KR101870201B1 - A compact bandstop filter using frequency-selecting coupling structure with interdigital and spiral types - Google Patents

A compact bandstop filter using frequency-selecting coupling structure with interdigital and spiral types Download PDF

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KR101870201B1
KR101870201B1 KR1020170027780A KR20170027780A KR101870201B1 KR 101870201 B1 KR101870201 B1 KR 101870201B1 KR 1020170027780 A KR1020170027780 A KR 1020170027780A KR 20170027780 A KR20170027780 A KR 20170027780A KR 101870201 B1 KR101870201 B1 KR 101870201B1
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band
bsf
pass filter
interdigital
resonator
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KR1020170027780A
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Korean (ko)
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이종철
장소우
왕양
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광운대학교 산학협력단
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/203—Strip line filters
    • H01P1/20309—Strip line filters with dielectric resonator
    • H01P1/20318—Strip line filters with dielectric resonator with dielectric resonators as non-metallised opposite openings in the metallised surfaces of a substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/203—Strip line filters
    • H01P1/20327—Electromagnetic interstage coupling
    • H01P1/20336—Comb or interdigital filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P7/00—Resonators of the waveguide type
    • H01P7/08—Strip line resonators
    • H01P7/082—Microstripline resonators

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Abstract

The present invention relates to a small bandstop filter (BSF) using an interdigital and spiral frequency-selecting coupling structure (FSCS), capable of reducing the size of a circuit to be more miniaturized, which comprises: a BSF having a microstrip structure on a front surface of a substrate; a ground formed of a copper foil on a rear surface of the substrate; and a 50 Ω connector of transmission lines on left and right sides of the substrate, respectively.

Description

[0001] The present invention relates to a compact bandstop filter using inter-digital and spiral frequency selective coupling structures,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a compact band-pass filter using an interdigital and spiral frequency selective coupling structure, and more particularly, to a 1/4 wavelength frequency selective coupling structure (FSCS) having an open circuit resonator on a Teflon substrate (BSF), which has a low-pass filter (BSF). A quarter-wavelength FSCS with an open circuit resonator is used to implement the BSF. The spiral structure and the interdigital structure are designed to achieve further miniaturization. The performance of a band-stop filter is evaluated both in simulation and in measurement. At broadband frequencies in the band-pass filter (BSF) range of 2.3 to 6.1 GHz, the operating frequency of the band-pass filter (BSF) is 4.3 GHz, the insertion loss (IL) is less than 15.2 dB and the 3dB partial bandwidth is 94.2%. There was a good agreement between simulation and measurement results. The circuit size of the proposed band-pass filter (BSF) is 4.6 x 8.79 mm 2 (electrical size 0.1 x 0.196 λ g 2 ).

This study was supported by the Korea Research Foundation (NRF-2016R1D1A1B03935640) and the research grant of Kwangwoon University in 2016.

Bandstop filters (BSFs) play a key role in RF / microwave systems for blocking unwanted signals. As microwave systems become increasingly smaller and integrated, we are paying attention to the size as well as the function of the components. A conventional type of band-pass filter (BSF) is generally constructed with a periodically quarter-wave structure, which takes a relatively large size and provides a narrow bandwidth.

Therefore, nowadays, the band-pass filter (BSF) requires a lot of new structure to widen the bandwidth, reduce the size of the circuit, and improve the characteristics of the filter. Coupled lines are adopted in [1-4] to reduce the size and achieve broaden the bandwidth. In [5], a defected ground structure with a folded L-arm has been proposed to achieve a constant flat impedance bandwidth. In [6, 7], lines such as diagonal lines are presented to achieve compact size and wide bandwidth. A wideband BSF with a frequency selective combining structure (FSCS) is presented in [1].

However, the existing band-pass filter (BSF) does not provide a filter consisting of a frequency selective coupling structure (FSCS) and a quarter-wavelength open-circuited resonator, It is necessary to reduce the size of the circuit and to improve the characteristics of the filter.

