Slew rate boosting circuit and operational amplifier

Abstract

The invention is suitable for the technical field of slew rate improvement of operational amplifiers, and provides a slew rate improvement circuit and an operational amplifier. The slew rate increasing circuit comprises a first slew rate triggering module, a first slew rate enhancing module, a second slew rate triggering module and a second slew rate enhancing module, the first slew rate triggering module is electrically connected with the first slew rate enhancing module, and the first slew rate enhancing module is used for being electrically connected with a grid electrode of an upper power tube. The second slew rate triggering module is electrically connected with the second slew rate strengthening module, and the second slew rate strengthening module is used for being electrically connected with the grid electrode of the lower power tube. The first slew rate triggering module and the second slew rate triggering module are additionally arranged, the establishment requirement of the output signal is directly judged according to the difference value between the first voltage and the second voltage, and the corresponding slew rate enhancing module is triggered in real time so as to quickly open the upper power tube or the lower power tube. The loop response delay problem does not exist in the whole process, the establishment time of the output signal can be remarkably shortened, and the output slew rate is more efficiently improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of slew rate improvement of operational amplifiers, and particularly relates to a slew rate improvement circuit and an operational amplifier. BACKGROUND

[0002] In application scenarios such as LCD (Liquid Crystal Display) liquid crystal deflection driving that require high-voltage and high-power rail-to-rail input and output operational amplifiers, the operational amplifier often needs to drive a large load capacitor, at which time the slew rate of the output signal becomes a key indicator affecting the rapid establishment of the signal. Insufficient slew rate will cause the output signal to fail to follow the change of the input signal in time, especially when driving a large swing signal, which is prone to problems such as excessively long setup time and waveform distortion, affecting the overall performance of the system. In order to improve the output slew rate, the existing technology generally adopts a slew rate strengthening scheme based on output current detection. However, since the operational amplifier is often connected in a buffer mode in actual application, the change of the output current needs to be detected after the response process of the operational amplifier loop, which causes inherent delay in the start of the slew rate strengthening circuit, and the output slew rate is relatively slow to improve. SUMMARY

[0003] Embodiments of the application provide a slew rate improvement circuit and an operational amplifier, which can solve the problem that the existing slew rate strengthening scheme based on output current detection has inherent loop response delay, resulting in relatively slow improvement of the output slew rate.

[0004] In a first aspect, embodiments of the application provide a slew rate improvement circuit, which includes a first slew rate trigger module, a first slew rate strengthening module, a second slew rate trigger module, and a second slew rate strengthening module. The first slew rate trigger module is electrically connected to the first slew rate strengthening module. The first slew rate strengthening module is configured to be electrically connected to the gate of an upper power tube. The second slew rate trigger module is electrically connected to the second slew rate strengthening module. The second slew rate strengthening module is configured to be electrically connected to the gate of a lower power tube. The first slew rate trigger module is configured to receive a first voltage and a second voltage, and output a first trigger signal to the first slew rate strengthening module when the difference between the first voltage and the second voltage is greater than a first threshold. The first slew rate strengthening module is configured to output a first driving signal to the gate of the upper power tube according to the first trigger signal. The second slew rate trigger module is configured to receive the first voltage and the second voltage, and output a second trigger signal to the second slew rate strengthening module when the difference between the first voltage and the second voltage is less than a second threshold. The second slew rate strengthening module is configured to output a second driving signal to the gate of the lower power tube according to the second trigger signal.

[0005] In a possible implementation manner of the first aspect, the first swing rate trigger module comprises a first switch unit and a first current mirror unit, and the first current mirror unit is electrically connected with the first switch unit and the first swing rate enhancement module respectively. The first switch unit is configured to output a first current to the first current mirror unit when a difference between the first voltage and the second voltage is greater than a first threshold; and the first current mirror unit is configured to output the first trigger signal to the first swing rate enhancement module according to the first current. In a possible implementation manner of the first aspect, the first switch unit comprises a first switch tube, a gate of the first switch tube is configured to receive the first voltage, a source of the first switch tube is configured to receive the second voltage, and a drain of the first switch tube is electrically connected with the first current mirror unit. In a possible implementation manner of the first aspect, the first current mirror unit comprises a second switch tube and a third switch tube, a gate of the second switch tube is electrically connected with a gate of the third switch tube, a drain of the second switch tube and the first switch unit respectively, a source of the second switch tube and a source of the third switch tube are both configured to receive an input voltage, and a drain of the third switch tube is electrically connected with the first swing rate enhancement module. In a possible implementation manner of the first aspect, the first swing rate enhancement module comprises a first current comparator, an input end of the first current comparator is electrically connected with the first swing rate trigger module, and an output end of the first current comparator is electrically connected with a gate of the upper power tube. In a possible implementation manner of the first aspect, the second swing rate trigger module comprises a second switch unit and a second current mirror unit, and the second current mirror unit is electrically connected with the second switch unit and the second swing rate enhancement module respectively. The second switch unit is configured to output a second current to the second current mirror unit when a difference between the first voltage and the second voltage is less than a second threshold; and the second current mirror unit is configured to output the second trigger signal to the second swing rate enhancement module according to the second current. In a possible implementation manner of the first aspect, the second switch unit comprises a fourth switch tube, a gate of the fourth switch tube is configured to receive the first voltage, a source of the fourth switch tube is configured to receive the second voltage, and a drain of the fourth switch tube is electrically connected with the second current mirror unit. In a possible implementation manner of the first aspect, the second current mirror unit includes a fifth switch tube and a sixth switch tube, a gate of the fifth switch tube is electrically connected with a gate of the sixth switch tube and a drain of the fifth switch tube respectively, and a source of the fifth switch tube and a source of the sixth switch tube are grounded, a drain of the sixth switch tube is electrically connected with the second swing rate strengthening module.

