Quasi-lumped parameter high-intermodulation broadband isolator

Abstract

The invention discloses a quasi-lumped parameter high-intermodulation broadband isolator which comprises ferrite, a matching medium, a nonreciprocal junction, a winding inductor, a microstrip circuit, a ceramic substrate, a load and an iron cavity. The circuit center covers the whole ferrite, so that the high-frequency tangential magnetic field component on the surface of the ferrite is greatly reduced, and the intermodulation performance of the device is improved; matching of a non-reciprocal junction NRJ is realized through a mode of connecting an inductor in series and connecting a capacitor in parallel, and a broadband effect is achieved. The parallel-to-ground capacitor is realized by using a microstrip transmission line, so that the investment of a capacitor element is reduced; the inductor adopts a winding coil with a high Q value, so that the loss effect is reduced; in order to solve the problem of pure circular non-reciprocal junction parasitic harmonics, an external matching circuit is designed into a structure of a three-stage elliptic function low-pass filter circuit, so that the effect of harmonic suppression is achieved.

Description

Technical Field

[0001] The present invention relates to the field of isolators, and in particular to a quasi-lumped parameter high intermodulation broadband isolator. Background Art

[0002] With the development of broadband and high-demand RF communication systems, the RF front-end has increasingly stringent requirements for isolators. In the field of RF isolators, comprehensive requirements such as high intermodulation performance, broadband, and harmonic suppression have brought new challenges to isolator design.

[0003] In isolator design, device parameters such as bandwidth, intermodulation performance, and harmonic suppression are all related to the ferrite material, circuit structure, and internal field value design used in the device, and they influence each other to a certain extent. Especially in the P-band, isolators with high intermodulation performance generally only have a bandwidth of 5-8%. When the bandwidth is widened, the intermodulation value will decrease.

[0004] The high intermodulation isolator designed using the low current density method achieves a 20% operating bandwidth in the P-band while achieving very high intermodulation performance. However, due to the overly flat structure of the circuit center, it brings new problems such as harmonic parasitics. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes a quasi-lumped parameter high intermodulation broadband isolator.

[0006] A quasi-lumped parameter high intermodulation broadband isolator includes a ferrite, a matching medium, a non-reciprocal junction, a winding inductor, a microstrip circuit, a ceramic substrate, a load, and an iron cavity; The ferrite is covered by the center of the circular circuit, and the periphery is sequentially provided with a matching medium, a non-reciprocal junction, and an iron cavity; The load is arranged on a ceramic substrate on which a microstrip circuit is printed; A ceramic substrate is provided outside the iron cavity, and the non-reciprocal junction and the microstrip circuit of the ceramic substrate are interconnected by wire-wound inductive welding; The microstrip circuits on the ceramic substrate are interconnected by wire-wound inductive welding.

[0007] Among them, the load converts electrical energy into other forms of energy; Wherein, the load is connected to the microstrip circuit; The matching medium is ceramic with a dielectric constant of 30.

[0008] Furthermore, a quasi-lumped parameter high intermodulation broadband isolator further includes a magnet, a ground plate, a temperature patch, and a cover plate; The iron cavity comprises a magnet, a ground plate, a ferrite, a non-reciprocal junction, a ferrite, a ground plate, a magnet, a temperature patch and a cover plate from bottom to top; Among them, the central circuit structure is circular and is composed of the above components; The grounding plate includes a magnetic sheet.

[0009] Furthermore, in a quasi-lumped parameter high intermodulation broadband isolator, the magnet provides a uniform magnetic field to the ferrite through a ground plate; The iron cavity and the cover plate form a closed ferromagnetic environment to construct a magnetic circuit.

[0010] Furthermore, in a quasi-lumped parameter high intermodulation broadband isolator, the ceramic substrate is welded on the housing; The cover plate is matched with the screw thread of the shell to fix the magnet, the grounding plate, the ferrite, the non-reciprocal junction and the temperature patch.

