sample the first input voltage of the non-inverting input terminal of the operational amplifier 100 to obtain a first sampling signal, i.e., a sampling voltage VA, and output it. The second sampling circuit is used to sample the second input voltage of the inverting input terminal of the operational amplifier 100 to obtain a second sampling signal, i.e., a sampling voltage VB, and output it. The first input terminal of the error amplifier 210 is connected to the output terminal of the first sampling circuit, i.e., the non-inverting input terminal, for receiving the sampling voltage VA. The second input terminal of the error amplifier 210 is also the inverting input terminal, which is electrically connected to the output terminal of the second sampling circuit, for receiving the sampling voltage VB. The error amplifier 210 performs error amplification on the sampling voltages VA and VB to generate an amplified signal VEA. The amplified signal VEA passes through the rectifier circuit 220 (for example, including a rectifier 221 and an inverter 222 connected in sequence) to generate an enable signal EN, which is connected to the gate of the first switch tube P1 of the current extraction circuit 230 to control its conduction and shutdown. In the low temperature section, the input offset voltage is low, and the enable signal is the second enable signal. The first switch tube P1 of the current extraction circuit 230 is controlled to be turned off by the second enable signal, thereby turning off the current extraction circuit 230, that is, the current extraction circuit 230 is not connected to the output terminal V of the operational amplifier 100. OUT , so that the operational amplifier is not compensated; as the temperature rises, the input offset voltage gradually increases, and the EN signal is changed from "1" to "0", that is, the enable signal is changed from the first enable signal to the second enable signal, the first switch tube P1 is turned on, and the current extraction circuit 230 extracts current from the output node of the operational amplifier 100 (for example, a first-stage operational amplifier), that is, extracts a current proportional to absolute temperature (PTAT), which is also referred to as PTAT current in this article, to compensate for the input offset voltage in the high temperature section, thereby improving the high temperature section performance of the operational amplifier.

[0069] It is worth mentioning that the various switching tubes in the embodiments of the present application can be NMOS tubes or PMOS tubes. As long as the reasonable operation of the circuit can be guaranteed, some PMOS tubes can be replaced by NMOS tubes, or some NMOS tubes can be replaced by PMOS tubes. No specific limitation is made here.

[0070] The operational amplifier 100 of the present application may be a voltage follower, a comparator, a non-inverting amplifier, an inverting amplifier or any other possible operational amplifier circuit. In the embodiments of the present application, the operational amplifier 100 is mainly used as a first-stage operational amplifier circuit, such as a voltage follower that replicates a bandgap reference, to illustrate the compensation circuit 200 and the operational amplifier circuit of the embodiments of the present application, but this is not intended to constitute a limitation.

[0071] like Figure 2 and Figure 3 As shown, the operational amplifier 100, for example, a first-stage operational amplifier circuit, is used to amplify the voltage difference between the voltages VP and VN to generate the output voltage VOUT. The form of the operational amplifier is not limited, but the offset is basically inevitable. In order to highlight the influence of temperature on the offset voltage, a voltage follower that replicates the bandgap reference voltage is taken as an example. The bandgap reference is a circuit structure that requires extremely high temperature stability, so the voltage replicated by the operational amplifier also has extremely high requirements for temperature stability, so the sudden increase of the input offset voltage of the operational amplifier in the high temperature range will seriously reduce the accuracy of the replicated voltage.

[0072] In one embodiment, the circuit of the voltage follower replicating the bandgap reference is as follows Figure 3 As shown, it is mainly composed of NMOS tubes M1-M2, M7-M9, M12, M14-M15, PMOS tubes M3-M6, M10-M11, M13, M16, and resistors R1 and R2. Its working process is as follows: after the bandgap reference voltage BGR is established, the current flowing through the PMOS tube M6 is lower than the current flowing through the PMOS tube M5, and the current of the PMOS tube M6 is copied to the PMOS tube M11 through the NMOS tube M8 and the NMOS tube M9, and the PMOS tube. Similarly, the current of M5 is copied through the PMOS tube M12, and V C The potential drops, the current of M16 increases, V OUT The potential rises and is fed back to the gate of M5, making V OUT Complete the voltage replication of BGR. At the same time, the sampling voltage V A With V OUT The sampling voltage VB is respectively connected to the error amplifier 210 for error amplification. A That is, it is a node connecting the gate of the NMOS tube M7 and the gate of the PMOS tube M12, and the sampling voltage VB is a node connecting the gate of the NMOS tube M8 and the gate of the NMOS tube M9.

