Three-stage coupling filter integrated with external band rejection ratio enhancement circuit

Abstract

The utility model relates to the technical field of wireless communication, in particular to a three-stage coupling filter integrated with an external band rejection ratio enhancement circuit, which comprises a three-stage coupling resonator used for acquiring an external signal and processing the external signal to obtain a resonance signal; the adjustable resonance circuit based on the PID algorithm is used for performing center frequency dynamic offset compensation on the resonance signal and outputting an actual sensing signal and a frequency detection signal; the PID algorithm controller is used for acquiring an expected value of the sensing signal and an actual sensing signal and calculating a control signal based on a PID algorithm, and the control signal is used for performing center frequency dynamic offset compensation on the resonance signal; according to the utility model, the complex radio frequency performance requirement is disassembled into a multi-stage structure to be realized step by step, so that the engineering problem that the traditional single-stage / simple cascade structure cannot meet the requirements of broadband, high suppression, adjustability and stability at the same time is solved, and the multi-stage structure is particularly suitable for scenes with strict requirements on electromagnetic compatibility and environmental adaptability in multiple fields.

Description

Technical Field

[0001] This utility model relates to the field of wireless communication technology, specifically to a three-stage coupling filter with integrated out-of-band rejection ratio enhancement circuit. Background Technology

[0002] Filters are used to select the frequency of signals and are widely used in wireless communication technology.

[0003] In real-world scenarios, interference signals can cover an extremely wide frequency band. Traditional filters are typically designed for interference in a single application frequency band, making it difficult to suppress interference in multiple bands simultaneously. This causes interference signals to leak into the passband, leading to op-amp saturation or ADC overload. Furthermore, the amplitude of the interference signal may change dynamically, further impacting system performance.

[0004] Existing filters generally suffer from insufficient out-of-band interference suppression capability and limited dynamic range in complex environments. Utility Model Content

[0005] In view of this, the present invention discloses a three-stage coupled filter with an integrated out-band rejection ratio enhancement circuit to solve the above problems; comprising:

[0006] A three-stage coupled resonator is used to acquire and process external signals to obtain a resonant signal.

[0007] An adjustable resonant circuit based on PID algorithm is used to perform dynamic offset compensation of the center frequency of the resonant signal and output the actual sensing signal and the frequency detection signal.

[0008] The PID algorithm controller is used to obtain the expected value and the actual sensing signal of the sensing signal, and calculate the control signal based on the PID algorithm. The control signal is used to perform dynamic offset compensation of the center frequency of the resonant signal.

[0009] The beneficial effects of this utility model include:

[0010] By using a three-stage resonator cascade approach, the functional structure is layered, and the complex RF performance requirements are broken down into multi-stage structures to achieve them step by step. This solves the engineering problem that traditional resonators cannot simultaneously meet the requirements of wide bandwidth, high suppression, tunability, and stability. It is especially suitable for scenarios with stringent requirements for electromagnetic compatibility and environmental adaptability in multiple fields.

[0011] By constructing an adjustable resonant circuit using varactor diodes and controlling the adjustable resonant circuit based on a PID algorithm, ±5% dynamic offset compensation of the center frequency is achieved, solving the problem of limited dynamic range in complex environments. Attached Figure Description

[0012] Figure 1This is a schematic diagram of the adjustable resonant circuit based on the PID algorithm in this utility model;

[0013] Figure 2 This is a schematic diagram of the PID algorithm controller and the adjustable resonant circuit based on the PID algorithm in this utility model. Detailed Implementation

[0014] To make the objectives, technical solutions, features and advantages of this utility model clearer, the following description, in conjunction with the accompanying drawings and embodiments, will further illustrate this utility model.

[0015] This embodiment includes a three-stage coupled filter with an integrated out-band rejection ratio enhancement circuit, such as... Figure 1 As shown, it includes: a three-stage coupled resonator, an adjustable resonant circuit based on a PID algorithm, and a PID algorithm controller.

[0016] Specifically, the three-stage coupled resonator is used to acquire and process external signals to obtain a resonant signal, including:

[0017] The first resonator is used to acquire external signals and perform preliminary resonance on the external signals to obtain preliminary resonant signals.

[0018] The second resonator is used to cross-couple the initial resonant signal to obtain a multimode signal.

[0019] The third resonator is used to shape and suppress out-of-band signals of multimode signals to obtain resonant signals.

