TWI589056B - Filter configuration with defected ground structure - Google Patents

Description

Filter component with defective ground structure

The present invention relates to a filter assembly having a defective ground structure, and more particularly to a filter assembly for improving filter performance by using a defective ground structure.

Wireless communication technology has changed the way people send and receive messages. In order to meet the different needs of users when sending and receiving messages, wireless transceivers with multi-mode and multi-bandwidth have become impossible in the communication system. Necessary components missing. Taking the wireless communication standard IEEE802.11a and IEEE802.11g as an example, since the operating frequency bands of the above two standards include 2.4 GHz and 5.2 GHz, in order for the wireless transceiver to work normally in the above dual frequency band, the wireless transceiver must set a band pass filter. Bandpass Filter, and the bandpass filter can form a passband at frequencies of 2.4 GHz and 5.2 GHz, and suppress signals outside the passband, thereby achieving multi-band transmission.

The band pass filter may be formed by a Step Impedance Resonator (SIR). For example, the band pass filter may have two resonators, and the electrical lengths of the two resonators are usually Is a half-wavelength or a quarter-wavelength, and the two resonators are respectively composed of a plurality of microstrip lines, and by controlling the coupling relationship between the plurality of microstrip lines, the A bandpass filter can have a passband effect at a particular frequency.

In general, the control accuracy of the passband frequency and the attenuation value of the echo loss have always been an important indicator for judging the filter performance of the filter. However, the conventional bandpass filter is in control When the frequency and the attenuation value of the echo loss are increased, only the length or width of the microstrip line is usually changed, and the influence of the Defected Ground Structure (DGS) on the overall filtering performance is not further considered, so that the conventional band pass The filter cannot further accurately control the passband frequency and increase the attenuation value of the return loss.

In view of this, 遂 provides a filter component with a defective ground structure to solve the problem of poor filtering performance of the conventional band pass filter.

It is an object of the present invention to provide a filter assembly having a defective ground structure that can use an appropriate defect ground structure to accurately control the passband frequency and increase the attenuation value of the return loss, with the effect of improving filtering performance.

In order to achieve the foregoing object, the filter assembly of the present invention having a defective ground structure includes: a substrate having a first surface and a second surface, the second surface being a ground plane; a main microstrip line, The main microstrip line is disposed on the first surface and extends along a first direction; and a first defect ground structure is disposed on the second surface, the first defect ground structure has a first line a first circular segment, a second segment, a second circular segment and a third segment, the first segment, the first segment, the second segment, the second segment The circular section and the third line segment are sequentially connected along a second direction, and the first direction is perpendicular to the second direction, and in the second direction, the minimum length of the first line segment is smaller than the second line segment The minimum length of the first line segment is equal to the minimum length of the third line segment; wherein the main microstrip line covers the second line segment in a vertical projection direction of the first surface toward the second surface And in the second direction, the width of the main microstrip line To the minimum length of the second segment. This has the effect of improving the filtering performance.

The first line segment, the second line segment, and the third line segment have a common first center extension line, and the first center extension line passes through the first circular section. The center of the circle and the center of the second circular section. Thereby having improved filtering performance effect.

The width of the first line segment, the width of the second line segment, and the width of the third line segment are equal in the first direction. This has the effect of improving the filtering performance.

Wherein the radius of the first circular section is equal to the radius of the second circular section. This has the effect of improving the filtering performance.

The second defect grounding structure is disposed on the second surface, and the second defect grounding structure has a fourth line segment, a third circular segment, a fifth segment, and a second defect grounding structure. a fourth circular segment and a sixth segment, the fourth segment, the third segment, the fifth segment, the fourth segment, and the sixth segment are sequentially along the second direction Connecting, and in a vertical projection direction of the first surface toward the second surface, the main microstrip line covers the fifth line segment, and in the second direction, the width of the main microstrip line is equal to the fifth The minimum length of the line segment. This has the effect of improving the filtering performance.

Wherein, in the second direction, the fourth line segment, the fifth line segment and the sixth line segment have a common second center extension line, and the second center extension line passes through the third circular segment The center of the circle and the center of the fourth circular section. This has the effect of improving the filtering performance.