[0006] In a possible implementation manner of the first aspect, the second swing rate strengthening module includes a second current comparator, an input end of the second current comparator is electrically connected with the second swing rate trigger module, and an output end of the second current comparator is electrically connected with the gate of the lower power tube.

[0007] In a possible implementation manner of the first aspect, the second swing rate strengthening module includes a second current comparator, an input end of the second current comparator is electrically connected with the second swing rate trigger module, and an output end of the second current comparator is electrically connected with the gate of the lower power tube. Compared with the prior art, the embodiments of the present application have the beneficial effects that: The swing rate improving circuit provided in the embodiments of the present application comprises a first swing rate triggering module, a first swing rate strengthening module, a second swing rate triggering module and a second swing rate strengthening module. The first swing rate triggering module and the second swing rate triggering module can both receive a first voltage of a positive input end of an operational amplifier and a second voltage of a negative input end of the operational amplifier. When the difference between the first voltage and the second voltage is greater than a first threshold value, it indicates that the output signal needs to be established in a positive direction, at this time, the first swing rate triggering module is activated and starts to work, and outputs a first triggering signal to the first swing rate strengthening module. The first swing rate strengthening module outputs a first driving signal to the gate of an upper power tube according to the first triggering signal, so as to quickly open the upper power tube and accelerate the charging process of the load capacitor, thereby realizing the positive direction establishment of the output signal. When the difference between the first voltage and the second voltage is less than a second threshold value, it indicates that the output signal needs to be established in a reverse direction, at this time, the second swing rate triggering module is activated and starts to work, and outputs a second triggering signal to the second swing rate strengthening module. The second swing rate strengthening module outputs a second driving signal to the gate of a lower power tube according to the second triggering signal, so as to quickly open the lower power tube and accelerate the discharging process of the load capacitor, thereby realizing the reverse direction establishment of the output signal. It can be seen that the swing rate improving circuit provided in the embodiments of the present application constructs a direct triggering mechanism based on the difference of input voltages by adding the first swing rate triggering module and the second swing rate triggering module. That is, the circuit does not need to detect the output current, but directly judges the establishment requirement of the output signal according to the difference between the first voltage and the second voltage, and triggers the corresponding swing rate strengthening module to quickly open the upper power tube or the lower power tube. Since the whole process does not need to rely on the detection link of the response of the operational amplifier loop, there is no loop response delay problem, and the establishment time of the output signal can be significantly shortened, so that the output swing rate is more efficiently improved. BRIEF DESCRIPTION OF DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0009] Figure 1 is a working principle schematic diagram of an existing operational amplifier; Figure 2 is a circuit schematic diagram of an existing swing rate improving circuit; Figure 3 is a principle block diagram of a swing rate improving circuit provided in an embodiment of the present application; Figure 4 is a circuit connection schematic diagram of a swing rate improving circuit provided in an embodiment of the present application.

[0010] In the figure, 101, first swing rate trigger module; 1011, first switch unit; 1012, first current mirror unit; 102, first swing rate enhancement module; 103, second swing rate trigger module; 1031, second switch unit; 1032, second current mirror unit; 104, second swing rate enhancement module; 100, input stage module; 200, output stage module. DETAILED DESCRIPTION

[0011] In the following description, for the purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments described. However, it will be apparent to those skilled in the art that the application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the application with unnecessary detail.

[0012] It should be understood that the term "includes" when used in the specification and the appended claims herein, specifies the presence of features, integers, steps, operations, elements, and / or components but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0013] It should also be understood that the term "and / or" when used in the specification and the appended claims herein, means any one or more of the associated listed items and includes all possible combinations of the associated listed items.

[0014] As used in the description of the application and the appended claims herein, the term "if' can be interpreted as meaning "when" or "once" or "in response to a determination" or "in response to a detection" depending on the context. Similarly, the phrase "if determined" or "if detected [the described condition or event]" can be interpreted as meaning "once determined" or "in response to a determination" or "once detected [the described condition or event]" or "in response to a detection [the described condition or event]" depending on the context.

[0015] In addition, in the description of the application and the appended claims herein, the terms "first", "second", "third", etc. are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance.

[0016] Reference to“one embodiment” or“some embodiments” or“one implementation” or“some implementations” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase“in one embodiment” or“in some embodiments” or“in other embodiments” or“in other implementations” or“in some implementations” in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily referring to some, but not all, embodiments. Rather, they mean that, in some embodiments, the feature is included, while in others it is not.

[0017] In the application scenarios requiring high-voltage and high-power rail-to-rail input and output operational amplifiers, such as LCD liquid crystal deflection driving, as shown in Figure 1 An operational amplifier often needs to drive a large load capacitor COUT, at this time, the slew rate of the output signal VOUT becomes a key indicator affecting the rapid establishment of the signal. Insufficient slew rate will cause the output signal to fail to follow the changes of the input signal in time, especially when driving large swing signals, it is easy to appear problems such as long setup time and waveform distortion, which affects the overall performance of the system. In order to improve the output slew rate, the existing technology generally adopts a slew rate enhancement scheme based on output current detection, as shown in Figure 2 The scheme detects the output current of the power tube M1 or M2 on the output stage, when the current is detected to increase, the slew rate enhancement circuit is started through the current copying mechanism to speed up the voltage change rate of the internal node, and then accelerate the opening or closing of the power tube, to realize the slew rate improvement. However, since the operational amplifier is often connected in buffer mode in actual application, the change of the output current needs to go through the response process of the operational amplifier loop to be detected, which causes the inherent delay of the start of the slew rate enhancement circuit, and the output slew rate improvement is relatively slow.