[0073] The first sampling circuit and the second sampling circuit can be partial branches in a first-stage operational amplifier circuit. By sampling the voltages of the positive and negative input terminals of the operational amplifier 100 through the sampling circuit, the sampling voltage V input to the error amplifier 210 can be A and V B The input requirements of the error amplifier 210 are met, and the voltage range that the error amplifier 210 can identify is expanded, thereby ensuring that an accurate comparison result can be output, and also improving the accuracy of the error amplification comparison.

[0074] like Figure 4As shown in the figure, Bandgap is the bandgap reference voltage, and Bandgap_copy is the copied bandgap reference voltage, i.e., Vout. In the temperature range of -40℃-60℃, the bandgap reference voltage has high copy accuracy and the offset voltage of the op amp is low; as the temperature rises, Bandgap_copy gradually deviates from Bandgap and the offset voltage gradually increases. Especially when the temperature is higher than 125℃, the offset voltage increases sharply and the copy accuracy is poor.

[0075] Further, in order to solve the problem of sudden increase in offset voltage, the error amplifier 210 in the embodiment of the present application can be implemented as follows: Figure 5 In some embodiments, the error amplifier 210 may include NMOS tubes M17-M18, M23-M24, M26, and PMOS tubes M19-M22, M25, wherein the NMOS tubes M17 and M18 form a current mirror, the drain of the NMOS tube M17 is connected to the power supply voltage VCC, the source is grounded, the gate thereof is connected to the gate of the NMOS tube M18, and the gate of the NMOS tube M18 is also connected to the drain of the NMOS tube M17, the source of the PMOS tube M19 is connected to the power supply voltage VCC, the drain thereof is connected to the drain of the NMOS tube M18, the gate of the PMOS tube M19 is connected to the drain thereof, the gate of the PMOS tube M19 is also connected to the gate of the PMOS tube M20, the source of the PMOS tube M20 is connected to the power supply voltage VCC, the gate of the PMOS tube M20 is also connected to the gate of the PMOS tube M25, the source of the PMOS tube M25 is connected to the power supply voltage VCC, and the drain thereof is used as the amplified signal V EA The drain of the PMOS tube M20 is also connected to the sources of the PMOS tubes M21 and M22, and the gate of the PMOS tube M21 is connected to the second sampling signal V B , the gate of the PMOS tube M22 is connected to the first sampling signal V A The drains of the PMOS tubes M21 and M22 are respectively connected to the drains of the NMOS tubes M23 and M24, the sources of the NMOS tubes M23 and M24 are grounded, the gates of the NMOS tubes M23 and M24 are electrically connected and connected to the drain of the NMOS tube M23, the gate of the NMOS tube M26 is connected to the drain of the NMOS tube M24, the drain of the NMOS tube M26 is connected to the drain of the PMOS tube M25, and the source of the NMOS tube M26 is grounded.

[0076] The aforementioned Figure 3 The first sampling signal of the first stage operational amplifier 100 is shown as a sampling voltage V of BGR, for example. A With the second sampling signal such as V OUT The sampling voltage V B The inverting input terminal and the non-inverting input terminal of the error amplifier 210 are respectively connected to perform error amplification to generate an amplified signal VEA。

[0077] The specific working process is as follows: From the above-mentioned working process of the first-stage op amp, VOUT rises with BGR, and the sampling voltage V B The current of the PMOS tube M21 decreases, and the gate potential V G,M26 rises, making NMOS tube M26 conduction, V EA That is, when the error between the two is reduced, the V EA The signal also decreases. When the difference between the first sampling signal and the second sampling signal is less than the preset threshold, the amplified signal V EA The second amplified signal is, for example, a low-level signal.

[0078] like Figure 6 As shown, when V OUT When the difference between the sampling signal and the bandgap reference BGR signal is large, the V EA That is, when the difference between the first sampling signal and the second sampling signal is greater than the preset threshold, the amplified signal V EA The first amplified signal is, for example, a high level signal.