In the second direction, the first line segment, the second line segment, and the third line segment have a common first center extension line, and the main microstrip line has one of a pair of microstrip lines a second center extension line is disposed between the first center extension line and the bonding end, and in the first direction, the first center extension line and the second center extension line have a first a spacing distance, the second center extension line and the bonding end have a second separation distance, the first spacing distance being greater than the second spacing distance. This has the effect of improving the filtering performance.

The width of the fourth line segment, the width of the fifth line segment, and the width of the sixth line segment are equal in the first direction. This has the effect of improving the filtering performance.

The minimum length of the fourth line segment is smaller than the minimum length of the fifth line segment in the second direction, and the minimum length of the fourth line segment is equal to the minimum length of the sixth line segment. This has the effect of improving the filtering performance.

The minimum length of the first line segment is smaller than the minimum length of the second line segment in the second direction, the minimum length of the first line segment is equal to the minimum length of the third line segment, and the first line segment is The minimum length is greater than the minimum length of the fourth line segment, and the minimum length of the second line segment is equal to the minimum length of the fifth line segment. This has the effect of improving the filtering performance.

Wherein the radius of the third circular section is equal to the radius of the fourth circular section. This has the effect of improving the filtering performance.

The radius of the first circular segment is equal to the radius of the second circular segment, and the radius of the first circular segment is greater than the radius of the third circular segment. This has the effect of improving the filtering performance.

〔this invention〕

1‧‧‧Substrate

11‧‧‧ first surface

12‧‧‧ second surface

2‧‧‧Main microstrip line

21‧‧‧Binding end

3‧‧‧First defect grounding structure

31‧‧‧First line

32‧‧‧First circular section

33‧‧‧second line

34‧‧‧Second round section

35‧‧‧ third line segment

4‧‧‧First defect grounding structure

41‧‧‧ fourth line

42‧‧‧ Third circular section

43‧‧‧ fifth line

44‧‧‧fourth circular section

45‧‧‧ sixth line

A1‧‧‧ first direction

A2‧‧‧ second direction

D1‧‧‧first separation distance

D2‧‧‧Second separation distance

M‧‧‧Sub-microstrip line

R1‧‧‧First Resonator

R11‧‧‧first feed line

R12‧‧‧First coupled line

R12a‧‧‧ the first part of the line

R12b‧‧‧ second part of the line

R12c‧‧‧ third part of the line

R2‧‧‧ second resonator

R21‧‧‧second feed line

R22‧‧‧second coupling line

R22a‧‧‧Fourth line segment

R22b‧‧‧5th line segment

R22c‧‧‧Sixth line segment

Fig. 1 is a structural view of a filter assembly having a defective ground structure of the present invention.

Figure 2 is a block diagram of a filter assembly of the present invention having a defective ground structure.

Figure 3 is a block diagram of a filter assembly of the present invention having a defective ground structure.

Figure 4 is a block diagram of a filter assembly of the present invention having a defective ground structure.

Fig. 5 is a structural view showing the construction of a filter assembly having a defective ground structure of the present invention.

Figure 6: Frequency response diagram of the filter component without the defect ground structure.

Figure 7: Frequency response diagram of a filter assembly with a defective ground structure.

Figure 8: Frequency response diagram of a filter assembly with two sets of defective ground structures.

The above and other objects, features and advantages of the present invention will become more <RTIgt; "Coupling" as used throughout this disclosure refers to the manner in which energy is transferred from one medium to another.

Please refer to FIG. 1 and FIG. 2 , which are structural diagrams of the filter assembly with the defective ground structure of the present invention, comprising a substrate 1 , a main microstrip line 2 and a first defect ground structure 3 , the main micro The strip line 2 and the first defect ground structure 3 are respectively disposed on different surfaces of the substrate 1.

The substrate 1 has a first surface 11 and a second surface 12, and the second surface 12 is a ground plane. The substrate 1 can be a printed circuit board, and the main material of the substrate 1 is not limited herein, such as a fiberglass material.

