Class AB operational amplifiers, circuits, chips and electronic devices

Abstract

An AB-class operational amplifier, circuit, chip, and electronic device are disclosed. The differential input module of the AB-class operational amplifier receives and amplifies a differential voltage input signal to obtain a first differential current signal; a common-source cascode amplification module receives and amplifies the first differential current signal to obtain a second differential voltage signal; a common-source amplification module receives and amplifies the second differential voltage signal to obtain a third differential voltage signal; and an output module receives the third differential voltage signal and converts it into a fourth differential voltage signal before outputting it to an external circuit. Specifically, the signal input terminal of the common-source amplification submodule of the common-source amplification module receives the second differential voltage signal, and the voltage magnitudes at the positive and negative voltage change terminals alternately change to obtain and output the third differential voltage signal to the output module. The AB-class operational amplifier disclosed in this embodiment can effectively improve the operational amplifier gain while ensuring its energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of electronic technology, and more particularly to an AB class operational amplifier, circuit, chip, and electronic device. Background Technology

[0002] Operational amplifiers (op-amps) are functional devices that amplify input signals by a certain factor. Among them, Class A, Class B, and Class AB op-amps are common op-amp types in signal processing systems.

[0003] Class A operational amplifiers have output transistors that are always on, meaning the conduction angle is the full cycle. They are characterized by good linearity but low efficiency.

[0004] Class B operational amplifiers have output transistors that conduct alternately for half a cycle, meaning the conduction angle is half a cycle. They are characterized by higher efficiency than Class A operational amplifiers, but poor linearity and severe distortion.

[0005] Class AB op-amps have an output transistor conduction period between that of Class A and Class B op-amps, meaning the conduction angle is greater than half a cycle but less than a full cycle. They are characterized by relatively higher efficiency compared to Class A op-amps, while offering better linearity than Class B op-amps. In applications driving low-impedance loads with high linearity requirements (such as in the audio field), Class AB op-amps are often the preferred choice.

[0006] Please refer to Figure 1 This is a circuit schematic of a traditional Class AB operational amplifier. A traditional Class AB operational amplifier typically includes a differential input stage, a common-source cascode amplifier stage, and an output stage. The differential input stage is used to convert a small differential voltage into a larger differential current signal. The common-source cascode amplifier stage is used to amplify the differential current signal and obtain an amplified differential voltage signal. The output stage receives the amplified differential voltage signal and outputs the differential operation result of the operational amplifier.

[0007] However, when traditional Class AB op-amps are used in situations with low load impedance, such as in the audio field, the smaller load impedance is connected in parallel with the op-amp's output impedance, which lowers the op-amp's equivalent output impedance and thus reduces the op-amp's gain.

[0008] To increase the gain, the bias impedance in the cascode amplifier stage needs to be significantly increased to enhance its amplification capability, which in turn leads to a substantial increase in the power consumption of the op-amp.

[0009] Therefore, how to improve the gain of a Class AB operational amplifier while ensuring its energy efficiency has become an urgent technical problem to be solved. Summary of the Invention

[0010] Based on the above situation, the main objective of this invention is to provide an AB class operational amplifier, circuit, chip, and electronic device to solve the technical problem of how to improve the gain of an AB class operational amplifier while ensuring the energy efficiency of the operational amplifier.

[0011] Therefore, according to a first aspect, embodiments of the present invention disclose an AB-class operational amplifier connected between a positive power supply terminal and a negative power supply terminal (Vss) for amplifying a differential voltage input signal, comprising:

[0012] The differential input module is used to receive and amplify the differential voltage input signal to obtain the first differential current signal;

[0013] The common source cascode amplifier module is used to receive and amplify the first differential current signal to obtain the second differential voltage signal. The signal output terminal of the common source cascode amplifier module outputs the second differential voltage signal.

[0014] The common-source amplifier module is used to receive and amplify the second differential voltage signal to obtain the third differential voltage signal; the common-source amplifier module includes a common-source amplification submodule, a common-source feedback submodule, and a bias submodule;

[0015] The signal input terminal of the common-source amplifier submodule receives the second differential voltage signal; the first terminal of the bias submodule and the common-source amplifier submodule are both connected to the positive voltage change terminal, and the second terminal of the bias submodule and the common-source feedback submodule are both connected to the negative voltage change terminal; the voltage magnitude of the positive voltage change terminal and the voltage magnitude of the negative voltage change terminal alternately change to obtain and output the third differential voltage signal;

[0016] The output module is connected to the positive voltage change terminal and the negative voltage change terminal to receive the third differential voltage signal. The voltage at the output terminal of the operational amplifier of the output module changes with the third differential voltage signal to obtain the fourth differential voltage signal. The fourth differential voltage signal is the operational amplification result of the Class AB operational amplifier.

