Miniaturized broadband band-pass filter design method based on transformer resonator and filter

Abstract

The invention discloses a miniaturized broadband band-pass filter based on a transformer resonator, a design method and a filter, relates to the technical field of filters, and solves the technical problem of low efficiency caused by complex design of an on-chip filter. The design method comprises the following steps: determining a target performance index of a filter based on an application demand, and converting a prototype of the filter into a coupling matrix; performing one-to-one mapping on each element in the coupling matrix and the physical structure parameters of the filter to obtain a transformer structure layout; importing the transformer structure layout into electromagnetic simulation software for electromagnetic simulation, and outputting a multi-port S parameter model; operating circuit simulation to obtain the overall frequency response of the filter circuit, and verifying the accuracy of the preliminary design; and obtaining a final physical layout of the filter until all the performance indexes meet the requirements. The mapping relation from the coupling matrix theory to the physical layout parameters is established, a large number of simulation iterations in traditional design are avoided, and the design efficiency and the success rate are improved.

Description

Technical Field

[0001] This invention relates to the field of filter technology, and in particular to a design method and filter for a miniaturized broadband bandpass filter based on a transformer resonator. Background Technology

[0002] With the rapid development of wireless communication technologies such as 5G mobile communication, radio frequency front-end systems are evolving towards high integration and low cost. System-on-chip (SoC) technology, which integrates passive components such as filters with active circuits on the same chip, has become the mainstream trend. While standard CMOS (Complementary Metal Oxide Semiconductor) technology is inexpensive and easy to integrate, its high-loss silicon substrate severely degrades the quality factor of passive components such as on-chip inductors, affecting the design of high-performance on-chip filters.

[0003] To achieve miniaturization in CMOS processes, transformer-based resonant units have emerged. This technology replaces discrete resonant inductors with transformer structures, helping to save chip area. However, limited by the low Q-factor of silicon substrates, the transformer coils themselves suffer from high losses, resulting in excessively high in-band insertion loss in the filter, affecting the signal quality of the entire communication system. Simultaneously, to improve the out-of-band rejection capability of the filter, cross-coupling needs to be introduced between the two transformer resonators to generate transmission zeros. However, this coupling is extremely sensitive to physical layout, requiring extensive and tedious electromagnetic simulations for iterative adjustments to precisely control the transmission zeros at the target frequency, leading to high design difficulty, long development cycles, and low success rates.

[0004] In the process of realizing this invention, the inventors discovered at least the following problems in the prior art: On-chip filter design is relatively complex, resulting in low efficiency and difficulty in meeting the requirements of modern communication systems for radio frequency front-end devices. Summary of the Invention

[0005] The purpose of this invention is to provide a miniaturized broadband bandpass filter based on a transformer resonator, along with its design method and the filter itself. This addresses the technical problem in existing technologies where on-chip filter design is complex, leading to low efficiency and difficulty in meeting the demands of modern communication systems for radio frequency front-end devices. The numerous technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a design method for a miniaturized broadband bandpass filter based on a transformer resonator. The design, based on a transformer resonator and a capacitor network, includes the following steps: S100: Determine the target performance indicators of the filter based on application requirements, obtain a standardized filter prototype using filter theory, and transform the prototype into a coupling matrix; S200: Map each element in the coupling matrix to the physical structure parameters of the filter, and draw a preliminary physical layout based on the mapping relationship to obtain the transformer structure layout; S300: Import the transformer structure layout into a three-dimensional full-wave electromagnetic simulation software for electromagnetic simulation, and output a multi-port S-parameter model; S400: Import the S-parameter model into a circuit simulation environment, connect the S-parameter model with capacitors and resistors to obtain the filter circuit, run the circuit simulation to obtain the overall frequency response of the filter circuit, and compare it with the target performance indicators to verify the accuracy of the preliminary design; S500: If there is a deviation between the simulation results and the target performance indicators, perform systematic iterative optimization until all performance indicators meet the requirements, and obtain the final physical layout of the filter.

[0007] Preferably, in step S100, the target performance indicators include passband range, in-band return loss, and out-of-band suppression requirements. The passband range is 3.3 GHz to 6 GHz, the in-band return loss is better than -15 dB, and the coupling matrix contains all the normalized coupling coefficient values ​​of the filter.

