Class AB output level shift circuit and device

Abstract

The invention relates to an AB type output level shift circuit and equipment, and relates to the technical field of level shift. The AB type output level shift circuit comprises a first constant current source, a second constant current source, an input switch tube, a transconductance linear ring and an output module, a first electrode of the input switch tube is used for accessing a level signal, an input end of the output module is connected with an output end of the transconductance linear ring, and a power supply end of the output module is used for connecting a power supply. The grounding end of the output module is grounded, and the output end of the output module is connected with the second pole of the input switch tube, so that the transconductance linear ring is used for driving the output module to output AB type level shift signals based on the signals accessed from the input switch tube under the condition that the level signals are accessed to the input switch tube. By adopting the AB type output level shift circuit and the AB type output level shift equipment provided by the invention, the complexity of the circuit structure can be reduced.

Description

Technical Field

[0001] This application relates to the technical field of level shifting, and particularly to a class-AB output level shifting circuit and device. Background Art

[0002] Level shifting circuits are widely used in signal processing. Input and output signals generated by different modules may not be directly interconnected due to different power supply domains in which they operate. A level shifting circuit is required to shift the output signal of the previous stage to a port suitable for the input of the subsequent stage to complete normal signal conversion.

[0003] When performing level shifting on analog signals, for better signal transmission quality, the output type of operational amplifiers is usually the class-AB output method. Fixed proportional coefficients are formed by operational amplifiers to complete level shifting, such as non-inverting amplifier circuits and inverting amplifier circuits.

[0004] However, traditional solutions require the use of operational amplifiers to implement, which requires loop compensation inside the circuit, resulting in a complex circuit structure, increased power consumption, increased circuit occupied area, and increased circuit noise. Summary of the Invention

[0005] Based on this, it is necessary to provide a class-AB output level shifting circuit and device that can reduce the complexity of the circuit structure and implement the class-AB output level shifting function.

[0006] In a first aspect, this application provides a class-AB output level shifting circuit, including:

[0007] A first constant current source, the input end of the first constant current source is used to connect to a power supply;

[0008] A second constant current source, the output end of the second constant current source is grounded;

[0009] An input switching transistor, the first pole of the input switching transistor is used to access a level signal;

[0010] Wherein, the second pole of the input switching transistor is connected to the output end of the first constant current source, and the third pole of the input switching transistor is connected to the input end of the second constant current source; or, the second pole of the input switching transistor is connected to the input end of the second constant current source, and the third pole of the input switching transistor is connected to the output end of the first constant current source;

[0011] A translinear loop, the input end of the translinear loop is connected to the third pole of the input switching transistor, the power supply end of the translinear loop is used to connect to a power supply, the ground end of the translinear loop is grounded, and the translinear loop is used to support the output of class-AB signals;

[0012] An output module, the input end of the output module is connected to the output end of the translinear loop, the power supply end of the output module is used to connect to a power supply, the ground end of the output module is grounded, and the output end of the output module is connected to the second pole of the input switching transistor, so that the translinear loop is used to drive the output module to output a class AB level shift signal based on the signal accessed from the input switching transistor when the input switching transistor accesses a level signal.

[0013] In one embodiment, the input switching transistor is a MOS transistor, the first pole of the input switching transistor is the gate, the second pole of the input switching transistor is the source, and the third pole of the input switching transistor is the drain.

[0014] In one embodiment, when the input switching transistor is a P-type MOS transistor, the translinear loop includes: switching transistors Mn1, Mn2, Mn3, switching transistors Mp1, Mp2, Mp3, a third constant current source, a fourth constant current source, and a fifth constant current source;

[0015] Among them, the third constant current source, switching transistor Mn2, and switching transistor Mn3 are sequentially connected in series between the power supply and the ground, the gate and the drain of switching transistor Mn2 are connected, and the gate and the drain of switching transistor Mn3 are connected;

[0016] Switching transistor Mp3, switching transistor Mp2, and the fourth constant current source are sequentially connected in series between the power supply and the ground, the gate and the drain of switching transistor Mp3 are connected, and the gate and the drain of switching transistor Mp2 are connected;

[0017] The source of switching transistor Mn1 is connected to the drain of switching transistor Mp1, the gate of switching transistor Mn1 is connected to the gate of switching transistor Mn2, the drain of switching transistor Mn1 is connected to the source of switching transistor Mp1, and the gate of switching transistor Mp1 is connected to the gate of switching transistor Mp2; the drain of switching transistor Mn1 is connected to the first input end of the output module, and the source of switching transistor Mn1 is connected to the second input end of the output module;

[0018] The input end of the fifth constant current source is used to connect to the power supply, the output end of the fifth constant current source is connected to the drain of switching transistor Mn1, and the source of switching transistor Mn1 is connected to the drain of the input switching transistor.