[0017] Preferably, the common-source cascode amplifier module includes a common-gate amplifier submodule and an impedance submodule;

[0018] Preferably, the impedance submodule is connected between the positive power supply terminal and the signal output terminal. The impedance submodule is used to provide impedance so that the first current flows from the positive power supply terminal to the signal output terminal.

[0019] The common gate amplifier submodule receives the first differential current signal at its common gate stage signal input terminal, and the common gate amplifier submodule is connected between the signal output terminal and the negative power supply terminal (Vss) so that the first current self-impedance submodule flows to the common gate amplifier submodule.

[0020] The first current follows the change of the first differential current signal, so as to change the voltage at the signal output terminal to obtain the second differential voltage signal.

[0021] The common-gate amplifier submodule includes a current mirror and a common-gate current source. The current mirror is connected between the signal output terminal and the common-gate signal input terminal so that the first current flows from the current mirror to the common-gate signal input terminal.

[0022] The common gate current source is connected between the common gate signal input terminal and the negative power supply terminal (Vss) to provide a reference current to the common gate signal input terminal.

[0023] Preferably, the impedance submodule includes a variable impedance circuit and a resistor circuit, wherein the variable impedance circuit is connected between the positive power supply terminal and the signal output terminal so that the magnitude of the first current is variable.

[0024] A resistor circuit is connected between the signal output terminal and the control terminal of the variable impedance circuit so that the voltage at the control terminal is the common-mode voltage at the signal output terminal, thus keeping the voltage at the control terminal constant.

[0025] Preferably, the variable impedance circuit includes transistor ME1 and transistor ME2, and the resistor circuit includes resistor R1 and resistor R2;

[0026] The control terminals of transistors ME1 and ME2 are both connected to the control terminal, and the ends of resistors R1 and R2 that are furthest from the signal output terminal are both connected to the control terminal.

[0027] Preferably, both transistor ME1 and transistor ME2 are composite transistors.

[0028] Preferably, it further includes a common-mode feedback module. The input terminal of the common-mode feedback module receives the fourth differential voltage signal to obtain a negative feedback signal. The feedback output terminal of the common-mode feedback module is connected to the common-source feedback submodule so that the common-source feedback submodule receives the negative feedback signal and so that the negative feedback signal affects the fourth differential voltage signal.

[0029] Preferably, the common-source amplifier submodule includes transistor MC1 and transistor MC2. Transistor MC1 and transistor MC2 are both connected between the positive power supply terminal and the positive voltage change terminal. The control electrode of transistor MC1 and the control electrode of transistor MC2 are connected to the signal output terminal to receive the second differential voltage signal, so that the voltage at the positive voltage change terminal can change with the second differential voltage signal.

[0030] Preferably, the common-source feedback submodule includes transistor MB1 and transistor MB2. Both transistor MB1 and transistor MB2 are connected between the negative voltage change terminal and the negative power supply terminal (Vss). The control electrode of transistor MB1 and the control electrode of transistor MB2 are connected to the feedback output terminal of the common-mode feedback module to receive the negative feedback signal.

[0031] Preferably, the bias submodule is a transconducting linear loop circuit, which is connected between the positive voltage change terminal and the negative voltage change terminal so that the voltage magnitude at the positive voltage change terminal and the voltage magnitude at the negative voltage change terminal alternately change.

[0032] Preferably, the output module includes a positive voltage conduction transistor and a negative voltage conduction transistor. The positive voltage conduction transistor is connected between the positive power supply terminal and the operational amplifier output terminal, and the control electrode of the positive voltage conduction transistor is connected to the positive voltage change terminal.

[0033] The negative voltage conduction transistor is connected between the op-amp output terminal and the negative power supply terminal (Vss), and the control terminal of the negative voltage conduction transistor is connected to the negative voltage change terminal.

[0034] When the voltage at the positive voltage change terminal changes, the positive voltage conduction transistor is in the on state and the negative voltage conduction transistor is in the off state; when the voltage at the negative voltage change terminal changes, the negative voltage conduction transistor is in the on state and the positive voltage conduction transistor is in the off state; the off state includes the transistor cutoff state and the transistor subthreshold state.

[0035] Preferably, the output module further includes a phase compensation submodule, which is connected between the control electrode of the positive voltage conduction transistor, the control electrode of the negative voltage conduction transistor, and the output terminal of the operational amplifier.

[0036] Preferably, the differential input module includes an input stage current source and a common-source input transistor. The input stage current source is connected between the positive power supply terminal and the common-source input transistor to provide a stable input current to the common-source input transistor.

