Low noise amplifier based on phase inverter and multi-objective optimization method thereof

Abstract

The invention discloses a low-noise amplifier based on an inverter and a multi-objective optimization method of the low-noise amplifier. The low-noise amplifier comprises the inverter, an input capacitor CI, a feedback capacitor CF and a single-stage operational amplifier. The phase inverter is formed by connecting a PMOS (P-channel Metal Oxide Semiconductor) tube and an NMOS (N-channel Metal Oxide Semiconductor) tube in series, the input capacitor CI and the feedback capacitor CF are respectively of a split capacitor structure, the positive input end of the single-stage operational amplifier is connected with the output end of the phase inverter, the negative input end of the single-stage operational amplifier is connected with reference voltage, the output end of the single-stage operational amplifier is connected with a grid electrode of the NMOS tube through a resistor R2, the grid electrode of the PMOS tube is connected with a resistor R1, and the resistance value of the resistor R1 is equal to that of the resistor R2; the stability and the noise performance of the amplifier circuit are improved; by using a multi-objective optimization design method, the design parameters of the low-noise amplifier are optimized so as to meet the amplification requirements of ultrasonic pulse echo signals with different frequencies, and the design efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrasonic imaging simulation, and relates to an inverter-based low-noise amplifier and a multi-objective optimization method thereof. Background Art

[0002] In recent years, with the continuous advancement of medical technology, ultrasound imaging technology has become an indispensable and important tool in modern medical diagnosis. Especially in the field of intracardiac echocardiography, the application of this technology has greatly improved the accuracy and efficiency of diagnosis of heart diseases. In order to achieve more sophisticated imaging effects, the design of ultrasound probes has been continuously developed in the direction of miniaturization and integration, and has now been successfully reduced to the millimeter level. This technological breakthrough not only provides doctors with a more convenient operating experience, but also puts higher requirements on the overall performance of ultrasound imaging systems.

[0003] In the analog front end of ultrasound imaging systems, low-noise amplifiers (LNAs) play a vital role. Their main function is to amplify the weak echo signals received by the ultrasound probe to ensure that these signals can be effectively processed by subsequent circuits. Since the signals that need to be detected in ultrasound imaging are usually very weak, the LNA must have extremely low input equivalent noise to avoid introducing too much noise interference during the signal amplification process.

[0004] The design of traditional ultrasound analog front-end LNA often uses a transimpedance amplifier composed of a common source and a source follower, which is applied to piezoelectric ultrasonic transducers made of PZT materials, and its efficiency is low. The capacitive feedback amplifier based on the inverter structure amplifies the signal by inducing voltage, which is also convenient for impedance matching. However, the inverter structure LNA also has some significant defects, such as high noise, limited working bandwidth, and insufficient gain stability. In addition, when multiple performance indicators need to be met, the trade-off process of the traditional circuit design method is very time-consuming and inefficient. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems that traditional low-noise amplifiers in the prior art have large noise, limited operating bandwidth and insufficient gain stability, and the trade-off process of traditional circuit design methods is very time-consuming and inefficient when multiple performance indicators need to be met. A low-noise amplifier based on an inverter and a multi-objective optimization method thereof are provided.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention provides a low noise amplifier based on an inverter, comprising an inverter, an input capacitor C I , feedback capacitor C F and single-stage operational amplifiers;

[0008] The inverter is composed of a PMOS tube M P1 and NMOS tube M N1 The gates of the PMOS and NMOS tubes are connected in series, the drains are the output terminals, and the source of the PMOS tube is connected to the power supply V DD Connect the source of the NMOS tube to ground;

[0009] The input capacitor C I and feedback capacitor C F In parallel; the input capacitor C I is the capacitance C I1 and capacitor C I2 Series split capacitor structure; the signal input terminal is connected to capacitor C I1 and capacitor C I2 between; the input capacitor C I The two ends of the PMOS tube M are connected P1 The gate and NMOS tube M N1 The gate of the feedback capacitor C F is the capacitance C F1 and capacitor C F2 The series split capacitor structure, the output of the inverter is connected to the capacitor C F1 and capacitor C F2 between;

[0010] The positive input terminal of the single-stage operational amplifier is connected to the output terminal of the inverter, and the negative input terminal is connected to the reference voltage V REF The output end is connected to the resistor R2 and then to the NMOS tube M N1 The gate of PMOS tube M P1 The gate of the transistor is connected to a resistor R1, and the resistor R1 and the resistor R2 have the same resistance value.

