KR20200119688A - Front end module - Google Patents

Abstract

The present invention is to provide a front end module capable of securing sufficient attenuation characteristics for adjacent bands. According to an embodiment of the present invention, a front end module comprises: a first filter having a pass band of a first frequency band; a second filter having a pass band of a second frequency band higher than the first frequency band; a third filter having a pass band of a third frequency band higher than the second frequency band; and a sub filter connected to the second filter to provide an attenuation characteristic for the first frequency band. The second filter may include a plurality of parallel LC resonance units disposed between different nodes and ground among a plurality of nodes between first and second terminals, and an inductor connected to any one of the plurality of parallel LC resonance units.

Description

Front end module {FRONT END MODULE}

The present invention relates to a front end module.

The fifth generation (5G) communication is expected to efficiently connect more devices with more large-capacity data and faster data transmission speed compared to the existing LTE (Long Term Evolution) communication.

5G communication is developing in the direction of using the frequency band of 24250MHz ~ 52600MHz corresponding to the millimeter wave (mmWave) band and the frequency band of 450MHz ~ 6000MHz corresponding to the sub-6GHz band.

Each of the n77 band (3300MHz~4200MHz), n78 band (3300MHz~3800MHz) and n79 band (4400MH~5000MHz) was defined as one of the operating bands of sub-6GHz, and the n77 band (3300MHz~4200MHz), n78 band (3300MHz~3800MHz) and n79 band (4400MH~5000MHz) will be used as the main band according to the advantage of having a wide bandwidth.

An object of the present invention is to provide a front end module capable of securing sufficient attenuation characteristics for adjacent bands.

A front end module according to an embodiment of the present invention includes a first filter having a pass band of a first frequency band; A second filter having a passband of a second frequency band higher than the first frequency band; A third filter having a pass band of a third frequency band higher than the second frequency band; And a sub-filter connected to the second filter to provide an attenuation characteristic for the first frequency band. Including, the second filter is a plurality of parallel LC resonator disposed between the ground and a different node among a plurality of nodes between the first terminal and the second terminal and the parallel of any one of the plurality of parallel LC resonator It may include an inductor connected to the LC resonator.

According to an embodiment of the present invention, by reducing the number of antennas employed in mobile devices, it is possible to improve antenna isolation characteristics.

According to an embodiment of the present invention, sufficient attenuation characteristics for adjacent bands can be secured.

1 is a block diagram of a mobile device equipped with a front end module according to an embodiment of the present invention.
Figure 2 shows the frequency response of filters required to simultaneously support the 3.3GHz to 4.2GHz band (n77 band), the 4.4GHz to 5.0GHz band (n79 band), and the 5.15GHz to 5.95GHz band (Wi-Fi 5GHz band). Show.
Figure 3 shows the frequency response of the 4.4GHz ~ 5.0GHz band (n79 band) implemented with a Chebyshev filter.
4A and 4B are block diagrams of a front end module according to various embodiments of the present disclosure.
5 shows a process of deriving a second filter according to an embodiment of the present invention.
6 shows a process of deriving a second filter according to another embodiment of the present invention.
7 is a graph showing the frequency response of a filter to which a J-transformation (J-Inverter) technique or a K-transformation (K-Inverter) technique is applied.
8 shows the frequency response by the first to third filters according to an embodiment of the present invention.
9 shows frequency responses by first to third filters and first to third sub-filters according to an embodiment of the present invention.
10 is a block diagram illustrating an example of an amplification unit connected to a filter according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The detailed description of the present invention to be described later refers to the accompanying drawings, which illustrate specific embodiments in which the present invention may be practiced. These embodiments are described in detail sufficient to enable a person skilled in the art to practice the present invention. It is to be understood that the various embodiments of the present invention are different from each other, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention in relation to one embodiment. In addition, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description to be described below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scopes equivalent to those claimed by the claims. Like reference numerals in the drawings refer to the same or similar functions over several aspects.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to enable those of ordinary skill in the art to easily implement the present invention.