[0037] The control electrode of the common-source input transistor receives a differential voltage input signal, so that the current output by the common-source input transistor to the common-source cascode amplifier module changes with the differential voltage input signal, thus obtaining the first differential current signal.

[0038] According to a second aspect, an operational amplifier circuit is disclosed in an embodiment of the present invention, including a load circuit and an AB class operational amplifier as disclosed in the first aspect, wherein the load circuit is connected to the AB class operational amplifier to receive a fourth differential voltage signal.

[0039] According to a third aspect, embodiments of the present invention disclose a chip including an AB-class operational amplifier as disclosed in the first aspect.

[0040] According to a fourth aspect, embodiments of the present invention disclose an electronic device, including an operational amplifier circuit as disclosed in the second aspect, and / or a chip as disclosed in the third aspect.

[0041] Preferably, the electronic device is a headset or a speaker.

[0042] [Beneficial Effects]

[0043] The AB-class operational amplifier disclosed in this embodiment includes a differential input module, a common-source cascode amplifier module, a common-source amplifier module, and an output module. The differential input module receives and amplifies a differential voltage input signal to obtain a first differential current signal. The common-source cascode amplifier module receives and amplifies the first differential current signal to obtain a second differential voltage signal. The common-source amplifier module receives and amplifies the second differential voltage signal to obtain a third differential voltage signal. The output module receives the third differential voltage signal and converts it into a fourth differential voltage signal before outputting it to an external circuit. Specifically, the signal input terminal of the common-source amplifier submodule of the common-source amplifier module receives the second differential voltage signal. The first terminal of the bias submodule and the common-source amplifier submodule are both connected to positive voltage change terminals, and the second terminal of the bias submodule and the common-source feedback submodule are both connected to negative voltage change terminals. The voltage magnitudes at the positive and negative voltage change terminals alternately change, thereby obtaining and outputting the third differential voltage signal to the output module. As can be seen, by adding a common-source amplifier module after the common-source cascode amplifier module, the second differential voltage signal output by the common-source cascode amplifier module is amplified again, effectively improving the overall gain of the operational amplifier. Simultaneously, compared to traditional Class AB operational amplifiers, the addition of a common-source amplifier module between the common-source cascode amplifier module and the output module allows the common-source amplifier module to share the amplification requirements of the common-source cascode module. Therefore, the Class AB operational amplifier disclosed in this embodiment can significantly increase the overall gain of the operational amplifier while keeping the output impedance essentially unchanged or only slightly increased; or, it can significantly reduce the overall impedance of the operational amplifier while maintaining the overall gain. Thus, the Class AB operational amplifier disclosed in this embodiment can effectively improve the gain of the Class AB operational amplifier while ensuring its energy efficiency.

[0044] Other beneficial effects of the present invention will be explained in detail through the introduction of specific technical features and technical solutions in specific embodiments. Those skilled in the art should be able to understand the beneficial technical effects brought about by these technical features and technical solutions through the introduction of these technical features and technical solutions. Attached Figure Description

[0045] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is a circuit diagram for a traditional Class AB operational amplifier;

[0047] Figure 2 This is a schematic diagram of the AB class operational amplifier module disclosed in this embodiment;

[0048] Figure 3 This is a circuit diagram of the Class AB operational amplifier disclosed in this embodiment;

[0049] Figure 4 This is a circuit diagram of the common-source cascode amplification module of the Class AB operational amplifier disclosed in this embodiment;

[0050] Figure 5 This is a circuit diagram of the common-source amplifier module of the AB class operational amplifier disclosed in this embodiment. Detailed Implementation

[0051] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0054] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0055] For ease of understanding, a brief explanation of differential signals is provided below: A circuit has two signal input terminals. Two input signals are input one-to-one from these terminals. These two input signals have the same amplitude but opposite phases. The difference between these two input signals is the effective input signal of the circuit, and this effective input signal is called the differential input signal. The differential voltage signal mentioned later refers to a voltage signal with two input signals of the same amplitude and opposite phases; the differential current signal mentioned later refers to a current signal with two input signals of the same amplitude and opposite phases.

[0056] To improve the accuracy of charging cutoff voltage detection and charging current control, this embodiment discloses a Class AB operational amplifier. Please refer to... Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the AB-class operational amplifier module disclosed in this embodiment. Figure 3 This is a circuit diagram of the Class AB operational amplifier disclosed in this embodiment. The Class AB operational amplifier is connected between the positive power supply terminal Vdd and the negative power supply terminal Vss to amplify the differential voltage input signal. The Class AB operational amplifier includes a differential input module 100, a common-source cascode amplifier module 200, a common-source amplifier module 300, an output module 400, and a common-mode feedback module 500, wherein:

[0057] The differential input module 100 is used to receive and amplify the differential voltage input signal to obtain the first differential current signal.

