Ring amplifier and analog-to-digital converter

Abstract

The invention discloses a ring amplifier and an analog-to-digital converter. The ring amplifier comprises a first input stage module, a first intermediate stage module and a first output stage module; the input end of the first input stage module is connected with a first input signal, and the first input stage module is used for performing first-stage gain on the first input signal to form a first-stage amplification signal; the first intermediate stage module is used for performing second-stage gain amplification on the first-stage amplification signal and adjusting the voltage difference between the input end and the power supply end of the first output stage module to be within a first preset range according to the first-stage amplification signal; the output end of the first output stage module serves as the output end of the ring amplifier, and the first output stage module is used for conducting third-stage gain amplification on the first-stage amplification signal. The power consumption of the ring amplifier can be remarkably reduced, and larger bandwidth and higher gain can be provided.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of integrated circuits, and in particular to a ring amplifier and an analog-to-digital converter. Background Art

[0002] In the field of analog integrated circuit design, the analog-to-digital converter (ADC) serves as a bridge between the analog world and the digital world, and its performance directly affects the accuracy, speed, and energy efficiency of the entire system.

[0003] As two mainstream ADC architectures, Successive Approximation Register Analog to Digital Converter (SAR ADC) and Pipeline Analog to Digital Converter (Pipeline ADC) each have their own unique advantages, such as the low power consumption and small area of ​​SAR ADC and the high speed and high precision of Pipeline ADC. However, in order to further improve the overall performance of ADC, hybrid ADC design has gradually become a research hotspot, aiming to combine the strengths of both to achieve more efficient analog-to-digital conversion.

[0004] In the design of hybrid ADC, the operational amplifier (Operational Amplifier, Op-Amp for short) is a core component, and its performance directly determines the overall performance of the ADC, including key indicators such as gain, bandwidth, power consumption, and linearity. However, under advanced processes, traditional operational amplifier design faces many challenges. First, due to the continuous reduction of power supply voltage, traditional operational amplifiers are difficult to maintain high gain and wide bandwidth at lower power supply voltages, which limits their performance in low-power applications. Second, traditional operational amplifiers tend to have high power consumption and are difficult to meet the strict energy efficiency requirements of modern electronic systems. Summary of the invention

[0005] The present invention provides a ring amplifier and an analog-to-digital converter, so as to significantly reduce the power consumption of the ring amplifier and provide a larger bandwidth and a higher gain.

[0006] In a first aspect, an embodiment of the present invention provides a ring amplifier, the ring amplifier comprising a first input stage module, a first intermediate stage module and a first output stage module;

[0007] The input end of the first input stage module is connected to the first input signal, the output end of the first input stage module is connected to the input end of the first intermediate stage module, and the first input stage module is used to perform a first-stage gain amplification on the first input signal to form a first-stage amplified signal;

[0008] The output end of the first intermediate stage module is connected to the input end of the first output stage module, the power supply end of the first output stage module is connected to a fixed potential, and the first intermediate stage module is used to perform a second-stage gain amplification on the first-stage amplified signal, and adjust the voltage difference between the input end and the power supply end of the first output stage module within a first preset range according to the first-stage amplified signal;

[0009] The output end of the first output stage module serves as the output end of the ring amplifier, and the first output stage module is used to perform a third-stage gain amplification on the first-stage amplified signal.

[0010] In a second aspect, an embodiment of the present invention further provides an analog-to-digital converter, which includes the ring amplifier described in any one of the embodiments of the present invention.

[0011] The present invention provides a ring amplifier and an analog-to-digital converter. The ring amplifier includes a first input stage module, a first intermediate stage module and a first output stage module. The first input stage module performs a first stage gain amplification on a first input signal to form a first stage amplified signal. The first intermediate stage module performs a second stage gain amplification on the first stage amplified signal, and adjusts the voltage difference between the input end and the power supply end of the first output stage module within a first preset range according to the first stage amplified signal, so that the transistor in the first output stage module is in a subthreshold state. The first output stage module in the subthreshold state performs a third stage gain amplification on the first stage amplified signal, thereby reducing the power consumption of the first output stage module. The transistor in the subthreshold state in the first output stage module has the characteristics of large bandwidth and high gain, so that the ring amplifier in the present invention can still have high gain and bandwidth at low voltage, can meet the application requirements of high-performance analog-to-digital converters, and has significant advantages over traditional operational amplifiers. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic structural diagram of a ring amplifier provided in an embodiment of the present invention.

