C / X wave band ultra-wideband GaAs MMIC low-noise amplifier

Abstract

The invention discloses a C / X wave band ultra-wideband GaAs MMIC low-noise amplifier, and mainly relates to the technical field of radio frequency front ends. Comprising an input matching network used for receiving a radio frequency signal and performing impedance matching so as to effectively transmit the signal to a subsequent active amplification part; and the active amplification part adopts an improved cascode-cascode cascade amplification structure and is used for amplifying the radio frequency signal transmitted by the input matching network. The amplifier has the advantages that an improved cascode-cascode cascade amplification structure is adopted, the gain is improved through an improved Cascode structure, the noise coefficient of the circuit is reduced, and the performance indexes of ultra wide band, low noise and high gain are achieved. The design of the structure not only improves the overall performance of the amplifier, but also enables the amplifier to keep stable gain output in a broadband range, and effectively solves the problems of low gain and high noise of a traditional low-noise amplifier in broadband application.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency front-ends, and specifically to a C / X-band ultra-wideband GaAs MMIC low-noise amplifier. Background Technique

[0002] The statements in this part merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] In recent years, the independent research and development of radio frequency chips has become a key task in the development of China's semiconductor industry. As a key component of the radio frequency front-end system, the low-noise amplifier plays a decisive role in communication quality, signal transmission distance, and system performance. The low-noise amplifier is located in the receiving link of the radio frequency system and is the first active module in the receiving link. The function of the low-noise amplifier is to amplify the received weak signal as much as possible while ensuring signal quality, thereby improving the receiving sensitivity of the system. At the same time, it tries to minimize the introduction of its own noise, improve the sensitivity of the receiver as much as possible, and ensure the dynamic range of the receivable signal. The performance of the low-noise amplifier directly determines the quality of the entire radio frequency system.

[0004] Traditional low-noise amplifiers face many challenges in terms of wide bandwidth, low noise, high gain, etc. On the one hand, with the continuous increase in communication frequency, the bandwidth requirements for low-noise amplifiers are getting higher and higher, and traditional low-noise amplifiers often have difficulty maintaining stable gain and low-noise performance within a wide bandwidth. On the other hand, with the continuous development of communication technologies, the requirements for performance indicators such as the noise figure and linearity of low-noise amplifiers are also getting higher and higher, and traditional low-noise amplifiers often have significant limitations in these aspects.

[0005] Therefore, developing a low-noise amplifier that can maintain stable gain and low-noise performance within a wide bandwidth, while having high linearity and noise figure, is of great significance for improving the performance of modern wireless communication systems.

[0006] In a wireless communication system, the design of a low-noise amplifier needs to consider various factors, including the operating frequency band, gain, noise figure, linearity, stability, etc. Among them, the operating frequency band is the basis for the design of the low-noise amplifier and needs to be determined according to the specific requirements of the communication system. Gain is one of the main performance indicators of the low-noise amplifier, which determines the amplification degree of the amplifier for the input signal. The noise figure reflects the amplification degree of the amplifier for the noise of the input signal and is an important indicator for evaluating the performance of the low-noise amplifier. Linearity determines the performance of the amplifier when processing large signals and is of great significance for ensuring the signal quality of the communication system. Stability is one of the important considerations in the design of the low-noise amplifier, and it is necessary to ensure that the amplifier does not exhibit unstable phenomena such as self-oscillation during operation.

[0007] To meet the requirements of modern wireless communication systems for high-performance amplifiers, the present invention adopts an improved cascode-cascade amplification structure, expands the bandwidth through negative feedback broadband technology, and uses a single-power active biasing circuit for temperature compensation and reduction of process fluctuations. This structure can effectively improve the gain and linearity of the amplifier, while reducing the noise figure, achieving the performance indicators of ultra-wideband, low-noise, and high-gain.