[0058] Specifically, the differential input module 100 converts the received voltage signal into a current signal, which is then used as the input signal to the cascode amplifier module 200, enabling the cascode amplifier module 200 to amplify the received signal. Simultaneously, the differential input module 100 also amplifies the received voltage signal for the first time to improve the overall gain of the Class AB operational amplifier.

[0059] In this embodiment, the differential input module 100 includes an input stage current source 110 and a common-source input transistor 120. The input stage current source 110 is connected between the positive power supply terminal Vdd and the common-source input transistor 120 to provide a stable input current to the common-source input transistor 120. This stable input current is DC, meaning its magnitude and direction do not change. The control electrode of the common-source input transistor 120 receives a differential voltage input signal, causing the current output by the common-source input transistor 120 to the common-source cascode amplifier module 200 to change with the differential voltage input signal, thereby obtaining and outputting a first differential current signal.

[0060] In a specific embodiment, the input stage current source 110 is current source I1, and the common-source input transistor 120 includes transistor MIN and transistor MIP. Both transistor MIN and transistor MIP are connected to the common source, meaning that the differential voltage input signal is input from the gates of transistor MIN and transistor MIP, amplified to obtain a first differential current signal, and this first differential current signal is output from the drains of transistor MIN and transistor MIP to the common-gate signal input terminal I. In a specific embodiment, the common-gate signal input terminal I includes a common-gate signal input terminal I1 and a common-gate signal input terminal I2 to transmit the first differential current signal.

[0061] The AB-class operational amplifier disclosed in this embodiment also includes a common-source cascode amplifier module 200. Please refer to... Figure 2 , Figure 3 and Figure 4 , Figure 4 This is a circuit diagram of a common-source cascode amplifier module. The common-source cascode amplifier module 200 is used to receive and amplify the first differential current signal to obtain the second differential voltage signal. The signal output terminal A of the common-source cascode amplifier module 200 outputs the second differential voltage signal.

[0062] In this embodiment, the common-source common-gate amplifier module 200 includes a common-gate amplifier submodule 210 and an impedance submodule 220. The impedance submodule 220 is connected between the positive power supply terminal Vdd and the signal output terminal A, and provides impedance to allow the first current to flow from the positive power supply terminal Vdd to the signal output terminal A. The common-gate stage signal input terminal I of the common-gate amplifier submodule 210 receives the first differential current signal, and the common-gate amplifier submodule 210 is connected between the signal output terminal A and the negative power supply terminal Vss, so that the first current flows from the impedance submodule 220 to the common-gate amplifier submodule 210. The first current follows the change of the first differential current signal, so that the voltage of the signal output terminal A changes to obtain a second differential voltage signal.

[0063] In some embodiments, the common-gate amplifier submodule 210 includes a current mirror 211 and a common-gate current source 212. The current mirror 211 is connected between the signal output terminal A and the common-gate signal input terminal I, so that a first current flows from the current mirror 211 to the common-gate signal input terminal I. The common-gate current source 212 is connected between the common-gate signal input terminal I and the negative power supply terminal Vss, so as to provide a reference current to the common-gate signal input terminal I.

[0064] Specifically, the common-gate current source 212 ensures that the current flowing from the common-gate current source 212 to the negative power supply terminal Vss is a stable current. This stable current does not change with the change of the first differential current signal; that is, the sum of the first current flowing from the positive power supply terminal Vdd to the common-gate signal input terminal I and the first differential current signal remains unchanged. When the first differential current signal is input to the common-gate amplifier submodule 210 from the common-gate signal input terminal I, the current flowing from the common-gate signal input terminal I to the common-gate current source 212 changes with the first differential current signal, causing a change in the impedance of the first current and impedance submodule 220, thereby causing a change in the voltage at the signal output terminal A, and thus obtaining the second differential voltage signal.

[0065] In a specific embodiment, the impedance submodule 220 includes a variable impedance circuit 221 and a resistor circuit 222. The variable impedance circuit 221 is connected between the positive power supply terminal Vdd and the signal output terminal A so that the magnitude of the first current is variable. The resistor circuit 222 is connected between the signal output terminal A and the control terminal E of the variable impedance circuit 221 so that the voltage of the control terminal E is the common-mode voltage of the signal output terminal A, so that the voltage of the control terminal E remains constant.