(Non-Patent Document 1) Hsieh, M. Y. and Wang, S. M .: 'Compact and wideband microstrip bandstop filter', IEEE Microwave and Wireless Components Lett., 2005, 15, (7), pp. 472-474, doi: 10.1109 / LMWCL.2005.851572 (Non-Patent Document 2) Sa'nchez-Soriano, M.A., Torregrosa-Penalva, G., and Bronchalo, E .: 'Compact wideband bandstop filter with four transmission zeros', IEEE Microwave and Wireless Components Lett. 2010, 20, (6), pp. 313-315, doi: 10.1109 / LMWC.2010.2047468 2015, 25, (10), "A new wideband elliptic bandstop filter with cross coupling", IEEE Microwave and Wireless Components Lett., Pp. , pp. 639-641, doi: 10.1109 / LMWC.2015. 2463098 (Non-Patent Document 4) Wu, XH, Chu, QX, and Qiu, LL: 'Differential Wideband Bandpass Filter with High-Selectivity and Common-Mode Suppression', IEEE Microwave and Wireless Components Lett., 2013, , pp. 644-646, doi: 10.1109 / LMWC.2013.2284787 (Non-patent document 5) Habibi, R., Ghobadi, Ch., Nourinia, J., Ojaroudi, M., and Ojaroudi, N .: 'Very compact broad band- complementary structure for X-band application ', Electron. Lett., 2012, 48, (23), pp. 1483-1484, doi: 10.1049 / el.2012.2718 (Non-patent document 6) Weng, TW, Tsai, CH, Chen, CH, Han, DH, and Wu, TL: Synthesis model and design of a common-mode bandstop filter for high-speed differential signals', IEEE Trans. Microwave Theory Tech., 2014, 62, (8), pp.1647-1656, doi: 10.1109 / TMTT.2014.2328314 (Non-Patent Document 7) Jankovic ', N., Geschke, R., and Crnojevic'-Bengin, V .:' Compact tri-band bandpass and bandstop filters based on Hilbert-fork resonators', IEEE Microwave and Wireless Components Lett. , ≪ / RTI > 2013, 23, 6, pp. 282-284, doi: 10.1109 / LMWC.2013.2258005

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art, and it is an object of the present invention to provide a band-stop filter having a frequency-selecting coupling structure (FSCS) having an open circuit resonator formed on a Teflon substrate. (BSF). The spiral structure and the interdigital structure have a simple circuit structure, a compact size by reducing the circuit size, and a characteristic of a band-stop filter (BSF). And a small band cutoff filter using an interdigital and spiral frequency selective coupling structure.

In order to accomplish the object of the present invention, a compact band-pass filter using an interdigital and spiral frequency selective coupling structure (FSCS) has a 1/4 wavelength frequency selective coupling Band strap filter (BSF) used as a signal line with a frequency-selecting coupling structure (FSCS), a ground (GND) as a copper foil on the back side, Lt; RTI ID = 0.0 > 50 < / RTI >

The band-pass filter (BSF)

A left input unit formed on the substrate and receiving an even-mode signal or an odd-mode signal; Coupling occurs in a comb line structure in which the left and right sides of the shape of the bill are coupled to each other at the empty space, and a 1/4 wavelength frequency selective coupling structure (open loop resonator) having an open circuit resonator FS, and a frequency-selecting coupling structure, and the L and C values are adjusted to form an interdigital structure; A rectangular spiral structure provided at a lower portion of the interdigital structure; And a right output unit connected to the interdigital structure unit and outputting a signal of a band cut filter (BSF).

The center frequency, bandwidth, and quality factor of the band-pass filter (BSF) are adjusted at design time in the width and length of the interdigital structure.

The substrate is a Teflon substrate, and the Teflon substrate has a dielectric constant? R of 2.54.