[0019] In one embodiment, when the input switching transistor is an N-type MOS transistor, the translinear loop includes: switching transistors Mn1, Mn2, Mn3, switching transistors Mp1, Mp2, Mp3, a third constant current source, a fourth constant current source, and a fifth constant current source;

[0020] Among them, the third constant current source, switching transistor Mn2, and switching transistor Mn3 are sequentially connected in series between the power supply and the ground, the gate and the drain of switching transistor Mn2 are connected, and the gate and the drain of switching transistor Mn3 are connected;

[0021] The switching transistor Mp3, the switching transistor Mp2, and the fourth constant current source are connected in series between the power supply and the ground in sequence. The gate and the drain of the switching transistor Mp3 are connected, and the gate and the drain of the switching transistor Mp2 are connected;

[0022] The source of the switching transistor Mn1 is connected to the drain of the switching transistor Mp1. The gate of the switching transistor Mn1 is connected to the gate of the switching transistor Mn2. The drain of the switching transistor Mn1 is connected to the source of the switching transistor Mp1. The gate of the switching transistor Mp1 is connected to the gate of the switching transistor Mp2. The drain of the switching transistor Mn1 is connected to the first input terminal of the output module, and the source of the switching transistor Mn1 is connected to the second input terminal of the output module;

[0023] The output terminal of the fifth constant current source is used for grounding. The input terminal of the fifth constant current source is connected to the source of the switching transistor Mn1, and the drain of the switching transistor Mn1 is connected to the drain of the input switching transistor.

[0024] In one embodiment, the class AB output level shift circuit further includes:

[0025] A voltage dividing circuit, which is connected in series between the output terminal of the output module and the ground. The output terminal of the voltage dividing circuit is connected to the second pole of the input switching transistor.

[0026] In one embodiment, the voltage dividing circuit includes:

[0027] A plurality of voltage dividing resistors connected in series between the output terminal of the output module and the ground. Among them, an output terminal is led out between two adjacent voltage dividing resistors and connected to the second pole of the input switching transistor.

[0028] In one embodiment, the output module is a push-pull output circuit.

[0029] In one embodiment, when the input switching transistor is a P-type MOS transistor, the push-pull output circuit includes:

[0030] The switching transistor Mpout and the switching transistor Mnout;

[0031] Among them, the switching transistor Mpout and the switching transistor Mnout are connected in series between the power supply and the ground in sequence. The gate of the switching transistor Mpout is connected to the power supply through the fifth constant current source in the translinear loop, and the gate of the switching transistor Mnout is connected to the third pole of the input switching transistor.

[0032] In one embodiment, when the input switching transistor is an N-type MOS transistor, the push-pull output circuit includes:

[0033] The switching transistor Mpout and the switching transistor Mnout;

[0034] Among them, the switching transistor Mpout and the switching transistor Mnout are connected in series between the power supply and the ground in sequence. The gate of the switching transistor Mnout is grounded through the fifth constant current source in the translinear loop, and the gate of the switching transistor Mpout is connected to the third pole of the input switching transistor.

[0035] In a second aspect, the present application further provides a device, including:

[0036] A pre-stage circuit for outputting a level signal;

[0037] An AB-class output level shift circuit according to any one of the embodiments of the first aspect, where the first pole of the input switching transistor is connected to the level signal;

[0038] A post-stage circuit, where the input end of the post-stage circuit is connected to the output end of the output module.

[0039] For the above-mentioned AB-class output level shift circuit and device, first, the signal input is realized through a single input switching transistor, which greatly simplifies the circuit structure. At the same time, by setting the first constant current source and the second constant current source at the source and drain of the input switching transistor, the stability of the current at the source and drain of the input switching transistor is ensured in the case of large changes in the input voltage and the output voltage. Then, by introducing a translinear loop, the use of an operational amplifier is avoided, and instead, a circuit composed of a smaller number of transistors is selected, and the AB-class output of the circuit is realized in cooperation with the output module. Finally, through the negative feedback loop from the input module to the output module, the circuit is provided with the function of level shift. Therefore, the AB-class output level shift circuit provided by the embodiments of the present application reduces the complexity of the circuit structure on the premise of realizing the AB-class output level shift function, thereby reducing the power consumption of the circuit, reducing the design area of the circuit, and reducing the noise of the circuit. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is the first structural block diagram of the AB-class output level shift circuit in an embodiment;

[0042] Figure 2 It is the second structural block diagram of the AB-class output level shift circuit in an embodiment;

[0043] Figure 3 It is the first circuit diagram of the AB-class output level shift circuit in an embodiment;

[0044] Figure 4 The second circuit diagram of the class-AB output level-shifting circuit in an embodiment;

[0045] Figure 5 The third structural block diagram of the class-AB output level-shifting circuit in an embodiment;

[0046] Figure 6 The third circuit diagram of the class-AB output level-shifting circuit in an embodiment;

[0047] Figure 7 The fourth circuit diagram of the class-AB output level-shifting circuit in an embodiment. Detailed implementation manners

[0048] For ease of understanding of the present application, the present application will be described more comprehensively below with reference to the relevant accompanying drawings. Embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application is more thorough and comprehensive.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0050] It can be understood that the terms "first", "second", etc. used in this application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor can be referred to as a second resistor, and similarly, a second resistor can be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0051] It can be understood that "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is an electrical signal or data transfer between the connected circuits, modules, units, etc.

