KR101726540B1 - Bandpass Filter of Ring Resonator Type Using Artificial Transmission Line - Google Patents

Abstract

The present invention relates to a ring-resonator bandpass filter using an artificial transmission line, capable of preventing harmonic wave from being suppressed by adjusting a noise frequency using a cut-off characteristic of a low pass filter of a low-pass filter unit cell (LUC) of an artificial transmission line. According to the present invention, a ring-resonator bandpass filter using an artificial transmission line includes an input stage transmission line and an output stage transmission line, a ring-resonator, and first and second inter-digital coupling lines. The input and output stage transmission lines formed on one surface of a substrate. The ring-resonator includes an upper transmission line coupled between the input stage transmission line and the output stage transmission line and a lower transmission line coupled to the upper transmission line. The first and second inter-digital coupling lines are inserted between the input and output transmission lines and the upper transmission line of the ring resonator to serve as a capacitor. The upper transmission line of the ring resonator includes first and second transmission lines a first artificial transmission line LUC. The first and second transmission lines have two terminal parts coupled to the first and second inter-digital coupling lines, respectively, and form the upper transmission line of the ring resonator. The first artificial transmission line LUC has both terminal parts interposed and coupled between the first transmission line and the second transmission line, and is designed in an artificial transmission line (ATL) manner having a low-pass filter characteristic. The lower transmission line of the ring resonator includes third and fourth transmission lines and a second artificial transmission line LUC. The third and fourth transmission lines have two terminals parts coupled to the first and second transmission lines, respectively, and form the lower transmission line of the ring resonator. The second artificial transmission line LUC have two terminal parts interposed and coupled between the third transmission line and the fourth transmission line and is designed in the ATL manner having a low-pass filter characteristic.

Description

[0001] The present invention relates to a ring resonator band pass filter using an artificial transmission line,

In the present invention, since a single-wavelength ring resonator is constructed using an artificial transmission line (ATL) having low-pass characteristics, the physical size of the ring resonator can be reduced to enable miniaturization design, The present invention relates to a ring resonator bandpass filter using an artificial transmission line capable of suppressing harmonics by adjusting a notch frequency by using a blocking characteristic of a low-pass filter of a filter unit cell.

Recently, wireless communication technology has been used in almost all electronic devices and wired communication is also being replaced by wireless communication. Accordingly, various wireless communication technologies such as an Ultra Wide Band (UWB), a high-speed wireless LAN, a Zigbee, and a Bluetooth have been developed. In addition, Performance is also rapidly evolving. With the rapid development of communication technology and performance, development of miniaturization and light weight of wireless communication devices and devices is rapidly accelerating at the same time.

However, in proportion to the increasing use of the radio communication system due to the technological development and improvement of the performance of the radio communication system, communication noise factors such as communication interference between radio devices and radio wave sources are also increasing. Therefore, in recent years, the elements constituting the wireless communication system are basically required to have resistance against noise and harmonics.

In response to these demands, recently, the importance of balanced signal elements such as amplifiers and mixers using a balanced signal that is easy to remove noise and harmonics has been increasing in the wireless communication system. However, in a wireless communication system, not only these balanced signal elements are used. Devices using unbalanced signals such as conventional filters and antennas are also important, and they are written simultaneously as necessary elements. Therefore, in the system, the unbalanced signal element and the balancing element are used at the same time, and a device called balun is used as an intermediate conversion between the elements using these two signals. For this reason, the balun has become an essential element in all wireless communication systems that use the latest unbalanced and balanced signals.

In Korean Patent Registration No. 10-08331076 (Patent Document 1), unbalanced phase characteristics are obtained by positioning each output terminal at a symmetrical position in a dual-mode ring resonator having a short-wave length, and an impedance difference between input and output single- We proposed a dual - mode ring resonator with dual - mode bandpass characteristics to realize unbalanced - balanced conversion of input and output signals.

However, the balun-band pass filter (Balun-BPF) of Patent Document 1 can realize the characteristics of the balun and the band-pass filter simultaneously in a bandwidth with a simple microstrip line structure, but the size of the resonator is determined according to the frequency of use There is a limitation in miniaturization, and there is also a problem in that it is not possible to prevent unwanted operation from appearing in harmonics other than the fundamental wave.