[0011] Furthermore, a quasi-lumped parameter high intermodulation broadband isolator is provided, wherein the port of the non-reciprocal junction is welded to one end pin of a winding inductor, the other end pin of the winding inductor is welded to a microstrip circuit on a ceramic substrate, and the two end pins of the winding inductor are welded between the microstrip circuits; Among them, the winding inductor is adjusted by using tweezers to adjust the inductance; Among them, the microstrip circuit fine-tunes the capacitance by cutting and re-soldering the microstrip line.

[0012] Furthermore, a quasi-lumped parameter high intermodulation broadband isolator is provided, wherein the number of ports of the non-reciprocal junction is 3, and the ports are respectively connected to microstrip circuits.

[0013] Furthermore, in a quasi-lumped parameter high intermodulation broadband isolator, the ferrite is garnet ferrite.

[0014] Furthermore, a quasi-lumped parameter high intermodulation broadband isolator is provided, wherein the magnetization intensity of the garnet ferrite is 4πMs=1850Gs, the resonance linewidth is 16Oe, and the dielectric constant is 14.5.

[0015] Furthermore, a quasi-lumped parameter high intermodulation broadband isolator is provided, wherein the normalized internal field value of the isolator is 1.6, corresponding to an internal magnetic field of 563 Oe.

[0016] Furthermore, a quasi-lumped parameter high intermodulation broadband isolator is provided, wherein the microstrip circuit of the ceramic substrate is a three-level elliptic function low-pass filter circuit.

[0017] The beneficial effects of the present invention are as follows: by taking the circuit center to cover the entire ferrite, the high-frequency tangential magnetic field component on the ferrite surface is greatly reduced, and the intermodulation performance of the device is improved; the matching of the non-reciprocal junction NRJ is achieved by means of series inductance and parallel capacitance, so as to achieve a broadband effect; the parallel capacitance is realized by using a microstrip transmission line, which reduces the investment in capacitance components; the inductor adopts a winding coil with a high Q value, which reduces the loss effect; in order to solve the problem of parasitic harmonics of the pure circular non-reciprocal junction, the external matching circuit is designed as a three-level elliptic function low-pass filter circuit structure to achieve the effect of harmonic suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the planar structure of a quasi-lumped parameter high intermodulation broadband isolator.

[0019] Figure 2 This is a schematic diagram of the forward structure of a quasi-lumped parameter high intermodulation broadband isolator.

[0020] Figure 3 This is the principle circuit diagram of a three-level elliptic function low-pass filter circuit.

[0021] Figure 4 This is the complete circuit model diagram of the quasi-lumped parameter high intermodulation broadband isolator.

[0022] Figure 5 This is the simulation effect diagram of the quasi-lumped parameter high intermodulation broadband isolator.

[0023] In the figure, 1-ferrite, 2-matching medium, 3-non-reciprocal junction, 4-wound inductor, 5-microstrip circuit, 6-ceramic substrate, 7-load, 8-iron cavity, 9-magnet, 10-ground plate, 11-temperature patch, 12-cover, 13-metal conductor. DETAILED DESCRIPTION

[0024] The present invention is further described below, but the protection scope of the present invention is not limited to the following description.

[0025] Specific embodiment 1 Structure of a quasi-lumped parameter high intermodulation broadband isolator As attached Figures 1 and 2 As shown, a quasi-lumped parameter high intermodulation broadband isolator includes a ferrite 1, a matching medium 2, a non-reciprocal junction 3, a winding inductor 4, a microstrip circuit 5, a ceramic substrate 6, a load 7, an iron cavity 8, a magnet 9, a ground plate 10, a temperature patch 11, and a cover plate 12; The load 7 is provided on a ceramic substrate 6 on which a microstrip circuit 5 is printed; A ceramic substrate 6 is provided outside the iron cavity 8, and the non-reciprocal junction 3 and the microstrip circuit 5 of the ceramic substrate 6 are interconnected by welding a winding inductor 4; Inside the iron cavity 8 , from bottom to top, there are respectively a magnet 9 , a grounding plate 10 , a ferrite 1 , a non-reciprocal junction 3 , a ferrite 1 , a grounding plate 10 , a magnet 9 , a temperature patch 11 and a cover plate 12 .