The operating frequency band of the BSF is adjustable and the stopband of the BSF is from 2.3 GHz to 6.1 GHz including 2.45 GHz and 5.8 GHz, The operating frequency of the band-pass filter (BSF) is 4.3 GHz, the insertion loss (IL) is 15.2 dB or less, and the 3-dB partial bandwidth is 94.2%.

The circuit size of the band-pass filter (BSF) is 4.6 x 8.79 mm 2 and the electrical size is 0.1 x 0.196 λ g 2 (λ g is a wavelength).

The band-pass filter (BSF) having a quarter-wave frequency selective coupling structure (FSCS) with the open-circuit resonator is manufactured in an interdigital structure and a spiral structure, and the circuit size of the band- More compact,

The spiral structure of the helical structure is used to replace the quarter-wavelength stub of the resonator.
The rectangular spiral structure may have a total length of the resonator and a width of the line for a rectangular spiral resonator having a spiral structure. W and a gap S between the three parameters. The distributed inductance is proportional to the length, and the line of the spiral resonator A mutual inductance occurs between the lines, and the gap between the lines produces a capacitance of the proposed structure,
The characteristics of the proposed band-pass filter (BSF) of the transmission zeros, bandwidth, and center frequency of the band-pass filter (BSF) depend on the length, width of the line ) And the gap (gaps), the length of the resonator affects the center frequency shift, and the width of the line and gap is controlled by the out-of-band and in-band performance return loss ) And the transmission zeros frequencies.

In addition, a small band cutoff filter using a frequency selective combining structure (FSCS) of an interdigital structure according to another embodiment of the present invention is formed on a substrate and includes an even-mode signal or odd-mode a left input unit for inputting a -mode signal; Coupling occurs in a comb line structure in which the left and right sides of the shape of the bill are coupled to each other at the empty space, and a 1/4 wavelength frequency selective coupling structure (open loop resonator) having an open circuit resonator FS, and a frequency-selecting coupling structure, and the L and C values are adjusted to form an interdigital structure; A rectangular spiral structure provided at a lower portion of the interdigital structure; And a right output unit connected to the interdigital structure and outputting a signal of a band-pass filter (BSF).

A band-stop of a microstrip structure used as a signal line having a frequency-selecting coupling structure (FSCS) having an open circuit resonator on the front surface of the substrate, Filter (BSF, bandstop filter), a ground (GND) as a copper foil on the back, and a 50-ohm connector for transmission lines on the right and left sides.

The center frequency, bandwidth, and quality factor of the band-pass filter (BSF) are adjusted at design time in the width and length of the interdigital structure.

The substrate uses a Teflon substrate.
The rectangular spiral structure may have a total length of the resonator and a width of the line for a rectangular spiral resonator having a spiral structure. W and a gap S between the three parameters. The distributed inductance is proportional to the length, and the line of the spiral resonator A mutual inductance occurs between the lines, and the gap between the lines produces a capacitance of the proposed structure,
The characteristics of the proposed band-pass filter (BSF) of the transmission zeros, bandwidth, and center frequency of the band-pass filter (BSF) depend on the length, width of the line ) And the gap (gaps), the length of the resonator affects the center frequency shift, and the width of the line and gap is controlled by the out-of-band and in-band performance return loss ) And the transmission zeros frequencies.

The operating frequency band of the band-pass filter (BSF) is characterized by being adjustable during design.

The band-pass filter (BSF) having a quarter-wave frequency selective coupling structure (FSCS) with the open circuit resonator is manufactured in an interdigital structure or a spiral structure, and the circuit size of the band-pass filter (BSF) Is further reduced in size.

The BSF (bandstop filter) using an interdigital and spiral frequency selective coupling structure according to the present invention can be realized by using a 1/4 wavelength frequency selective coupling scheme (FSCS) having an open circuit resonator (BSF), which has a very small size, and the helical structure and interdigital structure are designed to realize even more miniaturization, which has a great advantage in the circuit size of a further downsized band-stop filter. The spiral structure and the interdigital structure are designed to achieve further miniaturization. The performance of the band-stop filter is evaluated both in simulation and in measurement. The operating frequency of the band-pass filter (BSF) is 4.3 GHz, the insertion loss (IL) is 15.2 dB or less, and the 3dB partial bandwidth is 94.2%. There was a good agreement between simulation and measurement results. The circuit size of the proposed band-pass filter (BSF) is 4.6 x 8.79 mm 2 (electrical size 0.1 x 0.196 λ g 2 ).