[0020] In this embodiment, the first resonator and the second resonator transfer energy through interdigital coupling. The electrodes of the two resonators are arranged in an interdigital pattern, and energy transfer is achieved based on the interaction of electric fields. When an external signal is received, the first resonator generates an alternating electric field, and the second resonator senses the change in its electric field. Based on electromagnetic induction, energy is coupled from the first resonator to the second resonator. In this embodiment, the interdigital coupling uses five pairs of electrodes with an electrode width of 5-10 μm, an electrode spacing of 3-8 μm, and an electrode length of 100-200 μm. The electrodes form a coupling capacitor with a capacitance of 0.5-2 pF to achieve efficient transfer of electric field energy in the 0.8-2 GHz frequency band.

[0021] The second and third resonators are connected in the circuit through a JK impedance inverter with a microstrip line structure. By utilizing the characteristics of the transmission line, impedance matching and energy transfer are achieved, which can improve the out-of-band rejection to more than 30dB. It also has the advantages of compact structure, easy integration and strong phase compensation adaptability.

[0022] The selected microstrip line has a length of λ / 4, where λ represents the wavelength of the electromagnetic wave in the microstrip line medium. The width is 5–10 μm, and the characteristic impedance is 50 Ω. The characteristic impedance Z = 50 Ω. Phase compensation is achieved through a parallel capacitor of 0.3–0.8 pF, which improves the out-of-band rejection to ≥40 dB at ±10% of the center frequency. The electromagnetic field of the microstrip line is distributed in the space around the microstrip line and interacts with the electromagnetic fields in the two resonators, generating corresponding currents and charges in the resonators. Through electromagnetic coupling, the signal is transmitted between the second and third resonators.

[0023] The third resonator adjusts the phase and amplitude of the multimode signal through a coupled JK impedance inverter. Utilizing the impedance transformation characteristics of the JK impedance inverter, the output impedance of the second resonator is transformed into a form that matches the input impedance of the third resonator, thereby achieving effective impedance matching between the two resonators. During the matching process, the phase and amplitude of the signal are adjusted to complete the shaping and out-of-band suppression of the multimode signal.

[0024] Furthermore, the other end of the first resonator serves as the input of the three-stage coupled resonator, and the other end of the third resonator serves as the output of the three-stage coupled resonator.

[0025] Furthermore, the adjustable resonant circuit based on the PID algorithm is connected to a three-stage coupled resonator to perform dynamic offset compensation of the center frequency of the resonant signal and output a frequency detection signal.

[0026] Specifically, such as Figure 1 As shown, the adjustable resonant circuit based on the PID algorithm includes the following components: three varactor diodes VD1 to VD3, two capacitors C1 and C2, and three resistors R1 to R3; the connection method is as follows:

[0027] The input terminal of the three-stage coupled resonator is connected to one end of R1. The output terminal of the three-stage coupled resonator is connected to one end of C1, one end of C2, and the positive terminal of VD2 respectively; the negative terminal of VD2 is grounded. The other end of C1 is connected to the negative terminal of VD1 and one end of R2 respectively; the positive terminal of VD1 is grounded. The other end of C2 is connected to the negative terminal of VD3 and one end of R3 respectively; the positive terminal of VD3 is grounded.

[0028] Furthermore, the other end of R1 serves as the input terminal of the adjustable resonant circuit, the other end of R2 serves as the first output terminal of the adjustable resonant circuit, and the other end of R3 serves as the second output terminal of the adjustable resonant circuit.

[0029] like Figure 2As shown, the first output terminal is connected to the input terminal through a PID algorithm controller. During the detection process, the first output terminal outputs the actual sensing signal of the filter. The PID algorithm controller obtains the expected value of the filter detection signal and calculates the deviation value between the actual sensing signal and the expected value. It calculates the deviation value according to the proportional, integral, and derivative functional relationship and outputs a control signal to the input terminal of the adjustable resonant circuit. The adjustable resonant circuit adjusts the capacitance of the varactor diode according to the control signal and outputs a frequency detection signal at the second output terminal.

[0030] The three-stage coupling filter with integrated out-of-band rejection ratio enhancement circuit in this invention operates in the frequency band of 30MHz to 6GHz.

[0031] The first, second, and third resonators all employ a resonator based on DRIE etching of the air gap and SiO2 passivation layer technology.

[0032] Specifically, the air gap structure parameters are as follows: the DRIE etched air gap height is 2-5 μm, the sidewall verticality is ≥89°, and the bottom roughness of the air gap is ≤5 nm, which is used to reduce acoustic energy leakage and improve the resonator quality factor Q value to 1500-3000; the interdigital coupling structure uses photolithography etching process (ultraviolet / electron beam lithography + dry etching) to process the AlN piezoelectric layer and Au / Al electrode, and forms the air gap through sacrificial layer technology (photoresist) to realize the transfer of electric field energy.