[0011] Furthermore, the resistor R1 is connected to a PMOS tube M P2 , and PMOS tube M P2 The gate of the PMOS tube M P2 The source is connected to the power supply V DD ; The PMOS tube M P2 The drain of the PMOS tube M P2 The gate is connected.

[0012] Furthermore, the PMOS tube M P2 The drain terminal is connected with bias current.

[0013] A second aspect of the present invention provides a multi-objective optimization method for a low noise amplifier, comprising the following steps:

[0014] S1, determining design parameters, fitness functions and circuit constraints according to the circuit structure of the low noise amplifier and the target performance indicators to be optimized;

[0015] S2, based on the determined design parameters, performing simulation analysis on the circuit structure of the low noise amplifier to obtain a data set of the design parameters and corresponding target performance indicators under the circuit structure;

[0016] S3, training the neural network model based on the design parameters under the circuit structure and the corresponding target performance index data set to obtain a trained neural network model;

[0017] S4, based on the trained neural network model, fitness function and circuit constraints, the PSO-LDIW algorithm is used to find the optimal design parameters under the circuit structure.

[0018] Furthermore, the design parameters include the magnitude of the bias current, the magnitude of the input capacitance, the gate width of the NMOS tube in the inverter, the gate width of the PMOS tube in the inverter, and the gate length of the inverter.

[0019] Furthermore, the target performance indicators include open-loop voltage gain, bandwidth, total power consumption, noise and center frequency.

[0020] Further, the fitness function is described as:

[0021] min f(x)=α(A V -A V,TAR ) 2 +β(BW-BW TAR ) 2 +γ(P t -P t,TAR ) 2 +κ(Noise-Noise TAR ) 2 +η(C F -C F,TAR ) 2

[0022] Among them, A V is the open-loop voltage gain, BW is the bandwidth, P t is the total power consumption, Noise is the noise, C F Indicates the center frequency, A V,TAR Indicates the target value of the open-loop voltage gain, BW TAR Indicates the target value of bandwidth; P t,TAR Indicates the target value of total power consumption; Noise TAR represents the target value of noise; C F,TAR represents the target value of the center frequency; α, β, γ, η and κ are all weight coefficients.

[0023] Furthermore, the constraint conditions on the circuit are basic performance requirements for the operation of the low noise amplifier circuit.

[0024] Furthermore, the neural network model is a NN model.

[0025] Furthermore, based on the trained neural network model, fitness function and circuit constraints, the PSO-LDIW algorithm is used to find the optimal design parameters under the circuit structure, specifically:

[0026] Randomly generate a number of particles; each particle represents a set of design parameters;

[0027] Input each particle into the trained neural network model to obtain the corresponding target performance index;

[0028] Screen the particles based on the constraints of the circuit;

[0029] For the particles that have passed the screening, the fitness function is used to evaluate their fitness, and the position and speed of the particles are updated until the particles with the best fitness are found; and the best design parameters are obtained; the fitness function is obtained based on the target performance index.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention discloses a low noise amplifier based on an inverter, wherein a PMOS tube M P1 and NMOS tube M N1 The input capacitor C is connected in series to effectively balance the current and reduce the noise. This structure helps to provide low noise performance at the input, thereby improving the noise factor of the entire amplifier. I Adopt split capacitor structure (capacitor C I1 and capacitor C I2 This design can further reduce the noise interference at the input while maintaining the integrity of the signal, thereby further improving the noise performance of the LNA; the feedback capacitor C F The same split capacitor structure (capacitor C F1 and capacitor C F2 This design not only helps to stabilize the output of the amplifier, but also provides the required gain within a specific frequency range, so that the LNA can maintain good performance in a wide frequency band; the introduction of a single-stage operational amplifier enhances the gain capability of the circuit, and at the same time, through a reasonable negative feedback design, the stability of the amplifier is ensured, avoiding the occurrence of unstable phenomena such as self-oscillation; through the reasonable configuration of the symmetrical resistors R1 and R2, the frequency response characteristics of the amplifier can be adjusted, so that the LNA has a flat gain curve and a small phase distortion in the required frequency band.