Meanwhile, with the development of wireless communication systems, miniaturization and integration of microwave circuit elements have been increasingly demanded, and research for miniaturization of circuit using artificial transmission line (ATL) is increasing. An artificial transmission line can be realized in various structures, but it refers to lines satisfying the electric length ( θ ) and characteristic impedance (Z ₀ ) of a general transmission line. When a microwave circuit element is realized by embodying an artificial transmission line in an arbitrary form, the size of the element can be miniaturized, and the device can be synthesized with various structures.

: Korean Patent Registration No. 10-08331076 : Korean Patent Publication No. 10-2006-0020693

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a wavelength ring resonator using an artificial transmission line (ATL) low-pass filter unit cell (LUC) And to provide a ring resonator band-pass filter using an artificial transmission line capable of reducing the physical size of the ring resonator according to the size of the ring resonator.

It is another object of the present invention to provide a ring resonator bandpass filter using an artificial transmission line capable of suppressing harmonics by adjusting a notch frequency by using a cutoff characteristic of a low pass filter of an artificial transmission line (ATL) LUC.

It is another object of the present invention to provide a ring resonator of a fundamental type, wherein the impedance of the two lines constituting the ring resonator is different to induce a dual mode, and the impedance difference is adjusted to adjust the coupling amount And a bandpass filter of a ring resonator using an artificial transmission line in which a filter is implemented by adjusting a bandwidth.

It is another object of the present invention to provide a ring resonator bandpass filter using an artificial transmission line capable of reducing the overall size using two artificial transmission line (ATL) LUC and four transmission lines.

According to a first aspect of the present invention, there is provided a semiconductor device comprising: a substrate made of an insulating material; An input terminal and an output terminal transmission line formed on one surface of the substrate and each having an input port and an output port connected to an inlet and an outlet of the line, respectively; A ring resonator including an upper transmission line connected between the input end and the output end transmission line, and a lower transmission line coupled with the upper transmission line; And first and second interdigital coupling lines inserted between the input and output transmission lines and the upper transmission line of the ring resonator and serving as a capacitance, respectively, wherein the upper transmission line of the ring resonator has two ends, First and second transmission lines connected to the first and second interdigital coupling lines and forming an upper transmission line of the ring resonator; A first artificial transmission line LUC (low-pass filter unit cell) designed as an artificial transmission line (ATL) system having a low-pass filter characteristic and inserted between the first transmission line and the second transmission line, Wherein the lower transmission line of the ring resonator has third and fourth transmission lines connected to the first and second transmission lines at both ends, respectively, and constituting a lower transmission line of the ring resonator; And a second artificial transmission line LUC designed to be connected to the third transmission line and the fourth transmission line, respectively, the artificial transmission line system having a low-pass filter characteristic, and a ring resonator band pass Filter.

The first artificial transmission line LUC is a pair of phase delay coupling lines, one end of which is bent at right angles to the first and second transmission lines and are arranged parallel to each other at a predetermined interval. And a first open stub disposed in parallel with the pair of phase delay coupling lines and having a square shape.

The second artificial transmission line LUC is a pair of phase delay coupling lines, one end of which is bent at a right angle to the third or fourth transmission line, and is arranged parallel to each other at a predetermined interval. And a second open stub disposed parallel to the pair of phase delay coupling lines or bent at a right angle and connected to each other and having a rectangular shape.

The second artificial transmission line LUC may be disposed inside or outside the ring resonator.

When the second artificial transmission line LUC is disposed inside the ring resonator, one ends of the pair of phase delay coupling lines are bent twice at right angles at the ends of the third and fourth transmission lines, respectively, so that the first and second And the second open stub may be connected to the other end of the pair of phase delay combining lines.

When the second artificial transmission line LUC is disposed outside the ring resonator, one end of the pair of phase delay coupling lines is bent at right angles at the ends of the third and fourth transmission lines and extended in parallel to each other, And the second open stub may be connected to the other end of the phase delay coupled line.

Each of the first and second artificial transmission lines LUC has a " [pi] "shape, and may be a Cheby Shevary low pass filter.

In addition, the first and second transmission lines may have the same impedance as the first artificial transmission line LUC, and the third and fourth transmission lines and the second artificial transmission line LUC may be set to have the same impedance.

It is preferable that the first and second transmission lines have the same impedance and the same electrical length and have a symmetrical structure.