[0066] In a specific embodiment, the variable impedance circuit 221 includes transistors ME1 and ME2, and the resistor circuit 222 includes resistors R1 and R2. The control electrodes of transistors ME1 and ME2 are both connected to the control terminal E. The ends of resistors R1 and R2 furthest from signal output terminal A are both connected to the control terminal E. Signal output terminal A includes signal output terminals A1 and A2. The difference between the voltage at signal output terminals A1 and A2 is the second differential voltage signal. Since the voltages at signal output terminals A1 and A2 are always equal in magnitude and opposite in direction, and the voltage at the control terminal E is the common-mode voltage of the voltages at signal output terminals A1 and A2, the voltage at the control terminal E can remain constant.

[0067] It should be noted that transistors ME1 and ME2 can be composite transistors, single transistors, or multiple transistors, as long as the parameters of transistors ME1 and ME2 are consistent and their impedances are variable. In this embodiment, both transistors ME1 and ME2 are composite MOSFETs. Resistors R1 and R2 can be single resistors or equivalent resistors, as long as their resistance values ​​are consistent.

[0068] The AB-class operational amplifier disclosed in this embodiment also includes a common-source amplifier module 300. Please refer to... Figure 2 , Figure 3 and Figure 5 ,in Figure 5 This is a circuit diagram of a common-source amplifier module 300, which is used to receive and amplify the second differential voltage signal to obtain the third differential voltage signal.

[0069] In a specific embodiment, the common-source amplification module 300 includes a common-source amplification submodule 310, a common-source feedback submodule 320, and a bias submodule 330. The signal input terminal of the common-source amplification submodule 310 receives a second differential voltage signal. The first terminal of the bias submodule 330 and the common-source amplification submodule 310 are both connected to a positive voltage change terminal C, and the second terminal of the bias submodule 330 and the common-source feedback submodule 320 are both connected to a negative voltage change terminal B. The voltage magnitude at the positive voltage change terminal C and the voltage magnitude at the negative voltage change terminal B alternately change to output a third differential voltage signal.

[0070] Therefore, compared to traditional Class AB operational amplifiers, the Class AB operational amplifier disclosed in this embodiment, with a common-source cascode amplifier module 300 after the common-source cascode amplifier module 200, allows the common-source amplifier module 300 to share the amplification requirements of the common-source cascode amplifier module 200. Since an additional amplification stage is added, the total gain is the product of the original gain and the gain of the newly added amplification stage, meaning the gain increases exponentially. Meanwhile, the total equivalent output impedance is approximately the original equivalent output impedance plus the equivalent output impedance of the newly added amplification stage in parallel, meaning the increase in equivalent output impedance is minimal. Therefore, by placing the common-source amplifier module 300 after the common-source cascode amplifier module 200, the amplification effect of the Class AB operational amplifier can be significantly improved with a minimal increase in equivalent output impedance, thus effectively increasing the gain of the Class AB operational amplifier while ensuring its energy efficiency.

[0071] In a specific embodiment, the common-source amplifier submodule 310 includes transistor MC1 and transistor MC2. Transistor MC1 and transistor MC2 are both connected between the positive power supply terminal Vdd and the positive voltage change terminal C. The control electrode of transistor MC1 and the control electrode of transistor MC2 are connected to the signal output terminal A to receive the second differential voltage signal, so that the voltage magnitude of the positive voltage change terminal C can change with the second differential voltage signal.

[0072] The common-source feedback submodule 320 includes transistors MB1 and MB2, both connected between the negative voltage change terminal B and the negative power supply terminal Vss. The control terminals of transistors MB1 and MB2 are connected to the feedback output terminal F of the common-mode feedback module 500 to receive the negative feedback signal. Therefore, the negative feedback signal affects the voltage at the positive voltage change terminal C and the voltage at the negative voltage change terminal B by influencing the current flowing through transistors MB1 and MB2, thereby affecting the third differential voltage signal.

[0073] Furthermore, compared to traditional Class AB operational amplifiers, the equivalent impedance of the impedance submodule 220 is significantly reduced because the amplification requirements of the common-source cascode amplifier module 400 are shared by the common-source amplifier module 300. This increases the voltage margin at signal output terminal A, resulting in a larger voltage swing at signal output terminal A. Simultaneously, the increased voltage margins at both the positive and negative voltage change terminals C and B further enhance the voltage swing of both terminals, leading to higher accuracy of the third differential voltage signal sent to the output module 400 and effectively improving the linearity of the entire operational amplifier.

[0074] In a specific embodiment, the bias submodule 330 is a transconducting linear loop circuit, which is connected between the positive voltage change terminal C and the negative voltage change terminal B, so that the voltage magnitude of the positive voltage change terminal C and the voltage magnitude of the negative voltage change terminal B alternately change.