[0008] Preferably, in step S200, the coupling matrix is: M= , Wherein, the main coupling coefficient M12=M34=0.800, the interstage coupling coefficient M23=1.050, and the cross coupling coefficient M14=0.100; the main coupling coefficient is mapped to the mutual inductance between the primary and secondary coils inside each transformer, the interstage coupling coefficient is mapped to the capacitance value of the interstage coupling capacitor, and the cross coupling coefficient is mapped to the physical spacing between the primary coils of two transformer-type resonators.

[0009] Preferably, in step S200, the transformer layout is used to determine the shape, size, metal layers used, and key spacing of the coils.

[0010] Preferably, in step S300, electromagnetic simulation is performed on self-inductance, mutual inductance, parasitic capacitance, and substrate loss.

[0011] Preferably, in step S500, the iterative optimization method includes at least one of the following: if the center frequency is offset, the capacitance value of the parallel resonant capacitor is finely adjusted; if the passband bandwidth is mismatched, the capacitance value of the interstage coupling capacitor or the overlap size inside the transformer is adjusted; if the transmission zero point position is inaccurate, the cross coupling spacing between the two transformer-type resonators is adjusted.

[0012] A miniaturized broadband bandpass filter based on a transformer resonator is obtained through any of the above-described design methods for a miniaturized broadband bandpass filter based on a transformer resonator. The filter is a fully differential structure, including a dual-transformer resonator, a multi-path coupling network, and an on-chip capacitor network. The dual-transformer resonator includes a first dual-transformer resonator and a second dual-transformer resonator arranged symmetrically side-by-side, placed at the input and output stages of the signal path, respectively. The first dual-transformer resonator includes a primary coil L1 and a secondary coil L2, and the second dual-transformer resonator includes a primary coil L3 and a secondary coil L4. The multi-path coupling network includes a main path coupling path and a cross-coupling path. The on-chip capacitor network includes parallel resonant capacitors and interstage coupling capacitors. The parallel resonant capacitors and the coils of the dual-transformer resonator together form four resonant poles. The parallel resonant capacitors include capacitors C1, C2, C5, and C6, and the interstage coupling capacitors include capacitors C3 and C4.

[0013] Preferably, the two ends of the primary coil L1 are connected to the two plates of the capacitor C1; one end of the secondary coil L2 is connected to the first plates of capacitors C2 and C3, and the other end is connected to the second plates of capacitors C2 and C4; one end of the primary coil L3 is connected to the first plates of capacitors C5 and C3, and the other end is connected to the second plates of capacitors C5 and C4; the two ends of the secondary coil L4 are connected to the two plates of the capacitor C6.

[0014] Preferably, in the dual-transformer type resonator, the primary coil L1, primary coil L4, secondary coil L2, and secondary coil L3 are all inductive elements of the filter resonant network, and the secondary coil L2 and secondary coil L3 are respectively surrounding or nested inside or near the primary coil L1 and primary coil L4.

[0015] Preferably, in the main path coupling path, energy is coupled from the input end to the first dual-transformer resonator, and then transferred to the second dual-transformer resonator through the capacitors C3 and C4 before reaching the output end; the cross-coupling path is obtained by placing the primary coils L1 and L4 symmetrically side by side. By adjusting the distance between the two first dual-transformer resonators and the second dual-transformer resonator, the cross-coupling path introduces two transmission zeros in the filter response.

[0016] Implementing one of the above-described technical solutions of the present invention has the following advantages or beneficial effects: This invention establishes a clear mapping relationship from abstract coupling matrix theory to specific physical layout parameters of the filter. This method directly links key performance indicators such as filter bandwidth and zero-point location with physical dimensions such as coupling capacitor value and transformer spacing, accurately mapping abstract filter indicators to specific physical layouts. This avoids a large amount of blind simulation iteration in traditional design methods, improving design efficiency and success rate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a flowchart of a miniaturized broadband bandpass filter design method based on a transformer resonator according to Embodiment 1 of the present invention; Figure 2 This is a filter circuit diagram obtained from a miniaturized broadband bandpass filter design method based on a transformer resonator according to Embodiment 1 of the present invention. Figure 3 This is the overall layout of the filter drawn according to Embodiment 1 of the present invention, which describes a design method for a miniaturized broadband bandpass filter based on a transformer resonator. Figure 4 This is the simulation result of a miniaturized broadband bandpass filter based on a transformer resonator in the 1-10GHz range according to Embodiment 2 of the present invention; Figure 5 This is the simulation result of a miniaturized broadband bandpass filter based on a transformer resonator in an actual layout according to Embodiment 2 of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be used to implement the present invention. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of the present invention disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of the present invention.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "multiple" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] To illustrate the technical solution described in this invention, specific embodiments are described below, showing only the parts related to the embodiments of this invention.