[0008] In addition, the present invention also adopts a variety of optimization measures to improve the performance of the amplifier. For example, in the input matching network, an inductor is connected in parallel to ground and a capacitor is connected in series to the transistor gate to match the input impedance and provide high-frequency decoupling and DC blocking, reducing parasitic effects. In the active amplification part, an improved cascode-cascade amplification structure is adopted to expand the bandwidth, improve the gain and linearity through negative feedback technology. In the inter-stage matching network, the combined action of capacitors and inductors is used to optimize the matching and improve the gain flatness and noise. In the output matching network, components such as inductors, capacitors, and resistors are used to jointly optimize the impedance matching to maximize the power transmission to the output terminal. Summary of the Invention

[0009] The object of the present invention is to provide a C / X-band ultra-wideband GaAs MMIC low-noise amplifier. The present invention adopts an improved cascode-cascade amplification structure, improves the gain through the improved Cascode structure, reduces the noise figure of the circuit, and achieves the performance indicators of ultra-wideband, low-noise, and high-gain. The design of this structure not only improves the overall performance of the amplifier, but also enables the amplifier to maintain a stable gain output and reduce the noise figure within a wide frequency band, effectively solving the problems of low gain and high noise of traditional low-noise amplifiers in broadband applications.

[0010] To achieve the above object, the present invention is realized through the following technical solutions:

[0011] A C / X-band ultra-wideband GaAs MMIC low-noise amplifier includes:

[0012] An input matching network for receiving a radio frequency signal and performing impedance matching to effectively transmit the signal to the subsequent active amplification part;

[0013] An active amplification part adopting an improved cascode-cascade amplification structure for amplifying the radio frequency signal transmitted by the input matching network;

[0014] An inter-stage matching network arranged between the first-stage improved cascode amplifier circuit and the second-stage common-source amplifier circuit, introducing a neutralizing inductor for optimizing the inter-stage impedance matching and improving the gain flatness and noise figure;

[0015] An output matching network for impedance - matching the amplified RF signal output by the active amplification part so as to effectively transmit the signal to the subsequent circuit;

[0016] A DC bias circuit for providing a stable DC bias voltage for the active amplification part, ensuring the normal operation of the amplifier, and providing adaptive bias and temperature compensation;

[0017] A negative - feedback network is set between the output end and the input end of the second - stage common - source amplification circuit for stabilizing the gain and improving the linearity.

[0018] The input matching network includes an inductor L1, one end of the inductor L1 is connected to the RF signal input terminal, the other end is grounded, and a capacitor C1 is connected in series between the inductor L1 and the gate of the first - stage transistor M1 of the active amplification part, which is used to block DC and cooperate with the inductor L1 to complete the input impedance matching.

[0019] The active amplification part includes a first - stage improved cascode amplification circuit and a second - stage common - source amplification circuit. The first - stage improved cascode amplification circuit is composed of a transistor M1, its gate receives the signal transmitted by the input matching network through the capacitor C1, its source is grounded through the inductor L2, and its drain is connected to the input end of the second - stage common - source amplification circuit through the inductor L3; the second - stage common - source amplification circuit is composed of a transistor M2, and also includes a third - stage amplification circuit, the third - stage amplification circuit is composed of a transistor M3, its gate receives the output signal of the first - stage improved cascode amplification circuit, and its drain outputs the amplified RF signal.

[0020] The inter - stage matching network includes a capacitor C2 and an inductor L3. The capacitor C2, as an AC coupling capacitor, is connected between the output end of the first - stage improved cascode amplification circuit and the input end of the second - stage common - source amplification circuit for blocking DC; the inductor L3 is in parallel with the capacitor C2 and jointly acts on the inter - stage impedance matching to improve the gain flatness.

[0021] The output matching network includes an inductor L4, a capacitor C3 and a resistor R1. The inductor L4, the capacitor C3 and the resistor R1 are connected in series between the output end of the second - stage common - source amplification circuit of the active amplification part and the RF signal output terminal. The inductor L4 provides impedance matching, the capacitor C3 is used as a decoupling capacitor for providing high - frequency decoupling, and the resistor R1 is used as a stabilizing resistor for suppressing parasitic oscillation and improving the circuit stability.