[0052] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprise / include" or "have" etc. specify the presence of the stated features, wholes, steps, operations, components, parts or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0053] In traditional technologies, level-shifting circuits are widely used in signal processing. Input and output signals generated by different modules may not be directly interconnected due to different power supply domains. A level-shifting circuit is needed to shift the output signal of the previous stage to a port suitable for the input of the subsequent stage to complete normal signal conversion. The signals converted by common level-conversion circuits are digital signals similar to high and low levels and cannot accurately shift analog signals, so the application scenarios are limited. For the shifting technology of analog signals, operational amplifiers are mostly used. To achieve better signal transmission quality, such as small distortion and a large output common-mode range, the output type of operational amplifiers is usually class AB output. If only power supply is required, an LDO is usually used to amplify the input signal by a fixed coefficient to complete level shifting. Therefore, level-shifting circuits are widely used.

[0054] In traditional technologies, there are two types of traditional level-shifting circuits: (1) shifting of high and low levels similar to digital signals; (2) level-shifting circuits for analog signals. This type of level-shifting requires ensuring high signal quality during shifting. The commonly used technology is to use operational amplifiers to form a fixed proportional coefficient to complete level shifting. For example, non-inverting amplifier circuits and inverting amplifier circuits. The essential principle of an LDO is a non-inverting amplifier circuit. However, the traditional level-shifting circuits provided in the existing technologies have the following drawbacks: they need to use operational amplifiers to implement, require internal loop compensation, the circuit structure is complex, and it is difficult to make the power consumption, area, and noise very small. Therefore, a trade-off design is usually required in common use.

[0055] Based on this, in one embodiment, as Figure 1 and Figure 2 shown, a class AB output level-shifting circuit is provided, including: a first constant current source 110, a second constant current source 120, an input switching transistor 130, a translinear loop 140, and an output module 150. Among them, the input end of the first constant current source 110 is used to connect to a power supply 160, the output end of the second constant current source 120 is grounded, and the first pole of the input switching transistor 130 is used to access a level signal.

[0056] Among them, the input switching transistor 130 is connected in series with the first constant current source 110 and the second constant current source 120, and they are connected based on the principle that the current directions in their respective branches are the same. As Figure 1 shown, when the input switching transistor 130 is a P-type MOS transistor, the second pole of the input switching transistor 130 is connected to the output end of the first constant current source 110, and the third pole of the input switching transistor 130 is connected to the input end of the second constant current source 120. As Figure 2As shown, when the input switching transistor 130 is an N-type MOS transistor, the second pole of the input switching transistor 130 is connected to the input terminal of the second constant current source 120, and the third pole of the input switching transistor 130 is connected to the output terminal of the first constant current source 110.

[0057] Optionally, the input switching transistor 130 has a first pole a, a second pole b, and a third pole c. Further, taking the input switching transistor 130 as a MOS transistor as an example, the first pole a of the input switching transistor 130 is the gate, the second pole b is the source, and the third pole c is the drain.

[0058] In Figure 1 and Figure 2 , the input terminal of the transconductance linear loop 140 is connected to the third pole c of the input switching transistor 130, the power supply terminal of the transconductance linear loop 140 is used to connect to the power supply 160, the ground terminal of the transconductance linear loop 140 is grounded, and the transconductance linear loop 140 is used to support the output of class AB signals.

[0059] In Figure 1 and Figure 2 , the input terminal of the output module 150 is connected to the output terminal of the transconductance linear loop 140, the power supply terminal of the output module 150 is used to connect to the power supply 160, the ground terminal of the output module 150 is grounded, and the output terminal of the output module 150 is connected to the second pole b of the input switching transistor 130, so that the transconductance linear loop 140 is used to drive the output module 150 to output a class AB level shift signal based on the signal received from the input switching transistor 130 when the input switching transistor 130 receives a level signal.