[0079] Further, in some embodiments, the input end of the rectifier circuit 220 is electrically connected to the output end of the error amplifier circuit, and is configured to: rectify the amplified signal to obtain an enable signal, wherein the first enable signal is obtained when the rectifier circuit 220 receives the first amplified signal, and the second enable signal is obtained when the rectifier circuit 220 receives the second amplified signal, and the conduction and shutdown of the first switch tube P1 corresponding to the current extraction circuit 230 are controlled by the enable signal, wherein when the first switch tube P1 is a PMOS tube, the first enable signal is a low-level signal to control the conduction of the first switch tube P1, and the second enable signal is a high-level signal to control the shutdown of the first switch tube P1.

[0080] Optionally, the rectifier circuit 220 may include a rectifier 221 and an odd number of inverters 222, which are used to rectify and invert the first amplified signal and the second amplified signal to obtain a first enable signal and a second enable signal respectively. The amplified signal is rectified by the rectifier 221 so that the voltage output to the inverter 222 becomes smoother and more stable, and the signal can be inverted by the inverter 222, thereby controlling the enable signal that controls the output switch tube to be turned on or off.

[0081] For example, when the difference between the first sampling signal and the second sampling signal is less than a preset threshold, the amplified signal V EAThe second amplified signal is pulled low, that is, the second amplified signal is a low-level signal, and after being rectified by the rectifier 221 and inverted by the inverter 222, a second enabling signal such as "1" is output. Since the temperature is at a relatively low low temperature end at this time, the offset voltage is small, and the output of the operational amplifier 100 will not be compensated. When the difference between the first sampling signal and the second sampling signal is greater than or equal to the preset threshold, the amplified signal V EA The enable signal En is changed from "1" to "0" after being rectified by the rectifier circuit 220, so that the first switch tube P1 of the PMOS tube is turned on, and the PTAT current is established. Therefore, the current extraction circuit 230 extracts part of the current output from the output end of the operational amplifier 100 to obtain the extraction current, so as to compensate the output voltage of the operational amplifier 100. The extraction current is a current proportional to the absolute temperature.

[0082] For example, Figure 6 As shown, when the temperature is within the range of -40°C to 60°C, the EN signal is a high level signal, for example, 5.0V, that is, V EA The enable signal EN generated by the rectifier circuit 220 is set to "1", the first switch tube P1 is turned off, the current extracted by the current extraction circuit 230 is almost zero, and the PTAT current is not established. When the temperature is higher than 60°C, the EN signal is a low-level signal, that is, EN is set from "1" to "0", the switch tube P1 is turned on, and the current extraction circuit 230 extracts a current proportional to the absolute temperature, thereby selectively compensating the operational amplifier in the high temperature section without affecting the low offset characteristics of the operational amplifier in the low temperature section, thereby significantly improving the full temperature stability of the operational amplifier.

[0083] The current extraction circuit 230 in the embodiment of the present application can be implemented by any suitable circuit structure, such as a PTAT current extraction circuit. Figure 7 The circuit configuration shown in is for illustration purposes only, but this is not intended to be limiting.

[0084] In some embodiments, Figure 7 As shown, when the temperature is higher than 60°C, the EN signal is a low level signal, that is, EN is changed from "1" to "0", the first switch tube P1 is turned on, and the transistor V BE The negative temperature characteristic generates a PTAT current and is connected to the output node V OUT The sampling is performed to compensate for the input offset voltage of the operational amplifier 100 .

[0085] like Figure 7As shown, the current extraction circuit 230 includes a first switch tube P1, and the output end of the rectifier circuit 220 is connected to the gate of the gate P1 of the first switch tube, which is used to: when the first enable signal is output, the first switch tube is controlled to be turned on, so that the current extraction circuit 230 extracts part of the current output by the output end of the operational amplifier 100 to obtain the extracted current; when the second enable signal is output, the first switch tube is controlled to be turned off, so that the current extraction circuit 230 is turned off, wherein the first switch tube P1 can be an NMOS tube or a PMOS tube. For example, when it is an NMOS tube, the inverter 222 may not be set or an even number of inverters 222 may be set, and when it is a PMOS tube, an odd number of inverters 222 may be set, so as to control the first switch tube P1 to be turned on at high temperature and turned off at low temperature.