[0022] The DC bias circuit includes a 5V power supply, a bias control transistor M4, and a resistor voltage division network. The 5V power supply is supplied to the drain of the bias control transistor M4 through an off-chip resistor R5. The source of M4 is grounded, and the gate is connected to the ground through the resistor voltage division network. The resistor voltage division network consists of resistors R6, R7, R8, and R9, which is used to divide the voltage to generate an appropriate gate voltage. This gate voltage is supplied to the gates of transistors M1 and M2 of the first-stage improved cascode amplifier circuit and the second-stage common-source amplifier circuit through resistors R7 and R8 respectively, ensuring that they operate at appropriate quiescent operating points.

[0023] The inter-stage compensation network consists of a capacitor C5 and a resistor R8. The capacitor C5 serves as a coupling capacitor to construct a radio frequency energy feedforward path between the drain of transistor M2 and the gate of transistor M3. The resistor R10 is connected in series in the path of capacitor C5 to control the strength of the feedforward signal through its resistance value. The inter-stage compensation network shunts and attenuates the non-linear output harmonics of transistor M2. This structure can increase the third-order intermodulation intercept point by 2 - 3 dB.

[0024] The negative feedback network includes a resistor R3 and a capacitor C4. One end of the resistor R3 is connected to the output terminal of the second-stage common-source amplifier circuit, and the other end is connected to the input terminal of the second-stage common-source amplifier circuit through the capacitor C4 to form a negative feedback path.

[0025] Input matching network: The input signal first passes through an inductor L1 connected in parallel to the ground, which is used to match the input impedance and provide high-frequency decoupling to reduce parasitic effects. Then it enters a capacitor C1 connected in series to the gate of transistor M1. The capacitor C1 is used to block DC, and at the same time participates in input matching with L1 to match the input impedance to the standard 50Ω.

[0026] First-stage improved cascode amplifier circuit: The source of transistor M1 is connected to the ground in series through an inductor L2, which is used to increase the gain and optimize the input impedance matching to a certain extent. The drain of transistor M1 is connected to the gate of the second-stage transistor M2 through an inductor L3 in series.

[0027] Inter-stage matching network. The inter-stage matching network includes a capacitor C2 and an inductor L3. The capacitor C2 serves as an AC coupling capacitor and is connected between the output terminal of the first-stage cascode amplifier circuit and the input terminal of the second-stage common-source amplifier circuit to block DC. The inductor L3 is a neutralizing inductor and is connected to the drain of transistor M1 and the source of transistor M2 respectively. While acting on inter-stage impedance matching, it reduces the overall noise figure of the circuit.

[0028] Second-stage common-source amplifier circuit: The drain of transistor M2 is connected to an inductor L4, a capacitor C3, and a resistor R1. Among them, C3 serves as a drain decoupling capacitor to provide high-frequency decoupling and optimize the signal path; L4 provides impedance matching and gain optimization; R1 serves as a stabilizing resistor to suppress parasitic oscillations and improve the stability of the circuit.

[0029] Third-stage Amplification and Feedback Network: Transistor M3 serves as the third-stage amplifier. Its drain is connected to resistor R3 through capacitor C4, forming a negative feedback network for stabilizing the gain, improving linearity, and optimizing the frequency response. Inductor L3 acts as a gate bias resistor for stabilizing the bias voltage.

[0030] DC Power Supply and Bias Network: The 5V power supply is supplied to transistor M4 through an off-chip resistor R5. M4 serves as a bias control transistor, and through resistor networks such as R4, R7, R9, R10, and R11 for voltage division, it ensures an appropriate gate voltage supply to each stage of transistors.

[0031] Inter-stage Compensation Network: Composed of capacitor C5 and resistor R8, capacitor C5 acts as a coupling capacitor to construct a RF energy feed-forward path between the drain of transistor M2 (output-stage drive point) and the gate of transistor M3 (input of the final-stage amplifier). Resistor R10 is in series with the path of capacitor C5, and controls the feed-forward signal strength through its resistance value. The inter-stage compensation network shunts and attenuates the non-linear output harmonics of transistor M2. This structure can increase the third-order intermodulation intercept point (IIP3) by 2 - 3 dB.

