TWI578607B - Differential dual-band filter - Google Patents

Description

Differential dual frequency filter

This invention relates to a filter and, more particularly, to a differential dual frequency filter.

Due to the faster processing speed of digital products, the conventional single-end transmission circuit has been unable to meet the requirements for high-speed digital products, and has been gradually replaced by differential transmission circuits in recent years. At present, various high-speed electronic products digital signal transmission lines, such as SATA2, SATA3, USB 3.0 and PCI express 3, are transmitted using differential signals, so the advantage of the differential signal is that it has low noise and high common mode noise suppression. Ability.

The traditional filter design is mostly based on a single-end transmission circuit. Generally, a single-ended transmission circuit type filter only follows certain design rules and according to the desired bandwidth and related specifications. , you can design it. Nowadays, circuits like wi-fi adopt dual-band (2.4G and 5G), so if you want to deal with the filtering problem of individual frequency bands, you must separately design filters of different frequency bands for filtering. However, there will be a problem of increasing cost.

The invention provides a differential dual-frequency filter capable of band-pass filtering two frequency bands at the same time.

The differential dual frequency filter of the present invention includes a substrate, a wire layer, and a metal layer. The substrate has a first surface and a second surface. The wire layer is disposed on the first surface, and the wire layer comprises a first ring resonator, a second ring resonator, a first-order impedance resonator, a second step impedance resonator, a first differential input port, and a second difference The input 埠, the first differential output 埠, and the second differential output 埠. Wherein the first ring resonator has a first opening, the second ring resonator has a second opening, the second ring resonator being axially symmetric with respect to the first axis of symmetry, wherein the first opening is The second openings are opposite, and the first opening and the second opening are located on both sides of the first axis of symmetry. The first step impedance resonator has a first microstrip line and a second microstrip line, and the first microstrip line and the second microstrip line are disposed on both sides of the first ring resonator along an extending direction of the first symmetry axis And the first microstrip line is axially symmetric with the second microstrip line with respect to the second axis of symmetry, wherein one side of the first microstrip line and the second microstrip line respectively have a periodic tooth structure, first The microstrip line and the second microstrip line are respectively configured to be curled toward a side adjacent to the first ring resonator to form a first rectangular structure and a second rectangular structure, the first rectangular structure and the inner side of the second rectangular structure Has a tooth structure. The second step impedance resonator has a third microstrip line and a fourth microstrip line, and the second step impedance resonator is axially symmetric with the first order impedance resonator with respect to the first symmetry axis. The first differential input 埠 and the second differential input 埠 are connected to the first-order impedance resonator for receiving the differential signal. The first differential output 埠 and the second differential output 埠 are connected to the second step impedance resonator for outputting the filtered differential signal. The metal layer is disposed on the second surface.

In an embodiment of the invention, one end of the first microstrip line is connected to one end of the second microstrip line through the wire layer.

In an embodiment of the invention, the shortest distance between the other end of the first microstrip line on the wire layer and the other end of the second microstrip line is the wavelength corresponding to the resonant frequency of the first-order impedance resonator. One-half of an integer multiple.

In an embodiment of the invention, the first ring resonator includes a fifth microstrip line, the second ring resonator includes a sixth microstrip line, and the fifth microstrip line is configured to have a first opening A notched rectangle, the sixth microstrip line is configured as a second notch rectangle having a second opening.

In an embodiment of the invention, the length of the fifth microstrip line is an integer multiple of one-half of the wavelength of the resonant frequency of the first ring resonator.

In an embodiment of the invention, the first ring resonator further includes a seventh microstrip line and an eighth microstrip line, and the second ring resonator includes a ninth microstrip line and a tenth microstrip line, wherein The seventh microstrip line and the eighth microstrip line are respectively connected to the head and the tail end of the fifth microstrip line and are located in the first notch rectangle, and the ninth microstrip line and the tenth microstrip line and the sixth microstrip line respectively The head and the end are connected to each other and are located in the second notch rectangle.

In an embodiment of the invention, the first notch rectangle and the long side of the second notch rectangle are parallel to the first axis of symmetry.

In an embodiment of the invention, the toothed structure has a plurality of rectangular projections that are periodically arranged.

In an embodiment of the invention, the tooth structure of the first microstrip line is at a first length from one end of the first microstrip line and a second length from the other end of the first microstrip line.