[0021] Example 1: like Figure 1As shown, this invention provides a miniaturized broadband bandpass filter design method based on a transformer resonator. The design is based on a transformer-type resonator and a capacitor network; that is, the core of the filter is the transformer-type resonator and the capacitor network. The transformer itself can be considered as a resonant element in the filter. The method includes the following steps: S100: Determine the target performance indicators of the filter based on application requirements, obtain a standardized filter prototype based on filter theory, and transform this prototype into a coupling matrix. The coupling matrix contains all the standardized coupling coefficient values ​​of the filter, thus forming the theoretical blueprint for the entire filter design. S200: Map each element in the coupling matrix to the physical structure parameters of the filter one-to-one. Based on the mapping relationship, perform preliminary physical layout drawing, such as in the layout design tool Cadence Virtuoso (a complete analog / RF chip design platform that connects "circuit diagram → layout → simulation → approval"), to obtain the transformer structure layout, such as... Figure 2 As shown, the layout of the transformer-type resonator and capacitor is illustrated, with the overall layout area controlled within 500µm × 750µm (0.375mm²). S300: The transformer structure layout is imported into 3D full-wave electromagnetic simulation software (such as Keysight EMX, designed for efficient simulation design of on-chip passive devices (such as inductors, transmission lines, transformers, etc.), integrated into the Cadence electronic design automation environment, and supports foundry processes from TSMC, GLOBALFOUNDRY, UMC, etc.) for electromagnetic simulation. The electric / magnetic fields are transformed into S-parameters, current diagrams, and radiation diagrams, outputting a multi-port S-parameter model. S-parameters (scattering parameters) are standard mathematical models in the RF / microwave field describing the "multi-port incident-reflected-transmitted" behavior of linear networks. The voltage-current concept is converted into "incident wave a and reflected wave b," thus matching a 50Ω instrument environment. This model file constitutes an accurate digital model of the transformer structure. S400: Import the S-parameter model into a circuit simulation environment (such as Keysight ADS, an electronic design automation (EDA) software platform developed by Keysight Technologies, mainly used for the design and simulation of high-frequency and high-speed digital physical layer components). Connect the S-parameter model with capacitors (MOM capacitors, i.e., metal-oxide-metal in CMOS technology, thus ensuring on-chip integration) and resistors (50Ω value) to obtain the filter circuit, such as... Figure 3As shown, the capacitance and inductance values ​​are calculated based on the coupling synthesis matrix, and a circuit diagram composed of ideal components is built in Keysight ADS. Circuit simulation is run to obtain the overall frequency response of the filter circuit (such as the S(2,1) parameters describing transmission and the S(1,1) parameters describing reflection), and this response is compared with the target performance indicators to verify the accuracy of the preliminary design. Figure 4 As shown, S(2,1) and S(1,1) perform well within the 3.3GHz-6GHz band, while generating transmission zeros in the out-of-band 1-3GHz and 7-10GHz ranges, demonstrating excellent suppression capabilities in these two bands. Figure 5 As shown, after considering the actual transformer-type resonator and capacitor, even under standard CMOS technology, the in-band insertion loss of the filter can still be controlled at around 4dB, and no significant frequency offset appears at the out-of-band transmission zeros, indicating good out-of-band suppression. S500: If the simulation results deviate from the target performance indicators, systematic iterative optimization is performed. Due to the clear parameter mapping relationship in step S200, this optimization process is efficient and goal-oriented. Through a few targeted adjustments and simulation verifications, the filter performance can quickly converge to the target until all performance indicators meet the requirements, resulting in the final physical layout of the filter. This invention establishes a clear mapping relationship from abstract coupling matrix theory to specific physical layout parameters of the filter. This method directly correlates key performance indicators such as filter bandwidth and zero-point location with physical dimensions such as coupling capacitor values ​​and transformer spacing, accurately mapping abstract filter indicators to specific physical layouts. This avoids a large amount of blind simulation iteration in traditional design methods, improving design efficiency and success rate.