[0013] Figure 2 A schematic diagram of the structure of another ring amplifier provided in an embodiment of the present invention.

[0014] Figure 3 A schematic structural diagram of an analog-to-digital converter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0016] Figure 1 A schematic diagram of the structure of a ring amplifier provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the ring amplifier includes a first input stage module 110, a first intermediate stage module 120 and a first output stage module 130; the input end of the first input stage module 110 is connected to the first input signal VIP, the output end of the first input stage module 110 is connected to the input end of the first intermediate stage module 120, and the first input stage module 110 is used to perform a first-stage gain amplification on the first input signal VIP to form a first-stage amplified signal; the output end of the first intermediate stage module 120 is connected to the input end of the first output stage module 130, the power supply end of the first output stage module 130 is connected to a fixed potential, the first intermediate stage module 120 is used to perform a second-stage gain amplification on the first-stage amplified signal, and adjust the voltage difference between the input end and the power supply end of the first output stage module 130 within a first preset range according to the first-stage amplified signal; the output end of the first output stage module 130 serves as the output end of the ring amplifier, and the first output stage module 130 is used to perform a third-stage gain amplification on the first-stage amplified signal.

[0017] The ring amplifier in the embodiment of the present invention is composed of a first input stage module 110, a first intermediate stage module 120 and a first output stage module 130. Each stage is usually composed of one or more amplifier devices, such as transistors. Each stage amplifies the first input signal VIP, so that the ring amplifier provides a higher total gain.

[0018] Specifically, the first input signal VIP first enters the first input stage module 110, and is subjected to the first stage gain amplification by the first input stage module 110. After the first input signal VIP is preliminarily amplified, a first stage amplified signal is formed and transmitted to the first intermediate stage module 120. The first intermediate stage module 120 performs the second stage gain amplification on the first stage amplified signal, and outputs the amplified first stage amplified signal to the first output stage module 130. In order to improve the gain of the first output stage module 130, an additional circuit element (such as a resistor) is set in the first intermediate stage module 120, so that the voltage difference between the input end and the power supply end of the first output stage module 130 is adjusted within a first preset range according to the first stage amplified signal after gain. The first preset range is the voltage range in which the transistors in the first output stage module 130 are in a subthreshold state, so that the transistors in the first output stage module 130 are in a subthreshold state, and the transistors in the subthreshold state can provide a large gain and have low power consumption, so that the first output stage module 130 as a whole is also in a subthreshold state, and at the same time, it serves as a ring amplifier. The main pole makes the loop stable, and the first output stage module 130 can provide a higher gain and bandwidth, and perform a third-stage gain amplification on the first-stage amplified signal. Since the first output stage module 130 is also in a subthreshold state, the first output stage module 130 can provide a higher third-stage gain amplification and a larger bandwidth under low voltage conditions, so that the first-stage amplified signal is further amplified to form a first output signal OUTP, that is, the first input signal VIP is amplified by the first stage gain, the second stage gain, and the third stage gain to form the first output signal OUTP, and the first output signal OUTP is output from the output end of the first output stage module 130. Since the transistors in the subthreshold state in the first output stage module 130 have the characteristics of large bandwidth and high gain, the first output stage module 130 performs a third-stage gain amplification on the first-stage amplified signal in the subthreshold state, so that the ring amplifier in the present invention can still have a higher gain and bandwidth at low voltage, and has the characteristics of high stability, which can meet the application requirements of high-performance analog-to-digital converters and has significant advantages over traditional operational amplifiers.

[0019] The embodiment of the present invention provides a ring amplifier, including a first input stage module, a first intermediate stage module and a first output stage module; the first input stage module performs a first stage gain amplification on the connected first input signal to form a first stage amplified signal; the first intermediate stage module performs a second stage gain amplification on the first stage amplified signal, and adjusts the voltage difference between the input end and the power supply end of the first output stage module within a first preset range according to the first stage amplified signal, so that the transistor in the first output stage module is in a subthreshold state, and the first output stage module in the subthreshold state performs a third stage gain amplification on the first stage amplified signal, thereby reducing the power consumption of the first output stage module, and the transistor in the subthreshold state in the first output stage module has the characteristics of large bandwidth and high gain, so that the ring amplifier in the present invention can still have a high gain and bandwidth at a low voltage, can meet the application requirements of a high-performance analog-to-digital converter, and has significant advantages over traditional operational amplifiers.

