Operational amplifier, chip and electronic device

Abstract

The application provides an operational amplifier, a chip and an electronic device, which can increase the stability and establishment speed of a common-mode feedback circuit. The operational amplifier comprises: N-stage amplifiers connected in series and M common-mode feedback circuits, wherein N and M are integers, N is greater than or equal to 3, N is greater than or equal to M and M is greater than 1; wherein the i th common-mode feedback circuit in the M common-mode feedback circuits is used for detecting the common-mode output voltage of the j+b th amplifier, and adjusting the electrical parameter of at least one amplifier in the j th to j+b th amplifiers to stabilize the common-mode output voltage of the j+b th amplifier, and the M th common-mode feedback circuit is used for detecting and stabilizing the common-mode output voltage of the N th amplifier, i, j and b are integers, M is greater than or equal to i and i is greater than or equal to 1, N is greater than or equal to j and j is greater than or equal to 1, i is greater than or equal to j and b is greater than or equal to 0.

Description

Technical Field

[0001] This application relates to the field of electronic technology, and more particularly to an operational amplifier, a chip, and an electronic device. Background Technology

[0002] Operational amplifiers (OPAs) are key components in analog circuits and are widely used in analog signal processing systems. For example, in radio frequency transceiver systems, OPAs are typically used in key modules such as trans-impedance amplifiers (TIAs), low-pass filters (LPFs), variable gain amplifiers (VGAs), analog-to-digital converters (ADCs), and digital-to-analog converters (DACs).

[0003] For a typical fully differential two-stage operational amplifier, common-mode feedback (CMFB) can be achieved by sharing two differential signal paths and adding an error amplifier, so the CMFB loop is usually three stages. With the development of integrated circuit technology, the supply voltage is becoming increasingly lower, making it more difficult to design high-gain, high-bandwidth operational amplifiers at low operating voltages. High-performance op-amps can usually be achieved by increasing the number of operational amplifier stages; however, for multi-stage operational amplifiers, if the same CMFB design as a two-stage amplifier is used, the increased number of poles in the CMFB loop makes the stability design of the CMFB loop more difficult. Summary of the Invention

[0004] This application provides an operational amplifier that can increase the stability and settling speed of a common-mode feedback circuit.

[0005] In a first aspect, an operational amplifier is provided, comprising: N stages of amplifiers connected in series and M common-mode feedback circuits, wherein N and M are integers, and N≥3, N≥M>1; wherein the i-th common-mode feedback circuit among the M common-mode feedback circuits is used to detect the common-mode output voltage of the (j+b)-th stage amplifier and adjust the electrical parameters of at least one amplifier from the j-th to the (j+b)-th stage amplifier to stabilize the common-mode output voltage of the (j+b)-th stage amplifier, and the M-th common-mode feedback circuit is used to detect and stabilize the common-mode output voltage of the N-th stage amplifier, where i, j, and b are integers, M≥i≥1, N≥j≥1, i≥j, and b≥0.

[0006] In this embodiment, the N-stage cascaded amplifier is divided into M combinations, each of which includes one or more stages of amplifier. Each of the M combinations corresponds to one or more common-mode feedback circuits. Each common-mode feedback circuit is used to adjust the degraded one or more stages of amplifier, thereby reducing the difficulty of multi-stage common-mode feedback compensation, facilitating the design of multi-stage high-gain, high-speed operational amplifiers, and increasing the stability and settling speed of the common-mode feedback circuit.

[0007] In conjunction with the first aspect, in one possible implementation of the first aspect, N > M > 1.

[0008] In this embodiment, the N-stage cascaded amplifier is divided into M combinations, each of which includes one or more stages of amplifiers. Each of the M combinations corresponds to one or more common-mode feedback circuits. Each common-mode feedback circuit is used to adjust the degraded one or more stages of amplifiers, thereby reducing the difficulty of multi-stage common-mode feedback compensation. This facilitates the design of multi-stage high-gain, high-speed operational amplifiers and increases the stability and settling speed of the common-mode feedback circuit. Furthermore, the number of common-mode feedback circuits is less than the number of stages in the cascaded amplifier, thus appropriately simplifying the circuit structure of the common-mode feedback circuit.

