Common-mode feedback circuit and differential amplifier thereof

Abstract

The invention provides a common-mode feedback circuit and a differential amplifier thereof, the common-mode feedback circuit comprises a sampling circuit and an amplifier circuit, the sampling circuit comprises a first input end, a second input end and a first output end, the first input end receives a first differential signal Voutp, and the second input end receives a second differential signal Voutn; the level shift module comprises a third input end, a fourth input end and a second output end, receives a common-mode signal VCMS and a reference common-mode signal VOCM output by the sampling circuit, and adjusts the common mode of the common-mode signal VCMS and the reference common-mode signal VOCM to enable the second output end to output a common-mode feedback signal VCMFB processed by the level shift module; the amplifier circuit receives a common mode feedback signal VCMFB. After the technical scheme is adopted, the same speed as that of a differential loop can be realized, the current of a main operational amplifier can be multiplexed, the power consumption of a common-mode loop is far lower than that of a main loop, and meanwhile, the common-mode level can be randomly adjusted.

Description

Technical Field

[0001] The present invention relates to the technical field of common - mode feedback, and particularly to a common - mode feedback circuit and a differential amplifier having the common - mode feedback circuit. Background Art

[0002] In the application of differential output amplifiers, due to mismatches, the common - mode signal shows a significant offset and cannot be stabilized through differential - mode feedback. Therefore, a common - mode feedback circuit is required. Especially in practical applications, the gain - bandwidth product of the common - mode feedback circuit should generally be the same as that of the differential - mode feedback circuit, so as to be able to respond quickly to signals, especially in single - ended - to - differential applications. However, it is very difficult for traditional common - mode feedback circuits to achieve the same speed as differential - mode feedback circuits. Even if it can be achieved, it requires high power consumption, and in some cases, the power consumption of the common - mode feedback circuit even exceeds that of the main amplifier. And some low - power common - mode feedback circuits are very slow and cannot freely adjust the common - mode level.

[0003] To solve the above problems, a common - mode feedback circuit based on MOS in the linear region can generally be used, which can reuse the main op - amp current and save power consumption. However, limited by the output common - mode level, only MOS in the linear region can be used. Therefore, the speed of the common - mode feedback circuit is not as fast as that of the differential - mode loop, and this circuit cannot freely adjust the output common - mode level.

[0004] Therefore, a new type of common - mode feedback circuit is needed, which can use a level - shift module to realize a high - regulation and low - power - consumption high - speed common - mode feedback circuit. A common - mode feedback circuit with the same bandwidth as the differential signal or even a larger bandwidth can be realized with extremely low power consumption, and the common - mode level can be adjusted arbitrarily. Summary of the Invention

[0005] In order to overcome the above - mentioned technical defects, the purpose of the present invention is to provide a common - mode feedback circuit and its differential amplifier, which can achieve the same speed as the differential loop, can reuse the current of the main op - amp, make the power consumption of the common - mode loop much lower than that of the main loop, and can also arbitrarily adjust the common - mode level.

[0006] The present invention discloses a common - mode feedback circuit, including a sampling circuit and an amplifier circuit. The sampling circuit includes a first input terminal, a second input terminal, and a first output terminal, wherein the first input terminal receives a first differential signal Voutp, and the second input terminal receives a second differential signal Voutn;

[0007] The common-mode feedback circuit further includes a level shift module connected between the sampling circuit and the amplifier circuit. The level shift module includes a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal is connected to the first output terminal to receive the common-mode signal VCMS output by the sampling circuit. The fourth input terminal receives a reference common-mode signal VOCM. The level shift module adjusts the common mode of the common-mode signal VCMS and the reference common-mode signal VOCM so that the second output terminal outputs a common-mode feedback signal VCMFB processed by the level shift module.

[0008] The amplifier circuit includes a fifth input terminal, and the fifth input terminal is connected to the second output terminal to receive the common-mode feedback signal VCMFB.