[0020] Figure 2 A schematic diagram of the structure of another ring amplifier provided by an embodiment of the present invention is shown in FIG. Figure 2 As shown, the ring amplifier also includes a second input stage module 210, a second intermediate stage module 220 and a second output stage module 230; the input end of the second input stage module 210 is connected to the second input signal VIN, the output end of the second input stage module 210 is connected to the input end of the second intermediate stage module 220, the first voltage input end of the second input stage module 210 is connected to the first voltage input end of the first input stage module 110, and the second voltage input end of the second input stage module 210 is connected to the second voltage input end of the first input stage module 110; the second input stage module 210 is used to perform a first-stage gain amplification for the second input signal VIN to form a second-stage amplified signal.

[0021] The output end of the second intermediate stage module 220 is connected to the input end of the second output stage module 120, and the power supply end of the second output stage module 230 is connected to the fixed potential. The second intermediate stage module 220 is used to perform a second-stage gain amplification for the second-stage amplified signal, and adjust the voltage difference between the input end and the power supply end of the second output stage module 230 within a second preset range according to the second-stage amplified signal; the second output stage module 230 is used to provide a third-stage gain amplification for the second-stage amplified signal, and output the gained second input signal from the output end of the second output stage module 230.

[0022] Among them, the second input stage module 210 has the same structure as the first input stage module 110, the second intermediate stage module 220 has the same structure as the first intermediate stage module 120, and the second output stage module 230 has the same structure as the first output stage module 130; the second input signal VIN and the first input signal VIP are two completely symmetrical differential input signals.

[0023] Specifically, the second input stage module 210, the second intermediate stage module 220 and the second output stage module 230 constitute a second gain branch, the first input stage module 110, the first intermediate stage module 120 and the first output stage module 130 constitute a first gain branch, the first gain branch and the second gain branch are two branches with completely identical and symmetrical circuit structures in the ring amplifier, that is, the second input stage module 210 has the same structure as the first input stage module 110, the second intermediate stage module 220 has the same structure as the first intermediate stage module 120, the second output stage module 230 has the same structure as the first output stage module 130, and the first gain branch and the second gain branch are connected to each other through the first voltage input terminal and the second voltage input terminal of the first input stage module 110 and the second input stage module 210. The second input signal VIN and the first input signal VIP are equal in magnitude and opposite in phase. The three-stage structure in the second gain branch has the same role and function as the three-stage structure in the first gain branch, and the second input stage module 210 in the second gain branch can perform a first-stage gain amplification on the second input signal VIN to form a second-stage amplified signal. The second intermediate stage module 220 performs a second stage gain amplification for the second stage amplified signal, and adjusts the voltage difference between the input end and the power supply end of the second output stage module 230 within a second preset range according to the second stage amplified signal. The second preset range is the voltage range in which the transistors in the second output stage module 230 are in a subthreshold state, so that the transistors in the second output stage module 230 are in a subthreshold state. The transistor in the subthreshold state can provide a large gain and low power consumption, so that the second output stage module 230 is also in the subthreshold state as a whole. At the same time, the second output stage module 230 serves as the main pole of the ring amplifier to stabilize the loop. The second output stage module 230 can provide a higher gain and bandwidth, and perform a third-stage gain amplification on the second-stage amplified signal. Since the second output stage module 230 is also in the subthreshold state, the second output stage module 230 can provide a higher third-stage gain amplification and a larger bandwidth under low voltage conditions, so that the second-stage amplified signal is further amplified to form a second output signal OUTN, that is, the second input signal VIN is amplified by the first stage gain, the second stage gain and the third stage gain to form the second output signal OUTN, and the second output signal OUTN is output from the output end of the second output stage module 230. Since the transistor in the subthreshold state in the second output stage module 230 has the characteristics of large bandwidth and high gain, the ring amplifier in the present invention can still have a higher gain and bandwidth at low voltage, and has the characteristics of high stability, which can meet the application requirements of high-performance analog-to-digital converters and has significant advantages over traditional operational amplifiers.

[0024] Optionally, the second preset range is also the same as the first preset range. Under the premise that the second output stage module 230 and the first output stage module 130 have the same structure, the voltage range of the transistors in the second output stage module 230 and the first output stage module 130 in the subthreshold state is the same, so the second preset range is also the same as the first preset range.