As described above, according to the present invention, by constructing a wavelength ring resonator using an artificial transmission line (ATL) low-pass filter unit cell (LUC) having low-pass characteristics, the physical size of the ring resonator is reduced, Is possible.

In the present invention, harmonic suppression is possible by adjusting the notch frequency using the blocking characteristic of the low pass filter of the ATL LUC.

The present invention is based on a single-wavelength ring resonator, in which the impedance of the two lines constituting the ring resonator are made different from each other to induce a dual mode and the impedance difference is adjusted to adjust the coupling amount between the two resonators Can be adjusted to implement a filter.

1 is a schematic view showing a band-pass filter using a general impedance inverter.
2 is a schematic view showing a band-pass filter using a general admittance inverter.
3 is an explanatory diagram for explaining a method of designing a two-stage bandpass filter using mutual coupling between two resonators.
4 is a block diagram showing a general dual mode ring resonator structure.
5 is an equivalent circuit of the ring resonator filter of Fig.
6 is a? -Type equivalent circuit of the ring resonator.
7 is a circuit diagram showing a two-stage band-pass filter using an inverter.
8 (a) and 8 (b) are graphs showing S-parameters of two artificial transmission line LUCs, respectively.
9 is an explanatory view for explaining a method of designing a ring resonator bandpass filter using an artificial transmission line according to the present invention.
FIG. 10 is a schematic diagram showing a method of designing an artificial transmission line (ATL) used in the upper and lower transmission lines of FIG.
11 is a photograph showing a fabricated sample of the ring resonator band-pass filter according to the present invention.
12 and 13 are graphs showing simulations of a ring resonator band-pass filter according to the present invention and S-parameters of narrow band characteristics and wide band characteristics, respectively, for fabricated samples.
FIG. 14 is a configuration diagram illustrating an inter-digital line employed to realize a capacitance of an input stage inverter and an output stage inverter in a ring resonator band-pass filter according to the present invention.
15 is an explanatory view illustrating a design process of a ring resonator band-pass filter according to the present invention.
16 is a plan view showing the structure of a ring resonator band-pass filter using an artificial transmission line according to the present invention.
17 is a plan view showing a modified structure of a ring resonator bandpass filter using an artificial transmission line according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The sizes and shapes of the components shown in the drawings may be exaggerated for clarity and convenience.

Hereinafter, a method of designing a ring resonator band-pass filter (BPF) using an artificial transmission line according to the present invention will be described with reference to FIGS. 1 to 7. FIG.

<Bandpass Filter Design>

In general, when converting from basic types of low pass filter (LPF) to band pass filter (BPF) or band stop filter (BRF), it is constituted using a series resonator and a parallel resonator. However, when a filter is implemented for a particular type of transmission line, only a series element as shown in Fig. 1 or only a parallel element as shown in Fig. 2 may be used.

That is, impedance K inverters K ₀₁ , K ₁₂ , K ₂₃ ,..., K _{nn +1} are inserted between LC series resonators having a multi-stage structure as shown in FIG. 1, A band-pass filter or a band-stop filter can be realized by inserting an admittance (J) inverter (J ₀₁ , J ₁₂ , ..., J _{nn +1} ).

In the present invention, a filter using the admittance (J) inverter and the parallel resonators (L, C) shown in FIG. 2 is implemented. The admittance inverters J ₀₁ , J ₁₂ , ..., J _{nn +1} are proportional to the coupling coefficient k expressed by the following equations (1) and (2). Therefore, it is possible to design the band-pass filter (BPF) using the coupling coefficient k.

Generally, when the intermediate stage inverter 32 or the coupling element is applied between the two first and second resonators 31 and 33 having the same resonance frequency f ₀ as in FIG. 3, the frequency varies based on the resonance frequency. That is, as the coupling coefficient (k) increases, the frequency interval at which vibration occurs increases. At this time, the two resonance frequencies (modes) which are gathered into one are divided into two due to the coupling element, which is called a dual-mode.

Therefore, a two-stage bandpass filter as shown in FIG. 5 can be designed using mutual coupling between resonators having the same frequency response characteristics.