[0032] Output Matching Network: At the drain output of transistor M3, in addition to the DC-Block capacitor, it also includes components such as the inter-stage matching inductor L4, capacitor C3, and resistor R1, which jointly optimize the impedance matching to maximize the power transfer to the output. The output impedance is adjusted to 50Ω to adapt to the standard interface of the subsequent RF system.

[0033] The neutralization inductor is mainly used to cancel the Miller effect caused by the internal capacitance of the transistor at high frequencies. By introducing an inductor to form a parallel resonance with the parasitic capacitance, the equivalent impedance of the parasitic capacitance approaches infinity at a specific frequency, eliminating its negative impact on the input impedance and stability. It can provide RF choke and inter-stage matching, and at the same time significantly reduce the noise figure of the first-stage modified cascode amplifier circuit

[0034] Impedance Matching: Through its inductance characteristics, the neutralization inductor can adjust these impedances so that the output impedance of the first stage can better match the input impedance of the second stage, thus achieving more efficient power transfer.

[0035] Improving Gain Flatness: In a multi-stage amplifier circuit, due to the different frequency response characteristics of each stage of the circuit, it may cause large fluctuations in the gain of the entire circuit at different frequencies. The neutralization inductor can form a resonant circuit at a specific frequency through its inductance-capacitance resonance characteristics, thereby compensating for the gain roll-off effect in the circuit, enabling the entire amplifier circuit to maintain a relatively flat gain characteristic over a wider frequency range.

[0036] Optimizing the Noise Figure: The noise figure is an indicator that measures the degree of signal noise amplification in an amplifier circuit. In a multi-stage amplifier circuit, the noise of the front-stage circuit will be further amplified through the amplification of the subsequent-stage circuit, thus affecting the noise performance of the entire circuit. By reasonably designing the parameters of the neutralizing inductor, the noise figure of the first-stage improved cascode amplifier circuit can be optimized, thereby reducing the noise figure of the entire amplifier circuit. This usually requires a trade-off between noise matching and gain matching.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The present invention adopts an improved cascode-cascade amplification structure. By using the improved Cascode structure, the gain is increased and the circuit noise figure is reduced, achieving the performance indicators of ultra-wideband, low noise, and high gain. The design of this structure not only improves the overall performance of the amplifier but also enables the amplifier to maintain a stable gain output within a wide frequency band, effectively solving the problems of low gain and high noise in the broadband application of traditional low-noise amplifiers.

[0039] The negative feedback broadband technology is adopted to expand the bandwidth and improve the frequency response range of the amplifier. The introduction of negative feedback not only increases the bandwidth of the amplifier but also improves its frequency response characteristics, enabling the amplifier to maintain good performance within a wider frequency range.

[0040] A single-power-supply active biasing circuit is used for temperature compensation and reducing process fluctuations, providing a stable quiescent operating point. This design effectively improves the stability and reliability of the amplifier, enabling the amplifier to maintain consistent performance output under different temperature and environmental conditions. At the same time, the static current can be adjusted through an off-chip resistor, and the static bias point of the transistor can be changed according to application requirements, further enhancing the flexibility and adaptability of the amplifier.

[0041] The overall circuit design is compact with a small chip area, meeting the requirements of modern wireless communication systems for miniaturization and high performance. In addition, the amplifier of the present invention also has good linearity and noise figure, and can effectively amplify the received weak signal on the premise of ensuring signal quality, thereby improving the receiving sensitivity of the system. Description of the Drawings

[0042] Att Figure 1 is a schematic structural diagram of a C / X-band ultra-wideband MMIC low-noise amplifier provided by the present invention.

[0043] Att Figure 2 is a graph comparing the measured and simulated data of the noise figure of a C / X-band ultra-wideband MMIC low-noise amplifier provided by the present invention.

[0044] Att Figure 3It is a graph showing the comparison data of the measured and simulated small-signal gain S21 of a C / X-band ultra-wideband MMIC low-noise amplifier provided by the present invention.