[0026] Both ends of the metal conductor 13 are placed on the ceramic substrate, and the surface of the ceramic substrate is metallized.

[0027] The magnet 9 provides a uniform magnetic field to the ferrite 1 through the ground plate 10; The iron cavity 8 and the cover plate 12 form a closed ferromagnetic environment to construct a magnetic circuit.

[0028] The ceramic substrate 6 is welded to the housing; The cover plate 12 fixes the magnet 9, the ground plate 10, the ferrite 1, the non-reciprocal junction 3, and the temperature patch 11 by means of threads engaged with the housing.

[0029] One end pin of the winding inductor 4 is welded to the port of the non-reciprocal junction 3 , the other end pin of the winding inductor 4 is welded to the microstrip circuit 5 on the ceramic substrate 6 , and the two end pins of the winding inductor 4 are welded between the microstrip circuits 5 .

[0030] The number of ports of the non-reciprocal junction 3 is 3, and the ports are respectively connected to the microstrip circuits 5 .

[0031] The ferrite 1 is garnet ferrite.

[0032] The microstrip circuit 5 on the ceramic substrate 6 is a three-stage elliptic function low-pass filter circuit.

[0033] Specific embodiment 2: Circuit principle of quasi-lumped parameter high intermodulation broadband isolator As attached Figures 3 and 4 As shown in FIG, the simplest structure of the elliptic function low-pass filter circuit model is used as the matching circuit of the quasi-lumped parameter high intermodulation broadband isolator. The three ports of the non-reciprocal junction 3 are respectively connected to the circuit models corresponding to the microstrip circuit 5 on the ceramic substrate 6. The simulation is performed in circuit simulation software such as AWR or ADS, where the non-reciprocal junction simulation parameters simulated by HFSS are used as the basic data.

[0034] Specific embodiment 3: Design principle of quasi-lumped parameter high intermodulation broadband isolator As attached Figure 5 As shown, according to the parameters of the selected ferrite 1, a suitable internal field design is selected, and the approximate size of the non-reciprocal junction 3, NRJ, is simulated first. Then, through circuit simulation, the parameters of each level of the matching circuit are optimized, and the area of the printed microstrip circuit 5 on the ceramic substrate 6 and the size of the winding coil are determined by the size of the capacitance and inductance.

[0035] S1: Determine the basic material parameters for the circulator design based on parameters such as passband frequency, size, and power capacity. The selected material is garnet ferrite with a resonance linewidth of 16Oe and a dielectric constant of 14.5, and the external matching dielectric ring is ceramic with a dielectric constant of 30. S2: Determine the appropriate normalized internal field value based on the selected ferrite 1 material and passband frequency. Set the normalized internal field value to 1.6, which corresponds to an internal magnetic field of approximately 475 Oe. S3: Calculate the non-reciprocal junction 1 structure, using a circular center circuit structure to make the device resonate within the required passband; S4: Calculate the prototype of the third-order elliptic function filter circuit and preliminarily determine the inductance and capacitance values according to the required passband frequency; S5: Use circuit calculation software such as HFSS, ADS, and AWR to build a complete isolator circuit model, set optimization targets, and optimize the capacitance and inductance of each part.

[0036] S6: Based on the capacitor size obtained in the above steps, a ceramic substrate 6 with a suitable dielectric constant is selected. The printed circuit dimensions corresponding to each part of the capacitor are obtained using the inter-board capacitance calculation formula. The printed circuit dimensions should be slightly larger during design. During subsequent debugging, the circuits can be cut to achieve the desired capacitance debugging effect. S7: Place the magnet 9, ground plate 10, ferrite 1, non-reciprocal junction 3, ferrite 1, ground plate 10, magnet 9, temperature patch 11 and cover plate 12 in this order, and then fasten the components by using the threads of the cover plate 12 and the housing; S8: Solder the ceramic substrate 6 to the housing, and then make a winding coil with the corresponding inductance according to the inductance value obtained in S4. Solder the two pins of the coil inductor 4 to the port of the non-reciprocal junction 3 and the microstrip circuit 5 on the ceramic substrate 6 respectively. Solder the other coil inductors 4 according to the attached Figure 1 The connection position is soldered on the microstrip circuit 5 corresponding to the ceramic substrate 6.