In an embodiment of the invention, the substrate is a glass fiber substrate.

Based on the above, the embodiment of the present invention simultaneously band-pass filters two frequency bands by using a first ring resonator, a second ring resonator, a first-order impedance resonator, and a second step impedance resonator to Achieve cost savings. In addition, the differential design effectively isolates interference from common mode noise. In addition, the first-order impedance resonator and the second-step impedance resonator respectively have a periodic tooth structure, which can increase the bandwidth of the frequency band with a lower frequency.

The above described features and advantages of the invention will be apparent from the following description.

1 is a schematic diagram of a differential dual-frequency filter according to an embodiment of the invention. Please refer to FIG. The differential dual-frequency filter includes a substrate B1, a wire layer LY1, and a metal layer MY1. The substrate B1 can be, for example, a fiberglass substrate, the substrate B1 has a first surface and a second surface, and the wire layer LY1 is disposed on the substrate B1. On one surface, the metal layer MY1 is disposed on the second surface of the substrate B1. The wire layer LY1 includes a ring resonator 102, a ring resonator 104, a step impedance resonator 106, and a step impedance resonator 108, and the metal layer MY1 is a complete planar metal layer. The ring resonator 102 has a first opening, and the ring resonator 104 has a second opening. The second opening is axially symmetric with the ring resonator 102 with respect to the axis of symmetry X1, wherein the first opening is opposite to the second opening, and the first opening An opening and a second opening are located on both sides of the axis of symmetry X1.

Further, the ring resonator 102 includes a microstrip line ML5, the ring resonator 104 includes a microstrip line ML5 configured as a first notch rectangle having a first opening, and the microstrip line ML6 is configured to have a second notch rectangle of the second opening, wherein the first notch rectangle and the long side of the second notch rectangle are parallel to the axis of symmetry X1, but not limited thereto, in some embodiments, the first notch rectangle and the second notch The length and width of the rectangle can be adjusted according to the frequency band actually used by the differential dual-frequency filter. In detail, the length of the microstrip line ML5 may be an integral multiple of one-half of the wavelength of the resonant frequency of the ring resonator 102 (shown by a broken line on the ring resonator 102 in the schematic diagram of the wire layer LY1 of FIG. 2). Similarly, the length of the microstrip line ML6 may be an integer multiple of one-half of the wavelength of the resonant frequency of the ring resonator 104.

In addition, the step impedance resonator 106 of the present embodiment has a microstrip line ML1 and a microstrip line ML2, and the microstrip line ML1 and the microstrip line ML2 are disposed along the extending direction of the symmetry axis X1 and are located on both sides of the ring resonator 102. And the microstrip line ML1 is axisymmetric with respect to the microstrip line ML2 with respect to the axis of symmetry X2. One end of the microstrip line ML1 is connected to one end of the microstrip line ML2 through the wire layer LY1, and the shortest distance between the other end of the microstrip line ML1 on the wire layer LY1 and the other end of the microstrip line ML2 is a corresponding step impedance resonance. An integer multiple of one-half of the wavelength of the resonant frequency of the device 106 (shown by the dashed line on the stepped-impedance resonator 106 in the schematic of the wire layer LY1 of FIG. 2).

In addition, one side of the microstrip line ML1 and the microstrip line ML2 respectively have a periodic tooth structure S1, and the microstrip line ML1 and the microstrip line ML2 are respectively configured to be curled toward a side adjacent to the ring resonator 102, The first rectangular structure R and the second rectangular structure R2 are formed, and the first rectangular structure R1 and the second rectangular structure R2 have a toothed structure S1 inside. In detail, the tooth structure S1 has a plurality of rectangular protrusions arranged periodically. In the present embodiment, the tooth structure S1 does not occupy one side of the microstrip line ML1 and the microstrip line ML2, such as a microstrip. The tooth structure S1 of the line ML1 is spaced apart from one end of the microstrip line ML1 by a first length and is spaced apart from the other end of the microstrip line ML2 by a second length.

It should be noted that the distribution range of the above-mentioned tooth structure S1 on the side of the microstrip line ML1 and the arrangement density of the rectangular protrusions on the tooth structure S1 are not limited to the embodiment, and in other embodiments, According to the application frequency band of the differential dual-frequency filter, for example, the tooth structure S1 can be covered on one side of the microstrip line ML1, and the arrangement density of the rectangular protrusions can be increased.