[0018] Based on the above problems, the swing rate improvement circuit provided by the embodiment of the present application includes a first swing rate trigger module, a first swing rate strengthening module, a second swing rate trigger module and a second swing rate strengthening module. The first swing rate trigger module and the second swing rate trigger module can both receive a first voltage of the positive input end of the operational amplifier and a second voltage of the negative input end of the operational amplifier. When the difference between the first voltage and the second voltage is greater than a first threshold value, it indicates that the output signal needs to be established in a positive direction, at this time, the first swing rate trigger module is activated and starts to work, and outputs a first trigger signal to the first swing rate strengthening module. The first swing rate strengthening module outputs a first driving signal to the gate of the upper power tube according to the first trigger signal, so as to quickly open the upper power tube, accelerate the charging process of the load capacitor, and realize the positive direction establishment of the output signal. When the difference between the first voltage and the second voltage is less than a second threshold value, it indicates that the output signal needs to be established in a reverse direction, at this time, the second swing rate trigger module is activated and starts to work, and outputs a second trigger signal to the second swing rate strengthening module. The second swing rate strengthening module outputs a second driving signal to the gate of the lower power tube according to the second trigger signal, so as to quickly open the lower power tube, accelerate the discharging process of the load capacitor, and realize the reverse direction establishment of the output signal. It can be seen that the swing rate improvement circuit provided by the embodiment of the present application constructs a direct trigger mechanism based on the difference of the input voltage by adding the first swing rate trigger module and the second swing rate trigger module. That is, the circuit does not need to detect the output current, but directly judges the establishment requirement of the output signal according to the difference between the first voltage and the second voltage, and triggers the corresponding swing rate strengthening module to quickly open the upper power tube or the lower power tube. Since the whole process does not need to rely on the detection link of the response of the operational amplifier loop, there is no loop response delay problem, and the establishment time of the output signal can be significantly shortened, so that the output swing rate is more efficiently improved.

[0019] In order to illustrate the technical solutions described in the present application, specific embodiments are described below.

[0020] Figure 3 The principle block diagram of the swing rate improvement circuit provided by an embodiment of the present application is shown. Referring to FIG. 1, Figure 3 As shown in FIG. 1, the swing rate improvement circuit includes a first swing rate trigger module 101, a first swing rate strengthening module 102, a second swing rate trigger module 103 and a second swing rate strengthening module 104, the first swing rate trigger module 101 is electrically connected with the first swing rate strengthening module 102, the first swing rate strengthening module 102 is used to be electrically connected with the gate of the upper power tube M1, the second swing rate trigger module 103 is electrically connected with the second swing rate strengthening module 104, and the second swing rate strengthening module 104 is used to be electrically connected with the gate of the lower power tube M2. Specifically, the first swing rate trigger module 101 and the second swing rate trigger module 103 can each receive a first voltage VINP at the positive input terminal of the operational amplifier and a second voltage VINN at the negative input terminal of the operational amplifier. When the difference between the first voltage VINP and the second voltage VINN is greater than a first threshold value, it indicates that the output signal VOUT needs to be established in a positive direction, and at this time, the first swing rate trigger module 101 is activated and starts to work, and outputs a first trigger signal to the first swing rate enhancement module 102. The first swing rate enhancement module 102 outputs a first driving signal to the gate of the upper power tube M1 according to the first trigger signal, so as to quickly open the upper power tube M1 and accelerate the charging process of the load capacitor, thereby achieving the positive direction establishment of the output signal VOUT. When the difference between the first voltage VINP and the second voltage VINN is less than a second threshold value, it indicates that the output signal VOUT needs to be established in a negative direction, and at this time, the second swing rate trigger module 103 is activated and starts to work, and outputs a second trigger signal to the second swing rate enhancement module 104. The second swing rate enhancement module 104 outputs a second driving signal to the gate of the lower power tube M2 according to the second trigger signal, so as to quickly open the lower power tube M2 and accelerate the discharging process of the load capacitor, thereby achieving the negative direction establishment of the output signal VOUT. It can be seen that the swing rate enhancement circuit provided in the embodiment of the present application constructs a direct trigger mechanism based on the difference of the input voltage VIN by additionally arranging the first swing rate trigger module 101 and the second swing rate trigger module 103. That is, the circuit does not need to detect the output current, but directly judges the establishment requirement of the output signal VOUT according to the difference between the first voltage VINP and the second voltage VINN, and triggers the corresponding swing rate enhancement module to quickly open the upper power tube M1 or the lower power tube M2. Since the whole process does not need to rely on the detection link of the response of the operational amplifier loop, there is no problem of loop response delay, and the establishment time of the output signal VOUT can be significantly shortened, so that the output swing rate is more efficiently improved.