[0045] Appendix Figure 4 It is a graph showing the comparison data of the measured and simulated small-signal isolation S12 of a C / X-band ultra-wideband MMIC low-noise amplifier provided by the present invention.

[0046] Appendix Figure 5 It is a graph showing the comparison data of the measured and simulated small-signal input return loss S11 of a C / X-band ultra-wideband MMIC low-noise amplifier provided by the present invention.

[0047] Appendix Figure 6 It is a graph showing the comparison data of the measured and simulated small-signal output return loss S22 of a C / X-band ultra-wideband MMIC low-noise amplifier provided by the present invention.

[0048] Appendix Figure 7 It is a graph showing the comparison data of the measured and simulated P1dB of a C / X-band ultra-wideband MMIC low-noise amplifier provided by the present invention. Detailed Description of the Specific Embodiment

[0049] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by this application.

[0050] The present invention relates to a C / X-band ultra-wideband GaAs MMIC low-noise amplifier, and its main structure includes

[0051] I. Detailed Explanation of Circuit Connection Relationship

[0052] The ultra-wideband low-noise amplifier (LNA) described in the present invention is designed using domestic 0.25μm GaAs pHEMT process, applicable to the working frequency band of 4 - 12 GHz, covering the C-band and X-band, and is widely used in fields such as national defense, communication, aerospace, and civil electronics. Its core circuit design is fine and efficient, and the specific connection relationship is as follows:

[0053] Input matching network: The input signal first passes through the inductor L1, which is connected in parallel to the ground. Its main function is to provide a decoupling path for high-frequency signals, effectively reducing the influence of parasitic effects on the input impedance matching. Subsequently, the signal passes through the capacitor C1 in series to the gate of the transistor M1 in the first-stage improved cascode amplifier circuit. The capacitor C1 plays a role in blocking direct current here, and at the same time cooperates with the inductor L1 to ensure that the input impedance matches the standard 50Ω system impedance, thus achieving efficient signal transmission.

[0054] The first - stage improved cascode amplifier circuit: Transistor M1 serves as the first stage of the amplifier, and its source is grounded in series through inductor L2. Inductor L2 not only provides a necessary DC grounding path for the circuit but also forms a resonant network together with the internal resistance of transistor M1 through its inductance characteristics, which helps improve the stability of the circuit and reduce the circuit noise figure. The drain of transistor M1 is connected to the source of transistor M2 in the second - stage common - source amplifier circuit through neutralizing inductor L3. Inductor L3 plays an inter - stage coupling role here, helping to maintain signal integrity and reduce noise, and at the same time participating in inter - stage impedance matching.

[0055] Inter - stage matching network: Between the first - stage and second - stage common - source amplifier circuits, an inter - stage matching network composed of capacitor C2 and inductor L3 is inserted. Capacitor C2 acts as an AC coupling capacitor, isolating the DC component and ensuring pure signal transmission. Inductor L3 provides noise reduction technology, blocking RF signals from entering the bias network, suppressing the channel noise of common - gate transistor M2, and optimizing the high - frequency gain flatness.

[0056] The second - stage common - source amplifier circuit: Transistor M2 constitutes the second stage of the amplifier. Its drain is connected to a composite network composed of inductor L4, capacitor C3, and resistor R1. Inductor L4 provides the necessary impedance matching, helping to optimize the signal transmission path. Capacitor C3 acts as a drain - decoupling capacitor, effectively reducing high - frequency signal interference and improving the stability of the circuit. Resistor R1 serves as a stabilizing resistor, suppressing potential parasitic oscillations and further enhancing the stability of the circuit.

[0057] The third - stage amplification and negative - feedback network: Transistor M3 serves as the third stage of the amplifier, and its gate receives a stable bias voltage through inductor L3. The drain is connected to resistor R3 through capacitor C4, forming a negative - feedback network. The role of the negative - feedback network is to stabilize the gain of the amplifier, improve its linearity, and optimize the frequency response. By adjusting the resistance value of resistor R3, the depth of feedback can be finely controlled to achieve the best performance.