[0075] Therefore, when the voltage at signal output terminal A is a positive voltage, the voltage at positive voltage change terminal C changes with the second differential voltage signal, while the voltage at negative voltage change terminal B remains stable (almost unchanged); when the voltage at signal output terminal A is a negative voltage, the voltage at negative voltage change terminal B changes with the second differential voltage signal, while the voltage at positive voltage change terminal C remains stable (almost unchanged).

[0076] In a specific embodiment, the positive voltage change terminal C includes positive voltage change terminals C1 and C2, and the negative voltage change terminal B includes negative voltage change terminals B1 and B2, so as to obtain and output a third differential voltage signal. Furthermore, transistors MC1 and MC2 can be composite transistors, single transistors, or multiple transistors. In a preferred embodiment, both transistors MC1 and MC2 are composite MOS transistors.

[0077] The AB-class operational amplifier disclosed in this embodiment also includes an output module 400. The output module 400 is connected to both the positive voltage change terminal C and the negative voltage change terminal B to receive a third differential voltage signal. The voltage at the operational amplifier output terminal D of the output module 400 changes with the third differential voltage signal to obtain a fourth differential voltage signal, which is the operational amplification result of the AB-class operational amplifier. In a specific embodiment, the operational amplifier output terminal D includes operational amplifier output terminals D1 and D2 to obtain and output a fourth differential current signal. Furthermore, depending on the actual needs of the external circuit connected to the operational amplifier output terminal D, the output module 400 can also output a drive current to the external circuit.

[0078] In a specific embodiment, the output module 400 includes a positive voltage conduction transistor 401 and a negative voltage conduction transistor 402. The positive voltage conduction transistor 401 is connected between the positive power supply terminal Vdd and the operational amplifier output terminal D, and the control electrode of the positive voltage conduction transistor 401 is connected to the positive voltage change terminal C. The negative voltage conduction transistor 402 is connected between the operational amplifier output terminal D and the negative power supply terminal Vss, and the control electrode of the negative voltage conduction transistor 402 is connected to the negative voltage change terminal B.

[0079] When the voltage at the positive voltage change terminal C changes, the voltage at the negative voltage change terminal B remains stable. In this state, the positive voltage transistor 401 is on and the negative voltage transistor 402 is off. Conversely, when the voltage at the negative voltage change terminal B changes, the voltage at the positive voltage change terminal C remains stable. In this state, the negative voltage transistor 402 is on and the positive voltage transistor 401 is off. The alternating changes in the voltage at the positive voltage change terminal C and the negative voltage change terminal B control the alternating conduction of the positive voltage transistor 401 and the negative voltage transistor 402, thereby enabling the output module 400 to output a fourth differential voltage signal to the external circuit via a Class AB output method.

[0080] It should be noted that the non-conducting states of the positive voltage conducting transistor 401 and the negative voltage conducting transistor 402 include the transistor cutoff state and the transistor subthreshold state. In the preferred embodiment, the non-conducting state is the transistor subthreshold state. Therefore, while ensuring the response speed of the positive voltage conducting transistor 401 and the negative voltage conducting transistor 402, the power consumption of the output module 400 can be further reduced, thereby further reducing the overall power consumption of the AB class operational amplifier disclosed in this embodiment.

[0081] In a preferred embodiment, the output module 400 further includes a phase compensation submodule 420, which is connected between the control electrode of the positive voltage conduction transistor 401, the control electrode of the negative voltage conduction transistor 402, and the output terminal D of the operational amplifier.

[0082] The AB-class operational amplifier disclosed in this embodiment also includes a common-mode feedback module 500. The input terminal of the common-mode feedback module 500 receives a fourth differential voltage signal to obtain a negative feedback signal. The feedback output terminal F of the common-mode feedback module 500 is connected to the common-source feedback submodule 320 so that the common-source feedback submodule 320 receives the negative feedback signal so that the negative feedback signal affects the fourth differential voltage signal.

[0083] Preferably, the transistor in this embodiment is a MOS transistor.

[0084] In summary, in the Class AB operational amplifier disclosed in this embodiment, a common-source amplifier module 300 is provided after the common-source cascode amplifier module 200 to further amplify the second differential voltage signal output by the common-source cascode amplifier module 200, thereby effectively improving the overall gain of the operational amplifier. Simultaneously, compared to traditional Class AB operational amplifiers, the addition of the common-source amplifier module 300 between the common-source cascode amplifier module 200 and the output module 400 allows the common-source amplifier module 300 to share the amplification requirements of the common-source cascode module 200, resulting in a significant increase in the total gain of the operational amplifier while maintaining minimal increase in equivalent impedance. This substantially improves the gain of the Class AB operational amplifier while ensuring its energy efficiency. Furthermore, in the Class AB operational amplifier disclosed in this embodiment, since the voltage swings at the signal output terminal A, the positive voltage change terminal C, and the negative voltage change terminal B are all effectively increased, the signal is less prone to distortion during the amplification of the differential voltage input signal into a fourth differential voltage signal, thus improving the linearity of the Class AB operational amplifier and enhancing its overall performance.