That is, the band-pass filter (BPF) using the admittance inverter according to the present invention includes an intermediate-stage inverter 32 (J ₁₂ ) between two first and second resonators 31 and 33 having the same resonance frequency f ₀ And an input stage inverter 34 (J ₀₁ ) and an output stage inverter (J ₀₂ ) are connected between the input terminal P ₁ and the first resonator 31, between the second resonator 33 and the output terminal P ₂ , .

5, the bandwidth of the band-pass filter (BPF) can be adjusted by changing mutual coupling amounts (inverter values) according to the following equations (3) to (5).

The definitions of the symbols in the above Equations 1 to 5 are as follows:

k: Coupling coefficient

K: Impedance inverter value

J: Admittance inverter value

: 비대역폭

: Non-bandwidth

x: reactance slope parameter of the resonator

b: susceptance slope parameter of resonator

g: filter element value

G: Input conductance

= 비대역폭(fractional bandwidth)(대역폭/중심 주파수), g는 필터 소자값으로서 리플(ripple) 값에 따라 변화하는 값이다.J ₀₁ is the input stage inverter value of the ring resonator 40, and J ₀₂ is the output stage inverter value of the ring resonator 40. Also,

= Fractional bandwidth (bandwidth / center frequency), and g is a value that varies with the ripple value as the filter element value.

(BPF) having a center frequency (f ₀ ) of 2.42 GHz, a bandwidth (BW) of 100 MHz, and an insertion loss of 3.5 dB using the design equations of Equations (3) Respectively.

On the other hand, the ring resonator can easily produce a filter having a band pass response characteristic due to discontinuity by applying a simple patch, a slot, or a perturbation such as a notch, and has a low radiation loss. It is a common structure when implementing.

The basic principle of the ring resonator is that, in a circular ring structure, when a patch, slot or notch is inserted at the midpoint of the input / output portion, two different paths are formed from the input to the output, An odd-odd mode, degenerate mode, occurs.

In the present invention, the width and the length of the upper transmission line 43 and the lower transmission line 44 in the general ring resonator 40 shown in FIG. 4 are set differently to make the impedances different from each other, The positions of the terminals 41 and 42 (P ₁ and P ₂ ) are adjusted to adjust the values of the input stage inverter 34 (J ₀₁ ) and the output stage inverter 35 (J ₀₂ ). As a result, And a two-stage band pass filter (BPF) using the resonator 40.

5 is an equivalent circuit of the band-pass filter according to the present invention, the ring resonator 40 is expressed as π-type equivalent circuit, the intermediate stage inverter (J ₁₂₎ between a pair of resonators (B _1, B ₂₎ insertion Is expressed as a structure. When an input stage inverter J ₀₁ and an output stage inverter J ₀₂ are connected to the ring resonator 40 as a? / 4 transmission line inverter, an equivalent circuit of a band-pass filter having two-stage bandpass characteristics is obtained.

<Ring resonator>

The ring resonator 40 shown in FIG. 4 is expressed as a transmission line, expressed as an ABCD parameter, and then transformed into a Y parameter. The ring resonator of FIG. 4 can be viewed as a parallel structure of two lower and upper transmission lines 44 and 43 as shown in FIG. 5. At this time, the admittance of the two transmission lines 44 and 43 can be viewed as Y ₁ and Y ₂ have.

The ABCD parameters of the two lines are converted into Y parameters, and the Y parameter (Y _T ) of the entire ring resonator can be obtained. The process of obtaining the Y parameter (Y _T ) is described in the following Equations (6) to (11).

The Y parameter can be expressed by a pi-type equivalent circuit as shown in Fig. Here, Y ₁₂ Portion indicates the portion of the intermediate stage inverter 32 (J ₁₂ ) of the band-pass filter (BPF). Using the relational expression (11), the value of the intermediate stage inverter (32: J ₁₂ ) can be obtained as shown in the following equation ( ₁₂ ).

<Bandpass Filter Design Using Ring Resonator>

)과 필터 소자값(g)을 대입하면 링 공진기(40)의 슬로프(slope) 파라미터(b)를 알 수 있다. 제1 및 제2 공진기(31,33)는 공진 주파수가 동일한 것을 사용하므로 수학식 4에서 슬로프 파라미터 b₁과 b₂의 값은 같다. In the equivalent circuit of a ring resonator band-pass filter (BPF) shown in Figure 5 by the equation (12) Knowing the admittance value (Y _1, Y ₂₎ of the ring resonator 40 to the two transmission lines (44,43) intermediate It is possible to know the value of the inverter 32 (J ₁₂ ) and calculate the fractional bandwidth of the band-pass filter (BPF)

(B) of the ring resonator 40 can be obtained by substituting the filter element value g and the filter element value g. Since the first and second resonators 31 and 33 use the same resonance frequency, the slope parameters b ₁ and b ₂ in Equation (4) are the same.