[0058] DC power supply and bias network: The entire amplifier is powered by a 5V power supply. This power supply is connected to the gate of transistor M4 through an off - chip resistor R5. M4 serves as a bias - control transistor, and its drain is connected to ground. By adjusting the resistance values of resistors R5, R6, R7, R8, and R9, the gate voltages of transistors M1, M2, and M3 can be precisely controlled to ensure that they operate in the best state.

[0059] Cross-level compensation network: It consists of capacitor C5 and resistor R8. Capacitor C5 serves as a coupling capacitor, building a radio frequency energy feedforward path between the drain of transistor M2 (output stage drive point) and the gate of transistor M3 (input of the final-stage amplifier). Resistor R10 is in series with the path of capacitor C5, controlling the feedforward signal strength through its resistance value. The cross-level compensation network shunts and attenuates the non-linear output harmonics of transistor M2. This structure can increase the third-order intermodulation intercept point (IIP3) by 2 - 3 dB.

[0060] Output matching network: The output terminal of the amplifier is led out from the drain of transistor M3. To ensure that the output impedance matches the standard interface (50Ω) of the subsequent system, a composite network is connected to the output terminal, which includes inductor L4 (reused from the second-stage common-source amplifier circuit), capacitor C3 (reused for the decoupling function of the second-stage common-source amplifier circuit), and possibly additional matching components (such as other inductors or capacitors not explicitly specified). This output matching network ensures maximum power transfer from the amplifier to the load while reducing signal reflection and distortion.

[0061] The neutralizing inductor is mainly used to cancel the Miller effect caused by the internal capacitance of the transistor at high frequencies. By introducing an inductor to form a parallel resonance with the parasitic capacitance, the equivalent impedance of the parasitic capacitance approaches infinity at a specific frequency, eliminating its negative impact on the input impedance and stability. It can provide radio frequency chokes and inter-stage matching, while significantly reducing the noise figure of the first-stage improved cascode amplifier circuit.

[0062] Impedance matching: Through its inductive characteristics, the neutralizing inductor can adjust these impedances so that the output impedance of the first stage can better match the input impedance of the second stage, thus achieving more efficient power transfer.

[0063] Improve gain flatness: In a multi-stage amplifier circuit, due to the different frequency response characteristics of each stage of the circuit, it may cause large fluctuations in the gain of the entire circuit at different frequencies. The neutralizing inductor can form a resonant circuit at a specific frequency through its inductance-capacitance resonance characteristics, thereby compensating for the gain roll-off effect in the circuit and enabling the entire amplifier circuit to maintain a relatively flat gain characteristic over a wider frequency range.

[0064] Optimize the noise figure: The noise figure is an index to measure the degree of signal noise amplification by an amplifier circuit. In a multi-stage amplifier circuit, the noise of the front-stage circuit will be further amplified by the subsequent stage circuit, thus affecting the noise performance of the entire circuit. By reasonably designing the parameters of the neutralizing inductor, the noise figure of the first-stage improved cascode amplifier circuit can be optimized, thereby reducing the noise figure of the entire amplifier circuit. This usually requires a trade-off between noise matching and gain matching.

[0065] II. Explanation of the circuit working principle

[0066] The working principle of the ultra-wideband low-noise amplifier can be summarized into four main processes: signal reception, amplification, output, and feedback control.

[0067] Signal reception: When the input signal enters the input matching network, the inductor L1 and capacitor C1 work together to match the input impedance to the standard 50Ω system impedance, thus minimizing signal reflection and improving signal transmission efficiency. During this process, the decoupling effect of inductor L1 effectively reduces the influence of high-frequency parasitic effects on the signal, while capacitor C1 isolates the DC component, ensuring the purity of the signal.