[0021] It should be noted that, since the first voltage VINP is the voltage at the positive input terminal of the operational amplifier, and the second voltage VINN is the voltage at the negative input terminal of the operational amplifier, the first threshold value is set to be positive, and the second threshold value is set to be negative. Specifically, when the first voltage VINP is greater than the second voltage VINN by a first threshold value, the first swing rate trigger module 101 is activated and starts to work, and outputs a first trigger signal to the first swing rate enhancement module 102; when the first voltage VINP is less than the second voltage VINN by an absolute value of a second threshold value, the second swing rate trigger module 103 is activated and starts to work, and outputs a second trigger signal to the second swing rate enhancement module 104. In addition, in order to ensure the symmetry of the circuit design, the first swing rate trigger module 101 and the second swing rate trigger module 103 adopt the same design architecture, so that the absolute values of the first threshold value and the second threshold value can be equal.

[0022] It should be noted that in actual use, the op amp is connected as a buffer, that is, the output of the op amp is connected to the negative input of the op amp. This connection method fully cooperates with the working logic of the slew rate boost circuit. By real-time detection and response to the input voltage difference, it further accelerates the settling speed of the output signal VOUT, effectively solving the problem of insufficient slew rate under large load capacitance.

[0023] In one embodiment of the present application, Figure 4 As shown, the first slew rate trigger module 101 includes a first switch unit 1011 and a first current mirror unit 1012 , and the first current mirror unit 1012 is electrically connected to the first switch unit 1011 and the first slew rate enhancement module 102 respectively.

[0024] Specifically, the first switch unit 1011 functions as a voltage difference detection switch unit. When the difference between the first voltage V INP and the second voltage V INN is greater than a first threshold, the first switch unit 1011 turns on, providing a first current to the first current mirror unit 1012. The first current mirror unit 1012 receives the first current output by the first switch unit 1011 after it turns on, replicates the current according to a preset ratio, and transmits the replicated current as a first trigger signal to the first slew rate enhancement module 102. The current mirroring mechanism stabilizes the amplitude of the first trigger signal, ensuring that the first slew rate enhancement module 102 can reliably respond and output a driving signal that meets the requirements.

[0025] In one embodiment of the present application, Figure 4 As shown, the first switch unit 1011 includes a first switch tube MPS1, a gate of the first switch tube MPS1 is used to receive a first voltage VINP, a source of the first switch tube MPS1 is used to receive a second voltage VINN, and a drain of the first switch tube MPS1 is electrically connected to the first current mirror unit 1012.

[0026] Specifically, the first switch transistor MPS1 serves as the core detection and control device for the difference between the first voltage V INP and the second voltage V INN. It controls its conduction state based on the voltage difference between its gate and source (i.e., the difference between the first voltage V INP and the second voltage V INN). When the difference between the first voltage V INP and the second voltage V INN exceeds a first threshold, the first switch transistor MPS1 turns on, electrically connecting its drain and source to the first current mirror unit 1012 and generating a first current. Otherwise, the first switch transistor MPS1 remains off, blocking the signal path.

[0027] For example, designers can select the type of the first switch MPS1 according to actual conditions, that is, a fully controlled power device such as a metal oxide field effect transistor or an insulated gate bipolar transistor can be used. For example, the first switch MPS1 can be selected as an NMOS transistor.

[0028] In one embodiment of the present application, as shown in Figure 4 The first current mirror unit 1012 includes a second switch tube MP2 and a third switch tube MP3. The gate of the second switch tube MP2 is electrically connected with the gate of the third switch tube MP3, the drain of the second switch tube MP2 and the drain of the first switch tube MPS1 respectively. The source of the second switch tube MP2 and the source of the third switch tube MP3 are both used for receiving an input voltage VIN. The drain of the third switch tube MP3 is electrically connected with the first swing rate enhancement module 102.

[0029] Specifically, the second switch tube MP2 and the third switch tube MP3 constitute a current mirror structure, which can realize the replication and transmission of current. The gate of the second switch tube MP2 is connected with the drain and receives the first current output by the first switch tube MPS1, forming a diode connection mode to stabilize the gate voltage of itself, and at the same time, the gate voltage synchronously controls the on-off state of the third switch tube MP3. Since the gate voltages of the second switch tube MP2 and the third switch tube MP3 are consistent and the sources are connected to the same input voltage VIN, the third switch tube MP3 will replicate the first current according to a preset ratio (determined by the matching degree of device parameters) with the second switch tube MP2, and output a current signal (i.e. the first trigger signal) in a fixed ratio with the first current through the drain to the first swing rate enhancement module 102. The first current mirror unit 1012 ensures the stability and proportional controllability of the first trigger signal through the current mirror principle, and provides a reliable driving basis for the first swing rate enhancement module 102.

[0030] For example, the designer can select the types of the second switch tube MP2 and the third switch tube MP3 according to actual conditions, i.e. using metal oxide field effect transistors or insulated gate bipolar transistors and other fully controlled power devices. For example, the second switch tube MP2 and the third switch tube MP3 can be both PMOS tubes.

[0031] It should be noted that only one circuit structure of the first swing rate trigger module 101 is shown in the embodiments provided in the present application, and it does not mean that only this circuit structure can realize the function of the first swing rate trigger module 101. Other circuit structures that can realize the function can also be replaced, and are not limited to this.

[0032] In one embodiment of the present application, the first swing rate enhancement module 102 includes a first current comparator. The input end of the first current comparator is electrically connected with the first swing rate trigger module 101. The output end of the first current comparator is electrically connected with the gate of the upper power tube M1.