1 is a diagram illustrating a structure of a proposed band-pass filter (BSF).
FIG. 2A is a diagram showing an interdigital structure and a distributive equivalent form. FIG.
2B is an even-mode / odd-mode analysis diagram of one unit cell.
2C is a view for explaining stop-band analysis of the band-pass filter (BSF).
3 is a layout of a band-pass filter (BSF) according to the present invention.
4 is a photograph of the proposed band-stop filter.
5 is a diagram showing the simulated S-parameter and the measured S-parameter.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a structure of a proposed band-stop filter.

In an embodiment, a quarter-wave frequency-selective coupling structure (FSCS) with an open circuit resonator formed on a Teflon substrate (relative permittivity of Teflon substrate, dielectric constant? R = 2.54) (BSF) uses a wide band frequency in the range of 2.3 to 6.1 GHZ, and the center frequency of the band-pass filter (BSF) is 4.3 GHz.

The spiral structure and the interdigital structure have a simple structure and a compact size by reducing the circuit size.

FIG. 2A is a diagram showing an interdigital structure and a distributive equivalent form. FIG.

A left input unit formed on the substrate and receiving an even-mode signal or an odd-mode signal; Coupling occurs in a comb line structure in which the left and right sides of the shape of the bill are coupled to each other at the empty space, and a 1/4 wavelength frequency selective coupling structure (open loop resonator) having an open circuit resonator FS, and a frequency-selecting coupling structure, and the L and C values are adjusted to form an interdigital structure; A rectangular spiral structure provided at a lower portion of the interdigital structure; And a right output unit connected to the interdigital structure unit and outputting a signal of a band cut filter (BSF).

3 is a layout of a band-pass filter (BSF) according to the present invention.

In the present invention, a miniature BSF based on a quarter-wave frequency selective coupling structure (FSCS) with an open circuit resonator with an advanced layout has been proposed. Can provide three 'transmission zeros' at the stopband of the band-pass filter (BSF). An interdigital structure or a spiral structure is applied as an advanced layout for realizing the circuit size reduction of the band-stop filter. The center frequency, bandwidth and Q factor (quality factor) of the band-pass filter (BSF) are designed by adjusting the width and length of the interdigital structure. Can be adjusted. The band-pass filter (BSF) proposed in the present invention can provide a wide stopband frequency range including 2.45 GHz and 5.8 GHz. Mobile, wireless location (radiolocation), and the like.

Anti-coupled lines with short circuits at one end characterize the 'multiple transmission zeros' named FSCS [1]. This structure is simple and easy to implement. As shown in Fig. 1 (a), a conceptual diagram of lossless FSCS is shown. Here, Y 0o and Y 0e are the even-mode characteristic admittance and the odd-mode characteristic admittance, respectively. Fig. 1 (b) shows the FSCS with a quarter wave open circuit resonator. Conventional methods of conventional even-mode and odd-mode excitations can be used in the structure of FIG. 1 (b) [1]. θ is the electrical length, and the upper and lower electrical lengths are λ / 4, respectively. The circuit of the band-pass filter (BSF) can provide transmission zeros at frequencies of? =? / 2 and? =? / 2 ± ??. Here, ?? is a positive number. It is possible to excite the three transmit zeros in the operating stopband of the band-pass filter (BSF).

An even-mode signal is an in-phase signal of the same phase.

An odd-mode signal is a signal whose phase is opposite.

The bandpass filter (BSF) consists of a quarter-wavelength quarter-wave frequency selective coupling (FSCS) and an open-circuited stub line resonator. It has the size of a compact, compact circuit with wide bandwidth, low insertion loss and relatively small circuit size. The interdigital structure was designed as an advanced type of FSCS.