[0025] In addition, since the second input signal VIN and the first input signal VIP are two completely symmetrical differential input signals, the first gain branch and the second gain branch respectively perform three-stage amplification gain on the second input signal VIN and the first input signal VIP, so that the ring amplifier of the embodiment of the present invention can be applied to the successive approximation-pipeline hybrid ADC. When performing residual amplification in the successive approximation-pipeline hybrid ADC, the first gain branch and the second gain branch in the ring amplifier of the embodiment of the present invention can be used to achieve a higher amplification gain for the differential input signal, thereby improving the gain of the residual amplifier in the successive approximation-pipeline hybrid ADC and reducing the power consumption in the successive approximation-pipeline hybrid ADC.

[0026] For further information, please refer to Figure 2 The first input stage module 110 includes a first transistor M1 and a second transistor M2; the gate of the first transistor M1 is connected to the gate of the second transistor M2, and the connection line between the gate of the first transistor M1 and the gate of the second transistor M2 is connected to the first input signal VIP; the drain of the first transistor M1 is connected to the drain of the second transistor M2, and the connection line between the drain of the first transistor M1 and the drain of the second transistor M2 is connected to the input end of the first intermediate stage module 120; the source of the first transistor M1 serves as the first voltage input end of the first input stage module 110, and the source of the second transistor M2 serves as the second voltage input end of the first input stage module 110.

[0027] Among them, the first transistor M1 and the second transistor M2 are the input pair of transistors of the first gain branch of the ring amplifier. The gate length of the first transistor M1 and the second transistor M2 is relatively short, and the gate width is relatively large, so that the first transistor M1 and the second transistor M2 perform preliminary amplification gain on the first input signal VIP, and the gain size is the first stage gain amplification.

[0028] It should be noted that if Figure 2As shown, the second input stage module 210 also includes two transistors, namely transistor M7 and transistor M8, the connection line of the gate of transistor M7 and transistor M8 is connected to the second input signal VIN, the source of the first transistor M1 is connected to the source of transistor M7, and the source of the second transistor M2 is connected to the source of transistor M8, so as to realize the connection between the second input stage module 210 and the first input stage module 110. The specifications of transistor M7 and the first transistor M1 are the same, and the specifications of transistor M8 and the second transistor M2 are the same, so that the second input stage module 210 achieves the same gain effect as the first input stage module 110, that is, the second input stage module 210 and the first input stage module 110 are both provided to the first stage gain amplification to the input signal connected to each module. In addition, the first transistor M1 and the second transistor M2 are used as the first stage of the ring amplifier, which can improve the bandwidth of the circuit.

[0029] For further information, please refer to Figure 2 The ring amplifier also includes a first common-mode feedback transistor N1 and a second common-mode feedback transistor N2; the gate of the first common-mode feedback transistor N1 and the gate of the second common-mode feedback transistor N2 are both connected to the common-mode feedback voltage bias signal VCMFB; the drain of the first common-mode feedback transistor N1 is connected to the source of the first transistor M1, the drain of the second common-mode feedback transistor N2 is connected to the source of the second transistor M2, the source of the first common-mode feedback transistor N1 is connected to the output end of the first power supply VDD1, and the source of the second common-mode feedback transistor N2 is grounded.

[0030] The first common-mode feedback transistor N1 and the second common-mode feedback transistor N2 are two different types of transistors. Optionally, the first common-mode feedback transistor is a PMOS transistor and the second common-mode feedback transistor is an NMOS transistor. The common-mode feedback voltage bias signal VCMFB is connected to the gate of the first common-mode feedback transistor N1 and the gate of the second common-mode feedback transistor N2. Through the synergistic effect of the two types of transistors, the effect of the common-mode feedback can be ensured to be normal.

[0031] Specifically, the gate of the first common-mode feedback transistor N1 is connected to the gate of the second common-mode feedback transistor N2, and the connection line between the gate of the first common-mode feedback transistor N1 and the gate of the second common-mode feedback transistor N2 is connected to the common-mode feedback voltage bias signal VCMFB. The drain of the first common-mode feedback transistor N1 is connected to the source of the first transistor M1 and the source of the transistor M7, and the drain of the second common-mode feedback transistor N2 is connected to the source of the second transistor M2 and the source of the transistor M8. The common-mode feedback voltage bias signal VCMFB is provided by the common-mode feedback circuit connected to the ring amplifier. Through the three-dimensional synergy of the first common-mode feedback transistor N1 and the second common-mode feedback transistor N2, the effect of the common-mode feedback in the ring amplifier can be ensured to be normal. Optionally, the gate lengths of the first common-mode feedback transistor N1 and the second common-mode feedback transistor N2 can be set to be relatively small, and the width-to-length ratio of the first common-mode feedback transistor N1 and the second common-mode feedback transistor N2 can be set to be much larger than the width-to-length ratio of the third transistor M3 and the fourth transistor M4, thereby ensuring that the main pole of the circuit is at the output stage rather than the input stage, thereby improving the amplification factor and bandwidth of the ring amplifier.