[0022] As an optional implementation, in step S100, the target performance indicators include passband range (the frequency range in which the signal passes through with essentially no loss) and in-band return loss (the port reflection coefficient |S_n| within the passband range). 11 | The forced suppression (how many dB) and out-of-band suppression requirements (how many dB of energy is outside the passband range), the passband range is 3.3 GHz to 6 GHz, the in-band return loss is better than -15 dB, the coupling matrix contains all the standardized coupling coefficient values ​​of the filter, the coupling coefficient value is a quantitative indicator that measures the degree of energy coupling or mutual influence between two systems or components.

[0023] As an optional implementation, in step S200, the coupling matrix is: M= , Among them, the main coupling coefficient M12=M34=0.800, the interstage coupling coefficient M23=1.050, and the cross coupling coefficient M14=0.100. The main coupling coefficient is mapped to the mutual inductance between the primary and secondary coils inside each transformer, and its value is mainly determined by the overlap and geometry between the coils. The interstage coupling coefficient is mapped to the capacitance value of the interstage coupling capacitors (capacitor C3, capacitor C4), and the cross coupling coefficient is mapped to the physical spacing between the primary coils of two transformer-type resonators. Cross coupling is used to generate transmission zeros. Transmission zeros are complex frequency points that make the system transfer function zero, that is, some frequency components are completely suppressed or blocked and cannot be transmitted from the input to the output.

[0024] As an optional implementation, in step S200, the transformer layout is used to determine the shape, size, metal layers used (usually a top layer of thick metal with a high Q value) and key spacing of the coils.

[0025] As an optional implementation, in step S300, electromagnetic simulation is performed on self-inductance, mutual inductance, parasitic capacitance and substrate loss, that is, the electromagnetic simulation will take into account all electromagnetic effects.

[0026] As an optional implementation, in step S500, the iterative optimization method includes at least one of the following: if the center frequency is offset, the capacitance values ​​of the parallel resonant capacitors (capacitors C1, C2, C5, and C6) are finely adjusted; if the passband bandwidth is mismatched, the capacitance values ​​of the interstage coupling capacitors (capacitors C3 and C4) or the overlap size inside the transformer are adjusted; if the transmission zero point position is inaccurate, the cross-coupling spacing between the two transformer-type resonators is adjusted.

[0027] The embodiment is merely a specific example and does not indicate that this is the only way to implement the present invention.

[0028] Example 2: A miniaturized broadband bandpass filter based on a transformer resonator is obtained through the design method of a miniaturized broadband bandpass filter based on a transformer resonator in Embodiment 1. The filter has a fully differential structure, including a dual-transformer resonator, a multi-path coupling network, and an on-chip capacitor network. The dual-transformer resonator includes a first dual-transformer resonator and a second dual-transformer resonator arranged symmetrically side by side, which facilitates a compact layout and places them in the input and output stages of the signal path, respectively. Under specific application or layout constraints, an asymmetrical transformer resonator structure can also be used. For example, the transformers in the input and output stages can have different inductance values ​​to achieve specific impedance matching or response. The first dual-transformer resonator includes a primary coil L1 and a secondary coil L2, and the second dual-transformer resonator includes a primary coil L3 and a secondary coil L4. Unlike traditional filters that use multiple independent inductors, the transformer coils in this invention also serve as inductor elements of the resonant network, greatly saving chip area. The multi-path coupling network includes main path coupling paths and cross-coupling paths; the on-chip capacitor network includes parallel resonant capacitors and interstage coupling capacitors. The parallel resonant capacitors, together with the coils of the dual-transformer resonator, form four resonant poles, realizing a fourth-order filter and determining the filter's center frequency and bandwidth. The parallel resonant capacitors include capacitors C1, C2, C5, and C6, and the interstage coupling capacitors include capacitors C3 and C4. All of these capacitors are fixed capacitors. By precisely controlling the interstage coupling capacitors, a wide operating bandwidth covering 3.3GHz to 6GHz is achieved, meeting the application requirements of multiple key frequency bands such as 5G NR n77 / n78 / n79. Alternatively, the fixed capacitors in the filter, especially the parallel resonant capacitors that determine the center frequency, can be replaced with variable capacitors. By applying an external DC control voltage, the capacitance values ​​of these variable capacitors can be changed, thereby achieving tuning of the filter's center frequency. This allows a single filter to adapt to different communication standards or operating scenarios, greatly improving the filter's application flexibility and value. For applications requiring higher out-of-band rejection performance, the structure of this invention can be extended to a sixth- or eighth-order filter. For example, this can be achieved by cascading three or four transformer-type resonators and introducing cross-coupling between non-adjacent resonators, thereby obtaining a greater number of transmission zeros and a steeper roll-off characteristic. This invention effectively utilizes the natural electromagnetic field interaction between two symmetrically placed dual-transformer-type resonators. By controlling the physical spacing between them, a cross-coupling path is directly formed in the layout, not only stably generating the transmission zeros required for improved performance but also simplifying complex circuit functions into an intuitive geometric layout problem. A fourth-order filter traditionally requires at least four independent inductors and resonant capacitors. This invention achieves the complex function of a fourth-order filter with cross-coupling using only two transformers and four capacitors, significantly reducing chip area and achieving high-efficiency device miniaturization.According to the simulation design of this invention, under the 65nm CMOS process, the core area of ​​the entire filter is controlled within 500µm×750µm (0.375mm²). Compared with existing CMOS filters that achieve similar functions (whose area is usually between 0.5mm² and 1.0mm²), the area efficiency is improved by more than 30%, saving a lot of manufacturing costs and chip space.