[0033] Specifically, the first current comparator is configured to compare the first trigger signal (a current signal) output by the first swing rate trigger module 101 with a preset current threshold value, and output a first drive signal to the gate of the upper power transistor M1 when the first trigger signal exceeds the threshold current, so that the upper power transistor M1 can be quickly and stably turned on. Meanwhile, the comparison characteristic of the first current comparator can further filter the effective trigger signal according to the preset current threshold value, so as to avoid the false triggering of the upper power transistor M1 by noise or weak interference signals, thereby ensuring the swing rate improvement speed and enhancing the reliability of the circuit operation.

[0034] It should be noted that the first swing rate enhancement module 102 can be composed of a current amplification unit, a push-pull drive unit and a bias circuit in addition to the first current comparator, so as to more accurately realize the fast driving of the upper power transistor M1. The current amplification unit receives the first trigger signal, amplifies the signal amplitude through a multi-stage current mirror or a common-emission amplification structure, and enhances the driving capability. The push-pull drive unit is composed of complementary power transistors (such as PMOS and NMOS), which can convert the amplified current signal into a high-swing voltage signal and directly act on the gate of the upper power transistor M1 to accelerate the opening speed. The bias circuit provides a stable static working point for the entire module, so as to ensure that each unit can quickly respond when the trigger signal is input and avoid driving delay or distortion caused by unstable bias. The above combined structure can not only amplify the strength of the trigger signal, but also match the gate capacitance characteristics of the upper power transistor M1, further shorten the opening time, and thus more efficiently improve the output swing rate.

[0035] It should be noted that only one circuit structure of the first swing rate enhancement module 102 is shown in the embodiments provided in the present application, and this circuit structure does not represent that only this circuit structure can realize the function of the first swing rate enhancement module 102. Other circuit structures that can realize the function can also be replaced, and are not limited thereto.

[0036] In an embodiment of the present application, as shown in Figure 4 The second swing rate trigger module 103 includes a second switch unit 1031 and a second current mirror unit 1032, and the second current mirror unit 1032 is electrically connected with the second switch unit 1031 and the second swing rate enhancement module 104 respectively.

[0037] Specifically, the second switch unit 1031 functions as a switch unit for reverse voltage difference detection and is turned on when the difference between the first voltage VINP and the second voltage VINN is less than the second threshold value (negative value), thereby providing the second current mirror unit 1032 with a second current. The second current mirror unit 1032 functions to receive the second current output by the second switch unit 1031 after being turned on, and to copy the current according to a preset ratio, and transmit the copied current to the second swing enhancement module 104 as a second trigger signal. The current mirror mechanism stabilizes the amplitude of the second trigger signal, and ensures that the second swing enhancement module 104 can reliably respond and output a driving signal meeting the requirements.

[0038] In an embodiment of the present application, as shown in Figure 4 The second switch unit 1031 includes a fourth switch tube MPS2, the gate of the fourth switch tube MPS2 is configured to receive the first voltage VINP, the source of the fourth switch tube MPS2 is configured to receive the second voltage VINN, and the drain of the fourth switch tube MPS2 is electrically connected to the second current mirror unit 1032.

[0039] Specifically, the second switch tube MP2 functions as a core detection and control device for the difference between the first voltage VINP and the second voltage VINN, and controls its conduction state through the voltage difference between the gate and the source (i.e., the difference between the first voltage VINP and the second voltage VINN). When the difference between the first voltage VINP and the second voltage VINN is less than the second threshold value, the second switch tube MP2 is turned on, so that the drain, the source and the second current mirror unit 1032 form an electrical connection and generate a second current. Otherwise, it remains off and blocks the signal path.

[0040] For example, the designer can select the type of the fourth switch tube MPS2 according to the actual situation, i.e., can use a metal oxide field effect transistor or an insulated gate bipolar transistor, etc. For example, the fourth switch tube MPS2 can be selected as a PMOS tube.

[0041] In an embodiment of the present application, as shown in Figure 4 The second current mirror unit 1032 includes a fifth switch tube MN5 and a sixth switch tube MN6, the gate of the fifth switch tube MN5 is electrically connected to the gate of the sixth switch tube MN6, the drain of the fifth switch tube MN5 and the drain of the fourth switch tube MPS2, the source of the fifth switch tube MN5 and the source of the sixth switch tube MN6 are both grounded, and the drain of the sixth switch tube MN6 is electrically connected to the second swing enhancement module 104.

[0042] Specifically, the fifth switch tube MN5 and the sixth switch tube MN6 constitute a current mirror structure, and current replication and transmission can be realized. The gate of the fifth switch tube MN5 is connected with the drain and receives the second current output by the fourth switch tube MPS2, forms a diode connection mode to stabilize the gate voltage of itself, and simultaneously the gate voltage synchronously controls the on state of the sixth switch tube MN6. Since the gate voltages of the fifth switch tube MN5 and the sixth switch tube MN6 are consistent and the sources are both grounded, the sixth switch tube MN6 will replicate the second current according to a preset ratio (determined by the matching degree of device parameters) with the fifth switch tube MN5, and output a current signal (i.e. a second trigger signal) in a fixed ratio with the second current through the drain to the second swing rate enhancement module 104. The second current mirror unit 1032 ensures the stability and the proportion controllability of the second trigger signal through the current mirror principle, and provides a reliable driving basis for the second swing rate enhancement module 104.

[0043] For example, the designer can select the types of the fifth switch tube MN5 and the sixth switch tube MN6 according to actual conditions, that is, full-controlled power devices such as metal oxide field effect transistors or insulated gate bipolar transistors can be used. For example, the fifth switch tube MN5 and the sixth switch tube MN6 can be both NMOS tubes.