Referring to FIG. 2A, since the proposed structure of the interdigital structure and the distributive equivalent form can provide more coupling area than the original frequency selective coupling structure (FSCS) And the coupling effect of the interdigital structure is extended to adjacent fingers. The length of the finger can equally contribute to a fraction of the electrical length of the FSCS. The electrical length of the interdigital structure is reduced 0.127λ g (λ g is the wavelength) from 0.25λ g. Compared to the original FSCS, the interdigital structure occupies a circuit size area smaller than the circuit size of the basic BSF to obtain the same filter characteristics, thus reducing the overall circuit size of the band-pass filter (BSF).

In the present invention, the coupling effect, the characteristic impedance and the electrical line of the 1/4 wavelength selective coupling structure affect the characteristics (bandwidth, operating frequency and Q factor) of the BSF It can be adjusted by changing the length and width (Fig. 3, L1 and W1). Similarly, a spiral structure can be used to replace a quarter-wavelength stub of a resonator.

Simulation and measurement results: The proposed band-pass filter (BSF) was designed using AWR's commercial simulation software.

2B is an even-mode / odd-mode analysis diagram of one unit cell.

(a) even-mode / odd-mode, (b) even-mode, and (c) odd-mode circuit.

[Stop-band analysis]

Z 1e is the even-mode impedance, Z 1o is the odd-mode impedance, θ is the electrical length, Z L is the load impedance of the open stub, (load impedance) and Z r is a characteristic impedance,

Z ine (even-mode input impedance ), Z ino (even-mode input impedance), Z Le (even-mode load impedance) is calculated by the following formula 1.

Figure 112017021750221-pat00001

Where Z ine is the even-mode input impedance, Z ino is the odd-mode input impedance, Z Le is the even-mode load impedance of the open stub even-mode load impedance.

2C is a view for explaining stop-band analysis of the band-pass filter (BSF).

When the insertion loss (IL) S 21 = 0, the band-

Figure 112017021750221-pat00002

Here, Γ e is the even-mode reflection coefficient, Γ o is the odd-mode reflection coefficient, Y o is the characteristic admittance, and Y ino is the odd-mode input impedance (even-mode input adimitance).

The admittance Y is calculated as an inverse of the impedance Z. [

Figure 112017021750221-pat00003

When Z ino = Z ine , that is, when the odd-mode input impedance (Z ino ) and the even-mode impedance (Z ine ) are the same, three zeroes are generated as follows.

Figure 112018034725880-pat00004

3 is a layout of a band-pass filter (BSF) according to the present invention.

The small band-pass filter (BSF) using the inter-digital and spiral frequency selective combining structure (FSCS)

A band-stop filter having a microstrip structure used as a signal line having a frequency-selecting coupling structure (FSCS) having an open circuit resonator on the front surface of the substrate, (BSF), a ground (GND) as a copper foil on the rear surface, and a 50-ohm connector for transmission lines on the right and left sides, respectively,

The band-pass filter (BSF)

A left input unit formed on the substrate and receiving an even-mode signal or an odd-mode signal;

Coupling occurs in a comb line structure in which the left and right sides of the shape of the bill are coupled to each other at the empty space, and a 1/4 wavelength frequency selective coupling structure (open loop resonator) having an open circuit resonator FS, and a frequency-selecting coupling structure, and the L and C values are adjusted to form an interdigital structure;

A rectangular spiral structure provided at a lower portion of the interdigital structure; And

And a right output unit connected to the interdigital structure unit and outputting a signal of a band cut filter (BSF).

The interdigital structure has a quarter-wavelength frequency selective coupling structure (FSCS) and has a quarter wavelength length.

The rectangular spiral structure is provided at a lower portion of the interdigital structure, has a length of 1/4 wavelength, and has a rectangular shape and a spiral structure.