[0009] In conjunction with the first aspect, in one possible implementation of the first aspect, the N-stage amplifier is a three-stage amplifier, and the M common-mode feedback circuits are two common-mode feedback circuits; wherein, the first common-mode feedback circuit is used to detect the first-stage amplifier and adjust the electrical parameters of the first-stage amplifier to stabilize the common-mode output voltage of the first-stage amplifier; the second common-mode feedback circuit is used to detect the output common-mode voltage of the third-stage amplifier and adjust the electrical parameters of at least one of the second-stage and third-stage amplifiers to stabilize the common-mode output voltage of the third-stage amplifier.

[0010] In conjunction with the first aspect, in one possible implementation of the first aspect, the first common-mode feedback circuit includes a first resistor (R1) and a second resistor (R2). The first terminal of the first resistor (R1) is connected to the drain of the first transistor (M1) in the input transistor pair of the first stage amplifier, and the first terminal of the second resistor (R2) is connected to the drain of the second transistor (M2) in the input transistor pair. The second terminals of the first resistor (R1), the second terminal of the second resistor (R2), the gate of the first bias transistor (M3) of the first stage amplifier, and the gate of the second bias transistor (M4) of the first stage amplifier are connected.

[0011] In conjunction with the first aspect, in one possible implementation of the first aspect, the second common-mode feedback circuit includes an error amplifier and a common-mode detection circuit. The common-mode detection circuit is used to detect and output the third common-mode output voltage output by the third-stage amplifier. The error amplifier is used to receive the third common-mode output voltage, calculate the difference between the third common-mode output voltage and the common-mode reference voltage, and output an error amplification signal. The error amplification signal is used to adjust the electrical parameters of at least one of the second-stage amplifier and the third-stage amplifier to stabilize the third common-mode output voltage.

[0012] In conjunction with the first aspect, in one possible implementation of the first aspect, the second stage amplifier includes a pair of bias transistors (M8, M14), the output of the error amplifier being connected to the gate of the pair of bias transistors (M8, M14).

[0013] In conjunction with the first aspect, in one possible implementation of the first aspect, the N-stage amplifier is a three-stage amplifier, and the M common-mode feedback circuits are three common-mode feedback circuits, wherein the i-th common-mode feedback circuit is used to detect the common-mode output voltage of the i-th stage amplifier and adjust the electrical parameters of the i-th stage amplifier to stabilize the common-mode output voltage of the i-th stage amplifier.

[0014] In conjunction with the first aspect, in one possible implementation of the first aspect, the N-stage amplifier is a four-stage amplifier, and the M common-mode feedback circuits are two common-mode feedback circuits. The first common-mode feedback circuit is used to detect the common-mode output voltage of the second-stage amplifier and adjust the electrical parameters of at least one of the first and second-stage amplifiers to stabilize the common-mode output voltage of the second-stage amplifier. The second common-mode feedback circuit is used to detect the common-mode output voltage of the fourth-stage amplifier and adjust the electrical parameters of at least one of the third and fourth-stage amplifiers to stabilize the common-mode output voltage of the fourth-stage amplifier.

[0015] In conjunction with the first aspect, in one possible implementation of the first aspect, adjusting the electrical parameters of at least one of the amplifiers from the j-th to the (j+b)-th stage includes adjusting the voltage or current of the bias node of at least one of the amplifiers from the j-th to the (j+b)-th stage.

[0016] In conjunction with the first aspect, in one possible implementation of the first aspect, the N-stage amplifier is an N-stage differential amplifier.

[0017] In a second aspect, a chip is provided, the chip comprising the operational amplifier described in the first aspect or any possible implementation thereof.

[0018] The third aspect provides an electronic device comprising the operational amplifier described in the first aspect or any possible implementation thereof. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the application environment of an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the structure of an operational amplifier according to an embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the structure of a three-stage operational amplifier according to an embodiment of this application.