1 is a block diagram of a mobile device equipped with a front end module according to an embodiment of the present invention.

Referring to FIG. 1, a mobile device 1 according to an embodiment of the present invention includes a plurality of front end modules connected to different antennas among a plurality of antennas ANT1 to ANT6 and a plurality of antennas ANT1 to ANT6. (FEM1 to FEM6) may be included.

The mobile device 1 performs wireless communication of a plurality of standards, such as cellular (LTE/WCDMA/GSM) communication, WiFi communication of 2.4 GHz and 5 GHz, and Bluetooth communication. A plurality of antennas ANT1 to ANT6 and a plurality of front end modules FEM1 to FEM6 included in the mobile device support wireless communication of a plurality of standards.

A MIMO (Multi-Input/Multi-Output) system may be applied to the mobile device 1. MIMO is a technology that can increase the bandwidth in proportion to the number of antennas. If N antennas are used, frequency efficiency of N times as compared to a single antenna can be obtained. However, according to the trend of slimming and miniaturization of mobile devices, there is a limit to the space in which an antenna is mounted, and physical restrictions are imposed on additionally implementing a plurality of antennas in a terminal under the condition that antennas used in the existing system are present.

Accordingly, there is a need for a front-end module connected to any one antenna to support a plurality of standard wireless communications, thereby reducing the number of antennas mounted in the mobile device 1.

Figure 2 shows the frequency response of filters required to simultaneously support the 3.3GHz to 4.2GHz band (n77 band), the 4.4GHz to 5.0GHz band (n79 band), and the 5.15GHz to 5.95GHz band (Wi-Fi 5GHz band). Show.

In FIG. 2, a first graph (graph 1) shows the frequency response of a filter A supporting a 3.3 GHz to 4.2 GHz band (n77 band), and a second graph (graph 2) is a 4.4 GHz to 5.0 GHz band (n79 band). ) Shows the frequency response of filter B supporting ), and the third graph (graph 3) is assumed to be the frequency response of filter C supporting the 5.15GHz to 5.95GHz band (Wi-Fi 5GHz band).

The 4.4GHz~5.0GHz band (n79 band) has only a 3.3~4.2GHz band (n77 band) and a band gap of 200MHz, and a 5.15GHz~5.95GHz band (Wi-Fi 5GHz band) and a band gap of only 150MHz. Therefore, carrier aggregation (CA), LTE in unlicensed spectrum (LTE-U) in the 3.3 to 4.2 GHz band (n77 band), 4.4 GHz to 5.0 GHz band (n79 band), and 5.15 GHz to 5.95 GHz band (Wi-Fi 5 GHz band) ), LAA (Licensed Assisted Access), etc., filter A supporting 3.3-4.2 GHz band (n77 band), filter B supporting 4.4 GHz-5.0 GHz band (n79 band), 5.15 GHz Filter C supporting ~5.95GHz band (Wi-Fi 5GHz band) needs to secure sufficient attenuation characteristics for each other.

Although the BAW filter has excellent attenuation characteristics, it is difficult to form a wide passband, and thus, it is difficult to apply to 5G communication requiring broadband frequency characteristics. Therefore, in order to satisfy the wideband frequency characteristic, it is necessary to configure the filters as an LC filter implemented by a combination of a capacitor and an inductor.

Figure 3 shows the frequency response of the 4.4GHz ~ 5.0GHz band (n79 band) implemented with a Chebyshev filter. The Chebyshev filter is an example of an LC filter, and corresponds to a filter composed of a combination of LC resonators.

In FIG. 3, a first graph (graph 1) represents the frequency response of a third-order Chebyshev filter, a second graph (graph 2) represents the frequency response of a fifth-order Chebyshev filter, and a third graph (graph 3) The frequency response of the 7th order Chebyshev filter is shown, and the fourth graph (graph 4) shows the frequency response of the 9th order Chebyshev filter.