[0060] It should be noted that the switching transistor in the embodiments of the present application may be a MOS transistor, or may be replaced with other types of transistors having the same conduction characteristics, and the selection is made based on the principle of meeting the required conduction characteristics. For example, the input switching transistor 130 may be a MOS transistor, specifically including a P-type MOS transistor or an N-type MOS transistor. A MOS transistor is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor); among them, the on-off rule of a P-type MOS transistor is: when the gate-source voltage VGS is less than the conduction voltage threshold VGS th When, the transistor is turned on, otherwise, if the conduction condition is not met, the P-type MOS transistor is turned off. The on-off rule of an N-type MOS transistor is: when the gate-source voltage VGS is greater than the conduction voltage threshold VGS th When, the transistor is turned on, otherwise, when the gate-source voltage VGS is less than the conduction voltage threshold, the transistor is turned off.

[0061] Among them, the power supply 160 is used to provide a power supply voltage (VCC, VoltCurrentCondenser), and the constant current source is CCS (ConstantCurrentSource, constant current source), which is used to provide a constant current source for the branch where it is located to ensure the stable operation of the devices in the circuit. Specifically, taking Figure 1 as an example, the first constant current source 110 is arranged between the source of the input switching transistor 130 and the power supply 160, which is used to ensure that the current of this branch is controllable and stable, maintain the normal operation of the field effect transistor, and facilitate the calculation of the VGS parameter value (that is, the parameter representing the voltage difference between the gate and the source) of the input switching transistor in the normal working state, so as to calculate the voltage change from input to output by using the VGS parameter value, thereby realizing the level shift. The second constant current source 120 is arranged between the input switching transistor 130 and the ground, and the drain of the input switching transistor 130 is connected to the output module 150 through the translinear loop 140, which is used to ensure the push-pull ability of the class AB output level shift circuit. Even if the voltage here fluctuates greatly, the second constant current source 120 can still provide a stable current to ensure the normal operation of the input switching transistor 130.

[0062] Among them, the translinear loop is a structure that uses the transconductance characteristics of transistors to achieve specific circuit functions. By connecting multiple transistors into a loop structure, the mathematical relationship between their currents and voltages is satisfied. For example, the translinear loop provided in the embodiment of the present application can improve the linear relationship between the output signal and the input signal, make the output of the entire circuit show good linearity within a certain range, and realize the class AB output of the circuit. More specifically, the class AB output is a working mode of the amplifier output stage between class A and class B, which combines the advantages of class A and class B. When there is a signal input, two complementary output transistors (such as NMOS and PMOS field effect transistors) work alternately according to the positive and negative half cycles of the signal, and the two transistors are turned on simultaneously near the zero crossing of the signal, effectively reducing the crossover distortion.

[0063] In the above class AB output level shift circuit, first, the signal is input through a single input switching transistor, which greatly simplifies the circuit structure. At the same time, by setting the first constant current source and the second constant current source at the source and drain of the input switching transistor, the stability of the current at the source and drain of the input switching transistor is ensured in the case of large changes in the input voltage and the output voltage; then, by introducing the translinear loop, the use of operational amplifiers is avoided, and instead, a circuit composed of a smaller number of transistors is selected, and the class AB output of the circuit is realized in cooperation with the output module; finally, through the negative feedback loop from the input module to the output module, the circuit has the function of level shift; in short, on the premise of realizing the class AB output level shift function, the complexity of the circuit structure is reduced, thereby reducing the power consumption of the circuit, reducing the design area of the circuit, and reducing the noise of the circuit.

[0064] In one embodiment, when the input switching transistor is a P-type MOS transistor, the translinear loop includes: switching transistors Mn1, Mn2, Mn3, Mp1, Mp2, Mp3, a third constant current source, a fourth constant current source, and a fifth constant current source. Among them, the switching transistors Mn1, Mn2, and Mn3 are N-type MOS transistors, and the switching transistors Mp1, Mp2, and Mp3 are P-type MOS transistors.

[0065] Among them, the constant current sources are distributed according to the branches of the translinear loop. Generally, each branch can be allocated a constant current source to control the stability of the current in that branch, thereby ensuring the normal operation of the transistors in that branch. As Figure 3 shown, Figure 3 An AB-class output level shift circuit is provided, which includes a translinear loop 140. The connection relationships of its components are as follows:

[0066] As Figure 3 shown, in a branch of the translinear loop 140, the third constant current source 143, the switching transistors Mn2 and Mn3 are connected in series between the power supply 160 and the ground in sequence. The gate and drain of the switching transistor Mn2 are connected, and the gate and drain of the switching transistor Mn3 are connected; in another branch of the translinear loop 140, the switching transistor Mp3, the switching transistor Mp2, and the fourth constant current source 144 are connected in series between the power supply 160 and the ground in sequence. The gate and drain of the switching transistor Mp3 are connected, and the gate and drain of the switching transistor Mp2 are connected; in yet another branch of the translinear loop 140, the source of the switching transistor Mn1 is connected to the drain of the switching transistor Mp1, the gate of the switching transistor Mn1 is connected to the gate of the switching transistor Mn2, the drain of the switching transistor Mn1 is connected to the source of the switching transistor Mp1, and the gate of the switching transistor Mp1 is connected to the gate of the switching transistor Mp2; the drain of the switching transistor Mn1 is connected to the first input terminal of the output module, and the source of the switching transistor Mn1 is connected to the second input terminal of the output module; it should be noted that the input terminals of the output module 150 include a first input terminal and a second input terminal. As Figure 3 shown, the first input terminal is used to connect the gate of the switching transistor Mpout, and the second input terminal is used to connect the gate of the switching transistor Mnout.

