A broadband miniaturized filter chip based on thin film ceramic technology

Abstract

The application discloses a kind of wideband miniaturization filter chip based on thin film ceramic technology, including upper layer metal microstrip line, intermediate layer microstrip dielectric plate and lower layer ground metal plate;Metal microstrip line includes a pair of input / output feed line, a pair of bending coupling line, parallel multi-line coupling line and serpentine line;Input / output feed line is located on the same straight line;Parallel multi-line coupling line includes at least three identical parallel coupling lines, and is coupled through gap formation;One end is connected to the junction of a pair of bending coupling line, and is perpendicular to bending coupling line;The other end is connected with serpentine line, and is perpendicular to serpentine line;Bending coupling line and serpentine line are mirror image symmetry about parallel multi-line coupling line.The application realizes the coverage to C, X band by the structure of central tight coupling line, and realizes good out-of-band rejection.Compared with prior art, the application realizes superior frequency band selectivity, low insertion loss and good impedance matching.

Description

Technical Field

[0001] This invention relates to a broadband miniaturized filter chip design based on thin-film ceramic technology, belonging to the field of microwave technology, and can be used in broadband receiving systems and applications for suppressing microwave interference signals. Background Technology

[0002] A filter is a frequency-selective device that extracts useful signals and suppresses unwanted signals. Therefore, it is widely used in low-frequency and high-frequency (such as millimeter-wave) radio frequency systems. As a key component in wireless communication systems, the size and performance of filters determine the overall performance of the system.

[0003] With the introduction of the "Beyond Moore" concept and the demand for ultra-small RF modules, thin-film ceramic technology has become an important means to realize miniaturized and lightweight filter chips due to its advantages of high processing precision, easy miniaturization, low high-frequency loss and low cost, and has received widespread attention from the academic and industrial communities at home and abroad.

[0004] Currently, most RF filter chips are low-order narrowband filters, whose design is mainly achieved through the coupling of distributed / lumped resonators and the replacement of low-pass elements. On the one hand, because the coupling coefficient and susceptance slope are accurate only at the center frequency, this method gradually becomes ineffective as the bandwidth increases; on the other hand, the insertion loss and circuit size of the filter increase exponentially with the order. Therefore, it is difficult to meet the requirements of communication systems for wide bandwidth and high selectivity. Although meandering lines and T-bridges can reduce the size to some extent, the problem of poor out-of-band rejection still exists. Therefore, how to achieve superior bandwidth selectivity, low insertion loss, and good impedance matching with small size and simple structure remains a design challenge. Summary of the Invention

[0005] Purpose of the invention: In view of the above-mentioned problems in the prior art, the purpose of this invention is to propose a broadband miniaturized filter chip with a simple structure and easy implementation, which achieves superior bandwidth selectivity, low insertion loss and good impedance matching.

[0006] Technical solution: The objective of this invention will be achieved through the following technical solution:

[0007] A broadband miniaturized filter chip based on thin-film ceramic technology includes an upper metal microstrip line, a middle microstrip dielectric substrate, and a lower ground metal plate; the metal microstrip line includes a pair of input / output feed lines, a pair of bent coupling lines, parallel multi-line coupling lines, and a meandering line;

[0008] The input / output feeders are located on the same straight line;

[0009] The parallel multi-line coupling line includes at least three identical parallel coupling lines, with coupling formed through gaps; one end is connected to the junction of the pair of bent coupling lines and is perpendicular to the bent coupling lines; the other end is connected to the meandering line and is perpendicular to the meandering line; the pair of bent coupling lines and the meandering line are mirror-symmetrical about the parallel multi-line coupling line.

[0010] Preferably, the bent coupling line is two 90-degree bent coupling lines, with the outer lines of the pair of bent coupling lines respectively connected to the input / output feed lines, and the inner lines connected to one end of the parallel multi-line coupling line.

[0011] Preferably, the parallel multi-line coupling line is three parallel coupling lines or four parallel coupling lines.

[0012] Preferably, the meandering line is composed of two sets of symmetrical microstrip lines, and its impedance characteristics are realized through the coupling relationship between the microstrip lines; each set of symmetrical microstrip lines is located in the space between the bent coupling line and the parallel multi-line coupling line.

[0013] Preferably, the electrical length of each of the parallel multi-line coupling lines is one-quarter wavelength.

[0014] Preferably, the input / output feed line, the parallel multi-line coupling line, and the meandering line are on the same side of the pair of bent coupling lines.

[0015] Preferably, the line width of the bent coupling line is 10 μm, and the spacing between the two lines is 36 μm.

[0016] Preferably, the line width of the coupling lines in the parallel multi-line coupling lines is 100 μm, and the gap between the coupling lines is 7.5 μm.

[0017] Preferably, the spacing between the meandering line and the parallel multi-line coupling line is greater than the spacing between their bent microstrip lines.

[0018] As a preferred method, by adjusting the structure of the central parallel multi-line coupling line, coverage of the C and X bands can be achieved, along with good out-of-band suppression.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0020] The broadband miniaturized filter chip based on thin-film ceramic technology proposed in this invention maintains a simple geometry and compact size while achieving high-performance filtering function.