[0044] It should be noted that only one circuit structure of the second swing rate trigger module 103 is shown in the embodiments provided in the present application, and it does not mean that only this circuit structure can realize the function of the second swing rate trigger module 103. Other circuit structures that can realize the function can also be replaced, and are not limited thereto.

[0045] In an embodiment of the present application, the second swing rate enhancement module 104 includes a second current comparator, the input end of the second current comparator is electrically connected with the second swing rate trigger module 103, and the output end of the second current comparator is electrically connected with the gate of the lower power tube M2.

[0046] Specifically, the second current comparator is used for comparing the second trigger signal (current signal) output by the second swing rate trigger module 103 with an internally preset current threshold value, and when it is detected that the second trigger signal exceeds the threshold current, a second driving signal is output to the gate of the lower power tube M2, so that the lower power tube M2 can be quickly and stably turned on. At the same time, the comparison characteristics of the second current comparator can further filter the effective trigger signal according to the preset current threshold value, so as to avoid the noise or weak interference signal from mis-triggering the lower power tube M2, thereby ensuring the swing rate improvement speed and enhancing the reliability of the circuit operation.

[0047] It should be noted that the second swing rate enhancement module 104 can be composed of a current amplification unit, a push-pull drive unit and a bias circuit in addition to the second current comparator, so as to more accurately realize the fast driving of the upper power tube M1. Similar to the first swing rate enhancement module 102, no more details are given here.

[0048] It should be noted that only one circuit structure of the second swing rate enhancement module 104 is shown in the embodiments provided in the present application, and it does not mean that only this circuit structure can realize the function of the second swing rate enhancement module 104. Other circuit structures that can realize the function can also be replaced, and are not limited thereto.

[0049] The present application also discloses an operational amplifier, comprising an input stage module 100, an output stage module 200 and the swing rate enhancement circuit described above, and the output stage module 200 is electrically connected with the input stage module 100, the first swing rate enhancement module 102 and the second swing rate enhancement module 104 in the swing rate enhancement circuit.

[0050] Specifically, the input stage module 100 is used to receive and process the input signal (the first voltage VINP and the second voltage VINN), realize the preliminary amplification and conversion of the signal, and provide a stable signal source for the subsequent circuit. The output stage module 200 is used to output a signal with sufficient driving capability to drive the external load under the cooperative control of the input stage module 100 and the swing rate enhancement circuit. Among them, the upper power tube M1 and the lower power tube M2 are the core devices of the output stage, which are responsible for realizing the power amplification and output of the signal. The operational amplifier adopts the swing rate enhancement circuit described above, which can directly trigger the swing rate enhancement mechanism through the input voltage VIN difference without relying on the output current detection, effectively avoiding the loop response delay problem, and can quickly open the upper power tube M1 or the lower power tube M2 when driving a large load capacitor, significantly improving the output swing rate, so that the output signal VOUT can follow the input signal change more quickly, reduce waveform distortion, and further improve the overall performance of the operational amplifier in the high-voltage and large load scene.

[0051] In an embodiment of the present application, as Figure 3 and Figure 4As shown, the element composition of the input stage module 100 and the connection relationship thereof are as follows: the input stage module 100 comprises a seventh switch tube M7, an eighth switch tube M8, a ninth switch tube M9, a tenth switch tube M10, a first current source I1 and a second current source I2, the gate of the seventh switch tube M7 and the gate of the ninth switch tube M9 are both used for receiving a second voltage VINN, the gate of the eighth switch tube M8 and the gate of the tenth switch tube are both used for receiving a first voltage VINP, the source of the seventh switch tube M7 and the source of the eighth switch tube M8 are both electrically connected with the first end of the first current source I1, the source of the ninth switch tube M9 and the source of the tenth switch tube M10 are both electrically connected with the first end of the second current source I2, and the drain of the seventh switch tube M7, the drain of the eighth switch tube M8, the drain of the ninth switch tube M9 and the drain of the tenth switch tube M10 are all electrically connected with the output stage module 200.

[0052] Specifically, the first current source I1 and the second current source I2 provide stable bias current for the input stage module 100, ensure that M7-M10 work at a preset static operating point, and provide a continuous and stable current driving basis for the circuit. The seventh switch tube M7 and the ninth switch tube M9 are a group of switch devices controlled by the second voltage VINN, the eighth switch tube M8 and the tenth switch tube M10 are a group of switch devices controlled by the first voltage VINP, and the four switch tubes jointly constitute a complementary differential pair structure. When the first voltage VINP and the second voltage VINN are input, the seventh switch tube M7 and the eighth switch tube M8, the ninth switch tube M9 and the tenth switch tube M10 respectively adjust the drain current according to the voltage difference between the two ends, convert the input voltage VIN signal into a current signal through a differential amplification mechanism, and transmit the processed current signal to the output stage module 200, thereby realizing preliminary amplification and conversion of the input signal and providing a basic signal for subsequent power amplification of the output stage.

[0053] For example, the designer can select the types of the seventh switch tube M7, the eighth switch tube M8, the ninth switch tube M9 and the tenth switch tube M10 according to actual conditions, that is, full-controlled power devices such as metal oxide field effect transistors or insulated gate bipolar transistors can be used. For example, the seventh switch tube M7 and the eighth switch tube M8 can be both NMOS tubes, and the ninth switch tube M9 and the tenth switch tube M10 can be both PMOS tubes.