Substituting slope parameters (b ₁ , b ₂ ) of the obtained first and second resonators 31 and 33 into equations (3) and (5), the input stage inverter J ₀₁ and the output stage inverter J ₀₂ ) can be obtained.

7, the size of the input stage inverter J ₀₁ and the output stage inverter J ₀₂ are determined by using the following Equation (13) and the C ₀₁ value is calculated using Equation (14) Conversion. The inverter of each stage can be equivalently converted into a circuit as shown by the dotted line in FIG. 7, and the value of the capacitor (C ₀₁ ) corresponding to the input stage inverter J ₀₁ and the output stage inverter J ₀₂ can be obtained .

<Ring resonator configuration using LUC>

In order to redesign the miniaturized ring resonator filter based on the ring resonator theory described above, an artificial transmission line (ATL) having a characteristic impedance (Z _A ) and an electrical length ( _A ) is designed.

The artificial transmission line (ATL) has a characteristic impedance (Z ₀ ) and an electrical length (?) Equal to those of a general transmission line. In addition, the artificial transmission line (ATL) has an electric characteristic equivalent to that of a general transmission line at a specific frequency and constitutes a low-pass filter unit cell (LUC) having a low-pass characteristic.

The design method of the artificial transmission line is as follows. After designing a 3-stage low-pass filter with a cut-off frequency of 4GHz and a ripple of 0.5dB with a Cheby Shev low-pass filter designed by a standard design method using capacitors and inductors, an accurate LUC (low-pass filter unit cell) Pass filter to a pair of phase delay coupled lines 51 and 52 to which an open stub 53 is added as shown in FIG.

The two artificial transmission line LUCs 50 and 50a corresponding to the characteristic impedance (Z _upper , Z _lower ) of the two upper and lower transmission lines 43 and 44 in the ring resonator are designed using Equations 15 through 20 do.

The characteristic impedance (Z _upper ) corresponding to the upper transmission line 43 is 40.4?, The electrical length? _Upper is 40.5?, And the characteristic impedance Z _upper is 40.4? When the center frequency is 2.45 GHz. The two artificial transmission line LUCs 50 and 50a have different characteristics. has a 71.6 °, characteristic corresponding to the lower side in the transmission line 44 the impedance (Z _lower) is 50.1Ω, electric length (θ _lower) is 74.2 °.

The S-parameters of the two artificial transmission line LUC (50, 50a) are shown in Figs. 8A and 8B. The low-pass characteristics and the position of the transmission zero can be seen. A ring resonator is constructed as shown in FIG. 9 by using two artificial transmission line LUCs 50 and 50a and four general first through fourth transmission lines 43a, 43b, 44a, and 44b having different impedances.

The first and second transmission lines 43a and 43b corresponding to the upper transmission line 43 have the same impedance and the same electrical length and have a symmetrical structure. The first and second transmission lines 43a and 43b, which correspond to the lower transmission line 44, The third and fourth transmission lines 44a and 44b are connected to the first and second transmission lines 43a and 43b so as to form a substantially rectangular ring together with the first and second transmission lines 43a and 43b as a whole, And 43b, but the actual lengths are set to be different from each other in accordance with the difference in electrical length.

θ _s : Stub electrical length

Z _c : Coupled line image parameter

Z _ce : Excellent Mode Impedance with Coupled Lines

Z _{co :} Coupled-Line Radix Mode Impedance

βℓ: image parameter of the coupled line

θ _c : Electrical length of the coupling line

θ _A : Electrical length to artificial transmission line

Z _A : Impedance to artificial transmission line

In Equation 17,? L represents the electrical length of the entire phase-delay coupling line of the LUC, and? C represents the electrical length of the coupling line of one of the two coupling lines constituting the phase delay coupling line of the artificial transmission line (ATL).

 <Simulation of filter and sample production>

Table 1 summarizes the S-parameter values used in the simulation designed in the above-described manner.