[0022] Figure 4 This is a schematic diagram of the structure of a three-stage operational amplifier according to an embodiment of this application.

[0023] Figure 5 This is a schematic diagram of the circuit structure of a three-stage operational amplifier according to an embodiment of this application. Detailed Implementation

[0024] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the application environment of an embodiment of this application. Figure 1 The diagram illustrates a link cascading configuration in a radio frequency (RF) system. This RF system is a receiver system, including a low-noise amplifier (LNA), a mixer, a trans-impedance amplifier (TIA), a low-pass filter (LPF), and an analog-to-digital converter (ADC). In this embodiment, the operational amplifier can be configured in… Figure 1 In the TIA, LPF, VGA, ADC and other modules. It should be noted that... Figure 1 The operational amplifiers described in this application are merely examples illustrating their application environments. Operational amplifiers can be widely used in various analog or digital-to-analog integrated circuits, such as filter circuits, amplifier circuits, operational circuits, signal generation circuits, signal conversion circuits, or power supplies.

[0026] This application proposes a common-mode feedback circuit design that can be applied to multi-stage operational amplifier circuits and is beneficial for realizing high-bandwidth, high-gain operational amplifiers under low operating voltage.

[0027] Figure 2This is a schematic diagram of the structure of an operational amplifier according to an embodiment of this application. Figure 2 As shown, the operational amplifier includes N stages of amplifiers connected in series and M common-mode feedback (CMFB) circuits, where N and M are integers, and N≥3, N≥M>1.

[0028] Among them, the i-th common-mode feedback circuit in the M common-mode feedback circuits is used to detect the common-mode output voltage of the j+b-th stage amplifier and adjust the electrical parameters of at least one amplifier from the j-th to the j+b-th stage amplifiers to stabilize the common-mode output voltage of the j+b-th stage amplifier, and the M-th common-mode feedback circuit is used to detect and stabilize the common-mode output voltage of the N-th stage amplifier, where i, j, and b are integers, M≥i≥1, N≥j≥1, i≥j, and b≥0.

[0029] This can be understood as follows: the aforementioned N-stage cascaded amplifiers are broken down into M combinations, each combination comprising one or more stages of cascaded amplifiers, and each combination corresponding to a common-mode feedback circuit. For example, the i-th combination may include amplifiers from stage j to stage j+b. The i-th common-mode feedback circuit detects the common-mode output voltage of the stage j+b amplifiers and stabilizes the common-mode output voltage of the stage j+b amplifiers by adjusting the electrical parameters of the amplifiers within the i-th combination. Specifically, the i-th common-mode feedback circuit can adjust the electrical parameters of all amplifiers within the i-th combination, or it can adjust the electrical parameters of only some amplifiers within the i-th combination, to stabilize the common-mode output voltage of the stage j+b amplifiers.

[0030] In some examples, adjusting the electrical parameters of at least one of the amplifiers from the j-th to the (j+b)-th stage includes adjusting the voltage or current of the bias node of at least one of the amplifiers from the j-th to the (j+b)-th stage.

[0031] Optionally, the Mth combination may include only the Nth stage amplifier, or the Mth combination may include the Nth stage amplifier and other amplifiers besides the Nth stage amplifier.

[0032] In this embodiment, the N-stage cascaded amplifier is divided into M combinations, each of which includes one or more stages of amplifier. Each of the M combinations corresponds to one or more common-mode feedback circuits. Each common-mode feedback circuit is used to adjust the degraded one or more stages of amplifier, thereby reducing the difficulty of multi-stage common-mode feedback compensation, facilitating the design of multi-stage high-gain, high-speed operational amplifiers, and increasing the stability and settling speed of the common-mode feedback circuit.

[0033] Optionally, the common-mode feedback circuits among the aforementioned M common-mode feedback circuits may include self-common-mode feedback circuits or common-mode feedback loops. A self-common-mode feedback circuit refers to a circuit that does not require common-mode voltage regulation through an external loop. A common-mode feedback loop refers to a circuit that regulates common-mode voltage through an external loop. For example, if the common-mode feedback circuit is used to regulate the common-mode output voltage of a single-stage amplifier, a self-common-mode feedback circuit or a common-mode feedback loop can be used; if the common-mode feedback circuit is used to regulate the common-mode output voltage of two or more stages of amplifiers, a common-mode feedback loop can be used.