[0067] In addition, the input terminal of the fifth constant current source 145 is used to connect the power supply 160, the output terminal of the fifth constant current source 145 is connected to the drain of the switching transistor Mn1, and the source of the switching transistor Mn1 is connected to the drain of the input switching transistor 130.

[0068] Specifically, Figure 3The AB - class output level - shifting circuit therein is a buffer circuit structure. The gate of the input switching transistor 130 (for example, it can be the P - type MOS transistor Min in the figure) is the input port of the signal. The working process of its circuit includes:

[0069] When the input voltage signal of the input switching transistor 130 becomes high, the gate - source voltage VGS of the input switching transistor 130 is greater than the gate - source conduction voltage threshold VGS th , the input switching transistor 130 turns off. The drain of the input switching transistor 130 is grounded, and the drain of the input switching transistor 130 is connected to the gate of the switching transistor Mnout and the source of the switching transistor Mn1 (N - type enhancement MOS transistor). So the gate of the switching transistor Mnout is at a low level, the switching transistor Mnout turns off, and the source of the switching transistor Mn1 is also at a low level. Also, because the gate of the switching transistor Mn1 is connected to the power supply VCC, when the source of the switching transistor Mn1 is at a low level, the gate - source voltage meets the conduction condition of the N - type MOS transistor, and the switching transistor Mn1 conducts. And since the drain of the switching transistor Mn1 is connected to the gate of the switching transistor Mpout, the gate of the switching transistor Mnout is grounded through the conducting switching transistor Mn1, the switching transistor Mpout conducts. One of the switching transistors Mnout and Mpout in the output module conducts. In addition, the drain of the output transistors (switching transistors Mnout and Mpout) is the output voltage becoming high, and the output signal is fed back to the source of the input switching transistor 130. The whole loop forms a negative - feedback system, which can ensure a fixed level difference between the input voltage Vin connected to the input switching transistor 130 and the output of the output module, thus realizing level shifting. The output voltage Vout of the AB - class output level - shifting circuit is Vout = Vin+VGS(Min), where VGS(Min) is the conduction threshold voltage of the input switching transistor. The static currents of the output transistors Mpout and Mnout are respectively determined by the translinear loop composed of Mp1, Mp2, Mp3 and Mn1, Mn2, Mn3, ensuring that the output is of AB - class output.

[0070] In one embodiment, in the case where the input switching transistor is an N - type MOS transistor, the translinear loop includes: switching transistor Mn1, switching transistor Mn2, switching transistor Mn3, switching transistor Mp1, switching transistor Mp2, switching transistor Mp3, the third constant - current source, the fourth constant - current source, and the fifth constant - current source.

[0071] Among them, the constant - current sources are distributed according to the branches of the translinear loop. For example, as Figure 4 shown. Figure 4 An AB - class output level - shifting circuit is provided, which includes a translinear loop 140. The connection relationship of its components is as follows:

[0072] In a branch of the translinear loop 140, a third constant current source 143, a switching transistor Mn2, and a switching transistor Mn3 are sequentially connected in series between a power supply 160 and ground. The gate and drain of the switching transistor Mn2 are connected, and the gate and drain of the switching transistor Mn3 are connected. In another branch of the translinear loop 140, a switching transistor Mp3, a switching transistor Mp2, and a fourth constant current source 144 are sequentially connected in series between the power supply 160 and ground. The gate and drain of the switching transistor Mp3 are connected, and the gate and drain of the switching transistor Mp2 are connected. In yet another branch of the translinear loop 140, the source of the switching transistor Mn1 is connected to the drain of the switching transistor Mp1, the gate of the switching transistor Mn1 is connected to the gate of the switching transistor Mn2, the drain of the switching transistor Mn1 is connected to the source of the switching transistor Mp1, and the gate of the switching transistor Mp1 is connected to the gate of the switching transistor Mp2. The drain of the switching transistor Mn1 is connected to the first input terminal of the output module, and the source of the switching transistor Mn1 is connected to the second input terminal of the output module. It should be noted that the input terminals of the output module 150 include a first input terminal and a second input terminal. As Figure 3 shown, the first input terminal is used to connect to the gate of the switching transistor Mpout, and the second input terminal is used to connect to the gate of the switching transistor Mnout.