[0009] Preferably, the level shift module includes:

[0010] An inverting amplifier having a third input terminal, a fourth input terminal, and a third output terminal. After receiving the common-mode signal VCMS and the reference common-mode signal VOCM, the inverting amplifier inverts the common-mode signal VCMS and the reference common-mode signal VOCM to generate an inverted signal V01.

[0011] A level shift circuit having a sixth input terminal and a second output terminal. The sixth input terminal is connected to the third output terminal to receive the inverted signal V01.

[0012] Preferably, the sampling circuit includes:

[0013] A first resistor R s , one end of which is connected to the first input terminal to receive the first differential signal Voutp;

[0014] A second resistor R s , one end of which is connected to the second input terminal to receive the second differential signal Voutn;

[0015] The other end of the first resistor R s and the other end of the second resistor R s are connected and connected to the third input terminal to input the common-mode signal VCMS to the third input terminal.

[0016] Preferably, the level shift module includes:

[0017] A first PNP transistor, the emitter of the first PNP transistor is connected to a voltage source, and the collector is connected to the third input terminal to receive the common-mode signal VCMS;

[0018] A second PNP transistor, the emitter of the second PNP transistor is connected to the voltage source;

[0019] An operational amplifier, the inverting input terminal of the operational amplifier is connected to the fourth input terminal to receive a reference common-mode signal VOCM, the non-inverting input terminal of the operational amplifier is connected to the collector of the second PNP transistor, and the seventh output terminal of the operational amplifier is respectively connected to the base of the first PNP transistor and the base of the second PNP transistor, so that the positive-phase signal Vfb input to the non-inverting input terminal is equal to the reference common-mode signal VOCM input to the inverting input terminal.

[0020] Preferably, the level shift module further includes:

[0021] A third resistor R LS , one end is connected to the collector of the first PNP transistor, and the other end is connected to the second output terminal;

[0022] A fourth resistor R LS , one end is connected to the collector of the second PNP transistor;

[0023] A first NPN transistor, the collector of the first NPN transistor is connected to the second output terminal, the base is connected to the other end of the fourth resistor R LS , and the emitter is grounded;

[0024] A second NPN transistor, the collector of the second NPN transistor is connected to the other end of the fourth resistor R LS , the base is connected to the other end of the fourth resistor R LS , and the emitter is grounded.

[0025] Preferably, the level shift module further includes:

[0026] A first feed-forward capacitor C LS , which is connected in parallel across the third resistor R LS .

[0027] Preferably, the first PNP transistor, the second PNP transistor, the first NPN transistor, and the second NPN transistor have the same size.

[0028] Preferably, the amplifier circuit includes:

[0029] A second feed-forward capacitor C S , which is connected in parallel across the first resistor R s ;

[0030] A third feed-forward capacitor C S , which is connected in parallel across the second resistor R s ;

[0031] A third NPN transistor, the base of the third NPN transistor is connected to a voltage source VIN, and the collector is connected to the first input terminal;

[0032] The fourth NPN transistor, the base of the fourth NPN transistor is connected to a voltage source VIP, and the collector is connected to the second input terminal;

[0033] The fifth NPN transistor, the base of the fifth NPN transistor is connected to the fifth input terminal, the collector is connected to the emitters of the third NPN transistor and the fourth NPN transistor, and the emitter is grounded.

[0034] The present invention also discloses a differential amplifier, including the common-mode feedback circuit as described above.

[0035] After adopting the above technical solutions, compared with the prior art, the following beneficial effects are achieved:

[0036] 1. The common-mode feedback circuit solves the common-mode feedback speed problem in high-speed amplifiers, and can achieve the same bandwidth as the main op-amp with low power consumption; thus, while responding to high-frequency signals, the common-mode signal can also respond quickly without significant offset, and for single-ended to differential applications, it can significantly suppress the rapid change of the input common mode and no significant common-mode offset will be observed at the output end;

[0037] 2. The common-mode feedback circuit can be applied to all differential amplifiers, achieving high speed with extremely low power consumption overhead, and can also arbitrarily adjust the common-mode level;