[0021] II. The broadband miniaturized filter chip based on thin-film ceramic technology proposed in this invention achieves coverage of the C and X bands and good out-of-band suppression through the structure of a central multi-line coupling line.

[0022] Third, the broadband miniaturized filter chip based on thin-film ceramic technology proposed in this invention can reduce the filter size and achieve good out-of-band suppression through the structure of central multi-line coupling line and high-impedance meandering line. Attached Figure Description

[0023] Figure 1 This is a perspective view of an embodiment of the present invention;

[0024] Figure 2 This is a top view of an embodiment of the present invention;

[0025] Figure 3 This is a dimensional diagram illustrating the various parts of the present invention;

[0026] Figure 4 This is a simulation frequency response curve of an embodiment of the present invention;

[0027] In the diagram: 1—Upper metal microstrip line, 2—Middle microstrip dielectric substrate, 3—Lower ground metal substrate, 4—Input / output feed line, 5—Bent coupling line, 6—Parallel multi-line coupling line, 7—High-impedance meandering line. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0029] like Figure 1 As shown, an embodiment of the present invention discloses a broadband miniaturized filter chip based on thin-film ceramic technology, comprising an upper metal microstrip line 1, a middle microstrip dielectric substrate 2, and a lower ground metal substrate 3, wherein the upper metal microstrip line constitutes the circuit structure. Figure 2 As shown, the metallic microstrip line includes a pair of input / output feed lines 4, a pair of bent coupling lines 5, a parallel multi-line coupling line 6, and a high-resistivity meandering line 7. The pair of input / output feed lines 4 are both narrowband transmission lines and are located on the same straight line. The parallel multi-line coupling lines 6 are all tightly coupled lines, each consisting of at least three identical parallel coupling lines. One end of each line connects to the junction of the pair of bent coupling lines 5 and is perpendicular to the bent coupling lines 5; the other end connects to the high-resistivity meandering line 7 and is perpendicular to the high-resistivity meandering line 7. The pair of bent coupling lines 5 and the high-resistivity meandering line 7 are mirror-symmetrical about the parallel multi-line coupling lines.

[0030] In this embodiment of the invention, the bent coupling line 5 consists of two 90-degree bent coupling lines. The outer line of the bent coupling line 5 connects to the input / output feed line, and the inner line is connected to one end of the parallel multi-line coupling line 6. The electrical length of the parallel multi-line coupling line 6 is one-quarter wavelength. Three or four parallel coupling lines can be used; this embodiment uses a three-parallel coupling line. By adjusting the structure of the central parallel multi-line coupling line, coverage of the C (4–8 GHz) and X (8–12 GHz) bands can be achieved, along with good out-of-band suppression.

[0031] like Figure 3 The dimensions of each part of the filter chip in this embodiment of the invention are shown below: I1 = 576um, I2 = 480um, W1 = 195um, W2 = 60um, W3 = 21um, W4 = 36um, W5 = 10um, W6 = 100um, L1 = 826um, L2 = 1866um, L3 = 2500um, L4 = 270um, L5 = 1177um, L6 = 100um.

[0032] like Figure 4 The figure shown is a simulated frequency response curve of an embodiment of the present invention. In the measured frequency curve, there are four transmission zeros within the stopband, and the frequency range with insertion loss all above 15dB is 5.84GHz-12.06GHz (relative bandwidth of 70%). The experimental results verify that the structure of the central multi-line tightly coupled line has advantages such as achieving good out-of-band suppression and reducing size. Furthermore, the experimental results also verify that this design has an ultra-wideband stopband bandwidth, excellent suppression characteristics, and stable performance.

[0033] In summary, the broadband miniaturized filter chip based on thin-film ceramic technology of the present invention can achieve four transmission zeros within the stopband, while its relative stopband bandwidth reaches 70%, making it well-suited for application in broadband systems. Furthermore, the present invention also features small size (only 2.57mm*2.7mm), light weight, simple processing, and low manufacturing cost.

[0034] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A thin film ceramic process based wideband miniaturized filter chip, characterized by, The microstrip line includes a pair of input / output feed lines, a pair of bent coupling lines, a parallel multi-line coupling line and a meander line. The input / output feed lines are located on the same straight line. The parallel multi-line coupling line includes at least three parallel coupling lines, and is coupled through a gap. The pair of bent coupling lines and the meander line are mirror symmetric about the parallel multi-line coupling line.

2. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The bent coupling line is a 90-degree bent coupling line.

3. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The parallel multi-line coupling line is a three-line or four-line parallel coupling line.

4. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The meander line is composed of two groups of symmetric microstrip lines.

5. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The parallel multi-line coupling line has a quarter wavelength electrical length.

6. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The input / output feed lines, the parallel multi-line coupling line and the meander line are located on the same side of the pair of bent coupling lines.

7. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The line width of the bent coupling line is 10 um, and the distance between the two lines is 36 um.

8. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The line width of the coupling line in the parallel multi-line coupling line is 100 um, and the gap between the coupling lines is 7.5 um.

9. The thin film ceramic process based wideband miniaturized filter chip of claim 1, wherein, The distance between the meander line and the parallel multi-line coupling line is greater than the distance between the bent microstrip lines. By adjusting the structure of the central parallel multi-line coupling line, the C and X bands are covered and the out-of-band suppression is realized.

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