The main microstrip line 2 is disposed on the first surface 11 of the substrate 1 and extends along a first direction A1. The main microstrip line 2 can be a coupling line for coupling in a resonator, or can be used as a signal input terminal or a signal output terminal (Tapped Line), which is not limited herein. In the example, the main microstrip line 2 is the feed line.

The first defect ground structure 3 is disposed on the second surface 12 of the substrate 1. The first defect ground structure 3 has a first line segment 31, a first circular segment 32, a second segment 33, and a first segment a second circular section 34 and a third line segment 35, the first line segment 31, the first circular section 32, the second line segment 33, the second circular section 34, and the third line segment 35 The systems are sequentially connected in a second direction A2, and the first direction A1 is perpendicular to the second direction A2. The main microstrip line 2 covers the second line segment 33 in a vertical projection direction of the first surface 11 toward the second surface 12, and in the second direction A2, the main microstrip line 2 The width is equal to the minimum length of the second line segment 33, that is, the main microstrip line 2 does not cover the first circular section 32 and the second circular section 34. Therefore, if the first defect ground structure 3 is disposed in the filter component, and the first defect ground structure 3 and the main microstrip line 2 have the above-mentioned arrangement relationship, the overall defect ground structure 3 can be improved. The filtering performance has the effect of improving the filtering performance.

More specifically, in the second direction A2, the first line segment 31, the second line segment 33 and the third line segment 35 have a common first center extension line L1, and the first center extension line L1 It passes through the center of the first circular section 32 and the center of the second circular section 34. Further, in the first direction A1, the width of the first line segment 31, the width of the second line segment 33, and the width of the third line segment 35 are equal; in the second direction A2, due to the first line segment 31. The second line segment 33 and the third line segment 35 each have at least one end connected to the first circular segment 32 or the second circular segment 34. Therefore, when the first center extension line L1 passes the first When the center of the circular section 32 and the center of the second circular section 34, the first line segment 31, the second line segment 33 and the third line segment 35 have a minimum on the first center extension line L1. The minimum length of the first line segment 31 is smaller than the minimum length of the second line segment 33, and the minimum length of the first line segment 31 is equal to the minimum length of the third line segment 35; in addition, the first circular segment 32 The radius is equal to the radius of the second circular section 34. Therefore, if the first defect ground structure 3 is disposed in the filter component, and the components of the first defect ground structure 3 have the above-mentioned dimensional relationship, the overall filter performance can be improved through the first defect ground structure 3. It has the effect of improving the filtering performance.

Referring to FIGS. 3 and 4, in the case where the present invention has the substrate 1, the main microstrip line 2, and the first defect ground structure 3, there may be another second defect ground structure 4, the second The defect grounding structure 4 is disposed on the second surface 12 of the substrate 1. The second defect grounding structure 4 has a fourth line segment 41, a third circular segment 42, a fifth segment 43, and a fourth circle. a section 44 and a sixth line segment 45, the fourth line segment 41, the third circular section 42, the fifth line segment 43, the fourth circular section 44 and the sixth line segment 45 are along the second The direction A2 is sequentially connected, and in the vertical projection direction of the first surface 11 toward the second surface 12, the main microstrip line 2 covers the fifth line segment 43, and in the second direction A2, the main The width of the microstrip line 2 is equal to the minimum length of the fifth line segment 43, that is, the main microstrip line 2 does not cover the third circular section 42 and the fourth circular section 44. Thereby, if the second component is set in the filter component When the defect grounding structure 4 and the second defect grounding structure 4 and the main microstrip line 2 have the above-mentioned arrangement relationship, the overall filtering performance can be improved through the second defect grounding structure 4, and the filtering performance is improved.