Line member number 44a 44b 50a 43a, 43b 50 Impedance (Ω) 50 50 50 40 40 Electrical length
(degree) 34 148 67 12 72

Using the Line Calculator function included in Agilent's ADS ^TM for producing the samples, the parameter values required for sample preparation of the ring resonator bandpass filter of Table 2 below can be derived from the parameter values in Table 1 .

The circuit was designed and simulated using ADS ^TM , a circuit design tool. The substrate was fabricated using MX0348ST0762CHCH with area of 27 x 27 mm2, dielectric constant (ε _r ) of 3.48, dielectric thickness of 0.762 mm and dielectric loss tan δ 0.003.

The fabricated dual mode ring resonator bandpass filter is shown in FIG. 11, and FIG. 12 and FIG. 13 show a simulation result of a dual mode ring resonator bandpass filter according to the present invention and a narrow band characteristic and a wide band characteristic S-parameters of the S-parameters are compared.

Line member number 44a 44b 51a, 52a 53a 43a, 43b 51,52 53 Thickness (mm) 1.69 1.69 0.26 2.4 2.4 0.26 4 Length (mm) 8.8 23.9 4.2 + 1.5 + 0.56 + 0.56 4.6 1.5 5.3 3.9 Spacing (mm) 0.3 0.3

When a pair of phase delay coupling lines 51a and 52a are bent and formed in the second artificial transmission line LUC 50a, the horizontal coupling line is 4.2 mm, the vertical coupling line is 1.5 mm, The one side of the bend portion is set to 0.56 mm, and the other side is set to 0.56 mm.

When the first and second artificial transmission line LUCs 50 and 50a are designed, the thickness of the open stub 53 (53a) is designed to be thicker than the pair of phase delay coupling lines 51 and 52 (51a and 52a) .

11, the input stage inverter J ₀₁ and the output stage inverter J ₀₂ are constituted by the coupled lines of the interdigital type shown in FIG. 14 in order to derive the capacitor C ₀₁ . The dimensional values for designing the capacitance of the interdigital coupling line to 0.6 pF are shown in Table 3 below.

track Finger length (L) Finger thickness Finger spacing W Wt Dimensions (mm) 4.3 0.15 0.15 1.65 0.2

11 and 16, a part of the existing transmission lines 43 and 44 is replaced with the artificial transmission line LUC 50 and 50a in the two paths of the ring resonator 40 between the input / output terminals P1 and P2 .

It can be seen that the transmission characteristic of the harmonics is suppressed as shown in FIG. 13 by replacing a part of two transmission lines corresponding to the two paths of the ring resonator with the artificial transmission line LUC.

The fabricated filter has a center frequency of 2.42 GHz, an insertion loss of 3.5 dB, and a bandwidth of 100 MHz. The ring area of the dual - mode ring resonator bandpass filter using the fabricated artificial transmission line (ATL) is 1/5 of that of the conventional one - wavelength ring resonator.

The lower LUC of the ring resonator bandpass filter shown in FIG. 11 is disposed inside the ring resonator, but it may be disposed outside the ring resonator as shown in FIG.

Referring to FIG. 12, it can be seen that the resonance points near the center frequency in the narrow-band S-parameter are divided into two rather than one and have a dual-mode.

As shown in FIG. 11, the dual mode ring resonator bandpass filter using the artificial transmission line according to the present invention is advantageous in miniaturization by reducing the ring area by using the artificial transmission line, and the structural efficiency is enhanced by the artificial transmission line LUC. The present invention is advantageous for miniaturization when a bandpass filter is designed and manufactured at a low frequency.

FIG. 15 shows a method of designing a ring resonator band-pass filter using an artificial transmission line according to the present invention.

First, a low pass filter is designed by a standard design method using a capacitor and an inductor.

Second, the low-pass filter is converted to the LUC structure.

Third, the ring resonator is regarded as a parallel connection of two transmission lines, and a part of each transmission line is replaced with an artificial transmission line. The impedance of the artificial transmission line is the same as the impedance of the transmission line that originally constituted the ring resonator, and the electrical length of the existing transmission line and the artificial transmission line is the same as that of the replaced part.