[0032] The present invention discloses a multi-objective optimization method for a low noise amplifier. By determining design parameters, fitness functions and circuit constraints, efficient multi-objective optimization can be performed for a low noise amplifier based on an inverter. By using a detailed data set obtained by simulation analysis and combining it with a trained neural network model, the target performance indicators under different design parameters can be quickly predicted, thereby greatly shortening the design cycle and improving the design accuracy. The introduced PSO-LDIW (ParticleSwarm Optimization-Linear Decreasing Inertia Weight, linear decreasing inertia weight particle swarm optimization) algorithm can be based on a trained neural network model, while maintaining global search capabilities, through a local density optimization strategy, more accurately locate the optimal design parameter combination that meets all constraints. This not only improves the optimization efficiency, but also ensures the practicality and reliability of the optimization results. Through the implementation of multi-objective optimization, the method can effectively balance the key performance indicators of the low noise amplifier, such as gain, noise figure, linearity and power consumption, to achieve overall performance optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 This is a schematic diagram of the structure of a low noise amplifier circuit based on an inverter according to an embodiment of the present invention;

[0035] Figure 2 This is a flow chart of a method for optimizing a low noise amplifier according to an embodiment of the present invention;

[0036] Figure 3 The results of multiple runs of the low noise amplifier optimization method according to the embodiment of the present invention;

[0037] Figure 4 is the voltage gain of each frequency signal amplified by the low noise amplifier in a closed loop in the embodiment of the present invention;

[0038] Figure 5 This is a diagram showing the effect of amplifying pulse echo signals of different frequencies by a low noise amplifier in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described and marked in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0042] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0043] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0044] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0046] See also Figure 1 The present invention discloses a low noise amplifier based on an inverter, comprising an inverter, an input capacitor C I , feedback capacitor C F and DC control loop;

[0047] The inverter is composed of PMOS tube M P1 and NMOS tube M N1 The gates of the PMOS and NMOS tubes are connected in series, the drains are the output terminals, and the source of the PMOS tube is connected to the power supply V DD Connect the source of the NMOS tube to ground;

[0048] The input capacitor C I and feedback capacitor C F In parallel; the input capacitor C I is the capacitance C I1 and capacitor C I2 Series split capacitor structure; the signal input terminal is connected to capacitor C I1 and capacitor C I2 between; the input capacitor C I The two ends of the PMOS tube M are connected P1 The gate and NMOS tube M N1 The gate of the feedback capacitor C F is the capacitance C F1 and capacitor C F2 The series split capacitor structure, the output of the inverter is connected to the capacitor C F1 and capacitor C F2 between;

[0049] The DC control loop includes a single-stage operational amplifier, the positive input terminal of the single-stage operational amplifier is connected to the output terminal of the inverter, and the negative input terminal is connected to the reference voltage V REF The output end is connected to the resistor R2 and then to the NMOS tube M N1 The gate of PMOS tube M P1 The gate is connected to the resistor R1, and the resistor R2 has the same resistance as the resistor R1; for the device-matched CMOS inverter structure, the highest gain point is V DD / 2, and use the DC control loop to control the inverter output at V DD / 2, thus obtaining the highest gain. The DC control loop consists of a single-stage operational amplifier, with the positive input connected to the inverter output and the negative input connected to the reference voltage V REF , so that the output voltage V OUT =V REF , V REF =V DD / 2; the resistor R1 is connected to the PMOS tube M P2 , and PMOS tube MP2 The gate of the PMOS tube M P2 The source is connected to the power supply V DD ; The PMOS tube M P2 The drain of the PMOS tube M P2 The gate of the PMOS tube M P2 The drain of the device is connected to a bias current. B Make the DC operating point of the low noise amplifier stable. Small signal V IN When the bias current I B By C I Coupled to the gate of the inverter, the output voltage V OUT V IN The amplified voltage and the reference voltage V REF of superposition.