[0034] In some examples, N = M, then i = j, and b = 0. In other words, the i-th common-mode feedback circuit is used to detect the common-mode output voltage of the i-th stage amplifier and adjust the electrical parameters of the i-th stage amplifier to stabilize its common-mode output voltage. Alternatively, each stage of the N-stage amplifier corresponds to a common-mode feedback circuit used to stabilize the common-mode output voltage of the corresponding amplifier.

[0035] For example, Figure 3 This is a schematic diagram of the structure of a three-stage operational amplifier according to an embodiment of this application. Figure 3 As shown, the three-stage operational amplifier can be divided into three single-stage amplifiers, each corresponding to a common-mode feedback circuit. Each common-mode feedback circuit is used to detect the common-mode output voltage of the corresponding single-stage amplifier and adjust the electrical parameters of the corresponding single-stage amplifier to stabilize the common-mode output voltage of that single-stage amplifier. Optionally, each common-mode feedback circuit can be a self-common-mode feedback circuit or a common-mode feedback loop.

[0036] In some examples, N > M > 1, meaning the number of common-mode feedback circuits is greater than 1 but less than the number of operational amplifier stages N. Therefore, the number of common-mode feedback circuits is less than the number of stages in a series amplifier, appropriately simplifying the circuit structure of the common-mode feedback circuit. In this case, the N-stage amplifier is split into at least two combinations, each corresponding to one common-mode feedback circuit. At least one combination includes two or more stages of amplifiers.

[0037] For example, Figure 4 This is a schematic diagram of the structure of a three-stage operational amplifier according to an embodiment of this application. Figure 4As shown, the three-stage operational amplifier can be broken down into a single-stage amplifier and a two-stage amplifier. The three-stage operational amplifier includes two common-mode feedback circuits. The first common-mode feedback circuit detects the first-stage amplifier and adjusts its electrical parameters to stabilize its common-mode output voltage. The second common-mode feedback circuit detects the common-mode output voltage of the third-stage amplifier and adjusts the electrical parameters of at least one of the second and third-stage amplifiers to stabilize its common-mode output voltage.

[0038] As an example, the first common-mode feedback circuit can be a self-common-mode feedback circuit, and the second common-mode feedback circuit can be a common-mode feedback loop. This common-mode feedback loop includes a second-stage amplifier, a third-stage amplifier, a common-mode detection circuit, and an error amplifier. The common-mode detection circuit is used to detect the differential-mode output voltage V of the third-stage amplifier. outp and V outn And output the common-mode output voltage V of the third-stage amplifier. CM The error amplifier is used to receive the common-mode output voltage V. CM and the common-mode output voltage V CM With common-mode reference voltage V CMREF The difference is calculated, and an error amplification signal is output. This error amplification signal is used to adjust the electrical parameters of at least one of the second-stage amplifier and the third-stage amplifier to stabilize the third common-mode output voltage. In this embodiment, for ease of distinction, the common-mode output voltages output by the first-stage amplifier, the second-stage amplifier, and the third-stage amplifier can be referred to as the first common-mode output voltage, the second common-mode output voltage, and the third common-mode output voltage, respectively. The third common-mode output voltage can be considered as the common-mode output voltage of the operational amplifier.

[0039] In some examples, the N-stage amplifier is an N-stage differential amplifier.

[0040] In some examples, the N-stage amplifier is a four-stage amplifier, and the M common-mode feedback circuits are two common-mode feedback circuits. The first common-mode feedback circuit is used to detect the common-mode output voltage of the second-stage amplifier and adjust the electrical parameters of at least one of the first-stage and second-stage amplifiers to stabilize the common-mode output voltage of the second-stage amplifier. The second common-mode feedback circuit is used to detect the common-mode output voltage of the fourth-stage amplifier and adjust the electrical parameters of at least one of the third-stage and fourth-stage amplifiers to stabilize the common-mode output voltage of the fourth-stage amplifier.