[0054] In an embodiment of the present application, as Figure 3 and Figure 4As shown, the element composition of the output stage module 200 and the connection relationship thereof are as follows: the output stage module 200 comprises an eleventh switch tube M11, a twelfth switch tube M12, a thirteenth switch tube M13, a fourteenth switch tube M14, a fifteenth switch tube M15, a sixteenth switch tube M16, a seventeenth switch tube M17, an eighteenth switch tube M18, a nineteenth switch tube M19, a twentieth switch tube M20, a twenty-first switch tube M21, a twenty-second switch tube M22, an upper power tube M1 and a lower power tube M2.

[0055] The gate of the eleventh switch tube M11 is electrically connected with the gate of the twelfth switch tube M12, the drain of the thirteenth switch tube M13, the drain of the fifteenth switch tube M15 and the source of the sixteenth switch tube M16 respectively, the source of the eleventh switch tube M11, the source of the twelfth switch tube M12 and the source of the upper power tube M1 are all used for receiving an input voltage VIN, the drain of the eleventh switch tube M11 is electrically connected with the source of the thirteenth switch tube M13 and the drain of the seventh switch tube M7 respectively, the gate of the fourteenth switch tube M14 is used for receiving a VBP signal together with the gate of the thirteenth switch tube M13, the source of the fourteenth switch tube M14 is electrically connected with the drain of the twelfth switch tube M12 and the drain of the eighth switch tube M8 respectively, the drain of the fourteenth switch tube M14 is electrically connected with the first swing rate strengthening module 102, the gate of the upper power tube M1, the drain of the seventeenth switch tube M17 and the source of the eighteenth switch tube respectively, the gate of the nineteenth switch tube M19 and the gate of the twentieth switch tube M20 are both used for receiving a VBN signal, the drain of the nineteenth switch tube M19 is electrically connected with the source of the fifteenth switch tube M15, the drain of the sixteenth switch tube M16, the gate of the twenty-first switch tube M21 and the gate of the twenty-second switch tube M22 respectively, the source of the nineteenth switch tube M19 is electrically connected with the drain of the twenty-first switch tube M21 and the drain of the ninth switch tube M9 respectively, the drain of the twentieth switch tube M20 is electrically connected with the source of the seventeenth switch tube M17, the drain of the eighteenth switch tube M18, the second swing rate strengthening module 104 and the gate of the lower power tube M2 respectively, the source of the twentieth switch tube M20 is electrically connected with the drain of the twenty-second switch tube M22 and the drain of the tenth switch tube M10 respectively, the source of the twenty-first switch tube M21, the source of the twenty-second switch tube M22 and the source of the lower power tube M2 are all grounded, the gate of the fifteenth switch tube M15 is used for receiving a first gate drive signal, the gate of the sixteenth switch tube M16 is used for receiving a second gate drive signal, the gate of the seventeenth switch tube M17 is used for receiving a third gate drive signal, and the gate of the eighteenth switch tube M18 is used for receiving a fourth gate drive signal.

[0056] Specifically, the M11-M22 form a class AB output stage with the upper power transistor M1 and the lower power transistor M2. The upper power transistor M1 and the lower power transistor M2 are core output devices, which are responsible for providing forward and reverse drive currents to the load, respectively, and realize large-current output through a push-pull working mode to drive an external load (such as a large-capacitance load).

[0057] The eleventh switch transistor M11 and the twelfth switch transistor M12 form a current mirror structure, and the thirteenth switch transistor M13 provides stable bias current for the upper power transistor M1 and the peripheral circuit. The drain of the eleventh switch transistor M11 is connected to the drain of the seventh switch transistor M7 in the input stage module 100, so as to realize the coupling of the input signal and the drive circuit of the upper power transistor M1. The fourteenth switch transistor M14 is a drive stage of the upper power transistor M1, receives the signal transmitted by the eighth switch transistor M8 in the input stage module 100 and transmits the signal to the gate of the upper power transistor M1, and is connected with the first slew rate enhancement module 102 to accelerate the opening of the upper power transistor M1 in cooperation with the first slew rate enhancement module 102.

[0058] The fifteenth switch transistor M15 and the sixteenth switch transistor M16 are controlled by the first and second gate drive signals, and are used as auxiliary transistors on the positive power supply side of the rail-to-rail output, which are turned on when the output voltage approaches the positive power supply rail, so as to widen the output voltage range. The seventeenth switch transistor M17 and the eighteenth switch transistor M18 are controlled by the third and fourth gate drive signals, and are used as auxiliary transistors on the ground side of the rail-to-rail output, which are turned on when the output voltage approaches the ground rail, so as to further improve the rail-to-rail output characteristics.

[0059] The nineteenth switch transistor M19 and the twentieth switch transistor M20 form a lower bias current source, which provides stable bias for the lower power transistor M2 and the peripheral circuit. The twentieth switch transistor M20 is connected with the second slew rate enhancement module 104 to accelerate the opening of the lower power transistor M2 in cooperation with the second slew rate enhancement module 104. The twenty-first switch transistor M21 and the twenty-second switch transistor M22 are used as active loads on the lower side, which cooperate with the nineteenth switch transistor M19 and the twentieth switch transistor M20 to stabilize the bias voltage of the lower power transistor M2, so as to ensure that the lower power transistor M2 can work linearly under small signals and large signals. As can be seen from the above, the devices form a complete output stage drive link through the above connection, which realizes the rail-to-rail output function, and significantly improves the establishment speed of the output signal VOUT through the cooperation with the slew rate improvement circuit.