[0085] This embodiment also discloses an operational amplifier circuit, including a load circuit and an AB-class operational amplifier as disclosed in the above embodiment. The load circuit is connected to the AB-class operational amplifier to receive a fourth differential voltage signal.

[0086] This embodiment also discloses a chip, including the Class AB operational amplifier as disclosed in the above embodiments.

[0087] This embodiment also discloses an electronic device, including the operational amplifier circuit as disclosed in the above embodiments, and / or the chip disclosed in the above embodiments.

[0088] In a specific embodiment, the electronic device can be an audio device such as headphones or a speaker.

[0089] Those skilled in the art will understand that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0090] It should be understood that the above embodiments are merely exemplary and not restrictive. Various obvious or equivalent modifications or substitutions that can be made by those skilled in the art regarding the above details without departing from the basic principles of the present invention will be included within the scope of the claims of the present invention.

Claims

1. An AB-class operational amplifier, connected between a positive power supply terminal (Vdd) and a negative power supply terminal (Vss), for amplifying a differential voltage input signal, characterized in that, include: A differential input module (100) is used to receive and amplify the differential voltage input signal to obtain a first differential current signal; A common-source cascode amplifier module (200) is used to receive and amplify the first differential current signal to obtain a second differential voltage signal. The signal output terminal (A) of the common-source cascode amplifier module (200) outputs the second differential voltage signal. A common-source amplifier module (300) is used to receive and amplify the second differential voltage signal to obtain a third differential voltage signal; the common-source amplifier module (300) includes a common-source amplifier submodule (310), a common-source feedback submodule (320), and a bias submodule (330); The signal input terminal of the common-source amplifier submodule (310) receives the second differential voltage signal; the first terminal of the bias submodule (330) and the common-source amplifier submodule (310) are both connected to the positive voltage change terminal (C), and the second terminal of the bias submodule (330) and the common-source feedback submodule (320) are both connected to the negative voltage change terminal (B); the voltage magnitude of the positive voltage change terminal (C) and the voltage magnitude of the negative voltage change terminal (B) alternately change to obtain and output the third differential voltage signal; The output module (400) is connected to the positive voltage change terminal (C) and the negative voltage change terminal (B) to receive the third differential voltage signal. The voltage of the operational amplifier output terminal (D) of the output module (400) changes with the third differential voltage signal to obtain a fourth differential voltage signal. The fourth differential voltage signal is the operational amplification result of the Class AB operational amplifier.

2. The Class AB operational amplifier as described in claim 1, characterized in that, The common-source cascode amplifier module (200) includes a common-code amplifier submodule (210) and an impedance submodule (220); The impedance submodule (220) is connected between the positive power supply terminal (Vdd) and the signal output terminal (A). The impedance submodule (220) is used to provide impedance so that the first current flows from the positive power supply terminal (Vdd) to the signal output terminal (A). The common gate amplifier submodule (210) receives the first differential current signal at its common gate level signal input terminal (I), and the common gate amplifier submodule (210) is connected between the signal output terminal (A) and the negative power supply terminal (Vss) so that the first current flows from the impedance submodule (220) to the common gate amplifier submodule (210). The first current follows the change of the first differential current signal, so as to change the voltage of the signal output terminal (A) to obtain the second differential voltage signal.

3. The Class AB operational amplifier as described in claim 2, characterized in that, The common-gate amplifier submodule (210) includes a current mirror (211) and a common-gate current source (212). The current mirror (211) is connected between the signal output terminal (A) and the common-gate signal input terminal (I) so that the first current flows from the current mirror (211) to the common-gate signal input terminal (I). The common gate current source (212) is connected between the common gate signal input terminal (I) and the negative power supply terminal (Vss) to provide a reference current to the common gate signal input terminal (I).

4. The Class AB operational amplifier as described in claim 2, characterized in that, The impedance submodule (220) includes a variable impedance circuit (221) and a resistor circuit (222). The variable impedance circuit (221) is connected between the positive power supply terminal (Vdd) and the signal output terminal (A) so that the magnitude of the first current is variable. The resistor circuit (222) is connected between the signal output terminal (A) and the control terminal (E) of the variable impedance circuit (221) so that the voltage of the control terminal (E) is the common-mode voltage of the signal output terminal (A) so that the voltage of the control terminal (E) remains unchanged.