[0041] It should be understood that Figure 3 and Figure 4The operational amplifier described above is merely an example. In the embodiments of this application, the N-stage amplifier can also be other types of multi-stage amplifiers. The way the multi-stage amplifier is split and the type of each common-mode feedback circuit can be reasonably modified and combined based on the above description, and all of them fall within the protection scope of this application.

[0042] Optionally, the operational amplifier in this embodiment can be manufactured using complementary metal-oxide-semiconductor (CMOS) technology, or other integrated circuit technologies, such as bipolar junction transistor (BJT) technology or silicon-on-insulator (SOI) technology.

[0043] Figure 5 This is a circuit diagram of an operational amplifier according to an embodiment of this application. Figure 5 As shown, this operational amplifier is a three-stage amplifier. The three-stage amplifier is divided into two groups. The first group includes a first-stage amplifier, i.e., a single-stage amplifier. The second group includes a second-stage and a third-stage amplifier, i.e., a two-stage amplifier. The single-stage amplifier corresponds to the first common-mode feedback circuit, and the two-stage amplifier corresponds to the second common-mode amplification circuit.

[0044] The first-stage amplifier includes transistors M1, M2, M3, M4, and M17. Transistors M1 and M2 are the input transistor pair of the first-stage amplifier, transistors M3 and M4 are the bias transistors of the first-stage amplifier, and transistor M17 is the tail bias transistor of the first-stage amplifier. The input terminal of the first-stage amplifier is the gate of the input transistor pair M1 and M2, and the output terminal is the drain of the input transistor pair M1 and M2. For ease of description, the input transistor pair M1 and M2 can also be referred to as the first transistor M1 and the second transistor M2, respectively. Transistors M3 and M4 can also be referred to as the first bias transistor M3 and the second bias transistor M4, respectively.

[0045] The second-stage amplifier includes transistors M5, M6, M7, M8, M11, M12, M13, and M14. Transistors M6 and M12 are the input transistor pair, while transistors M8 and M14 are the bias transistors. Transistors M7 and M13 are the amplifying transistors. The input terminals of the second-stage amplifier are the gates of transistors M6 and M12, and the output terminals are the drains of transistors M7 and M13.

[0046] The third-stage amplifier includes transistors M9, M10, M15, and M16. Transistors M9 and M15 are the input transistors of the third-stage amplifier, while transistors M10 and M16 are the bias transistors. The input terminals of the third-stage amplifier are the gates of transistors M9 and M15, and the output terminals are the drains of transistors M9 and M15.

[0047] like Figure 5 As shown, the first common-mode feedback circuit includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is connected to the drain of the first transistor M1 in the input transistor pair of the first stage amplifier, and the first end of the second resistor R2 is connected to the drain of the second transistor M2 in the input transistor pair. The second ends of the first resistor R1, the second end of the second resistor R2, the gate of the first bias transistor M3 of the first stage amplifier, and the gate of the second bias transistor M4 of the first stage amplifier are connected together.

[0048] In this circuit, the first resistor R1 and the second resistor R2 are used to detect and stabilize the common-mode output voltage of the first-stage amplifier. The first common-mode feedback circuit uses local resistors to detect and feedback the common-mode output voltage of the first-stage amplifier, which has a simple structure and good stability.

[0049] Optionally, the second common-mode feedback circuit may include a common-mode detection circuit, which is used to detect and output the first common-mode output voltage V from the third-stage amplifier. CM .

[0050] The common-mode detection circuit includes: a first input terminal for receiving the first differential output voltage V from the third-stage amplifier. outp The second input terminal is used to receive the second differential output voltage V from the third stage amplifier. outn The output terminal is used to output the common-mode output voltage V. CM The common-mode output voltage V CM The first differential output voltage V outp Second differential output voltage V outn The average value, i.e., V CM =(V outp +V outn ) / 2.