[0060] Exemplarily, the designer can select the types of the eleventh switch tube M11, the twelfth switch tube M12, the thirteenth switch tube M13, the fourteenth switch tube M14, the fifteenth switch tube M15, the sixteenth switch tube M16, the seventeenth switch tube M17, the eighteenth switch tube M18, the nineteenth switch tube M19, the twentieth switch tube M20, the twenty-first switch tube M21, the twenty-second switch tube M22, the upper power tube M1 and the lower power tube M2 according to actual conditions, that is, full-controlled power devices such as metal oxide field effect transistors or insulated gate bipolar transistors can be used. For example, the eleventh switch tube M11, the twelfth switch tube M12, the thirteenth switch tube M13, the fourteenth switch tube M14, the sixteenth switch tube M16, the eighteenth switch tube M18 and the upper power tube M1 can be PMOS tubes, and the fifteenth switch tube M15, the seventeenth switch tube M17, the nineteenth switch tube M19, the twentieth switch tube M20, the twenty-first switch tube M21, the twenty-second switch tube M22 and the lower power tube M2 can be NMOS tubes.

[0061] Since the processing and functions realized by the operational amplifier in the embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned slew rate improving circuit, the description of the embodiment does not describe the details, and the related descriptions in the aforementioned embodiments can be referred to, which will not be described herein.

[0062] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A slew rate boosting circuit, characterized in that: The device comprises a first slew rate trigger module, a first slew rate enhancement module, a second slew rate trigger module, and a second slew rate enhancement module, wherein the first slew rate trigger module is electrically connected to the first slew rate enhancement module, the first slew rate enhancement module is used to be electrically connected to the gate of the upper power tube, the second slew rate trigger module is electrically connected to the second slew rate enhancement module, and the second slew rate enhancement module is used to be electrically connected to the gate of the lower power tube; The first slew rate trigger module is used to receive a first voltage and a second voltage, and output a first trigger signal to the first slew rate enhancement module when the difference between the first voltage and the second voltage is greater than a first threshold; the first slew rate enhancement module is used to output a first drive signal to the gate of the upper power tube according to the first trigger signal; the second slew rate trigger module is used to receive the first voltage and the second voltage, and output a second trigger signal to the second slew rate enhancement module when the difference between the first voltage and the second voltage is less than a second threshold; the second slew rate enhancement module is used to output a second drive signal to the gate of the lower power tube according to the second trigger signal.

2. The slew rate boosting circuit according to claim 1, wherein: The first slew rate trigger module includes a first switch unit and a first current mirror unit, and the first current mirror unit is electrically connected to the first switch unit and the first slew rate enhancement module respectively; The first switch unit is used to output a first current to the first current mirror unit when the difference between the first voltage and the second voltage is greater than a first threshold; the first current mirror unit is used to output the first trigger signal to the first slew rate enhancement module according to the first current.

3. The slew rate boosting circuit according to claim 2, wherein: The first switch unit includes a first switch tube, a gate of the first switch tube is used to receive the first voltage, a source of the first switch tube is used to receive the second voltage, and a drain of the first switch tube is electrically connected to the first current mirror unit.

4. The slew rate boosting circuit according to claim 2, wherein: The first current mirror unit includes a second switch tube and a third switch tube, the gate of the second switch tube is electrically connected to the gate of the third switch tube, the drain of the second switch tube and the first switch unit respectively, the source of the second switch tube and the source of the third switch tube are both used to receive an input voltage, and the drain of the third switch tube is electrically connected to the first slew rate enhancement module.

5. The slew rate boosting circuit according to claim 1, wherein: The first slew rate enhancement module includes a first current comparator, an input end of the first current comparator is electrically connected to the first slew rate trigger module, and an output end of the first current comparator is electrically connected to the gate of the upper power tube.

6. The slew rate boosting circuit according to claim 1, wherein: The second slew rate trigger module includes a second switch unit and a second current mirror unit, and the second current mirror unit is electrically connected to the second switch unit and the second slew rate enhancement module respectively; The second switch unit is used to output a second current to the second current mirror unit when the difference between the first voltage and the second voltage is less than a second threshold; the second current mirror unit is used to output the second trigger signal to the second slew rate enhancement module according to the second current.

7. The slew rate boosting circuit according to claim 6, wherein: The second switch unit includes a fourth switch tube, a gate of the fourth switch tube is used to receive the first voltage, a source of the fourth switch tube is used to receive the second voltage, and a drain of the fourth switch tube is electrically connected to the second current mirror unit.

8. The slew rate boosting circuit according to claim 6, wherein: The second current mirror unit includes a fifth switch tube and a sixth switch tube. The gate of the fifth switch tube is electrically connected to the gate of the sixth switch tube, the drain of the fifth switch tube, and the second switch unit respectively. The source of the fifth switch tube and the source of the sixth switch tube are both grounded. The drain of the sixth switch tube is electrically connected to the second slew rate enhancement module.

9. The slew rate boosting circuit according to claim 1, wherein: The second slew rate enhancement module includes a second current comparator, an input end of the second current comparator is electrically connected to the second slew rate trigger module, and an output end of the second current comparator is electrically connected to the gate of the lower power tube.

10. An operational amplifier, characterized in that: It comprises an input stage module, an output stage module and the slew rate enhancement circuit according to any one of claims 1 to 9, wherein the output stage module is electrically connected to the input stage module, the first slew rate enhancement module and the second slew rate enhancement module in the slew rate enhancement circuit respectively.

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