Fourth, if the upper transmission line and the lower transmission line are circularly connected, a sample-fabricated filter as shown in FIG. 11 or 17 is obtained. However, the artificial transmission line LUC in the lower transmission line of the ring resonator is not located in the center, and the LUC protrudes to the right side of the ring resonator lower transmission line to reduce the area of the substrate.

Hereinafter, the structure of the ring resonator band-pass filter obtained according to the above-described design method will be described with reference to FIG.

16, the ring resonator band-pass filter using the artificial transmission line according to the present invention includes a substrate 60 made of an insulating material such as a dielectric substrate, and a substrate 60 formed on one surface of the substrate, Input and output transmission lines 61 and 62 to which the input port P1 and the output port P2 are connected and input and output transmission lines 61 and 62 formed on the same plane as the input and output transmission lines 61 and 62, First and second interdigital coupling lines C ₀₁ inserted between the first and second ring resonators 61 and 62 and serving as a capacitance are connected to the first and second interdigital coupling lines C ₀₁ , The first and second transmission lines 43a and 43b constituting the upper transmission line of the resonator and the first artificial transmission line LUC (43b) inserted and connected between the first and second transmission lines 43a and 43b, 50, both ends of which are connected to the first and second transmission lines 43a, 43b, respectively, Third and fourth transmission lines 44a and 44b constituting a lower transmission line of the ring resonator and a second artificial transmission line 44a and 44b inserted and connected between the third and fourth transmission lines 44a and 44b, LUC 50a.

Various transmission lines and artificial transmission line LUC formed on one surface of the substrate are formed of a conductive microstrip line.

The first artificial transmission line LUC 50 includes a pair of phase delay coupling lines, one end of which is bent at right angles to the first and second transmission lines 43a and 43b and are arranged parallel to each other at a predetermined interval, (51, 52), and a first open stub (53) arranged in parallel with the pair of phase delay coupling lines (51, 52) and having a square shape.

The second artificial transmission line LUC 50a is a pair of phase delay coupling lines, one end of which is bent perpendicularly to the third and fourth transmission lines 44a and 44b and connected parallel to each other at a predetermined interval And a second open stub 53a disposed parallel to the pair of phase delay coupling lines 51a and 52a or bent at right angles and having a rectangular shape.

The ring resonator band-pass filter using the artificial transmission line according to the present invention is characterized in that two first and second artificial transmission line LUCs 50 and 50a, which are designed by artificial transmission line (ATL) method, are connected to the upper transmission line and the lower transmission line The second artificial transmission line LUC 50a may be disposed inside the ring resonator by bending a pair of phase delay coupling lines 51a and 52a as shown in FIG. 16 or may be disposed outside as shown in FIG. 17, It is efficient to reduce the size of the ring resonator.

As a result, the first and second artificial transmission line LUCs 50 and 50a are each formed in a " [pi] "shape as a whole. The phase delay coupling lines 51 and 52a and open stubs 53 and 53a are Cheby Shev low pass filters having a phase delay function and have a cutoff frequency of 4 GHz and a ripple of 0.5 dB But it is a low-pass filter. The phase delay coupling lines 51 and 52a and the open stub 53 and 53a are phase delay artificial transmission lines implemented by a low pass filter unit cell (LUC) design method.

In the ring resonator bandpass filter of the present invention, the first and second transmission line paths 43a and 43b have the same impedance as that of the first artificial transmission line LUC 50 and are designed to have 40? 44a and 44b and the second artificial transmission line LUC 50a have the same impedance and are designed to have 50?

However, the first and second transmission lines 43a and 43b and the first artificial transmission line LUC 50 are designed to have different electrical lengths, and the sizes implemented in the samples are set differently. Also, the electrical lengths of the third and fourth transmission lines 44a and 44b and the second artificial transmission line LUC 50a are designed to have different lengths, and sizes implemented in the samples are set differently.

As described above, the dual mode ring resonator bandpass filter using the artificial transmission line according to the present invention has a bandwidth of 100 MHz and insertion loss of 3.5 dB at a center frequency of 2.42 GHz. In addition, the ring resonator band-pass filter according to the present invention suppresses the resonance of the fourth harmonic to show that the S21 parameter showing the filter characteristic of the pass band is -13 dB, and has a sharp skirt characteristic in the harmonic pass band.