[0051] like Figure 5 As shown, as an example, the common-mode detection circuit includes a third resistor R3 and a fourth resistor R4, wherein the first terminal of the third resistor R3 is connected to the first differential output terminal V of the third-stage amplifier. outp The second terminal of the third resistor R3 is connected to the first terminal of the fourth resistor R4, and the second terminal of the fourth resistor R4 is connected to the second differential output terminal V of the third stage amplifier.outn The second end of the third resistor R3 and the first end of the fourth resistor R4 are connected, and are the output terminals of the common-mode detection circuit.

[0052] Optionally, the operational amplifier further includes a common-mode loop compensation circuit, which is used for frequency compensation of the common-mode loop. For example... Figure 5 As shown, as an example, the common-mode loop compensation circuit includes a third capacitor C3 and a fourth capacitor C4. The first terminal of the third capacitor C3 is connected to the first differential output terminal V of the third-stage amplifier. outp The second terminal of the third capacitor C3 is connected to the first terminal of the fourth capacitor C4, and the second terminal of the fourth capacitor C4 is connected to the second differential output terminal V of the third stage amplifier. outn The second terminal of the third capacitor C3 is connected to the output terminal of the common-mode detection circuit, that is, the second terminal of the third capacitor C3 is connected to the second terminal of the third resistor R3.

[0053] Furthermore, the operational amplifier also includes an error amplifier circuit, which is used to compare the common-mode output voltage V. CM and common-mode reference voltage V CMREF And based on the comparison result, adjust the bias circuit of the operational amplifier so that the common-mode output voltage V CM With common-mode reference voltage V CMREF Equal. For example... Figure 5 As shown, the error amplifier circuit includes an error amplifier, which is used to receive the common-mode output voltage V from the third-stage amplifier. CM and the common-mode output voltage V CM With the first reference voltage V CMREF The difference is calculated, and an error amplification signal is output. The error amplification signal is used to adjust the electrical parameters of at least one of the second-stage amplifier and the third-stage amplifier to stabilize the first common-mode output voltage.

[0054] The first input terminal of the error amplifier is used to receive the common-mode reference voltage V of the operational amplifier. CMREF The second input terminal of the error amplifier is used to receive the common-mode output voltage V of the operational amplifier. CM That is, it is connected to the second terminal of the third resistor R3. Optionally, the output terminal of the error amplifier is connected to the bias circuit of the second-stage amplifier or the third-stage amplifier to facilitate adjustment of the bias circuit of the second-stage amplifier or the third-stage amplifier. As an example, Figure 5 The output of the error amplifier in the second stage is connected to the gates of the bias transistors M8 and M14 of the second stage amplifier.

[0055] It should be understood that for a 3-stage fully differential amplifier, if a single common-mode feedback circuit is used, the common-mode feedback loop can have up to 4 stages. To reduce the complexity of common-mode stability design, this application embodiment reduces the number of common-mode feedback loop stages by splitting the common-mode feedback loop. In this application embodiment, to simplify common-mode feedback, the three-stage operational amplifier can be split into a single-stage amplifier and a two-stage amplifier. The first-stage amplifier can use internal common-mode bias for common-mode feedback. The second and third-stage amplifiers use a common-mode feedback loop for stability compensation. The common-mode feedback loop consists of the second-stage amplifier, the third-stage amplifier, a common-mode detection circuit, and an error amplifier, thereby simplifying the common-mode stability design of multi-stage operational amplifiers.

[0056] It should be understood that Figure 5 This is merely an example of a specific circuit structure of an operational amplifier in an embodiment of this application and is not intended to be limiting. For example, Figure 5 The common-mode detection circuit, common-mode loop compensation circuit, or error amplification circuit in the embodiment can also be implemented in other ways, and this application does not limit them.