[0050] The present invention effectively optimizes the frequency response of the amplifier through the design of split capacitors, so that the gain is flatter within a specific frequency range, and at the same time reduces noise interference, improves the signal-to-noise ratio, and enables the amplifier to have a bandpass amplification effect, and further filters low-frequency and high-frequency noise; the DC control loop controls the output of the inverter to half of the power supply voltage VDD (VDD / 2), ensuring that the amplifier operates at the optimal operating point, thereby achieving the highest gain and the lowest noise coefficient; the single-stage operational amplifier of the DC control loop effectively stabilizes the output voltage of the amplifier through a negative feedback mechanism, and can maintain the stability of the output voltage even when the input signal fluctuates or the external environment changes, thereby enhancing the robustness of the amplifier; the introduction of resistors R1 and R2, and the symmetrical resistor R1 in the PMOS tube M P1 The connection of the gate further improves the symmetry and stability of the circuit, helps to reduce distortion and improve linearity.

[0051] See also Figure 2 The present invention discloses a multi-objective optimization method for a low noise amplifier, comprising the following steps:

[0052] S1. Determine the design parameters, fitness function and circuit constraints according to the circuit structure of the low noise amplifier and the target performance indicators that need to be optimized. The circuit constraints are the basic performance requirements for the circuit operation, including the requirements for the device size and the basic performance of the amplifier. The target performance indicators are the circuit performance corresponding to the various design parameters, which are obtained based on the actual needs of the ultrasound system. Based on the target performance indicators that need to be optimized, a fitness function is constructed according to the performance requirements to be achieved.

[0053] The design parameters of the low noise amplifier in this embodiment are:

[0054] x=[I B ,C I,L,W n ,W p ] (1)

[0055] Among them, I B is the bias current, C I is the input capacitance, L is the gate length of the inverter, W n is the gate width of the NMOS tube in the inverter, W p is the gate width of the PMOS tube in the inverter.

[0056] Fitness function:

[0057]

[0058] Constraints:

[0059]

[0060] Among them, A V is the open-loop voltage gain, BW is the bandwidth, P t is the total power consumption, Noise is the noise, C F Indicates the center frequency, A V,TAR Indicates the target value of the open-loop voltage gain, BW TAR Indicates the target value of bandwidth; P t,TAR Indicates the target value of total power consumption; Noise TAR represents the target value of noise; C F,TAR represents the target value of the center frequency; α, β, γ, η, and κ are all weight coefficients, and their sum is 1. In the constraint conditions, PM is the phase margin, SR is the slew rate, and V gs,N1 M N1 The gate-source voltage, V th,N1 M N1 The threshold voltage, V ds,N1 M N1 The drain-source voltage, V gs,P1 M P1 The gate-source voltage, V th,P1 M P1 The threshold voltage, V ds,P1 M P1 The drain-source voltage.

[0061] S2, based on the determined design parameters, performing simulation analysis on the circuit structure of the low noise amplifier to obtain a data set of the design parameters and corresponding target performance indicators under the circuit structure;

[0062] Based on the various design parameters under the circuit structure, the circuit of the low noise amplifier is simulated, and the data set of the design parameters under the circuit structure and the corresponding target performance indicators is used to generate training data; the neural network model is trained using the training data to obtain a trained neural network model.

[0063] The low noise amplifier circuit is simulated by Cadence to generate training data, and the NN model is trained with the simulated training data. The trained NN model can effectively describe the relationship between the design variables and the target performance indicators. The structure of the NN model is: input layer-hidden layer-output layer; the present invention establishes an NN model for each performance indicator, such as voltage gain, bandwidth, etc., so as to predict multiple performance indicators.

[0064] Each design parameter is input into the pre-trained neural network model to obtain the corresponding objective function.

[0065] S3, based on the trained neural network model, fitness function and circuit constraints, uses the PSO-LDIW (Particle Swarm Optimization-Linear Decreasing Inertia Weight) algorithm to find the optimal design parameters under the circuit structure; the PSO-LDIW algorithm adds inertia weight to PSO, and enhances the search capability and expands the search space by linearly reducing the inertia weight to find the global optimal solution.