[0029] As an optional implementation, the two ends of the primary coil L1 are connected to the two plates of capacitor C1; one end of the secondary coil L2 is connected to the first plate of capacitor C2 and the first plate of capacitor C3, and the other end is connected to the second plate of capacitor C2 and the first plate of capacitor C4; one end of the primary coil L3 is connected to the first plate of capacitor C5 and the second plate of capacitor C3, and the other end is connected to the second plate of capacitor C5 and the second plate of capacitor C4; the two ends of the secondary coil L4 are connected to the two plates of capacitor C6.

[0030] As an optional implementation, in the dual-transformer resonator, the primary coils L1 and L4, and the secondary coils L2 and L3 simultaneously serve as inductor elements in the filter resonant network. The secondary coils L2 and L3 are respectively nested or surrounded within or near the primary coils L1 and L4. By embedding the secondary coils within or near the primary coils on the layout, integrating resonance and coupling functions into a very small physical space, this is key to achieving extreme miniaturization of the filter, significantly improving chip area utilization efficiency, and representing an improvement over traditional discrete component filter layouts.

[0031] As an optional implementation, in the main path coupling path, energy is coupled from the input to the first dual-transformer resonator, then transferred through capacitors C3 and C4 to the second dual-transformer resonator before reaching the output. This path determines the basic passband characteristics of the filter. The cross-coupling path is obtained by placing primary coils L1 and L4 symmetrically side by side. By adjusting the distance between the two first and second dual-transformer resonators, the cross-coupling path introduces two transmission zeros into the filter response, located on the low-frequency side (1GHz-3GHz) and high-frequency side (7GHz-10GHz) of the passband, respectively. This creates a notch in the stopband, greatly enhancing out-of-band rejection and the filter's roll-off steepness. Cross-coupling can also be achieved through capacitive coupling. Specifically, a small bridging capacitor is added between the input and output stages of the filter. By precisely designing the capacitance value, transmission zeros can also be introduced in the stopband, achieving the purpose of enhancing out-of-band rejection and improving selectivity.

[0032] The above description is merely a preferred embodiment of the present invention. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A design method for a miniaturized broadband bandpass filter based on a transformer resonator, characterized in that, The design based on a transformer-type resonator and capacitor network includes the following steps: S100: Determine the target performance indicators of the filter based on application requirements, obtain a standardized filter prototype by combining filter theory, and transform the filter prototype into a coupling matrix. S200: Map each element in the coupling matrix to the physical structure parameters of the filter one by one, and draw a preliminary physical layout based on the mapping relationship to obtain the transformer structure layout. S300: Import the transformer structure layout into the 3D full-wave electromagnetic simulation software for electromagnetic simulation and output a multi-port S-parameter model. S400: Import the S-parameter model into the circuit simulation environment, connect the S-parameter model with capacitors and resistors to obtain the filter circuit, run the circuit simulation to obtain the overall frequency response of the filter circuit, and compare it with the target performance index to verify the accuracy of the preliminary design. S500: If the simulation results deviate from the target performance indicators, systematic iterative optimization is performed until all performance indicators meet the requirements, and then the final physical layout of the filter is obtained.