[0057] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0058] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0059] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0060] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0061] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0062] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An operational amplifier, characterized in that, include: An N-stage series amplifier and M common-mode feedback circuits, where N and M are integers, and N≥3, N≥M>1; The N-stage series amplifiers are M combinations, and each of the M combinations corresponds to one of the M common-mode feedback circuits. At least one of the M combinations includes two or more amplifier stages. Wherein, the i-th combination of the M combinations includes amplifiers from the j-th stage to the (j+b-th)-th stage. The i-th common-mode feedback circuit of the M common-mode feedback circuits is used to detect the common-mode output voltage of the (j+b-th)-th stage amplifier and adjust the electrical parameters of all amplifiers from the j-th stage to the (j+b-th)-th stage amplifier to stabilize the common-mode output voltage of the (j+b-th)-th stage amplifier. The M-th common-mode feedback circuit is used to detect and stabilize the common-mode output voltage of the N-th stage amplifier. i, j, b are integers, M≥i≥1, N≥j≥1, i≥j, b≥0.

2. The operational amplifier as described in claim 1, characterized in that, N > M > 1.

3. The operational amplifier as described in claim 1 or 2, characterized in that, The N-stage amplifier is a three-stage amplifier, and the M common-mode feedback circuits are two common-mode feedback circuits; wherein... The first common-mode feedback circuit is used to detect the first-stage amplifier and adjust the electrical parameters of the first-stage amplifier to stabilize the common-mode output voltage of the first-stage amplifier. The second common-mode feedback circuit is used to detect the output common-mode voltage of the third-stage amplifier and adjust the electrical parameters of at least one of the second-stage and third-stage amplifiers to stabilize the common-mode output voltage of the third-stage amplifier.

4. The operational amplifier as described in claim 3, characterized in that, The first common-mode feedback circuit includes a first resistor (R1) and a second resistor (R2). The first end of the first resistor (R1) is connected to the drain of the first transistor (M1) in the input transistor pair of the first stage amplifier. The first end of the second resistor (R2) is connected to the drain of the second transistor (M2) in the input transistor pair. The second ends of the first resistor (R1), the second ends of the second resistor (R2), the gate of the first bias transistor (M3) of the first stage amplifier, and the gate of the second bias transistor (M4) of the first stage amplifier are connected.

5. The operational amplifier as described in claim 3, characterized in that, The second common-mode feedback circuit includes an error amplifier and a common-mode detection circuit. The common-mode detection circuit is used to detect and output the third common-mode output voltage of the third-stage amplifier; The error amplifier is used to receive the third common-mode output voltage, and to calculate the difference between the third common-mode output voltage and the common-mode reference voltage to output an error amplification signal. The error amplification signal is used to adjust the electrical parameters of at least one of the second-stage amplifier and the third-stage amplifier to stabilize the third common-mode output voltage.

6. The operational amplifier as described in claim 5, characterized in that, The second-stage amplifier includes a pair of bias transistors (M8, M14), and the output of the error amplifier is connected to the gate of the pair of bias transistors (M8, M14).

7. The operational amplifier as claimed in claim 1, characterized in that, The N-stage amplifier is a four-stage amplifier, and the M common-mode feedback circuits are two common-mode feedback circuits. The first common-mode feedback circuit is used to detect the common-mode output voltage of the second-stage amplifier and adjust the electrical parameters of at least one of the first-stage and second-stage amplifiers to stabilize the common-mode output voltage of the second-stage amplifier. The second common-mode feedback circuit is used to detect the common-mode output voltage of the fourth-stage amplifier and adjust the electrical parameters of at least one of the third-stage and fourth-stage amplifiers to stabilize the common-mode output voltage of the fourth-stage amplifier.

8. The operational amplifier as described in claim 1 or 2, characterized in that, Adjusting the electrical parameters of at least one of the amplifiers from the j-th to the (j+b)-th stage includes adjusting the voltage or current of the bias node of at least one of the amplifiers from the j-th to the (j+b)-th stage.

9. The operational amplifier as described in claim 1 or 2, characterized in that, The N-stage amplifier is an N-stage differential amplifier.

10. A chip, characterized in that, The chip includes an operational amplifier as described in any one of claims 1 to 9.

11. An electronic device, characterized in that, The electronic device includes an operational amplifier as claimed in any one of claims 1 to 9.

Images