[0073] In addition, the output terminal of a fifth constant current source 145 is used to connect to ground. The input terminal of the fifth constant current source 145 is connected to the source of the switching transistor Mn1, and the drain of the switching transistor Mn1 is connected to the drain of the input switching transistor 130.

[0074] Specifically, Figure 4 the AB - class output level - shifting circuit in Figure 4 is a buffer circuit structure. The gate of the input switching transistor 130 (for example,

[0075] When the input voltage signal of the input switching transistor 130 becomes high to a high level, since its source is grounded, the gate-source voltage meets the conduction condition of the input switching transistor 130, and the input switching transistor 130 conducts. At this time, the gate of the Mpout transistor is grounded through the input switching transistor 130, the source of the Mpout transistor is connected to VCC, and the Mpout transistor conducts, so that the drain of the Mpout transistor outputs a high level; at the same time, the drain of the input switching transistor 130 is connected to the source of the Mp1 transistor. The source of the Mp1 transistor is grounded through the input switching transistor 130, and the gate of the Mp1 transistor is also grounded. At this time, the Mp1 transistor is turned off. The gate and source of the Mnout transistor (N-type enhancement MOS transistor) are both grounded, and the Mnout transistor is turned off. Then, the drains of the output transistors Mnout and Mpout, that is, the output voltage follows the input voltage signal to become high, and the output signal is fed back to the source of the input switching transistor 130. The entire loop forms a negative feedback system, which can ensure a fixed level difference between the input voltage and the output, thereby realizing level shift. The output voltage Vout = Vin - VGS(Min). The static currents of the output transistors Mpout and Mnout are respectively determined by the translinear loop composed of Mp1, Mp2, Mp3 and Mn1, Mn2, Mn3, ensuring that the output is class AB output.

[0076] In one embodiment, the class AB output level shift circuit further includes a voltage dividing circuit 170, as Figure 5 shown, on the basis of Figure 1 that, Figure 5 it further includes a voltage dividing circuit 170. The voltage dividing circuit 170 is connected in series between the output end of the output module 150 and the ground. The output end of the voltage dividing circuit 170 is connected to the second pole b (source) of the input switching transistor 130, forming a negative feedback loop to realize the voltage shift of the input level signal, and adjusting the change ratio of the voltage during the level shift process of the class AB output level shift circuit based on the voltage division principle.

[0077] In one embodiment, the voltage dividing circuit includes: a plurality of voltage dividing resistors connected in series between the output end of the output module and the ground in sequence. Among them, an output end is led out between two adjacent voltage dividing resistors and connected to the second pole of the input switching transistor. As Figure 6 shown, on the basis of Figure 3 that, Figure 6 a voltage dividing circuit composed of resistor R1 and R2 is added, that is, the voltage dividing circuit 170 includes two voltage dividing resistors (R1 and R2) connected in series between the output end of the output module 150 and the ground in sequence. Among them, an output end is led out between two adjacent voltage dividing resistors (R1 and R2) and connected to the second pole b of the input switching transistor 130.

[0078] Similarly, as Figure 7 shown, on the basis of Figure 4 that, Figure 7A voltage-dividing circuit composed of resistors R1 and R2 is added. That is, the voltage-dividing circuit 170 includes two voltage-dividing resistors connected in series between the output terminal of the output module 150 and the ground in sequence ( Figure 6 and Figure 7 R1 and R2 in

[0079] In this embodiment, the AB-class output level-shifting circuit is an LDO (Low Dropout Regulator) circuit. Take Figure 6 as an example, Figure 6 and Figure 3 The difference is that Figure 6 in Figure 6 the feedback point in the negative feedback loop is not the output, but the midpoint of the resistance voltage division of R2 and R1. In this way, the output voltage is no longer the input voltage plus the gate-source voltage VGS(Min) of the input switching transistor 130. The output voltage Vout = (Vin + VGS(Min)) * (1 + R2 / R1), where R2 in the formula is the resistance value of resistor R2, and R1 is the resistance value of resistor R1. It can be seen from the equation that Figure 3 the function implemented by the circuit is to multiply by a proportionality coefficient while realizing level shifting in Figure 7 Similarly, the feedback point in Figure 7 is also at the midpoint of R2 and R1. Similarly, it can be analyzed that

[0080] It can be known that Figure 6 and Figure 7 the circuits in the embodiments are respectively implemented by improving the circuits in Figure 3 and Figure 4 embodiments. Specifically, by changing the feedback point and adding an LDO circuit, proportional amplification of the input voltage can be achieved. The entire negative feedback loop is simple and efficient. For power supply scenarios requiring high response speed, the applicability is improved.

[0081] In summary, in the above embodiments Figure 3 、 Figure 4 、 Figure 6 and Figure 7 the corresponding four circuits can all complete the function of level shifting. By adding a negative feedback loop, the level shifting and following of the input and output signals are realized, and the shifting ratios are all different. Moreover, it is not implemented using a complex operational amplifier, but using a small number of MOS transistors to complete the corresponding functions, making the power consumption achieve a good trade-off design in terms of balancing area and noise.