The spiral structure is used in the proposed band-stop filter to obtain a compact and compact circuit size.

For the rectangular spiral resonator with the proposed spiral structure, the total line length of the resonator, the width of the line W and the line gap S) (gap (S) between lines). A distributed inductance occurs in proportion to the length and a mutual inductance occurs in the line of the spiral resonator. The gap between the lines creates the capacitance of the proposed structure.

In this study, the characteristics of the proposed band-pass filter (BSF) such as transmission zeros, bandwidth, and center frequency of a band-pass filter (BSF) , width of the line) and gaps. The length of the resonator affects the center frequency shift and the width of the lines and gaps is dependent on the out-of-band and in-band performance (return loss and transmission zeros frequencies) ].

W1 is the coupling width, W2 is the interdigital basic skeleton line width, W3 is the inter-digital lower line width, W4 is the overall width of the FSCS structure, and W5 is the line line width of the FSCS structure.

The center frequency, bandwidth and Q factor of the band-pass filter (BSF) adjust the width and length of the interdigital structure at design time ,

The band-pass filter (BSF) having a quarter-wave frequency selective coupling structure (FSCS) with the open-circuit resonator is manufactured in an interdigital structure and a spiral structure, and the circuit size of the band- .

In the embodiment, a Teflon substrate was used as the substrate, and a dielectric constant? R of the Teflon substrate was 2.54.

3, the layout of the proposed band-cut filter (BSF) has a relative dielectric constant of 2.54, a thickness of 0.54 mm, a loss tangent of 0.002 and a copper thickness of 0.018 mm A band-stop filter (BSF) is fabricated on a Teflon substrate.

Table 1 shows the size of the proposed band-pass filter (BSF) circuit.

Parameter     W1      W2      W3      W4 Value (mm)    3.46     0.57     0.37     2.64 Parameter     W5      S1      S2      LI Value (mm)    0.2     0.17     0.24     5.78

Figure 4 shows a photograph of the fabricated band-pass filter (BSF). The circuit size of the band-pass filter (BSF) proposed in the present invention is 4.6 x 8.79 mm 2 (electrical size 0.1 x 0.196 λg 2 ).

A band of microstrip structure used as a signal line based on a 1/4 wavelength frequency selective combining structure (FSCS) having an open circuit resonator on the front surface of the substrate, (BSF) on the rear side, a ground (GND) on the rear side as a copper foil, and a 50-ohm connector (SMA connector) on the left and right sides.

A Teflon substrate was used as the substrate, and a dielectric constant ∈ r of the Teflon substrate was 2.54.

The microstrip band-pass filter (BSF) is designed to achieve further miniaturization of the spiral and interdigital structures.

In the embodiment, the band-cut filter (BSF) uses a wide band frequency in the range of 2.3 to 6.1 GHZ, the dielectric constant ε r of the Teflon substrate is 2.54, the center frequency of the band-pass filter (BSF) A circuit size of 4.6 x 8.79 mm 2 and an electrical size of 0.1 x 0.196 λ g 2 (λ g is a wavelength) were used.

Figure 5 shows simulated and measured S-parameters.

In the S-parameter, S11 denotes a return loss (RL), and S21 denotes an insertion loss (IL). As shown in the figure, it can be seen that the return loss (RL) of S11 is almost zero, and the bandstop transmission zero (0) at the θ-π / 2, θ and θ + ) Were present. The characteristics of the band-pass filter (BSF) are excellent when the number of zeros is large.

The stop band of the measurement result was 2.3 GHz to 6.1 GHz, a 3dB partial bandwidth of 94.2%, a low return loss (RL) of 0.66dB and an insertion loss (IL) of 15.2dB. Simulation results and measured results are in good agreement. The difference is due to errors during PCB fabrication such as etching and soldering works. It has a small effect on the size of the filter. Circuit size comparisons between the proposed band-pass filter (BSF) and other related studies are listed in Table 2. ε r is the relative dielectric constant of the Teflon substrate is 2.54, the center frequency is 4.3 GHz, and the circuit size is 4.6 × 8.79 mm 2 (electrical size 0.1 × 0.196 λ g 2 ).