[0038] 3. In the present invention, an adjustable level shift is used to shift the detected output common mode to the required level, which can avoid using MOS in the linear region and can use MOS in the saturation region but is not limited to it, to obtain a larger bandwidth. In addition to MOS, transistors can also be used, and the applicable range of op-amps is wider. At the same time, the output common mode value can be freely adjusted, which is suitable for most applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0040] Figure 1 is a framework diagram of the common-mode feedback circuit in a preferred embodiment of the present invention;

[0041] Figure 2 is a framework diagram of the common-mode feedback circuit in another preferred embodiment of the present invention;

[0042] Figure 3 is a circuit schematic diagram of the common-mode feedback circuit in a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The advantages of the present invention are further elaborated below in conjunction with the drawings and specific embodiments.

[0044] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0045] The terms used in the present disclosure are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. The singular forms "a", "the", and "said" used in the present disclosure and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0046] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0047] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0048] In the description of the present invention, unless otherwise specified and defined, it should be noted that the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a mechanical connection or an electrical connection, or it may be the communication inside two elements. It may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms may be understood according to specific circumstances.

[0049] In the subsequent description, the suffixes such as "module", "component", or "unit" used to represent elements are only for the convenience of describing the present invention, and they have no specific meaning in themselves. Therefore, "module" and "component" may be used interchangeably.

[0050] Common-Mode Feedback (CMFB) is a technique used in analog circuit design to stabilize the common-mode voltage of a fully differential amplifier. Its core purpose is to ensure that the common-mode level of the circuit output (i.e., the average of the two differential output signals) remains stable, avoiding circuit operating point shifts caused by factors such as process variations, temperature changes, or power supply fluctuations, which could affect performance or cause distortion.

[0051] Refer to Figure 1 , which shows a block diagram of a common-mode feedback circuit according to a preferred embodiment of the present invention. In this embodiment, the common-mode feedback circuit can be applicable to various feedback forms, either in-phase feedback or anti-phase feedback, and includes a sampling circuit and an amplifier circuit. The sampling circuit includes a first input terminal, a second input terminal, and a first output terminal, where the first input terminal receives the first differential signal Voutp, and the second input terminal receives the second differential signal Voutn. In different embodiments, the common-mode sampling circuit can be implemented in various ways, such as resistor sampling or follower sampling.

[0052] The common-mode feedback circuit further includes a level shift module connected between the sampling circuit and the amplifier circuit. The level shift module includes a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal is connected to the first output terminal and receives the common-mode signal VCMS output by the sampling circuit. The fourth input terminal receives a reference common-mode signal VOCM. The level shift module adjusts the common-mode of the common-mode signal VCMS and the reference common-mode signal VOCM so that the second output terminal outputs the common-mode feedback signal VCMFB processed by the level shift module.

[0053] Through the above scheme, the common-mode signal VCMS can be shifted to the required common-mode feedback signal VCMFB, and the value of the level shift is affected by the reference common-mode signal VOCM. In other words, the reference common-mode signal VOCM is the common-mode signal that the amplifier circuit needs to achieve, which can be directly provided externally or generated internally. The amplifier circuit includes a fifth input terminal, which is connected to the second output terminal and receives the common-mode feedback signal VCMFB.

[0054] Since the finally generated common-mode feedback signal VCMFB is fed back into the amplifier circuit, the common-mode signals of the required first differential signal Voutp and second differential signal Voutn are the reference common-mode signal VOCM. And the feedback loop is an in-phase circuit. Since the level shift module and the sampling circuit do not introduce additional poles, the stability of the common-mode feedback loop is easily achieved. At the same time, since the amplifier circuit is reused and the transistors in the amplifier circuit can also be in the amplification region, the gain-bandwidth product of the common-mode circuit can be made the same as that of the amplifier circuit.

[0055] With the above-described embodiments, the circuit can adjust the output common mode by adjusting the value of the reference common mode signal V OCM, and is not affected by process corners, temperature, and power supply voltage, having good robustness.