[0032] Optional, continue to refer to Figure 2 The width-to-length ratio of the first common-mode feedback transistor N1 is greater than the width-to-length ratio of the first transistor M1 and the width-to-length ratio of the second transistor M2, and the width-to-length ratio of the second common-mode feedback transistor N2 is greater than the width-to-length ratio of the first transistor M1 and the width-to-length ratio of the second transistor M2.

[0033] Specifically, by setting the width-to-length ratio of the first common-mode feedback transistor N1 to be greater than the width-to-length ratio of the first transistor M1 and the width-to-length ratio of the second transistor M2, and the width-to-length ratio of the second common-mode feedback transistor N2 to be greater than the width-to-length ratio of the first transistor M1 and the width-to-length ratio of the second transistor M2, it is ensured that the main pole of the circuit is at the output stage rather than the input stage, thereby improving the amplification factor and bandwidth of the ring amplifier. Compared with the traditional ring amplifier architecture, the ring amplifier proposed in the embodiment of the present invention does not require additional switches and has a better common-mode rejection ratio.

[0034] It should be noted that the width-to-length ratio of the first common-mode feedback transistor N1 is greater than the width-to-length ratio of the transistor M7 and the width-to-length ratio of the transistor M8, and the width-to-length ratio of the second common-mode feedback transistor N2 is greater than the width-to-length ratio of the transistor M7 and the width-to-length ratio of the transistor M8, ensuring that the main pole of the circuit is at the output stage (including the second output stage module 230 and the first output stage module 130) rather than the input stage (including the second input stage module 210 and the first input stage module 110), thereby improving the amplification factor and bandwidth of the ring amplifier.

[0035] Furthermore, in order to avoid the loop instability problem that may occur in the ring amplifier, the first intermediate stage module 120 usually uses additional circuit elements (such as resistors) to introduce negative feedback or form a main pole, so that the entire ring amplifier circuit tends to a stable state, avoiding the loop instability problem that may occur in the ring amplifier. Figure 2 The first intermediate stage module 120 includes a third transistor M3, a fourth transistor M4 and a resistor R1; the gate of the third transistor M3 and the fourth transistor M4 are both used as input terminals of the first intermediate stage module 120, and are connected to the first stage amplified signal; the drain of the third transistor M3 is connected to the first end of the resistor R1, and the drain of the fourth transistor M4 is connected to the first end of the resistor R1; the source of the third transistor M3 is connected to the output terminal of the second power supply VDD2, and the source of the fourth transistor M4 is grounded; the first end of the resistor R1 and the second end of the resistor R1 are both used as output terminals of the first intermediate stage module 120, and are connected to the input terminal of the first output stage module 130.

[0036] Among them, the third transistor M3 and the fourth transistor M4 in the first intermediate stage module 120 can realize the second stage gain amplification of the first stage amplified signal, the resistor R1 can realize the adjustment of the voltage difference between the input end and the power supply end of the first output stage module 130 within the first preset range, and the resistor R1 can also realize the function of stabilizing the first output stage module 130 and stabilizing the changes of the main factors (process, voltage, temperature, referred to as PVT) affecting the performance of the integrated circuit in the circuit. PVT is the main factor affecting the performance of the integrated circuit, P refers to the process deviation in the chip manufacturing process, V refers to the power supply voltage of the chip, and T is the operating temperature of the chip. The resistor R1 can provide a bias voltage to the first output stage module 130, thereby stabilizing the PVT changes in the circuit and improving the stability of the first output stage module 130.