More specifically, in the second direction A2, the fourth line segment 41, the fifth line segment 43, and the sixth line segment 45 have a common second center extension line L2, and the second center extension line L2 is The center of the third circular section 42 and the center of the fourth circular section 44 are passed. Further, in the first direction A1, the width of the fourth line segment 41, the width of the fifth line segment 43 and the width of the sixth line segment 45 are equal; in the second direction A2, due to the fourth line segment 41, the The fifth line segment 43 and the sixth line segment 45 each have at least one end connected to the third circular section 42 or the fourth circular section 44, and therefore, when the second center extension line L2 passes through the third circular section When the center of the segment 42 and the center of the fourth circular segment 44, the fourth segment 41, the fifth segment 43 and the sixth segment 45 have a minimum length on the second center extension line L2. The minimum length of the fourth line segment 41 is smaller than the minimum length of the fifth line segment 43. The minimum length of the fourth line segment 41 is equal to the minimum length of the sixth line segment 45. Further, the radius of the third circular segment 42 is equal to the fourth length. The radius of the circular section 44. Therefore, if the second defect ground structure 4 is disposed in the filter component, and the components of the second defect ground structure 4 have the above-mentioned dimensional relationship, the overall filter performance can be improved through the second defect ground structure 4, It has the effect of improving the filtering performance.

Referring to FIG. 5 again, in the case where the present invention has both the first defect ground structure 3 and the second defect ground structure 4, if the main microstrip line 2 has a pair of micro One of the strips M is joined to the end 21, and the second center extension line L2 is located between the first center extension line L1 and the joint end 21, and in the first direction A1, the first center extension line L1 is The second center extension line L2 has a first separation distance D1. The second center extension line L2 and the joint end 21 have a second separation distance D2. The first separation distance D1 is greater than the second interval. Distance D2. Also, in the first direction A1, the first The width of the line segment 31, the width of the second line segment 33, the width of the third line segment 35, the width of the fourth line segment 41, the width of the fifth line segment 43, and the width of the sixth line segment 45 are all equal; In the two directions A2, the minimum length of the first line segment 31 is greater than the minimum length of the fourth line segment 41, and the minimum length of the second line segment 33 is equal to the minimum length of the fifth line segment 43. Again, the radius of the first circular section 32 is greater than the radius of the third circular section 42. Therefore, if the second defect ground structure 4 is disposed in the filter component, and the second defect ground structure 4 and the first defect ground structure 3 have the above-mentioned arrangement relationship, the second defect ground structure 4 can be improved. The overall filtering performance (for example, suppressing the harmonics after the frequency of 6.5 GHz through the first defect ground structure 3, and controlling the passband position to the frequencies of 2.4 GHz and 5.2 GHz through the second defect grounding structure 4), thereby improving the filtering performance. Effect.

Referring to FIG. 5, the filter component of the present invention is applied to an implementation structure of a one-step impedance resonance filter, wherein the stepped impedance resonance filter comprises a first resonator R1 and a second resonance. The first resonator R1 and the second resonator R2 are coupled to each other and disposed on the substrate 1. The first resonator R1 has a first feed line R11 and a first coupling line R12. The feed line R11 can be used as the main microstrip line 2 of the present invention. The first coupled line R12 has a first partial line segment R12a, a second partial line segment R12b and a third portion in the second direction A2. a portion of the line R12c; the second resonator R2 has a second feed line R21 and a second coupling line R22, the second feed line R21 can be used as the main microstrip line 2 of the present invention, the second coupling line R22 In the second direction A2, there is a fourth partial line segment R22a, a fifth partial line segment R22b and a sixth partial line segment R22c. The number of the first defect ground structures 3 is two, and the number An arrangement relationship between a defective ground structure 3 and the first feed line R11, and the first defect ground structure 3 The second feed line disposed relation R21 is, as the system of the first defect ground structure 3 is provided with the main microstrip line 2 relationship.