[0056] Further, referring to Figure 2 , a framework diagram of a common mode feedback circuit according to another preferred embodiment of the present invention is shown. When it is necessary to invert the reference common mode signal V OCM and the common mode signal V CMS, an inverting amplifier can be used. Specifically, the level shift module includes: an inverting amplifier having a third input terminal, a fourth input terminal, and a third output terminal. After receiving the common mode signal V CMS and the reference common mode signal V OCM, the inverting amplifier inverts the common mode signal V CMS and the reference common mode signal V OCM to generate an inverted signal V 01; a level shift circuit having a sixth input terminal and a second output terminal, and the sixth input terminal is connected to the third output terminal to receive the inverted signal V 01.

[0057] Wherein, after processing the inverted signal V 01 in the level shift circuit, a common mode feedback signal V CMFB can also be generated to the amplifier circuit. The circuit structure of the inverting common mode feedback is similar to that of the non-inverting common mode feedback. By adding an inverting amplifier in the level shift module, the inverting function is realized, and the others are the same. Although there will be an additional relatively high-frequency pole in the feedback path of the inverting circuit, the stability will be slightly affected, but compared with the traditional common mode feedback, high-speed applications can still be achieved.

[0058] As described above, there are various implementation manners for the sampling circuit and the level shift module. In a preferred embodiment, referring to Figure 3 , one of the implementation manners is shown. Specifically, the sampling circuit includes: a first resistor R s , one end of which is connected to the first input terminal to receive the first differential signal V outp; a second resistor R s , one end of which is connected to the second input terminal to receive the second differential signal V outn. The one end of the first resistor R s and the one end of the second resistor R s can be commonly connected to a voltage source. The other end of the first resistor R s and the other end of the second resistor R s are connected and are connected to the third input terminal to input the common mode signal V CMS to the third input terminal. Through the above sampling circuit, the common mode signals of V OUTP and the second differential signal V outn are sampled by two resistors R s to obtain the common mode signal V CMS.

[0059] Further, the level shift module includes: a first PNP transistor, the emitter of the first PNP transistor is connected to a voltage source, and the collector is connected to the third input terminal to receive the common mode signal VCMS; a second PNP transistor, the emitter of the second PNP transistor is connected to the voltage source; an operational amplifier (for example, it can be a low-speed and high-precision operational amplifier), the inverting input terminal of the operational amplifier is connected to the fourth input terminal to receive the reference common mode signal VOCM, the non-inverting input terminal of the operational amplifier is connected to the collector of the second PNP transistor, and the seventh output terminal of the operational amplifier is respectively connected to the base of the first PNP transistor and the base of the second PNP transistor. Through the design of the feedback loop, a part of the output signal is fed back to the non-inverting input terminal, thereby controlling the output signal and changing the gain of the operational amplifier until the positive phase signal Vfb input to the non-inverting input terminal is equal to the reference common mode signal VOCM input to the inverting input terminal. In other words, by virtue of the virtual short and virtual open characteristics of the operational amplifier, through the implementation of the entire negative feedback process, the voltage at the inverting input terminal is pulled down until it is close enough to the voltage at the non-inverting input terminal, and when it is close enough to be considered equal, it enters the steady state. Of course, there will be the characteristic of virtual short at this time.

[0060] Further, the level shift module further includes: a third resistor R LS , one end of which is connected to the collector of the first PNP transistor, and the other end is connected to the second output terminal; a fourth resistor R LS , one end of which is connected to the collector of the second PNP transistor; a first NPN transistor, the collector of the first NPN transistor is connected to the second output terminal, the base is connected to the other end of the fourth resistor R LS , and the emitter is grounded; a second NPN transistor, the collector of the second NPN transistor is connected to the other end of the fourth resistor R LS , the base is connected to the other end of the fourth resistor R LS , and the emitter is grounded. With the above configuration, the level shift is achieved by using the third resistor R LS and the fourth resistor R LS to translate the common mode signal VCMS to obtain the common mode feedback signal VCMFB. In other words, when the size configurations of the first PNP transistor and the second PNP transistor are the same, the current I1 flowing through the third resistor R LS and the current I2 flowing through the fourth resistor R LS are made equal by the operational amplifier.