[0086] Further, in some embodiments, the current extraction circuit 230 further includes a current generating branch, a current mirror circuit and a current extraction branch, which are connected between the power supply terminal and the ground terminal, and include a first switch tube, which is used to generate a first current proportional to the absolute temperature when the first switch tube is turned on, one end of the current mirror circuit is connected to the current generating branch, one end of the current extraction branch is connected to the output terminal of the operational amplifier 100, and the other end is grounded, and the current extraction branch is also electrically connected to the other end of the current mirror circuit, wherein the current mirror circuit copies the first current proportional to the absolute temperature generated by the current generating branch to the current extraction branch at a predetermined multiple, so that the current extraction branch extracts a second current proportional to the absolute temperature from the output terminal of the operational amplifier 100, and the second current is a predetermined multiple of the first current. The predetermined multiple can be reasonably set according to actual needs, which mainly depends on the replication ratio of the current mirror circuit, for example, the current mirror circuit can be 1:1, or 1:2 or other suitable ratios of the current mirror.

[0087] In some embodiments, Figure 7As shown, the current generating branch includes: a first PMOS tube M28, a first transistor Q1, a resistor R3, a second PMOS tube M27, and a second transistor Q2, wherein the source of the first PMOS tube M28 is connected to the power supply end (that is, the power supply voltage VCC), the drain of the first PMOS tube M28 is connected to the source of the first switch tube P1, the collector of the first transistor Q1 is connected to the drain of the first switch tube P1, one end of the resistor R3 is connected to the emitter of the first transistor Q1, and the other end is connected to the ground end, the gate of the second PMOS tube M27 is connected to the drain of the first PMOS tube M28, and the The source of the second PMOS tube M27 is connected to the power supply end, the base of the second triode Q2 is connected to the emitter of the first triode Q1, the collector of the second triode Q2 is connected to the base of the first triode Q1 and the drain of the second PMOS tube M27, and the negative temperature characteristic of the second triode Q2 is used to make the current flowing through the first triode Q1 a first current proportional to the absolute temperature, and based on the first current control, the extraction current positively correlated with the temperature is extracted from the operational amplifier 100, which effectively suppresses the voltage change of the operational amplifier 100 caused by high temperature, thereby improving the stability of the entire circuit.

[0088] The current mirror circuit can be implemented based on any suitable circuit structure that can play a role in current replication, for example, Figure 7 As shown, the current mirror circuit includes: a third PMOS tube M29 and a first NMOS tube M30, the gate of the third PMOS tube M29 is electrically connected to the gate and drain of the first PMOS tube M28, the source of the third PMOS tube M29 is connected to the power supply terminal, the drain of the first NMOS tube M30 is connected to the drain of the third PMOS tube M29, the gate of the first NMOS tube M30 is connected to the drain of the third PMOS tube M29, the source of the first NMOS tube M30 is connected to the ground terminal, and the gate of the first NMOS tube M30 is connected to the current extraction branch. Through such a circuit structure, the third PMOS tube M29 is used to copy the current of the first PMOS tube M28, that is, to copy the first current that is proportional to the absolute temperature flowing through the first triode Q1 and the resistor R3, and then the first current is copied to the current extraction branch through the first NMOS tube M30, so as to control the extraction of the extraction current positively correlated with the temperature from the operational amplifier 100, effectively suppress the voltage change of the operational amplifier 100 caused by high temperature, thereby improving the stability of the entire circuit.

[0089] In one embodiment, the current extraction branch includes a second NMOS transistor M31, the gate of the second NMOS transistor M31 is connected to the gate of the first NMOS transistor M30, and the drain of the second NMOS transistor M31 is connected to the output terminal of the operational amplifier 100, for example, to the output node V DThe second NMOS tube M31 and the first NMOS tube M30 form a current mirror to copy the current proportional to the absolute temperature to the branch where the first NMOS tube M30 is located, thereby controlling the extraction of the temperature-positive current from the operational amplifier 100, effectively suppressing the voltage change of the operational amplifier 100 caused by high temperature, and thus improving the stability of the entire circuit.