5. The Class AB operational amplifier as described in claim 4, characterized in that, The variable impedance circuit (221) includes transistor ME1 and transistor ME2, and the resistor circuit (222) includes resistor R1 and resistor R2; The control electrode of transistor ME1 and the control electrode of transistor ME2 are both connected to the control terminal (E), and the end of resistor R1 away from the signal output terminal (A) and the end of resistor R2 away from the signal output terminal (A) are both connected to the control terminal (E).

6. The Class AB operational amplifier as described in claim 5, characterized in that, Both transistor ME1 and transistor ME2 are composite transistors.

7. The Class AB operational amplifier as described in claim 1, characterized in that, It also includes a common-mode feedback module (500), the input terminal of which receives the fourth differential voltage signal to obtain a negative feedback signal, and the feedback output terminal (F) of the common-mode feedback module (500) is connected to the common-source feedback submodule (320) so that the common-source feedback submodule (320) receives the negative feedback signal so that the negative feedback signal affects the fourth differential voltage signal.

8. The Class AB operational amplifier as described in claim 1, characterized in that, The common-source amplifier submodule (310) includes transistor MC1 and transistor MC2. Both transistor MC1 and transistor MC2 are connected between the positive power supply terminal (Vdd) and the positive voltage change terminal (C). The control electrode of transistor MC1 and the control electrode of transistor MC2 are connected to the signal output terminal (A) to receive the second differential voltage signal, so that the voltage of the positive voltage change terminal (C) can change with the second differential voltage signal.

9. The Class AB operational amplifier as described in claim 7, characterized in that, The common-source feedback submodule (320) includes transistor MB1 and transistor MB2. Both transistor MB1 and transistor MB2 are connected between the negative voltage change terminal (B) and the negative power supply terminal (Vss). The control terminals of transistor MB1 and transistor MB2 are connected to the feedback output terminal (F) of the common-mode feedback module (500) to receive the negative feedback signal.

10. The Class AB operational amplifier as described in claim 7, characterized in that, The bias submodule (330) is a transconducting linear loop circuit, which is connected between the positive voltage change terminal (C) and the negative voltage change terminal (B) so that the voltage magnitude of the positive voltage change terminal (C) and the voltage magnitude of the negative voltage change terminal (B) alternate.

11. The Class AB operational amplifier as described in claim 1, characterized in that, The output module (400) includes a positive voltage conduction transistor (401) and a negative voltage conduction transistor (402). The positive voltage conduction transistor (401) is connected between the positive power supply terminal (Vdd) and the operational amplifier output terminal (D), and the control terminal of the positive voltage conduction transistor (401) is connected to the positive voltage change terminal (C). The negative voltage conduction transistor (402) is connected between the output terminal (D) of the operational amplifier and the negative power supply terminal (Vss), and the control terminal of the negative voltage conduction transistor (402) is connected to the negative voltage change terminal (B); When the voltage at the positive voltage change terminal (C) changes, the positive voltage conduction transistor (401) is in the conduction state and the negative voltage conduction transistor (402) is in the non-conducting state; when the voltage at the negative voltage change terminal (B) changes, the negative voltage conduction transistor (402) is in the conduction state and the positive voltage conduction transistor (401) is in the non-conducting state; wherein, the non-conducting state includes the transistor cut-off state and the transistor subthreshold state.

12. The Class AB operational amplifier as described in claim 11, characterized in that, The output module (400) further includes a phase compensation submodule (420), which is connected between the control electrode of the positive voltage conduction transistor (401), the control electrode of the negative voltage conduction transistor (402), and the output terminal (D) of the operational amplifier.

13. The Class AB operational amplifier as described in claim 11, characterized in that, The differential input module (100) includes an input current source (110) and a common-source input transistor (120). The input current source (110) is connected between the positive power supply terminal (Vdd) and the common-source input transistor (120) to provide a stable input current to the common-source input transistor (120). The control electrode of the common-source input transistor (120) receives the differential voltage input signal, so that the current output by the common-source input transistor (120) to the common-source cascode amplifier module (200) changes with the differential voltage input signal to obtain a first differential current signal.

14. An operational amplifier circuit, comprising a load circuit and an AB class operational amplifier as claimed in any one of claims 1-13, wherein the load circuit is connected to the AB class operational amplifier to receive the fourth differential voltage signal.

15. A chip, characterized in that, Includes the Class AB operational amplifier as described in any one of claims 1-13.

16. An electronic device, characterized in that, Includes the operational amplifier circuit as described in claim 14, and / or the chip as described in claim 15.

17. The electronic device as claimed in claim 16, characterized in that, The electronic device is a headset or a speaker.

Images