KR20230040194A - Broadband filter - Google Patents

Abstract

The present invention provides a broadband filter comprising: a first resonance part connected between a line and ground connecting an input end and an output end; a second resonance part connected between the line and the ground; an elastic wave resonance part connected on the line between the input end and the first resonance part; and an LC resonance part connected between the line between the output end and the second resonance part and the ground. Therefore, the present invention is capable of having an advantage of improving an insertion loss.

Description

Broadband filter {Broadband filter}

The present invention relates to a wideband filter, and more particularly, to a wideband filter applicable to 5G and next-generation communication systems.

In accordance with the rapid increase in demand for wireless communication technology, research on miniaturization, high performance, and low cost of communication components used in systems is being actively conducted.

In the field of radio communication using high frequencies, necessary signals and unnecessary signals are distinguished by extracting a signal of a specific frequency from among numerous signals.

A circuit that performs this function is called a filter and is installed in many wireless communication devices. When the frequency extracted by the filter is increased, the bandwidth also increases along with the center frequency. When the bandwidth is widened, the signal of the adjacent channel is also passed, which causes the generation of interfering waves. To prevent this, it is necessary to enable variable control of both the center frequency and the bandwidth.

A commonly used bandpass filter of the J-inverter structure connects a plurality of J-inverters in parallel between an input load and an output load, and connects a plurality of LC resonance circuits in parallel between each J-inverter. can be connected

At this time, it is difficult for the bandpass filter to implement excellent selectivity due to the quality factor of the plurality of LC resonant circuits, which may negatively affect the insertion loss of the desired band.

Recently, research on improving the insertion loss of a bandpass filter having a J-inverter structure is being conducted.

An object of the present invention is to provide a wideband filter applicable to 5G and next-generation communication systems.

Another object of the present invention is to provide a broadband filter that can easily improve insertion loss and attenuation characteristics by applying a J-inverter structure.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned above can be understood by the following description and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations indicated in the claims.

In the broadband filter according to the present invention, a first resonator unit connected between a line connecting an input terminal and an output terminal and the ground, a second resonator unit connected between the line and the ground, and between the input terminal and the first resonator unit An acoustic wave resonator connected to the line and an LC resonator connected between the line between the output terminal and the second resonator and the ground may be further included.

A capacitor connected to the line between the first and second resonators may be further included.

The first and second resonators and the capacitor may be formed in a J-inverter structure for electric field coupling.

Each of the first and second resonance units is an LC resonance circuit connected to the ground and an attenuation capacitor that is connected between the LC resonance circuit and the line and reduces frequency insertion loss by attenuating parasitic capacitance corresponding to the capacitor can include

The acoustic wave resonator may be a BAW (Bulk Acoustic Wave) resonator in which a frequency of a frequency attenuation band is set.

The broadband filter according to the present invention has an advantage of improving insertion loss and attenuation characteristics by additionally applying an acoustic wave resonator and an LC filter to a J-inverter structure.

On the other hand, the effects of the present invention are not limited to the effects mentioned above, and various effects may be included within a range apparent to those skilled in the art from the contents to be described below.

1 is a circuit diagram showing a broadband filter according to an embodiment of the present invention.
FIG. 2 is a diagram showing resonance characteristics of first and second resonators shown in FIG. 1 .
3 is a diagram showing simulation results of a broadband filter according to the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The term and/or includes a combination of a plurality of related recited items or any one of a plurality of related recited items.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Expressions in the singular number include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, it should not be interpreted in an ideal or excessively formal meaning. don't

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

1 is a circuit diagram showing a broadband filter according to an embodiment of the present invention, FIG. 2 is a diagram showing resonance characteristics of first and second resonators shown in FIG. 1, and FIG. 3 is a diagram showing simulation results of a wideband filter according to the present invention. am.

1 to 3, the broadband filter 100 includes an elastic wave resonator 110, a first resonator 120, a second resonator 130, a capacitor CS, and an LC resonator 140. can include

The elastic wave resonator 110 may be connected to a line connecting the input terminal IN and the output terminal OUT.

That is, the elastic wave resonator 110 is connected between the input terminal IN and the first resonator 120 and may be a Bulk Acoustic Wave (BAW) resonator for which a frequency of a frequency attenuation band is set.

The elastic wave resonator 110 can widen the bandwidth, that is, expand the amount of attenuation in the vicinity of the passband of the frequency and expand the amount of attenuation in the attenuation area away from the passband.

The frequency characteristics of the elastic wave resonator 110 may exhibit inductivity in a frequency domain between a resonance frequency and an anti-resonance frequency, and may exhibit capacitance in a frequency domain lower than the resonance frequency and higher than the anti-resonance frequency.