[0061] More specifically, with the above configuration, it is made such that , because , and , the value of the common mode signal VCMS finally obtained is: Among them, VCMFB-VD is the common-mode offset voltage. As long as the current densities of the first NPN transistor and the second NPN transistor are controlled to be the same, this value is approximately 0, thus achieving the purpose of VCMS = VOCM.

[0062] In a preferred embodiment, the first PNP transistor, the second PNP transistor, the first NPN transistor, and the second NPN transistor can be configured to have the same size, that is, the same package height, package width, pin pitch, etc.

[0063] In another preferred embodiment, the level shift module further includes: a first feed-forward capacitor C LS , connected in parallel across the third resistor R LS . The amplifier circuit includes: a second feed-forward capacitor C S , connected in parallel across the first resistor R s ; a third feed-forward capacitor C S , connected in parallel across the second resistor R s . With the first feed-forward capacitor C LS , the second feed-forward capacitor C S , and the third feed-forward capacitor C S , the sampling circuit and the level shift module do not need to introduce additional poles. In other words, there is only one low-frequency pole in the entire common-mode feedback loop in this example, which is the output pole of the main loop, approximately a single-pole system, and there is no stability problem. The amplifier circuit includes: a third NPN transistor, the base of the third NPN transistor is connected to a voltage source VIN, and the collector is connected to the first input terminal; a fourth NPN transistor, the base of the fourth NPN transistor is connected to a voltage source VIP, and the collector is connected to the second input terminal; a fifth NPN transistor, the base of the fifth NPN transistor is connected to the fifth input terminal, and the collector is connected to the emitters of the third NPN transistor and the fourth NPN transistor, and the emitter is grounded. The gain-bandwidth product GBW is determined by the tail current source transistor of the amplifier circuit. If the current densities of all NPN transistors are the same, then the GBW of the common-mode loop is equal to the GBW of the differential-mode loop.

[0064] With the above configuration, the power consumption of the entire common-mode feedback loop is only the currents I1 and I2 in the level shift module and the power consumption of the operational amplifier, and the power consumption of the low-speed operational amplifier can reach the nA level and can basically be ignored. The magnitudes of the currents I1 and I2 in the level shift module depend on the values of the third resistor R LS and the fourth resistor R LS . When the values of the third resistor R LS and the fourth resistor R LS are very large, the currents I1 and I2 in the level shift module are also much smaller than the current of the amplifier circuit. When the transistor is a MOS transistor, the third resistor R LS and the fourth resistor RLS The value can reach the MΩ level, and the current can be as small as the μA level. While the current of the operational amplifier is at the mA level, so the power consumption of the entire common-mode feedback loop is extremely low.

[0065] On the other hand, the present invention also discloses a differential amplifier, including the common-mode feedback circuit as described above.

[0066] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, according to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0067] Those skilled in the art can understand that in addition to implementing the systems, devices, units and their respective modules provided by the present invention in the form of pure computer-readable program codes, the method steps can be logically programmed to enable the systems, devices, units and their respective modules provided by the present invention to be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. to achieve the same program. Therefore, the systems, devices and their respective modules provided by the present invention can be regarded as a kind of hardware components, and the modules included therein for implementing various programs can also be regarded as the structures within the hardware components; the modules for implementing various functions can also be regarded as both software programs for implementing the methods and the structures within the hardware components.

[0068] In addition, all or part of the steps in the methods of the above embodiments can be completed by a program instructing relevant hardware. The program is stored in a storage medium, including several instructions for enabling a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the methods described in various embodiments of the present application. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks or optical disks and other various media that can store program codes.