2. The design method for a miniaturized broadband bandpass filter based on a transformer resonator according to claim 1, characterized in that, In step S100, the target performance indicators include passband range, in-band return loss, and out-of-band suppression requirements. The passband range is 3.3 GHz to 6 GHz, the in-band return loss is better than -15 dB, and the coupling matrix contains all the normalized coupling coefficient values ​​of the filter.

3. The design method for a miniaturized broadband bandpass filter based on a transformer resonator according to claim 1, characterized in that, In step S200, the coupling matrix is: M= ， Wherein, the main coupling coefficient M12=M34=0.800, the interstage coupling coefficient M23=1.050, and the cross coupling coefficient M14=0.100; the main coupling coefficient is mapped to the mutual inductance between the primary and secondary coils inside each transformer, the interstage coupling coefficient is mapped to the capacitance value of the interstage coupling capacitor, and the cross coupling coefficient is mapped to the physical spacing between the primary coils of two transformer-type resonators.

4. The design method for a miniaturized broadband bandpass filter based on a transformer resonator according to claim 1, characterized in that, In step S200, the transformer layout is used to determine the shape, size, metal layers used, and key spacing of the coils.

5. The design method for a miniaturized broadband bandpass filter based on a transformer resonator according to claim 1, characterized in that, In step S300, electromagnetic simulations are performed on self-inductance, mutual inductance, parasitic capacitance, and substrate loss.

6. The design method for a miniaturized broadband bandpass filter based on a transformer resonator according to claim 1, characterized in that, In step S500, the iterative optimization method includes at least one of the following: if the center frequency is offset, fine-tune the capacitance value of the parallel resonant capacitor; if the passband bandwidth is mismatched, adjust the capacitance value of the interstage coupling capacitor or the overlap size inside the transformer; if the transmission zero point position is inaccurate, adjust the cross-coupling spacing between the two transformer-type resonators.

7. A miniaturized broadband bandpass filter based on a transformer resonator, characterized in that, The miniaturized broadband bandpass filter based on a transformer resonator is obtained through any one of claims 1-6. The filter is a fully differential structure, including a dual transformer resonator, a multipath coupling network, and an on-chip capacitor network. The dual-transformer resonator includes a first dual-transformer resonator and a second dual-transformer resonator arranged symmetrically side-by-side, placed at the input and output stages of the signal path, respectively. The first dual-transformer resonator includes a primary coil L1 and a secondary coil L2, and the second dual-transformer resonator includes a primary coil L3 and a secondary coil L4. The multi-path coupling network includes a main path coupling path and a cross-coupling path. The on-chip capacitor network includes parallel resonant capacitors and interstage coupling capacitors. The parallel resonant capacitors and the coils of the dual-transformer resonator together form four resonant poles. The parallel resonant capacitors include capacitors C1, C2, C5, and C6, and the interstage coupling capacitors include capacitors C3 and C4.

8. A miniaturized broadband bandpass filter based on a transformer resonator according to claim 7, characterized in that, The two ends of the primary coil L1 are connected to the two plates of the capacitor C1; one end of the secondary coil L2 is connected to the first plate of capacitor C2 and the first plate of capacitor C3, and the other end is connected to the second plate of capacitor C2 and the first plate of capacitor C4; one end of the primary coil L3 is connected to the first plate of capacitor C5 and the second plate of capacitor C3, and the other end is connected to the second plate of capacitor C5 and the second plate of capacitor C4; the two ends of the secondary coil L4 are connected to the two plates of the capacitor C6.

9. A miniaturized broadband bandpass filter based on a transformer resonator according to claim 7, characterized in that, In the dual-transformer type resonator, the primary coil L1, primary coil L4, secondary coil L2, and secondary coil L3 are all inductive elements of the filter resonant network. The secondary coil L2 and secondary coil L3 are respectively surrounding or nested inside or near the primary coil L1 and primary coil L4.

10. A miniaturized broadband bandpass filter based on a transformer resonator according to claim 7, characterized in that, In the main path coupling path, energy is coupled from the input end to the first dual-transformer resonator, and then transferred to the second dual-transformer resonator through the capacitors C3 and C4 before reaching the output end; the cross-coupling path is obtained by placing the primary coils L1 and L4 symmetrically side by side. By adjusting the distance between the two first dual-transformer resonators and the second dual-transformer resonator, the cross-coupling path introduces two transmission zeros in the filter response.

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