[0068] Signal amplification: The signal processed by the input matching network enters the first-stage improved cascode amplifier circuit and is preliminarily amplified by transistor M1. Transistor M1 operates in the amplification region. Its gate receives the input signal, the source is grounded through inductor L2, and the drain outputs the amplified signal to the second-stage common-source amplifier circuit. Inductor L2 not only provides a DC grounding path but also forms a resonant network with the internal resistance of transistor M1 through its inductance characteristics, enhancing the stability of the circuit and reducing noise. Subsequently, the signal enters the second-stage common-source amplifier circuit through the inter-stage matching network and is further amplified by transistor M2. The working mode of transistor M2 is similar to that of M1, but the composite network (inductor L4, capacitor C3, and resistor R1) connected to its drain provides more optimized impedance matching and stability guarantee. Finally, the signal enters the third-stage amplifier circuit and is finally amplified by transistor M3. The gate of transistor M3 receives a stable bias voltage, and the drain stabilizes the output signal through the negative feedback network (resistor R3 and capacitor C4).

[0069] Signal output: The signal amplified through three stages enters the output matching network. This network matches the output impedance to the standard 50Ω system impedance by multiplexing inductor L4 and capacitor C3 in the second-stage common-source amplifier circuit and possibly adding additional matching components. This process ensures that the maximum power is transferred from the amplifier to the load while reducing signal reflection and distortion. Finally, the amplified signal is output through the output port to the subsequent circuit or system.

[0070] Feedback control: The negative feedback network (resistor R3 and capacitor C4) plays a key role in the third stage of the amplifier. By adjusting the resistance value of resistor R3, the depth of feedback can be finely controlled, thereby stabilizing the gain of the amplifier, improving its linearity, and optimizing the frequency response. The negative feedback mechanism effectively suppresses the nonlinear distortion and parasitic oscillation of the amplifier, ensuring the stability and reliability of the circuit.

[0071] The present invention adopts an improved common-source common-gate - common-source cascade amplification structure. By means of the improved Cascode structure, the gain is increased and the circuit noise figure is reduced, achieving the performance indicators of ultra-wideband, low noise, and high gain. The design of this structure not only improves the overall performance of the amplifier, but also enables the amplifier to maintain stable gain output and a low noise figure within a wide frequency band, effectively solving the problems of low gain and high noise of traditional low-noise amplifiers in broadband applications. The negative feedback broadband technology is adopted to expand the bandwidth and improve the frequency response range of the amplifier. The introduction of negative feedback not only increases the bandwidth of the amplifier, but also improves its frequency response characteristics, enabling the amplifier to maintain good performance within a wider frequency range. A single-power-supply active biasing circuit is used for temperature compensation and reducing process fluctuations, providing a stable quiescent operating point. This design effectively improves the stability and reliability of the amplifier, enabling the amplifier to maintain consistent performance output under different temperature and environmental conditions. At the same time, the static current can be adjusted through an off-chip resistor, and the static bias point of the transistor can be changed according to application requirements, further enhancing the flexibility and adaptability of the amplifier. The overall circuit design is compact and the chip area is small, meeting the requirements of modern wireless communication systems for miniaturization and high performance. In addition, the amplifier of the present invention also has good linearity and noise figure, and can effectively amplify the received weak signal on the premise of ensuring signal quality, thereby improving the receiving sensitivity of the system.

Claims

1. A C / X-band ultra-wideband GaAs MMIC low-noise amplifier, characterized in that: Comprising: An input matching network, which is used to receive a radio frequency signal and perform impedance matching so as to effectively transmit the signal to the subsequent active amplification part; An active amplification part, adopting an improved cascode-cascade amplification structure, which is used to amplify the radio frequency signal transmitted by the input matching network; An inter-stage matching network, which is arranged between the first-stage improved cascode amplification circuit and the second-stage common-source amplification circuit, introduces a neutralizing inductor, and is used to optimize the inter-stage impedance matching and improve the gain flatness and noise figure; An output matching network, which is used to perform impedance matching on the amplified radio frequency signal output by the active amplification part so as to effectively transmit the signal to the subsequent circuit; A DC bias circuit, which is used to provide a stable DC bias voltage for the active amplification part, ensure the normal operation of the amplifier, and provide adaptive bias and temperature compensation; A negative feedback network, which is arranged between the output end and the input end of the third-stage amplification circuit and is used to stabilize the gain and improve the linearity.