[0037] Specifically, the gate of the third transistor M3 is connected to the gate of the fourth transistor M4, and the connection line of the gate of the third transistor M3 and the gate of the fourth transistor M4 is connected to the source of the first transistor M1 and the connection line of the drain of the second transistor M2; the drain of the third transistor M3 is connected to the first end of the resistor R1, and the drain of the fourth transistor M4 is connected to the first end of the resistor R1; the source of the third transistor M3 is connected to the second power supply VDD2, and the source of the fourth transistor M4 is grounded. The gates of the third transistor M3 and the fourth transistor M4 are connected to the first stage amplification signal by accessing the first stage amplification signal, and the second stage gain amplification is performed on the first stage amplification signal, and the bandwidth of the circuit is improved. The resistor R1 serves as a feedback resistor, and makes the first output stage module 130 stable at the subthreshold. The resistor R1 can reduce the influence of PVT in the circuit. For example, in digital design, process corners are used to consider the impact of changes in the manufacturing process on circuit performance. They represent the combination of transistor characteristics (NMOS and PMOS) in the worst case. Process corners generally include: FF (fast-fast): both NMOS and PMOS run faster than standard conditions; SS (slow-slow): both NMOS and PMOS run slower than standard conditions. Therefore, when the circuit in the embodiment of the present invention is at the ff corner, the threshold voltage of the first output stage module 130 will decrease, which may cause the first output stage module 130 to not be in the subthreshold region, but because of the characteristics of the ff corner, the current in the first intermediate stage module 120 will increase, so the voltage on the resistor R1 will also increase, so that the first output stage module 130 is in the subthreshold region again; the same is true when the ss corner is used. The threshold voltage of the first output stage module 130 increases and may be directly in the cut-off region, but the current in the first intermediate stage module 120 decreases, so that the voltage on the resistor R1 decreases, so the first output stage module 130 is restored to the subthreshold region, so that the first output stage module 130 is stably in the subthreshold state.

[0038] Optional, continue to refer to Figure 2 , the voltage drop of the resistor R1 is 100mV-200mV, and the resistor R1 is used to make the first output stage module 130 in a sub-threshold state.

[0039] Exemplarily, when the voltage of the second power supply VDD2 is 1V, the resistor R1 will provide a voltage drop between 100mV and 200mV, so that the high threshold transistor of the first output stage module 130 will be in the subthreshold region. At the same time, if the voltage of the second power supply VDD2 of the circuit changes, because there is no fixed current bias, if the power supply voltage increases, the current on the resistor R1 will also increase, and the voltage drop of the resistor R1 will also increase accordingly, thereby ensuring that the first output stage module 130 continues to be in the subthreshold state. If the voltage of the second power supply VDD2 decreases, the static current decreases, and the voltage drop of the resistor R1 also decreases accordingly, ensuring that the first output stage module 130 will not directly enter the cut-off region, causing the subthreshold state of the first output stage module 130 to be abnormal, thereby ensuring that the first output stage module 130 is in the subthreshold state.

[0040] It should be noted that the second intermediate module 220 has the same structure as the first intermediate module 120, and the second intermediate module 220 has the same function as the first intermediate module 120. Figure 2 The second intermediate stage module 220 is provided with a transistor M9, a transistor M10 and a resistor R2, the specifications of the transistor M9 and the third transistor M3 are exactly the same, the specifications of the transistor M10 and the fourth transistor M4 are exactly the same, the specifications of the resistor R2 and the resistor R1 are exactly the same, and the second intermediate stage module 220 is powered by the power supply VDD4, so that the second input stage module 210 achieves the same function as the first input stage module 110. The second stage amplified signal is connected through the gates of the transistor M9 and the transistor M10, and the second stage amplified signal is amplified by the second stage gain, which can improve the bandwidth of the circuit. The resistor R2 is used as a feedback resistor to make the second output stage module 230 stable in a subthreshold state.

[0041] For further information, please refer to Figure 2 The first output stage module 130 includes a fifth transistor M5 and a sixth transistor M6; the gate of the fifth transistor M5 is connected to the first end of the resistor R1, and the gate of the sixth transistor M6 is connected to the second end of the resistor R1; the drain of the fifth transistor M5 is connected to the drain of the sixth transistor M6; the source of the fifth transistor M5 is connected to the output end of the third power supply VDD3, and the source of the sixth transistor M6 is grounded.

[0042] Among them, the source of the fifth transistor M5 can be used as the power supply terminal of the first output stage module 130, and the third power supply VDD3 can be used as a fixed potential to connect to the power supply. The first intermediate stage module 120 performs a second-stage gain amplification on the first-stage amplified signal, and adjusts the first-stage amplified signal after the second-stage gain amplification, so that the voltage difference between the input terminal and the power supply terminal of the first output stage module 130 is within a preset range, ensuring that the fifth transistor M5 and the sixth transistor M6 in the first output stage module 130 are in a subthreshold state, so that the fifth transistor M5 and the sixth transistor M6 are in a subthreshold state to perform a third-stage gain amplification on the second-stage amplified signal.