[0090] like Figure 7 The working process of the current extraction circuit 230 shown is as follows: when the enable signal EN is set to "1", the first switch tube P1 of the PMOS tube is turned off, the third PMOS tube M29 is turned off, causing the second NMOS tube M31 to be turned off, and the current extraction circuit 230 does not work. When EN is changed from "1" to "0", the first switch tube P1 is turned on, and the negative temperature characteristic of the VBE (base-emitter voltage) of the second transistor Q2 is utilized, that is, the higher the temperature, the lower the VBE of the second transistor Q2, and the base voltage of the second transistor Q2 will be correspondingly lower. Since the base of the second transistor Q2 is connected to the emitter of the first transistor Q1, that is, the base voltage of the second transistor Q2 is reduced, and the emitter of the first transistor Q1 is correspondingly pulled down, so that the current flowing through the first transistor Q1 presents a current proportional to the absolute temperature, and since the resistor R3 and the first transistor Q1 are in the same branch, a PTAT current is correspondingly generated on the resistor R3, and the PTAT current also flows through the first PMOS tube M28, and the second NMOS tube M31 copies the current of the first PMOS tube M28 and extracts it from the VOUT node, thereby realizing the offset compensation in the high temperature section.

[0091] like Figure 8 As shown in the figure, Bandgap is the bandgap reference voltage, Bandgap_copy is the copy voltage before compensation, and Bandgap_copy_compensate is the copy voltage after compensation. It can be seen that when the temperature is higher than 60°C, the input offset voltage of the op amp is significantly reduced, especially when the temperature is higher than 125°C, the offset voltage surge trend is significantly pulled back.

[0092] It is worth mentioning that the compensation circuit 200 in the embodiment of the present application has wide applicability and is not only suitable for voltage replication of bandgap reference. This circuit can compensate for the offset temperature drift of different types of op amps. The scheme of the present invention can compensate for different circuits by changing the compensation start-up temperature or the compensation current size or the current rise slope, and has wide applicability. For example, to compensate for the high temperature section of the constant voltage source, combined with Figure 1 and Fig. 9It can also be seen that Vref is the reference voltage, V_copy is the copy voltage before compensation, and V_copy_compensate is the copy voltage after compensation. When the temperature is higher than 60°C, the input offset voltage of the op amp is significantly reduced, which shows that its high temperature compensation effect on the constant voltage source is also significant.

[0093] Continue to refer Figure 2 In an embodiment of the present application, an operational amplifier circuit is further provided, the operational amplifier circuit comprising the aforementioned compensation circuit 200 and the operational amplifier 100, wherein the compensation circuit 200 is electrically connected to the operational amplifier 100. Since the operational amplifier circuit of the present application comprises the aforementioned compensation circuit 200, the operational amplifier can be selectively compensated in a high temperature section without affecting the low offset characteristics of the operational amplifier in a low temperature section, thereby significantly improving the full temperature stability of the operational amplifier.

[0094] On the other hand, the present application Fig.10 As shown, an electronic device 1000 is provided, and the electronic device 1000 includes the above operational amplifier circuit. The electronic device can be any electronic product or device such as a household appliance (such as a variable frequency air conditioner), a television, a mobile phone, a tablet computer, a laptop computer, a netbook, a game console, a television, a VCD, a DVD, a navigator, a camera, a video camera, a voice recorder, an MP3, an MP4, a PSP, etc. Since the electronic device of the present application has the above operational amplifier circuit, it has the advantages similar to the above operational amplifier circuit.

[0095] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0096] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0097] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0098] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0099] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0100] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims.

Claims

1. A compensation circuit for an operational amplifier, characterized in that: include: an error amplifier, wherein the error amplifier is configured to: obtain a first sampling signal of a first input voltage input to a non-inverting input terminal of the operational amplifier, and obtain a second sampling signal of a second input voltage input to an inverting input terminal of the operational amplifier, and perform error amplification on the first sampling signal and the second sampling signal to obtain an amplified signal, wherein when a difference between the first sampling signal and the second sampling signal is greater than or equal to a preset threshold, the amplified signal is a first amplified signal, and when a difference between the first sampling signal and the second sampling signal is less than the preset threshold, the amplified signal is a second amplified signal; a rectifier circuit, whose input end is electrically connected to the output end of the error amplifier circuit, and configured to: rectify the amplified signal to obtain an enable signal, wherein the first enable signal is obtained when the rectifier circuit receives the first amplified signal, and the second enable signal is obtained when the rectifier circuit receives the second amplified signal; A current extraction circuit is electrically connected to the output end of the operational amplifier and the output end of the rectifier circuit, and is configured as follows: when receiving the first enable signal output by the rectifier circuit, the current extraction circuit extracts part of the current output by the output end of the operational amplifier to obtain an extraction current to compensate for the output voltage of the operational amplifier, and the extraction current is a current proportional to the absolute temperature; when receiving the second enable signal output by the rectifier circuit, the current extraction circuit is turned off.