In addition, the step impedance resonator 108 has a microstrip line ML3 and a microstrip line ML4, and since the step impedance resonator 108 is axisymmetric with the step impedance resonator 106 with respect to the symmetry axis X1, the step impedance resonator 108 There is a microstrip line configuration corresponding to the step impedance resonator 106, and thus the detailed structure of the step impedance resonator 108 will not be described herein.

In addition, the wire layer LY1 of the differential dual-frequency filter further includes a differential input 埠P1, a differential input 埠P2, a differential output 埠P3, and a differential output 埠P4. The differential input 埠P1 and the differential input 埠P2 are connected to the step impedance resonator 106 for receiving the differential signal, and the differential output 埠P3 and the differential output 埠P4 are connected to the step impedance resonator 108 for output. The filtered differential signal is filtered.

The differential dual-frequency filter of this embodiment can perform band-pass filtering on two frequency bands simultaneously by the ring resonator 102, the ring resonator 104, the step impedance resonator 106 and the step impedance resonator 108, wherein the ring The resonator 102 and the ring resonator 104 are responsible for filtering the frequency band of the higher frequency, and the step impedance resonator 106 and the step impedance resonator 108 are responsible for filtering the frequency band of the lower frequency, so that it is not necessary to design the individual frequency bands. Filters of different frequency bands are used for filtering, and cost savings can be achieved. In addition, the differential design effectively isolates interference from common mode noise. In addition, the step impedance resonator 106 and the step impedance resonator 108 respectively have a periodic tooth structure S1, which can increase the bandwidth of the frequency band having a lower frequency.

FIG. 3 is a schematic view showing the configuration of a wire layer according to another embodiment of the present invention. Please refer to FIG. 3. The wire layer of this embodiment is different from the embodiment of FIG. 1 in that the wire layer of the present example further includes a microstrip line ML7 to a microstrip line ML10, wherein the ring resonator 302 further includes a microstrip than the ring resonator 106. The line ML7 and the microstrip line ML8, the ring resonator 304 further includes a microstrip line ML89 and a microstrip line ML10 compared to the ring resonator 108, wherein the microstrip line ML7 and the microstrip line ML8 respectively and the head of the microstrip line ML5, The tail ends are connected to each other and are located in the first notch rectangle. The microstrip line ML9 and the microstrip line ML10 are respectively connected to the head and the tail ends of the microstrip line ML6 and are located in the second notch rectangle. Similarly, the length of the distance between the end of the microstrip line ML7 and the end of the microstrip line ML8 may be an integer multiple of one-half of the wavelength of the resonant frequency of the ring resonator 302 (as shown in the schematic diagram of the wire layer of FIG. 3) The length of the line between the end of the microstrip line ML9 and the end of the microstrip line ML10 may be an integral multiple of one-half of the wavelength of the resonance frequency of the ring resonator 304. . By increasing the structure of the microstrip line ML7 to the microstrip line ML10, the frequency band at a higher frequency when the differential dual-frequency filter is filtered can be further adjusted.

In summary, the embodiment of the present invention performs band pass filtering on two frequency bands simultaneously by the first ring resonator, the second ring resonator, the first step impedance resonator and the second step impedance resonator. To achieve cost savings. In addition, the differential design effectively isolates interference from common mode noise. In addition, the first-order impedance resonator and the second-step impedance resonator respectively have a periodic tooth structure, which can increase the bandwidth of the frequency band with a lower frequency.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

102, 104, 302, 304‧‧‧ ring resonator

106, 108‧‧‧ step impedance resonator

B1‧‧‧Substrate

LY1‧‧‧ wire layer

MY1‧‧‧ metal layer

B1‧‧‧Substrate

X1, X2‧‧‧ axis of symmetry

ML1~ML10‧‧‧ microstrip line

S1‧‧‧ tooth structure

P1, P2‧‧‧Differential input埠

P3, P4‧‧‧Differential output埠

1 is a schematic diagram of a differential dual frequency filter in accordance with an embodiment of the present invention. 2 is a schematic view showing the configuration of a wire layer in accordance with an embodiment of the present invention. 3 is a schematic view showing the configuration of a wire layer in accordance with another embodiment of the present invention.