[0043] Specifically, by setting the resistance value of the resistor R1, the fifth transistor M5 and the sixth transistor M6 can be placed in a subthreshold state. The connection line between the drain of the fifth transistor M5 and the drain of the sixth transistor M6 can be used as the output end of the ring amplifier. After the fifth transistor M5 and the sixth transistor M6 are in a subthreshold state and perform a third-stage gain amplification on the second-stage amplified signal, a first output signal OUTP can be obtained, which is output from the connection line between the drain of the fifth transistor M5 and the drain of the sixth transistor M6. When the fifth transistor M5 and the sixth transistor M6 are in a subthreshold state and perform a third-stage gain amplification on the second-stage amplified signal, a higher gain can be provided, and the power consumption is lower than when the fifth transistor M5 and the sixth transistor M6 are in a threshold state, thereby saving the overall power consumption of the circuit, so that the ring amplifier in the present invention can still have a higher gain and bandwidth at a low voltage, and has the characteristics of high stability, which can meet the application requirements of a high-performance analog-to-digital converter, and has significant advantages over traditional operational amplifiers.

[0044] In the embodiment of the present invention, reference Figure 2 , the second output stage module 230 has the same structure as the first output stage module 130, the second output stage module 230 has the same function as the first output stage module 130, the second output stage module 230 is powered by the power supply VDD5, and the second output stage module 230 is provided with a transistor M11 and a transistor M12, the specifications of the transistor M11 and the fifth transistor M5 are exactly the same, and the specifications of the transistor M12 and the sixth transistor M6 are exactly the same, so that the second output stage module 230 achieves the same function as the first output stage module 130. The second output stage module 230 performs a third-stage gain amplification on the second-stage amplified signal by the transistor M11 and the transistor M12 being in a subthreshold state, so as to provide a higher gain and lower power consumption, thereby saving the overall power consumption of the circuit, so that the ring amplifier in the present invention can still have a higher gain and bandwidth at a low voltage, and has the characteristics of high stability, which can meet the application requirements of a high-performance analog-to-digital converter, and has significant advantages over traditional operational amplifiers.

[0045] Optionally, the first transistor M1, the third transistor M3, the fifth transistor M5 and the first common-mode feedback transistor N1 are PMOS transistors; the second transistor M2, the fourth transistor M4, the sixth transistor M6 and the second common-mode feedback transistor N2 are NMOS transistors.

[0046] The first common-mode feedback transistor N1 and the second common-mode feedback transistor N2 are high-threshold transistors.

[0047] Optionally, the ring amplifier in the embodiment of the present invention can be applied to the residual amplifier of the successive approximation-pipeline hybrid ADC. When residual amplification is performed in the successive approximation-pipeline hybrid ADC, when the residual signal is just input to the input stage, the PMOS tube or NMOS tube in the output stage is in a fully on state, the signal is in a fast establishment state, the gain of the circuit is low, and the bandwidth is high. After the residual signal is established and amplified to a certain process, the PMOS tube or NMOS tube in the output stage enters a subthreshold state, at which time the gain of the circuit gradually increases and the bandwidth gradually decreases until the signal is completely established and the gain reaches the maximum value. The ring amplifier in the embodiment of the present invention has low power consumption, does not need to use a higher voltage power supply, can provide good gain and bandwidth under low voltage conditions, thereby reducing the power consumption of the successive approximation-pipeline hybrid ADC, and has obvious advantages over traditional operational amplifiers.

[0048] The embodiment of the present invention provides a ring amplifier, which has low power consumption and can still have high gain and bandwidth at low voltage, can meet the application requirements of high-performance analog-to-digital converters, and has significant advantages over traditional operational amplifiers.

[0049] The embodiment of the present invention further provides an analog-to-digital converter, Figure 3 A schematic diagram of the structure of an analog-to-digital converter provided by an embodiment of the present invention is shown in FIG. Figure 3 As shown, the analog-to-digital converter 200 includes the ring amplifier 100 in any embodiment of the present invention. Optionally, the analog-to-digital converter 200 is a successive approximation-pipeline hybrid ADC, and the analog-to-digital converter 200 can achieve the same technical effects and functions as the ring amplifier 100 in the above embodiments.

[0050] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A ring amplifier, characterized in that: The ring amplifier comprises a first input stage module, a first intermediate stage module and a first output stage module; The input end of the first input stage module is connected to the first input signal, the output end of the first input stage module is connected to the input end of the first intermediate stage module, and the first input stage module is used to perform a first-stage gain amplification on the first input signal to form a first-stage amplified signal; The output end of the first intermediate stage module is connected to the input end of the first output stage module, the power supply end of the first output stage module is connected to a fixed potential, and the first intermediate stage module is used to perform a second-stage gain amplification on the first-stage amplified signal, and adjust the voltage difference between the input end and the power supply end of the first output stage module within a first preset range according to the first-stage amplified signal; The output end of the first output stage module serves as the output end of the ring amplifier, and the first output stage module is used to perform a third-stage gain amplification on the first-stage amplified signal.