[0066] In the particle swarm initialization phase, particles are randomly generated, and each particle represents a set of design parameters. Each particle is input into the trained NN model, and the target performance index is obtained through the trained NN model. At the same time, the particles are screened to see if they meet the constraints. The fitness of the particles that meet the constraints is evaluated, and the position and speed of the particles are updated until the particle with the best fitness is found, that is, the optimal design parameters are found.

[0067] The present invention determines the constraints of design parameters, fitness function and circuit, and provides clear direction and criteria for the optimization of low noise amplifier. The construction of fitness function fully considers the actual needs of ultrasound system, and ensures the practicality and pertinence of optimization target; the circuit structure is accurately simulated and analyzed by simulation tools such as Cadence, and a large number of reliable data sets of design parameters and target performance indicators are generated, which provides a basis for the training of neural network model; the relationship between design parameters and target performance indicators is modeled by using neural network model (NN model), and the rapid prediction of multiple performance indicators is realized. This model structure (input layer - hidden layer - output layer) is not only simple and efficient, but also has high prediction accuracy; by establishing an independent NN model for each performance indicator, the accuracy and flexibility of the prediction are further improved; based on the particle swarm optimization algorithm (PSO), the PSO-LDIW algorithm significantly enhances the search capability and expands the search space by introducing inertia weight and reducing it linearly, making it easier to find the global optimal solution. During the optimization process, the algorithm can efficiently screen particles that meet the constraints and evaluate them based on the fitness function, and finally find the optimal design parameters by continuously updating the position and speed of the particles; through the optimization method of the present invention, the low-noise amplifier has achieved significant improvements in multiple performance indicators such as voltage gain, bandwidth, power consumption, noise and center frequency, meeting the high-performance requirements of application scenarios such as ultrasound systems. At the same time, due to the use of efficient simulation analysis and optimization algorithms, the design cycle is greatly shortened.

[0068] An embodiment of the present invention provides a low noise amplifier, the parameters of which include but are not limited to the PMOS transistor M P1 Size, NMOS tube M N1 The size of the input capacitor C I The size of and the bias current are both designed using the above-mentioned low noise amplifier optimization method.

[0069] To demonstrate the superiority of the present invention, this embodiment evaluates the performance of the multi-objective optimization method for a low noise amplifier and a low noise amplifier based on an inverter, and the results are as follows:

[0070] See also Figure 3 , showing the results of running the multi-objective optimization method of the low noise amplifier of the present invention for 20 times, it can be seen that the fluctuations of the optimized indicators are very small, which shows that the present invention can stably find the optimal solution. Due to the small fluctuations, it can be considered that the multi-objective optimization method of the present invention can maintain a consistent optimization effect in multiple runs, thereby verifying its stability and reliability.

[0071] See also Figure 4, showing the closed-loop gain of the inverter-based low-noise amplifier of the present invention at different frequencies; it can be seen that the closed-loop gain of the inverter-based low-noise amplifier of the present invention is stable at about 20dB, which shows that the inverter-based low-noise amplifier of the present invention can maintain stable gain output at different frequencies. Stable gain output is crucial for signal amplification, especially in situations where precise amplification is required, such as amplification of ultrasonic pulse echo signals.

[0072] See also Figure 5 , showing the time domain and frequency domain effect diagrams of the signal amplification of the inverter-based low-noise amplifier of the present invention at different frequencies. It can be seen that the time domain signal is significantly amplified, which shows that the amplifier of the present invention can effectively enhance weak signals. IN (input voltage) and V OUT The normalized dB values ​​of (output voltage) are all overlapped above -6dB, which means that the amplifier has very little distortion and can maintain the original characteristics of the signal. Low distortion is one of the important indicators of amplifier performance, especially in situations where high-fidelity amplification is required. Figure 5 The results show that the amplifier can well maintain the original waveform and characteristics of the signal while amplifying the signal.