[0082] In one of the embodiments, the output module is a push-pull output circuit.

[0083] Among them, the push-pull output circuit is a circuit with the ability of push-pull output, which means that the circuit can effectively drive the load through the collaborative work of these two complementary devices, and can provide positive current to the load and absorb reverse current from the load. More specifically, as Figure 6 or Figure 7 shown, the two complementary devices can be two output transistors Mnout and Mpout.

[0084] In this embodiment, only single-tube input is required. According to the linear transconductance loop equivalent to class AB operational amplifier, finally, a negative feedback loop is introduced at the PMOS output transistor and NMOS output transistor ends to ensure the linearity of the entire system, that is, to ensure the degree of linear relationship between the output signal and the input signal, realize the level shift, so that the entire circuit has the ability of push-pull output, and also eliminates the need for a complex operational amplifier to realize the high and low translation of the input voltage.

[0085] In one embodiment, when the input switching transistor is a P-type MOS transistor, as Figure 6 shown, the push-pull output circuit includes a switching transistor Mpout and a switching transistor Mnout; among them, the switching transistor Mpout and the switching transistor Mnout are connected in series between the power supply 160 and the ground in sequence, the gate of the switching transistor Mpout is connected to the power supply 160 through the fifth constant current source 145 in the transconductance linear loop 140, and the gate of the switching transistor Mnout is connected to the third pole c of the input switching transistor 130.

[0086] In one embodiment, when the input switching transistor is an N-type MOS transistor, as Figure 7 shown, the push-pull output circuit includes: a switching transistor Mpout and a switching transistor Mnout; among them, the switching transistor Mpout and the switching transistor Mnout are connected in series between the power supply 160 and the ground in sequence, the gate of the switching transistor Mnout is grounded through the fifth constant current source 145 in the transconductance linear loop 140, and the gate of the switching transistor Mpout is connected to the third pole c of the input switching transistor 130.

[0087] In one embodiment, the present application also provides a device, including: a pre-stage circuit, a class AB output level shift circuit as in any of the above embodiments, and a post-stage circuit. Among them, the pre-stage circuit is used to output a level signal; the first pole of the input switching transistor accesses the level signal; the post-stage circuit, the input end of the post-stage circuit is connected to the output end of the output module.

[0088] The device provided by the embodiment of the present application, by integrating the above Class-AB output level-shifting circuit, and using the hierarchical design of its input stage, translinear loop, and output stage, obtains a level-shifting circuit with a simple structure, fast response speed, and good noise performance. At the same time, considering that the load is a low impedance, a push-pull output capability is required, so a translinear loop is added to ensure the output characteristics of Class-AB. By integrating the Class-AB output level-shifting circuit with a simple structure and small area, and using its characteristics of fast loop response, low power consumption, and low noise, the signal transmission between the front-stage circuit and the rear-stage circuit is realized. At the same time, it can also realize the high-low movement and proportional amplification of the input voltage input from the front-stage circuit to the rear-stage circuit, meeting the signal transmission requirements between the front-stage circuit and the rear-stage circuit.

[0089] In the description of this specification, the descriptions referring to terms "some embodiments", "other embodiments", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0090] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0091] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A class AB output level shift circuit, characterized in that: include: A first constant current source, wherein an input end of the first constant current source is used to connect to a power supply; A second constant current source, wherein an output terminal of the second constant current source is grounded; An input switch tube, wherein the first electrode of the input switch tube is used to access a level signal; Wherein, the second pole of the input switch tube is connected to the output end of the first constant current source, and the third pole of the input switch tube is connected to the input end of the second constant current source; or, the second pole of the input switch tube is connected to the input end of the second constant current source, and the third pole of the input switch tube is connected to the output end of the first constant current source; A translinear loop, wherein the input end of the translinear loop is connected to the third pole of the input switch tube, the power supply end of the translinear loop is used to connect to the power supply, the ground end of the translinear loop is grounded, and the translinear loop is used to support the output of a class AB signal; An output module, wherein the input end of the output module is connected to the output end of the translinear loop, the power supply end of the output module is used to connect to the power supply, the ground end of the output module is grounded, and the output end of the output module is connected to the second pole of the input switch tube, so that the translinear loop is used to drive the output module to output a class AB level shift signal based on the signal connected from the input switch tube when the input switch tube is connected to the level signal.

2. The class AB output level shift circuit according to claim 1, characterized in that: The input switch tube is a MOS tube, the first electrode of the input switch tube is a gate electrode, the second electrode of the input switch tube is a source electrode, and the third electrode of the input switch tube is a drain electrode.