2. The C / X-band ultra-wideband GaAs MMIC low-noise amplifier according to claim 1, wherein: The input matching network includes an inductor L1, one end of the inductor L1 is connected to the radio frequency signal input end, the other end is grounded, and a capacitor C1, which is connected in series between the inductor L1 and the gate of the first-stage transistor M1 of the active amplification part, is used to block DC and cooperate with the inductor L1 to complete the input impedance matching.

3. The low-noise amplifier of a C / X-band ultra-wideband GaAs MMIC according to claim 2, wherein: The active amplification part includes a first-stage improved cascode amplification circuit and a second-stage common-source amplification circuit. The first-stage improved cascode amplification circuit is composed of a transistor M1 and a transistor M2. The gate of the transistor M1 receives the signal transmitted by the input matching network through the capacitor C1, the source is grounded through the inductor L2, and the drain is connected to the source of the transistor M2 through the inductor L3; the second-stage common-source amplification circuit is composed of a transistor M3, its gate receives the output signal of the first-stage improved cascode amplification circuit, and the drain outputs the amplified radio frequency signal.

4. The low-noise amplifier of a C / X-band ultra-wideband GaAs MMIC according to claim 3, characterized in that: The inter-stage matching network includes a capacitor C2 and an inductor L3. The capacitor C2 is used as an AC coupling capacitor and is connected between the output end of the first-stage improved cascode amplification circuit and the input end of the second-stage common-source amplification circuit to block DC; the inductor L3 is a neutralizing inductor and is respectively connected to the drain of the transistor M1 and the source of the transistor M2. While acting on the inter-stage impedance matching, it reduces the overall noise figure of the circuit.

5. The C / X-band ultra-wideband GaAs MMIC low-noise amplifier according to claim 4, wherein: The output matching network includes an inductor L4, a capacitor C3, a resistor R1 and a resistor R2. The capacitor C3 and the resistor R1 are connected in parallel to ground after the output of the drain of the transistor M2; the inductor L4 and the resistor R2 are connected in series between the output end of the first-stage improved cascode amplification circuit of the active amplification part and the radio frequency signal output end of the second-stage common-source amplification circuit. The inductor L4 provides impedance matching, the capacitor C3 is used as a decoupling capacitor to provide high-frequency decoupling, and the resistors R1 and R2 are used as stabilizing resistors to suppress parasitic oscillation and improve the circuit stability.

6. The C / X-band ultra-wideband GaAs MMIC low-noise amplifier according to claim 5, characterized in that: The DC bias circuit includes a 5V power supply, a bias control transistor M4, a resistive voltage divider network, and a cross-stage compensation network; the 5V power supply is supplied to the drain of the bias control transistor M4 through an off-chip resistor R5, the source of M4 is grounded, and the gate is connected to the gates of each transistor through the resistive voltage divider network to provide the transistor's static operating point. The resistive voltage divider network consists of resistors R4, R7, R9, R10, and R11, which are used to divide the voltage to generate an appropriate gate voltage. This gate voltage is supplied to the gates of transistors M1, M2, and M3 of the first-stage improved cascode amplifier circuit and the second-stage common-source amplifier circuit through resistors R10, R11, and R4 respectively, ensuring that they operate at appropriate static operating points. The cross-stage compensation network consists of a capacitor C5 and a resistor R8. The capacitor C5 acts as a coupling capacitor to build a radio frequency energy feed-forward path between the drain of transistor M2 and the gate of transistor M3. The resistor R10 is connected in series in the path of capacitor C5, and the feed-forward signal strength is controlled by its resistance value. The cross-stage compensation network shunts and attenuates the non-linear output harmonics of transistor M2. This structure can increase the third-order intermodulation intercept point by 2 - 3 dB.

7. The C / X-band ultra-wideband GaAs MMIC low-noise amplifier according to claim 6, wherein: The negative feedback network includes a resistor R3 and a capacitor C4. One end of the resistor R3 is connected to the input end of the second-stage common-source amplifier circuit, and the other end is connected to the output end of the second-stage common-source amplifier circuit through the capacitor C4 to form a negative feedback path.

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