[0069] In addition, any combination can be made between various different embodiments of the embodiments of the present invention, as long as it does not violate the idea of the embodiments of the present invention, and it should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A common-mode feedback circuit, comprising a sampling circuit and an amplifier circuit, characterized in that: The sampling circuit includes a first input terminal, a second input terminal and a first output terminal, wherein the first input terminal receives a first differential signal Voutp, and the second input terminal receives a second differential signal Voutn; the common-mode feedback circuit also includes a level shift module connected between the sampling circuit and the amplifier circuit, the level shift module includes a third input terminal, a fourth input terminal and a second output terminal, the third input terminal is connected to the first output terminal, and receives a common-mode signal VCMS output by the sampling circuit, the fourth input terminal receives a reference common-mode signal VOCM, and the level shift module adjusts the common-mode signal VCMS to be common-mode with the reference common-mode signal VOCM, so that the second output terminal outputs a common-mode feedback signal VCMFB processed by the level shift module; the amplifier circuit includes a fifth input terminal, the fifth input terminal is connected to the second output terminal, and receives the common-mode feedback signal VCMFB.

2. The common-mode feedback circuit according to claim 1, characterized in that: The level shift module includes: an inverting amplifier having the third input terminal, the fourth input terminal and a third output terminal, and after receiving the common mode signal VCMS and the reference common mode signal VOCM, the inverting amplifier inverts the common mode signal VCMS and the reference common mode signal VOCM to generate an inverted signal V01; a level shift circuit having a sixth input terminal and the second output terminal, and the sixth input terminal is connected to the third output terminal to receive the inverted signal V01.

3. The common-mode feedback circuit according to claim 1, characterized in that: The sampling circuit includes: a first resistor R s , one end of which is connected to the first input end to receive the first differential signal Voutp; a second resistor R s , one end of which is connected to the second input end to receive the second differential signal Voutn; the first resistor R s The other end and the second resistor R s The other end of the transistor is connected to the third input terminal in parallel, so as to input a common mode signal VCMS to the third input terminal.

4. The common-mode feedback circuit according to claim 3, characterized in that: The level shift module includes: a first PNP transistor, the emitter of the first PNP transistor is connected to a voltage source, and the collector is connected to the third input terminal to receive the common mode signal VCMS; a second PNP transistor, the emitter of the second PNP transistor is connected to the voltage source; an operational amplifier, the inverting input terminal of the operational amplifier is connected to the fourth input terminal to receive the reference common mode signal VOCM, the positive input terminal of the operational amplifier is connected to the collector of the second PNP transistor, and the seventh output terminal of the operational amplifier is respectively connected to the base of the first PNP transistor and the base of the second PNP transistor, so that the positive phase signal Vfb input to the positive phase input terminal is equal to the reference common mode signal VOCM input to the negative phase input terminal.

5. The common mode feedback circuit according to claim 4, characterized in that: The level shift module further includes: a third resistor R LS , one end of which is connected to the collector of the first PNP transistor, and the other end of which is connected to the second output end; a fourth resistor R LS , one end of which is connected to the collector of the second PNP transistor; a first NPN transistor, the collector of the first NPN transistor is connected to the second output end, and the base is connected to the R of the fourth resistor LS The other end is connected, and the emitter is grounded; a second NPN transistor, the collector of the second NPN transistor is connected to the R of the fourth resistor LS The other end of the base is connected to the fourth resistor R LS The other end is connected to the emitter ground.

6. The common mode feedback circuit according to claim 5, characterized in that: The level shift module also includes: a first feedforward capacitor C LS , connected in parallel with the third resistor R LS both ends of .

7. The common mode feedback circuit according to claim 5, characterized in that: The first PNP transistor, the second PNP transistor, the first NPN transistor, and the second NPN transistor have the same size.

8. The common mode feedback circuit according to claim 5, characterized in that: The amplifier circuit comprises: a second feedforward capacitor C S , connected in parallel with the first resistor R s Two ends; the third feedforward capacitor C S , connected in parallel with the second resistor R s two ends; a third NPN transistor, the base of the third NPN transistor is connected to a voltage source VIN, and the collector is connected to the first input terminal; a fourth NPN transistor, the base of the fourth NPN transistor is connected to a voltage source VIP, and the collector is connected to the second input terminal; a fifth NPN transistor, the base of the fifth NPN transistor is connected to the fifth input terminal, the collector is connected to the emitter of the third NPN transistor and the emitter of the fourth NPN transistor, and the emitter is grounded.

9. A differential amplifier, characterized in that: Comprising the common-mode feedback circuit as described in any one of claims 1-8.

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