2. The compensation circuit according to claim 1, characterized in that: Also includes: A first sampling circuit, wherein the output end of the first sampling circuit is connected to the first input end of the error amplifier, and is used to sample the first input voltage of the non-inverting input end of the operational amplifier to obtain the first sampling signal and output it; A second sampling circuit, wherein the output end of the second sampling circuit is connected to the second input end of the error amplifier, and is used to sample the second input voltage of the inverting input end of the operational amplifier to obtain the second sampling signal and output it; Wherein, the first input end of the error amplifier is connected to the first sampling circuit, and the second input end of the error amplifier is connected to the second sampling circuit.

3. The compensation circuit according to claim 1, characterized in that: The first amplified signal is a low-level signal, the second amplified signal is a high-level signal, and the rectifier circuit includes a rectifier and an odd number of inverters connected in sequence, which are used to rectify and invert the first amplified signal and the second amplified signal to obtain the first enable signal and the second enable signal respectively.

4. The compensation circuit according to claim 1, characterized in that: The current extraction circuit includes a first switch tube, and the output end of the rectifier circuit is connected to the gate of the first switch tube, and is used to: when the first enable signal is output, control the first switch tube to be turned on, so that the current extraction circuit extracts part of the current output by the output end of the operational amplifier to obtain the extracted current; when the second enable signal is output, control the first switch tube to be turned off, so that the current extraction circuit is turned off.

5. The compensation circuit according to claim 4, characterized in that: The current extraction circuit further includes: A current generating branch is connected between the power supply terminal and the ground terminal and includes the first switch tube, which is used to generate a first current proportional to the absolute temperature when the first switch tube is turned on; A current mirror circuit, one end of which is connected to the current generating branch; A current extraction branch, one end of which is connected to the output end of the operational amplifier and the other end is grounded, and the current extraction branch is also electrically connected to the other end of the current mirror circuit, wherein the current mirror circuit copies the first current generated by the current generating branch and proportional to the absolute temperature to the current extraction branch at a predetermined multiple, so that the current extraction branch extracts a second current proportional to the absolute temperature from the output end of the operational amplifier, and the second current is the predetermined multiple of the first current.

6. The compensation circuit according to claim 5, characterized in that: The current generating branch comprises: a first PMOS tube, whose source is connected to the power supply terminal and whose drain is connected to the source of the first switch tube; A first triode, wherein the collector of the first triode is connected to the drain of the first switch tube; a resistor, one end of which is connected to the emitter of the first transistor, and the other end of which is connected to the ground; a second PMOS tube, wherein a gate of the second PMOS tube is connected to a drain of the first PMOS tube, and a source of the second PMOS tube is connected to the power supply end; A second transistor, wherein the base of the second transistor is connected to the emitter of the first transistor, the collector of the second transistor is connected to the base of the first transistor and the drain of the second PMOS tube, and the negative temperature characteristic of the second transistor is utilized to make the current flowing through the first transistor the first current which is proportional to the absolute temperature.

7. The compensation circuit according to claim 6, characterized in that: The current mirror circuit comprises: a third PMOS tube, wherein the gate of the third PMOS tube is electrically connected to the gate and drain of the first PMOS tube, and the source of the third PMOS tube is connected to the power supply end; A first NMOS tube, wherein the drain of the first NMOS tube is connected to the drain of the third PMOS tube, the gate of the first NMOS tube is connected to the drain of the third PMOS tube, the source of the first NMOS tube is connected to the ground terminal, and the gate of the first NMOS tube is connected to the current extraction branch.

8. The compensation circuit according to claim 7, characterized in that: The current extraction branch comprises: A second NMOS tube, wherein the gate of the second NMOS tube is connected to the gate of the first NMOS tube, the drain of the second NMOS tube is connected to the output end of the operational amplifier, and the source of the second NMOS tube is connected to the ground end.

9. An operational amplifier circuit, characterized in that: include: Operational amplifier; And the compensation circuit as claimed in any one of claims 1 to 8, wherein the compensation circuit is electrically connected to the operational amplifier.

10. An electronic device, characterized in that: include: The operational amplifier circuit as claimed in claim 9.

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