[0073] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low noise amplifier based on an inverter, characterized in that: Including inverter, input capacitor C I , feedback capacitor C F and single-stage operational amplifiers; The inverter is composed of a PMOS tube M P1 and NMOS tube M N1 The gates of the PMOS and NMOS tubes are connected in series, the drains are the output terminals, and the source of the PMOS tube is connected to the power supply V DD Connect the source of the NMOS tube to ground; The input capacitance C I and feedback capacitor C F In parallel; the input capacitor C I is the capacitance C I1 and capacitor C I2 Series split capacitor structure; the signal input terminal is connected to capacitor C I1 and capacitor C I2 between; the input capacitor C I The two ends of the PMOS tube M are connected P1 The gate and NMOS tube M N1 The gate of the feedback capacitor C F is the capacitance C F1 and capacitor C F2 The series split capacitor structure, the output of the inverter is connected to the capacitor C F1 and capacitor C F2 between; The positive input terminal of the single-stage operational amplifier is connected to the output terminal of the inverter, and the negative input terminal is connected to the reference voltage V REF The output end is connected to the resistor R2 and then to the NMOS tube M N1 The gate of PMOS tube M P1 The gate of the transistor is connected to a resistor R1, and the resistor R1 and the resistor R2 have the same resistance value.

2. The inverter-based low noise amplifier according to claim 1, characterized in that: The resistor R1 is connected to a PMOS tube M P2 , and PMOS tube M P2 The gate of the PMOS tube M P2 The source is connected to the power supply V DD ; The PMOS tube M P2 The drain of the PMOS tube M P2 The gate is connected.

3. The inverter-based low noise amplifier according to claim 2, characterized in that: The PMOS tube M P2 The drain of the device is connected with bias current.

4. A multi-objective optimization method for a low noise amplifier, based on the inverter-based low noise amplifier according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, determining design parameters, fitness functions and circuit constraints according to the circuit structure of the low noise amplifier and the target performance indicators to be optimized; S2, based on the determined design parameters, performing simulation analysis on the circuit structure of the low noise amplifier to obtain a data set of the design parameters and corresponding target performance indicators under the circuit structure; S3, training the neural network model based on the design parameters under the circuit structure and the corresponding target performance index data set to obtain a trained neural network model; S4, based on the trained neural network model, fitness function and circuit constraints, the PSO-LDIW algorithm is used to find the optimal design parameters under the circuit structure.

5. The multi-objective optimization method for a low noise amplifier according to claim 4, characterized in that: The design parameters include the magnitude of the bias current, the magnitude of the input capacitance, the gate width of the NMOS tube in the inverter, the gate width of the PMOS tube in the inverter and the gate length of the inverter.

6. The multi-objective optimization method for a low noise amplifier according to claim 4, characterized in that: The target performance indicators include open-loop voltage gain, bandwidth, total power consumption, noise and center frequency.

7. The multi-objective optimization method for a low noise amplifier according to claim 4, characterized in that: The fitness function is described as: min f(x)=α(A V -A V,TAR ) 2 +β(BW-BW TAR ) 2 +γ(P t -P t,TAR ) 2 +k(Noise-Noise TAR ) 2 +η(C F -c F,TAR ) 2 Among them, A V is the open-loop voltage gain, BW is the bandwidth, P t is the total power consumption, Noise is the noise, C F Indicates the center frequency, A V,TAR Indicates the target value of the open-loop voltage gain, BW TAR Indicates the target value of bandwidth; P t,TAR Indicates the target value of total power consumption; Noise TAR represents the target value of noise; C F,TAR represents the target value of the center frequency; α, β, γ, η and κ are all weight coefficients.

8. The multi-objective optimization method for a low noise amplifier according to claim 4, characterized in that: The constraints on the circuit are basic performance requirements for the operation of the low noise amplifier circuit.

9. The multi-objective optimization method for a low noise amplifier according to claim 4, characterized in that: The neural network model is a NN model.

10. The multi-objective optimization method for a low noise amplifier according to claim 4, characterized in that: Based on the trained neural network model, fitness function and circuit constraints, the PSO-LDIW algorithm is used to find the optimal design parameters under the circuit structure, specifically: Randomly generate a number of particles; each particle represents a set of design parameters; Input each particle into the trained neural network model to obtain the corresponding target performance index; Screen the particles based on the constraints of the circuit; For the particles that have passed the screening, the fitness function is used to evaluate their fitness, and the position and speed of the particles are updated until the particles with the best fitness are found; and the best design parameters are obtained; the fitness function is obtained based on the target performance index.

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