In order to prove that the filter component with the defective ground structure of the present invention does have the effect of improving the filtering performance, the simulation is performed by the above implementation structure, and the simulation can be performed by a processor, and the simulation software can be any conventionally used for performing The software of the frequency response analysis, which is well known to those skilled in the art, will not be described herein. The length or width of the first resonator R1 and the second resonator R2 can be as shown in Table 1:

The coupling length of the first resonator R1 and the second resonator R2, the coupling pitch, the connection position of the first feed line R11 and the first coupling line R12, and the second feed line R21 and the second The related setting parameters, such as the connection position of the coupling line R22, can be set by the person skilled in the art according to actual needs, and is not limited thereto. When the length and width of the first resonator R1 and the second resonator R2 are the above values, the radius of the first circular section 32 of the first defect ground structure 3 and the second circular section 34 The radius is between 0.8 mm and 1.4 mm, and preferably 0.8 mm; in the second direction A2, the first line segment 31, the first circular segment 32, the second segment 33, The total length of the second circular section 34 and the third line section 35 is between 7.2 mm and 11.2 mm, and preferably 7.2 mm.

Please refer to FIG. 5 to FIG. 7 , FIG. 6 is a frequency response diagram in which the first defect ground structure 3 is not disposed, and FIG. 7 is a frequency response diagram in which the first defect ground structure 3 is disposed, and S11 is back. Wave loss, S21 is an insertion loss, wherein, in the implementation structure of the frequency response diagram of FIG. 7, the radius of the first circular section 32 and the radius of the second circular section 34 are both 0.8 mm; In the first direction A1, the width of the first line segment 31, the width of the second line segment 33, and the width of the third line segment 35 are both 0.6 mm; in the second direction A2, the first line segment 31 The total length of the first circular segment 32, the second segment 33, the second circular segment 34, and the third segment 35 is 7.2 mm; in the first resonator R1, the first center The distance from the extension line L1 to the second partial line segment R12b is 6 mm; in the second resonator R2, the distance from the first center extension line L1 to the fifth partial line segment R22b is 6 mm. By comparing the sixth and seventh figures, when the first defect ground structure 3 is provided in the filter, the passband frequency can be accurately controlled to 2.4 GHz and 5.2 GHz, and at the above frequency values, the insertion loss is respectively 0.23dB and 0.9dB, and two transmission zeros can be generated at frequencies of 1.98GHz and 4.27GHz; in addition, the attenuation value of the return loss can be surely increased. The above frequency response diagram can prove that the filter component with the defective ground structure of the present invention can accurately control the passband frequency and increase the attenuation value of the return loss, and has the effect of improving the filtering performance.

Referring to Table 2 again, if the filter assembly of the present invention is implemented in the manner of FIG. 5, when the radius of the first circular segment 32 and the radius of the second circular segment 34 are the same, When the size is the above, harmonics of a higher frequency can be suppressed (for example, when the radius of the first circular section 32 and the radius of the second circular section 34 are 1.4 mm, the harmonic after 7.0 GHz can be suppressed. The wave), in turn, enables the passband frequency to be accurately controlled at 2.4 GHz and 5.2 GHz, and has the effect of accurately controlling the passband frequency.

Please refer to FIG. 8 , which is based on the embodiment of FIG. 7 , and further sets the frequency response diagram of the second defect ground structure 4 , wherein the implementation structure of the frequency response diagram in FIG. 8 The radius of the first circular section 32 and the radius of the second circular section 34 are both 1.4 mm; the radius of the third circular section 42 and the radius of the fourth circular section 44 are both 0.8 mm; in the second direction A2, the total length of the first line segment 31, the first circular segment 32, the second segment 33, the second circular segment 34, and the third segment 35 The degree is 11.2 mm; in the second direction A2, the total length of the fourth line segment 41, the third circular segment 42, the fifth segment 43, the fourth circular segment 44, and the sixth segment 45 The degree is 7.2 mm; the first spacing distance D1 is 6 mm; and the second spacing distance D2 is 4 mm. It can be seen from FIG. 8 that when the first defect ground structure 3 and the second defect ground structure 4 are disposed in the filter, the attenuation values can be increased not only at frequencies of 2.4 GHz and 5.2 GHz, but also at frequencies. The effect of harmonic suppression after 6.5 GHz is unpredictable by a conventional filter having a defective ground structure, and the present invention has an effect of improving filtering performance.