[0033] The JK impedance inverter between the second and third resonators employs a radio frequency microstrip line process based on a combination of photolithography and electroplating. By fabricating Cu / Au microstrip lines on a high-resistivity silicon / LTCC substrate, combining MIM capacitors, and integrating a SiO2 dielectric layer, 50Ω impedance matching and phase compensation are achieved. The resonator obtained based on the above process satisfies out-of-band rejection ≥40dB and insertion loss <1.8dB.

[0034] Furthermore, this invention reduces spurious radiation by 15 dBμV / m in the 6 GHz band, meeting the electromagnetic shielding requirements of UAV-borne equipment; and in an environment of -40℃ to 125℃, the frequency drift is <0.1%, which is better than the <0.5% requirement of the GR-468-CORE standard.

[0035] Finally, it should be noted that the above description only depicts some embodiments of the present utility model. For those skilled in the art, it is conceivable that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present utility model. The protection scope of the present utility model is defined by the appended claims and their equivalents, and all the above-mentioned behaviors should be covered within the protection scope of the present utility model.

Claims

1. A three-stage coupled filter with an integrated out-of-band rejection ratio enhancement circuit, characterized in that, include: A three-stage coupled resonator is used to acquire and process external signals to obtain a resonant signal. A three-stage coupled resonator includes: The first resonator is used to acquire an external signal and perform preliminary resonance on the external signal to obtain a preliminary resonant signal; The second resonator is used to cross-couple the initial resonant signal to obtain a multimode signal; The third resonator is used to shape and suppress out-of-band signals of multimode signals to obtain resonant signals; An adjustable resonant circuit based on PID algorithm is used to perform dynamic offset compensation of the center frequency of the resonant signal and output the actual sensing signal and the frequency detection signal. The PID algorithm controller is used to obtain the expected value and the actual sensing signal of the sensing signal, and calculate the control signal based on the PID algorithm. The control signal is used to perform dynamic offset compensation of the center frequency of the resonant signal.

2. The three-stage coupled filter with integrated out-of-band rejection ratio enhancement circuitry according to claim 1, characterized in that, The first resonator, the second resonator, and the third resonator are cascaded and coupled in sequence. One end of the first resonator is coupled to one end of the second resonator by interdigital coupling, and the other end of the second resonator is connected to one end of the third resonator by a JK impedance inverter with a microstrip line structure. The other end of the first resonator serves as the input of the three-stage coupled resonator, and the other end of the third resonator serves as the output of the three-stage coupled resonator.

3. The three-stage coupled filter with integrated out-of-band rejection ratio enhancement circuitry according to claim 2, characterized in that, The interdigital coupling uses at least 5 pairs of staggered electrodes with an electrode width of 5~10μm, an electrode spacing of 3~8μm, and an electrode length of 100~200μm; The electrodes form coupling capacitors with a capacitance of 0.5~2pF.

4. The three-stage coupled filter with integrated out-of-band rejection ratio enhancement circuitry according to claim 2, characterized in that, The JK impedance inverter with a microstrip line structure has a microstrip line length of λ / 4, where λ represents the wavelength of the electromagnetic wave in the microstrip line medium, a microstrip line width of 5~10μm, and a microstrip line characteristic impedance of 50Ω.

5. The three-stage coupled filter with integrated out-of-band rejection ratio enhancement circuitry according to claim 1, characterized in that, The first, second, and third resonators are resonators based on DRIE etching of the air gap and SiO2 passivation layer technology.

6. The three-stage coupled filter with integrated out-band rejection ratio enhancement circuitry according to claim 1, characterized in that, The components include: three varactor diodes VD1~VD3, two capacitors C1 and C2, and three resistors R1~R3. The connection method is as follows: one end of R1 is connected to the input terminal of the three-stage coupled resonator, and the output terminal of the three-stage coupled resonator is connected to one end of C1, one end of C2, and the positive terminal of VD2 respectively; the negative terminal of VD2 is grounded; the other end of C1 is connected to the negative terminal of VD1 and one end of R2 respectively; the positive terminal of VD1 is grounded; the other end of C2 is connected to the negative terminal of VD3 and one end of R3 respectively; the positive terminal of VD3 is grounded.

7. The three-stage coupled filter with integrated out-of-band rejection ratio enhancement circuitry according to claim 6, characterized in that, The other end of R1 serves as the input terminal of the adjustable resonant circuit, the other end of R2 serves as the first output terminal of the adjustable resonant circuit, and the other end of R3 serves as the second output terminal of the adjustable resonant circuit.

8. The three-stage coupled filter with integrated out-of-band rejection ratio enhancement circuitry according to claim 1, characterized in that, The three-stage coupling filter operates in the frequency band of 30MHz to 6GHz.

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