Here, the acoustic wave resonator 110 may prevent noise frequencies from passing by increasing the slope at the frequency edge of the frequency attenuation band.

The first resonator 120 may include a first LC resonator circuit 122 and a first attenuation capacitor CP1.

The first LC resonant circuit 122 may include a first resonant capacitor C1 and a first resonant inductor L1.

Here, the first resonant capacitor C1 and the first resonant inductor L1 are connected in parallel to each other and may be connected to ground.

The first attenuation capacitor CP1 may be connected between the first LC resonance circuit 122 and the line, and may reduce frequency insertion loss by attenuating parasitic capacitance corresponding to the capacitor CS.

The second resonator 130 may include a second LC resonator circuit 132 and a second attenuation capacitor CP2.

The second LC resonant circuit 132 may include a second resonant capacitor C2 and a second resonant inductor L2.

Here, the second resonant capacitor C2 and the second resonant inductor L2 are connected in parallel with each other and may be connected to ground.

The second attenuation capacitor CP2 may be connected between the second LC resonant circuit 132 and the line, and may reduce frequency insertion loss by attenuating parasitic capacitance corresponding to the capacitor CS.

Here, the first and second resonators 120 and 130 and the first capacitor CS1 may be formed in a J-inverter structure for electric field coupling, but are not limited thereto.

The LC resonator 140 may be connected on a line between the second resonator 130 and the output terminal OUT.

Here, the LC resonator 140 can improve the attenuation characteristics of the high pass band.

Here, FIG. 2 is a diagram showing the resonance characteristics of the first and second resonance units 120 and 130, the first and second damping capacitors CP1 and CP2 are 2 pF, the first and second resonance capacitors C1 and C2 ) is 1.98 pF and the first and second resonant inductors L1 and L2 have 1 nH, indicating resonance characteristics.

Here, each of the first and second resonators 120 and 130 may determine a transmission zero point and band edge of 2.52 GHz and susceptance values of 3.3 GHz and 4.2 GHz.

FIG. 3 is a diagram showing a simulator result for resonance characteristics of the broadband filter 100 shown in FIG. 1 .

The elastic wave resonator 110 may have a damping frequency of 2.595 GHz and an inductance of 54.29 nH.

Also, in the first resonator 120, the first attenuation capacitor CP1 can be set to 1.02 pF, the first resonant capacitors C1 and C2 to 0.11 pF, and the first resonant inductor L1 to 3.423 nH. .

In the second resonance unit 130, the second attenuation capacitor CP2 may be set to 1.81 pF, the second resonance capacitor C2 to 1.74 pF, and the second resonance inductor L2 to 1.09 nH.

The capacitor CS may be set to 0.6 pF, and in the LC resonator 140, the capacitor may be set to 0.65 pF and the inductor may be set to 0.65 nH.

At this time, looking at Figures 3 (a) and 3 (b), in the conventional LC filter shown in Figure 3 (a) and the broadband filter according to the present invention in Figure 3 (b), attenuation at a low insertion loss of 1.5 dB It can be seen that the characteristics are also improved by about 5 dB to 45 dB compared to the case of implementing only the conventional LC filter, and the attenuation characteristics of 5 GHz or more are also improved.

Features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified with respect to other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, contents related to these combinations and variations should be construed as being included in the scope of the present invention.

In addition, although the above has been described with reference to the embodiments, these are only examples and do not limit the present invention, and those skilled in the art to which the present invention belongs can exemplify the above to the extent that does not deviate from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention as defined in the appended claims.

Claims (5)

A first resonator connected between a line connecting an input end and an output end and a ground;
a second resonator connected between the line and the ground;
an elastic wave resonator connected to the line between the input end and the first resonator; and
Including an LC resonator connected between the line between the output terminal and the second resonator and the ground,
broadband filter. According to claim 1,
Further comprising a capacitor connected to the line between the first and second resonators,
broadband filter. According to claim 2,
The first and second resonators and the capacitor,
Formed as a J-inverter structure for electric field coupling,
broadband filter. According to claim 2,
Each of the first and second resonators,
an LC resonant circuit connected to the ground; and
An attenuation capacitor connected between the LC resonance circuit and the line and reducing frequency insertion loss by attenuating parasitic capacitance corresponding to the capacitor,
broadband filter. According to claim 1,
The elastic wave resonance part,
A BAW (Bulk Acoustic Wave) resonator in which the frequency of the frequency attenuation band is set,
broadband filter.

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