In addition, the band-pass filter according to the present invention can be realized as a small-sized 27 × 27 mm 2 by inserting the artificial transmission line LUC (50, 50a) between the upper and lower transmission lines of the ring resonator, , The physical size of the resonator can be reduced by about 21% when compared to a typical one-ring ring resonator.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein. Various changes and modifications may be made by those skilled in the art.

The dual mode ring resonator bandpass filter using the artificial transmission line according to the present invention has a bandwidth of 100 MHz and insertion loss of 3.5 dB at a center frequency of 2.42 GHz and suppresses the resonance of the fourth harmonic, It is a bandpass filter that exhibits sharp skirt filter characteristics and will be useful for the design and fabrication of miniaturized filters.

31, 33: resonator 32: intermediate stage inverter
34: input stage inverter 35: output stage inverter
40: ring resonator 41: input terminal
42: output terminal 43: upper transmission line
44: lower transmission line 50, 50a: artificial transmission line
43a, 43b, 44a, 44b: transmission line 53, 53a: open stub
51, 51a, 52, 52a: phase delay coupling line 60: substrate
61: input stage transmission line 62: output stage transmission line

Claims (11)

A substrate made of an insulating material;
An input terminal and an output terminal transmission line formed on one surface of the substrate and each having an input port and an output port connected to an inlet and an outlet of the line, respectively;
A ring resonator including an upper transmission line connected between the input end and the output end transmission line, and a lower transmission line coupled with the upper transmission line; And
And first and second interdigital coupling lines inserted between the input and output transmission lines and the upper transmission line of the ring resonator, respectively, and serving as a capacitance,
The upper transmission line of the ring resonator
First and second transmission lines connected to the first and second interdigital coupling lines at both ends and constituting an upper transmission line of the ring resonator; And
A first artificial transmission line LUC (Low-pass filter unit cell) designed to be inserted into the first transmission line and the second transmission line and designed as an artificial transmission line (ATL) system having a low-pass filter characteristic and,
The lower transmission line of the ring resonator
Third and fourth transmission lines connected to the first and second transmission lines, respectively, both ends of the ring resonator constituting the lower transmission line; And
A ring resonator bandpass filter using an artificial transmission line including a second artificial transmission line LUC designed in an artificial transmission line system having both end portions inserted between a third transmission line and a fourth transmission line and having a low pass filter characteristic, . The method according to claim 1,
The first artificial transmission line LUC
A pair of phase delay coupling lines, each of which is bent at right angles to the first and second transmission lines and arranged parallel to each other at a predetermined interval; And
And a first open stub disposed in parallel with the pair of phase delay coupling lines and having a square shape. The method according to claim 1,
The second artificial transmission line LUC
A pair of phase delay coupling lines bent in one direction at right angles to the third or fourth transmission line, respectively, and arranged parallel to each other at a predetermined interval; And
And a second open stub disposed parallel to the pair of phase delay coupling lines or bent at right angles and having a rectangular shape. The method according to claim 1,
And the second artificial transmission line LUC is an artificial transmission line disposed inside the ring resonator. The method according to claim 1,
And the second artificial transmission line LUC is an artificial transmission line disposed outside the ring resonator. The method according to claim 1,
And the first and second artificial transmission lines LUC are each formed in a "" -shaped artificial transmission line. The method according to claim 1,
Wherein the first and second artificial transmission line LUCs are Cheby Shev low pass filters that are artificial transmission lines. The method according to claim 1,
The first and second transmission lines have the same impedance as the first artificial transmission line LUC,
And the artificial transmission line is set to have the same impedance as the third and fourth transmission line and the second artificial transmission line LUC. 5. The method of claim 4,
The second artificial transmission line LUC is formed such that one end of a pair of phase delay coupling lines is bent twice at right angles from the ends of the third and fourth transmission lines and extended toward the first and second transmission lines in parallel to each other, And the second open stub is connected to the other end of the phase delay coupled line. 6. The method of claim 5,
The second artificial transmission line LUC has a pair of phase delay coupling lines, one end of which is bent at right angles at the ends of the third and fourth transmission lines and extended in parallel with each other, and the other end of the pair of phase- A ring resonator bandpass filter using an artificial transmission line to which a stub is connected. The method according to claim 1,
Wherein the first and second transmission lines have the same impedance and the same electrical length and form a symmetrical structure.

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