The band-stop filter (BSF) proposed in the present invention implements a small band-pass filter (BSF) based on a frequency-selective coupling structure (FSCS) having an open circuit resonator The spiral structure and the interdigital structure are designed to further reduce the circuit size of the pulser, and have a great advantage in the circuit size of a further miniaturized band-stop filter.

Table 2 compares the band-pass filter (BSF) proposed by the present invention with the other band-stop filters [1] to [6].

 Refs. ε r  Center frequency (GHz) Circuit size (mm 2 ) The electrical size (? 2 )  This work  2.54     4.3   4.6x8.79    0.1x0.196  [One]  3.38     6.0   3.6x15.5    0.13x0.57  [2]  5.93     2.0   25.3x22.4    0.35x.0.31  [3]  2.65     1.477   101x9.6    0.79x0.076  [4]  2.55     3.5   37.2x20.3    0.60x0.33  [5]  2.2     10.02   10x15    0.5x0.75  [6]  4.3     5.4   5.6x5.67    0.21x0.21

Conclusion: In this study, we designed and measured a small broadband band-pass filter (BSF) based on quarter-wave frequency selective coupling structure (FSCS). The spiral and interdigital structures were used in the advanced form of the original FSCS components to further reduce the band-pass filter (BSF). The operating frequency band is adjustable during design. The stopband of the proposed band-pass filter (BSF) is from 2.3 GHz to 6.1 GHz, including 2.45 GHz and 5.8 GHz.

There was a good agreement between the simulation results and the measurement results. And can be widely used in a duplexer, a Wi-Fi, an ISM, and other various applications of a mobile communication terminal.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that various modifications and changes may be made without departing from the scope of the present invention.

W1: Coupling width W2: Interdigital basic skeleton line width
W3: Inter-digital lower line width W4: Overall width of FSCS structure
W5: line width of FSCS structure (width)

Claims (14)