102, 104‧‧‧ Ring resonator

106, 108‧‧‧ step impedance resonator

B1‧‧‧Substrate

LY1‧‧‧ wire layer

MY1‧‧‧ metal layer

X1, X2‧‧‧ axis of symmetry

ML1~ML6‧‧‧ microstrip line

S1‧‧‧ tooth structure

P1, P2‧‧‧Differential input埠

P3, P4‧‧‧Differential output埠

Claims (10)

A differential dual-frequency filter comprising: a substrate having a first surface and a second surface; a wire layer disposed on the first surface, the wire layer comprising: a first ring resonator having a first opening; a second ring resonator having a second opening that is axisymmetric with respect to the first ring resonator with respect to a first axis of symmetry, wherein the first opening is opposite the second opening And the first opening and the second opening are located on opposite sides of the first symmetry axis; a first-order impedance resonator having a first microstrip line and a second microstrip line, the first microstrip line And the second microstrip line is disposed on opposite sides of the first ring resonator along the extending direction of the first symmetry axis, and the first microstrip line is opposite to the second symmetry axis and the second microstrip The line is axisymmetric, wherein one side of the first microstrip line and the second microstrip line respectively have a periodic tooth structure, and the first microstrip line and the second microstrip line are respectively configured to a side adjacent to the first ring resonator is crimped to form a first rectangular structure and a second rectangular structure The first rectangular structure and the second rectangular structure have the tooth structure inside; a second step impedance resonator having a third microstrip line and a fourth microstrip line, the second step impedance resonator Axis-symmetric with the first-order impedance resonator with respect to the first symmetry axis, the first-order impedance resonator having a parallel with the first symmetry axis and the first-order impedance resonator and the first a first step opposite to an adjacent side of the two-step impedance resonator, the second step impedance resonator having the first a second side of the symmetry axis parallel to the adjacent side of the first step impedance resonator and the second step impedance resonator; a first differential input 埠; a second differential input 埠The first differential input 埠 is connected to the second differential input 埠 to the first-order impedance resonator, and the first differential input 埠 and the second differential input 对 respectively correspond to the first rectangular structure and the second a rectangular structure is disposed on the first side for receiving a differential signal; a first differential output 埠; and a second differential output 埠, the first differential output 埠 and the second differential The output 埠 is connected to the second step impedance resonator, and the first differential output 埠 and the second differential output 对 are respectively disposed on the second side corresponding to the first rectangular structure and the second rectangular structure, And outputting the filtered differential signal; and a metal layer disposed on the second surface. The differential dual-frequency filter of claim 1, wherein one end of the first microstrip line is connected to one end of the second microstrip line through the wire layer. The differential dual-frequency filter according to claim 2, wherein the other end of the first microstrip line has a shortest distance between the wire layer and the other end of the second microstrip line. An integral multiple of one-half of the wavelength of the resonant frequency of the first-order impedance resonator. The differential dual-frequency filter according to claim 1, wherein the first ring resonator comprises a fifth microstrip line, and the second ring resonator comprises a sixth microstrip line configured to have a first notch rectangle having the first opening, the sixth microstrip line being configured as a second notch rectangle having the second opening. The differential dual-frequency filter of claim 4, wherein the length of the fifth microstrip line is an integer multiple of one-half of a wavelength corresponding to a resonant frequency of the first ring resonator. The differential dual-frequency filter of claim 4, wherein the first ring resonator further comprises a seventh microstrip line and an eighth microstrip line, and the second ring resonator comprises a a ninth microstrip line and a tenth microstrip line, wherein the seventh microstrip line and the eighth microstrip line are respectively connected to the head and the tail end of the fifth microstrip line and are located in the first notch rectangle. The ninth microstrip line and the tenth microstrip line are respectively connected to the head and the tail end of the sixth microstrip line and are located in the second notch rectangle. The differential dual-frequency filter of claim 4, wherein the first notch rectangle and the long side of the second notch rectangle are parallel to the first axis of symmetry. The differential dual-frequency filter of claim 1, wherein the toothed structure has a plurality of rectangular protrusions that are periodically arranged. The differential dual-frequency filter according to claim 1, wherein the tooth structure of the first microstrip line is spaced apart from a first length of the first microstrip line by a first length and the first microstrip line The other end is a second length. The differential dual-frequency filter according to claim 1, wherein the substrate is a glass fiber substrate.