3. The class AB output level shift circuit according to claim 2, characterized in that: When the input switch tube is a P-type MOS tube, the translinear loop includes: a switch tube Mn1, a switch tube Mn2, a switch tube Mn3, a switch tube Mp1, a switch tube Mp2, a switch tube Mp3, a third constant current source, a fourth constant current source, and a fifth constant current source; The third constant current source, the switch tube Mn2 and the switch tube Mn3 are sequentially connected in series between the power supply and the ground, the gate and the drain of the switch tube Mn2 are connected, and the gate and the drain of the switch tube Mn3 are connected; The switch tube Mp3, the switch tube Mp2 and the fourth constant current source are sequentially connected in series between the power supply and the ground, the gate and the drain of the switch tube Mp3 are connected, and the gate and the drain of the switch tube Mp2 are connected; The source of the switch tube Mn1 is connected to the drain of the switch tube Mp1, the gate of the switch tube Mn1 is connected to the gate of the switch tube Mn2, the drain of the switch tube Mn1 is connected to the source of the switch tube Mp1, and the gate of the switch tube Mp1 is connected to the gate of the switch tube Mp2; the drain of the switch tube Mn1 is connected to the first input terminal of the output module, and the source of the switch tube Mn1 is connected to the second input terminal of the output module; The input end of the fifth constant current source is used to connect to a power supply, the output end of the fifth constant current source is connected to the drain of the switch tube Mn1, and the source of the switch tube Mn1 is connected to the drain of the input switch tube.

4. The class AB output level shift circuit according to claim 2, characterized in that: When the input switch tube is an N-type MOS tube, the translinear loop includes: a switch tube Mn1, a switch tube Mn2, a switch tube Mn3, a switch tube Mp1, a switch tube Mp2, a switch tube Mp3, a third constant current source, a fourth constant current source, and a fifth constant current source; The third constant current source, the switch tube Mn2 and the switch tube Mn3 are sequentially connected in series between the power supply and the ground, the gate and the drain of the switch tube Mn2 are connected, and the gate and the drain of the switch tube Mn3 are connected; The switch tube Mp3, the switch tube Mp2 and the fourth constant current source are sequentially connected in series between the power supply and the ground, the gate and the drain of the switch tube Mp3 are connected, and the gate and the drain of the switch tube Mp2 are connected; The source of the switch tube Mn1 is connected to the drain of the switch tube Mp1, the gate of the switch tube Mn1 is connected to the gate of the switch tube Mn2, the drain of the switch tube Mn1 is connected to the source of the switch tube Mp1, and the gate of the switch tube Mp1 is connected to the gate of the switch tube Mp2; the drain of the switch tube Mn1 is connected to the first input terminal of the output module, and the source of the switch tube Mn1 is connected to the second input terminal of the output module; The output end of the fifth constant current source is used for grounding, the input end of the fifth constant current source is connected to the source of the switch tube Mn1, and the drain of the switch tube Mn1 is connected to the drain of the input switch tube.

5. The class AB output level shift circuit according to claim 1, characterized in that: Also includes: A voltage divider circuit is connected in series between the output end of the output module and the ground, and the output end of the voltage divider circuit is connected to the second pole of the input switch tube.

6. The class AB output level shift circuit according to claim 5, characterized in that: The voltage divider circuit comprises: A plurality of voltage-dividing resistors are sequentially connected in series between the output end of the output module and the ground, wherein an output end is drawn out between two adjacent voltage-dividing resistors and connected to the second electrode of the input switch tube.

7. The class AB output level shift circuit according to any one of claims 1 to 6, characterized in that: The output module is a push-pull output circuit.

8. The class AB output level shift circuit according to claim 7, characterized in that: When the input switch tube is a P-type MOS tube, the push-pull output circuit includes: Switching tube Mpout and switching tube Mnout; Among them, the switch tube Mpout and the switch tube Mnout are connected in series between the power supply and the ground in sequence, the gate of the switch tube Mpout is connected to the power supply through the fifth constant current source in the translinear loop, and the gate of the switch tube Mnout is connected to the third pole of the input switch tube.

9. The class AB output level shift circuit according to claim 7, characterized in that: When the input switch tube is an N-type MOS tube, the push-pull output circuit includes: Switching tube Mpout and switching tube Mnout; Among them, the switch tube Mpout and the switch tube Mnout are connected in series between the power supply and the ground in sequence, the gate of the switch tube Mnout is grounded through the fifth constant current source in the translinear loop, and the gate of the switch tube Mpout is connected to the third pole of the input switch tube.

10. A device, characterized in that: include: The pre-stage circuit is used for outputting level signals; The class AB output level shift circuit according to any one of claims 1 to 9, wherein the first electrode of the input switch tube is connected to the level signal; A subsequent circuit, wherein the input end of the subsequent circuit is connected to the output end of the output module.

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