In summary, the filter assembly with the defective ground structure of the present invention can use an appropriate defect ground structure to accurately control the passband frequency and increase the attenuation value of the return loss, which has the effect of improving the filtering performance.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

1‧‧‧Substrate

11‧‧‧ first surface

12‧‧‧ second surface

2‧‧‧Main microstrip line

3‧‧‧First defect grounding structure

31‧‧‧First line

32‧‧‧First circular section

33‧‧‧second line

34‧‧‧Second round section

35‧‧‧ third line segment

Claims (12)

A filter assembly having a defective ground structure, comprising: a substrate having a first surface and a second surface, wherein the second surface is a ground plane; a main microstrip line, the main microstrip line is disposed on the substrate a first surface extending along a first direction; and a first defect ground structure, the first defect ground structure is disposed on the second surface, the first defect ground structure having a first line segment and a first circular shape a segment, a second segment, a second segment, and a third segment, the first segment, the first segment, the second segment, the second segment, and the first segment The third line segments are sequentially connected along a second direction, and the first direction is perpendicular to the second direction. In the second direction, the minimum length of the first line segment is smaller than the minimum length of the second line segment, the first The minimum length of the line segment is equal to the minimum length of the third line segment; wherein, in the vertical projection direction of the first surface toward the second surface, the main microstrip line covers the second line segment, and in the second direction Upper, the width of the main microstrip line is equal to the minimum length of the second line segment . The filter assembly with a defective ground structure according to claim 1, wherein in the second direction, the first line segment, the second line segment and the third line segment have a common first center extension line And the first center extension line passes through a center of the first circular segment and a center of the second circular segment. A filter assembly having a defective ground structure according to claim 1, wherein in the first direction, the width of the first line segment, the width of the second line segment, and the width of the third line segment are equal. A filter assembly having a defective ground structure according to claim 1, wherein a radius of the first circular section is equal to a radius of the second circular section. A filter assembly having a defective ground structure as described in claim 2, wherein Having a second defect ground structure, the second defect ground structure is disposed on the second surface, the second defect ground structure has a fourth line segment, a third circular segment, a fifth segment, and a fourth circle a fourth segment, the third segment, the fifth segment, the fourth segment, and the sixth segment are sequentially connected along the second direction, and The main microstrip line covers the fifth line segment in a vertical projection direction of the first surface toward the second surface, and in the second direction, the width of the main microstrip line is equal to the minimum of the fifth line segment length. The filter assembly of claim 5, wherein the fourth line segment, the fifth line segment, and the sixth line segment have a common second center extension line in the second direction. And the second center extension line passes through the center of the third circular section and the center of the fourth circular section. The filter assembly with a defective ground structure according to claim 6, wherein in the second direction, the first line segment, the second line segment and the third line segment have a common first center extension line The main microstrip line has a bonding end for bonding a pair of microstrip lines, the second center extension line is located between the first center extension line and the bonding end, and in the first direction, the a first spacing distance between the first center extension line and the second center extension line, the second center extension line and the bonding end having a second separation distance, the first spacing distance being greater than the second spacing distance. A filter assembly having a defective ground structure according to claim 5, wherein the width of the fourth line segment, the width of the fifth line segment, and the width of the sixth line segment are equal in the first direction. A filter assembly having a defective ground structure according to claim 5, wherein in the second direction, a minimum length of the fourth line segment is smaller than a minimum length of the fifth line segment, and a minimum length of the fourth line segment is equal to The minimum length of the sixth line segment. A filter assembly having a defective ground structure as described in claim 9 of the patent application, wherein In the second direction, the minimum length of the first line segment is smaller than the minimum length of the second line segment, the minimum length of the first line segment is equal to the minimum length of the third line segment, and the minimum length of the first line segment is greater than The minimum length of the fourth line segment, the minimum length of the second line segment being equal to the minimum length of the fifth line segment. A filter assembly having a defective ground structure according to claim 5, wherein a radius of the third circular section is equal to a radius of the fourth circular section. The filter assembly having a defective ground structure according to claim 11, wherein a radius of the first circular section is equal to a radius of the second circular section, and a radius of the first circular section is greater than The radius of the third circular section.