[0037] S9: Test the device and adjust the inductance by using tweezers to move the coil inductor 4 and fine-tune the capacitance by cutting and re-soldering the microstrip line to adjust the device performance to the required indicators.

[0038] The frequency band of the third embodiment is 825-960 MHz, and the size is 1.25 inches.

[0039] Those skilled in the art will appreciate that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A quasi-lumped parameter high intermodulation broadband isolator, characterized in that: It includes ferrite (1), matching medium (2), non-reciprocal junction (3), winding inductor (4), microstrip circuit (5), ceramic substrate (6), load (7), and iron cavity (8); The ferrite (1) is covered by the center of the circular circuit, and the periphery is sequentially provided with a matching medium (2), a non-reciprocal junction (3), and an iron cavity (8); The load (7) is arranged on a ceramic substrate (6), and the ceramic substrate (6) is printed with a microstrip circuit (5); A ceramic substrate (6) is provided outside the iron cavity (8), and the non-reciprocal junction (3) and the microstrip circuit (5) of the ceramic substrate (6) are interconnected by welding via a winding inductor (4); The microstrip circuits (5) of the ceramic substrate (6) are interconnected by welding the winding inductors (4).

2. The quasi-lumped parameter high intermodulation broadband isolator according to claim 1, characterized in that: It also includes a magnet (9), a grounding plate (10), a temperature patch (11), and a cover plate (12); The iron cavity (8) comprises, from bottom to top, a magnet (9), a grounding plate (10), a ferrite (1), a non-reciprocal junction (3), a ferrite (1), a grounding plate (10), a magnet (9), a temperature patch (11), and a cover plate (12).

3. The quasi-lumped parameter high intermodulation broadband isolator according to claim 2, characterized in that: The magnet (9) provides a uniform magnetic field to the ferrite (1) through the grounding plate (10); The iron cavity (8) and the cover plate (12) form a closed ferromagnetic environment to construct a magnetic circuit.

4. The quasi-lumped parameter high intermodulation broadband isolator according to claim 3, characterized in that: The ceramic substrate (6) is welded to the housing; The cover plate (12) is engaged with the threads of the housing to fix the magnet (9), the grounding plate (10), the ferrite (1), the non-reciprocal junction (3), and the temperature patch (11).

5. The quasi-lumped parameter high intermodulation broadband isolator according to claim 1, characterized in that: The port of the non-reciprocal junction (3) is welded to one end pin of the winding inductor (4), the other end pin of the winding inductor (4) is welded to the microstrip circuit (5) of the ceramic substrate (6), and the two end pins of the winding inductor (4) are welded between the microstrip circuits (5).

6. The quasi-lumped parameter high intermodulation broadband isolator according to claim 5, characterized in that: The number of ports of the non-reciprocal junction (3) is 3, and the ports are respectively connected to the microstrip circuits (5).

7. The quasi-lumped parameter high intermodulation broadband isolator according to claim 1, characterized in that: The ferrite (1) is garnet ferrite.

8. The quasi-lumped parameter high intermodulation broadband isolator according to claim 7, characterized in that: The garnet ferrite has a magnetization intensity of 4πMs=1850Gs, a resonance line width of 16Oe, and a dielectric constant of 14.

5.

9. The quasi-lumped parameter high intermodulation broadband isolator according to claim 1, characterized in that: The normalized internal field value of the isolator is 1.6, corresponding to an internal magnetic field of 563 Oe.

10. The quasi-lumped parameter high intermodulation broadband isolator according to claim 1, characterized in that: The microstrip circuit (5) of the ceramic substrate (6) is a three-level elliptic function low-pass filter circuit.

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