2. The ring amplifier according to claim 1, characterized in that: Also included is a second input stage module, a second intermediate stage module, and a second output stage module; The input end of the second input stage module is connected to the second input signal, the output end of the second input stage module is connected to the input end of the second intermediate stage module, the first voltage input end of the second input stage module is connected to the first voltage input end of the first input stage module, and the second voltage input end of the second input stage module is connected to the second voltage input end of the first input stage module; the second input stage module is used to perform a first-stage gain amplification on the second input signal to form a second-stage amplified signal; The output end of the second intermediate stage module is connected to the input end of the second output stage module, the power supply end of the second output stage module is connected to a fixed potential, and the second intermediate stage module is used to perform a second-stage gain amplification for the second-stage amplified signal, and adjust the voltage difference between the input end and the power supply end of the second output stage module within a second preset range according to the second-stage amplified signal; The second output stage module is used to provide a third stage gain amplification for the second stage amplified signal, and output the second stage amplified signal after the gain from the output end of the second output stage module; Among them, the second input stage module has the same structure as the first input stage module, the second intermediate stage module has the same structure as the first intermediate stage module, and the second output stage module has the same structure as the first output stage module; the second input signal and the first input signal are two completely symmetrical differential input signals.

3. The ring amplifier according to claim 1 or 2, characterized in that: The first input stage module includes a first transistor and a second transistor; The gate of the first transistor is connected to the gate of the second transistor, and the connection line between the gate of the first transistor and the gate of the second transistor is connected to the first input signal; the drain of the first transistor is connected to the drain of the second transistor, and the connection line between the drain of the first transistor and the drain of the second transistor is connected to the input end of the first intermediate stage module; the source of the first transistor serves as the first voltage input end of the first input stage module, and the source of the second transistor serves as the second voltage input end of the first input stage module.

4. The ring amplifier according to claim 3, characterized in that: Also included is a first common-mode feedback transistor and a second common-mode feedback transistor; The gate of the first common-mode feedback transistor and the gate of the second common-mode feedback transistor are both connected to a common-mode feedback voltage bias signal; The drain of the first common-mode feedback transistor is connected to the source of the first transistor, the drain of the second common-mode feedback transistor is connected to the source of the second transistor, the source of the first common-mode feedback transistor is connected to the output end of the first power supply, and the source of the second common-mode feedback transistor is grounded.

5. The ring amplifier according to claim 1 or 2, characterized in that: The first intermediate stage module includes a third transistor, a fourth transistor and a resistor; The gate of the third transistor and the gate of the fourth transistor are both used as input terminals of the first intermediate stage module, and are connected to the first stage amplified signal; The drain of the third transistor is connected to the first end of the resistor, and the drain of the fourth transistor is connected to the second end of the resistor; the source of the third transistor is connected to the output end of the second power supply, and the source of the fourth transistor is grounded; the first end of the resistor and the second end of the resistor both serve as the output end of the first intermediate stage module and are connected to the input end of the first output stage module.

6. The ring amplifier according to claim 5, characterized in that: The first output stage module includes a fifth transistor and a sixth transistor; The gate of the fifth transistor is connected to the first end of the resistor, and the gate of the sixth transistor is connected to the second end of the resistor; The drain of the fifth transistor is connected to the drain of the sixth transistor; the source of the fifth transistor is connected to the output end of the third power supply, and the source of the sixth transistor is grounded.

7. The ring amplifier according to claim 6, characterized in that: The first transistor, the third transistor, the fifth transistor and the first common-mode feedback transistor are PMOS transistors; The second transistor, the fourth transistor, the sixth transistor and the second common-mode feedback transistor are NMOS transistors.

8. The ring amplifier according to claim 6, characterized in that: The aspect ratio of the first common-mode feedback transistor is greater than that of the first transistor and that of the second transistor, and the aspect ratio of the second common-mode feedback transistor is greater than that of the first transistor and that of the second transistor.

9. The ring amplifier according to claim 2, characterized in that: The first preset range is the same as the second preset range.

10. An analog-to-digital converter, characterized in that: The invention comprises the ring amplifier according to any one of claims 1 to 9.

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