A band-stop filter having a microstrip structure used as a signal line having a frequency-selecting coupling structure (FSCS) having an open circuit resonator on the front surface of the substrate, (BSF), a ground (GND) as a copper foil on the rear surface, and a 50-ohm connector for transmission lines on the right and left sides, respectively,
The band-pass filter (BSF)
A left input unit formed on the substrate and receiving an even-mode signal or an odd-mode signal;
Coupling occurs in a comb line structure in which the left and right sides of the shape of the bill are coupled to each other at the empty space, and a 1/4 wavelength frequency selective coupling structure (open loop resonator) having an open circuit resonator FS, and a frequency-selecting coupling structure, and the L and C values are adjusted to form an interdigital structure;
A rectangular spiral structure provided at a lower portion of the interdigital structure; And
A right output section connected to the interdigital structure section and outputting a signal of a band cut filter (BSF);
And a small bandpass filter using an interdigital and spiral frequency selective coupling structure. The method according to claim 1,
Characterized in that the center frequency, bandwidth and quality factor of the band-pass filter (BSF) adjust the width and length of the interdigital structure at design time. Small Band - Averaging Filters Using Spiral - Frequency Selective Coupling Structure. The method according to claim 1,
Wherein the substrate is a Teflon substrate and the Teflon substrate has a dielectric constant epsilon r of 2.54. The compact band-pass filter using the interdigital and spiral frequency selective coupling structure. The method according to claim 1,
The operating frequency band of the BSF is adjustable and the stopband of the BSF is from 2.3 GHz to 6.1 GHz including 2.45 GHz and 5.8 GHz, Wherein the operating frequency of the band-pass filter (BSF) is 4.3 GHz, the insertion loss (IL) is 15.2 dB or less, and the 3 dB partial bandwidth is 94.2%. filter. The method according to claim 1,
Wherein the circuit size of the band-pass filter (BSF) is 4.6 x 8.79 mm 2 and the electrical size is 0.1 x 0.196 λ g 2 (λ g is a wavelength). Small - Scale Bandstop Filter Using Frequency Selective Coupling Structure. The method according to claim 1,
The band-pass filter (BSF) having a quarter-wave frequency selective coupling structure (FSCS) with the open-circuit resonator is manufactured in an interdigital structure and a spiral structure, and the circuit size of the band- More compact,
Characterized in that the spiral structure of the helical structure is used to replace a quarter-wavelength stub of a resonator. The small band-pass filter using an interdigital and spiral frequency- . The method according to claim 1,
The rectangular spiral structure
For a rectangular spiral resonator having a spiral structure, the total line length of the resonator, the width of the line W, and the line gap S, (S) between lines, and a distributed inductance is generated in proportion to the length, and a mutual inductance at the line of the spiral resonator is And the gap between the lines produces the capacitance of the proposed structure,
The characteristics of the proposed band-pass filter (BSF) of the transmission zeros, bandwidth, and center frequency of the band-pass filter (BSF) depend on the length, width of the line ) And the gap (gaps), the length of the resonator affects the center frequency shift, and the width of the line and gap is controlled by the out-of-band and in-band performance return loss ) And transmission zeros frequencies. The small band-pass filter using an interdigital and spiral frequency selective coupling structure. A left input unit formed on the substrate and receiving an even-mode signal or an odd-mode signal;
Coupling occurs in a comb line structure in which the left and right sides of the shape of the bill are coupled to each other at the empty space, and a 1/4 wavelength frequency selective coupling structure (open loop resonator) having an open circuit resonator FS, and a frequency-selecting coupling structure, and the L and C values are adjusted to form an interdigital structure;
A rectangular spiral structure provided at a lower portion of the interdigital structure; And
(FSCS) of an interdigital structure, which is connected to the interdigital structure and has a band-pass filter (BSF) of an interdigital structure including a right output unit for outputting a signal of a band-pass filter (BSF) Used small band cutoff filter. 9. The method of claim 8,
A band-stop of a microstrip structure used as a signal line having a frequency-selecting coupling structure (FSCS) having an open circuit resonator on the front surface of the substrate, (FSCS), which has a filter (BSF, bandstop filter) on the rear side, a ground (GND) on the rear side, and a 50Ω connector on each side of the transmission line. 10. The method of claim 9,
The center frequency, bandwidth, and quality factor of the band-pass filter (BSF) are determined by the frequency and length of the interdigital structure, Small band cutoff filter using coupled structure (FSCS). 11. The method of claim 10,
Wherein the substrate is a Teflon substrate, the frequency selective coupling structure (FSCS) of an interdigital structure. 9. The method of claim 8,
The rectangular spiral structure
For a rectangular spiral resonator having a spiral structure, the total line length of the resonator, the width of the line W, and the line gap S, (S) between lines, and a distributed inductance is generated in proportion to the length, and a mutual inductance at the line of the spiral resonator is And the gap between the lines produces the capacitance of the proposed structure,
The characteristics of the proposed band-pass filter (BSF) of the transmission zeros, bandwidth, and center frequency of the band-pass filter (BSF) depend on the length, width of the line ) And the gap (gaps), the length of the resonator affects the center frequency shift, and the width of the line and gap is controlled by the out-of-band and in-band performance return loss ) And transmission zeros frequencies. The small band-pass filter using an interdigital and spiral frequency selective coupling structure. 9. The method of claim 8,
Wherein the frequency band of the band-pass filter (BSF) is adjustable. ≪ RTI ID = 0.0 > 11. < / RTI > 9. The method of claim 8,
The band-pass filter (BSF) having a quarter-wave frequency selective coupling structure (FSCS) with the open circuit resonator is manufactured in an interdigital structure or a spiral structure, and the circuit size of the band-pass filter (BSF) (FSCS) of the interdigital structure, which is characterized by further reducing the size of the filter.



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