Referring to FIG. 3, as the order of the Chebyshev filter increases, attenuation characteristics in 4,2 GHz and 5.150 GHz are improved, but insertion loss in the 4.4 GHz to 5.0 GHz band (n79 band) is deteriorated. In terms of insertion loss, the 5th Chebyshev filter is suitable for implementing the 4.4GHz~5.0GHz band (n79 band), but in terms of attenuation characteristics, the 9th Chebyshev filter is suitable for implementing the 4.4GHz~5.0GHz band (n79 band). . That is, a Chebyshev filter composed only of a combination of LC resonators has a problem in that it cannot simultaneously satisfy the broadband pass characteristic and the adjacent band attenuation characteristic.

4A and 4B are block diagrams of a front end module according to various embodiments of the present disclosure.

4A, the front end module according to an embodiment of the present invention includes a first filter F1, a second filter F2, and a third filter F3 connected to one antenna terminal T_ANT. A multiplexer including, a first sub-filter SF1, a second sub-filter SF2, and a third sub-filter SF3 may be included. Meanwhile, referring to FIG. 4B, a front end module may be configured in a form in which the first sub-filter SF1, the second sub-filter SF2, and the third sub-filter SF3 are omitted.

Hereinafter, for convenience of description, it is assumed that the front end module according to the present embodiment includes the first sub-filter SF1, the second sub-filter SF2, and the third sub-filter SF3.

The first filter F1 is disposed between the antenna terminal T_ANT and the first sub-filter SF1. One end of the first filter F1 is connected to the antenna terminal T_ANT, and the other end of the first filter F1 is connected to the first sub-filter SF1. An antenna ANT may be connected to the antenna terminal T_ANT.

The first filter F1 supports cellular communication in a first frequency band, specifically, a 3.3 GHz to 4.2 GHz band (n77 band) of the Sub-6 GHz band. According to an embodiment, the first filter F1 may support cellular communication in a 3.3 GHz to 3.8 GHz band (n78 band).

The first filter F1 operates as a band pass filter. As an example, the first filter F1 may include a band pass filter having a pass band of 3.3 GHz to 4.2 GHz, and a lower limit frequency of 3.3 GHz and an upper limit frequency of 4.2 GHz. According to an embodiment, the first filter F1 may include a band pass filter having a pass band of 3.3 GHz to 3.8 GHz and a lower limit frequency of 3.3 GHz and an upper limit frequency of 3.8 GHz.

The first filter F1 may be composed of an LC filter. For example, the LC filter of the first filter F1 may be implemented in a Chebyshev filter structure.

The first sub-filter SF1 is disposed between the first filter F1 and the first terminal T1. One end of the first sub-filter SF1 is connected to the first filter F1, and the other end of the first filter F1 is connected to the first terminal T1.

The first sub-filter SF1 operates as a band-stop filter. As an example, the first sub-filter SF1 may operate as a band-stop filter having a lower limit frequency of 4.4 GHz and an upper limit frequency of 4.6 GHz. The first sub-filter SF1 may be composed of a SAW filter or a BAW filter having high attenuation characteristics.

The first sub-filter SF1 is disposed in the signal path between the first terminal T1 and the antenna terminal T_ANT, so that the attenuation characteristics of the first filter F1 for the 4.4 GHz to 5.0 GHz band (n79 band) are obtained. You can secure enough.

Meanwhile, according to an embodiment, an inductor may be disposed in a signal path between the first terminal T1 and the antenna terminal T_ANT. The inductor provides a low pass characteristic to match the impedance of the 4.4 GHz to 5.0 GHz band (n79 band) and the 3.3 GHz to 4.2 GHz band (n77 band) located in the low frequency band.

The second filter F2 is disposed between the antenna terminal T_ANT and the second sub-filter SF2. One end of the second filter F2 is connected to the antenna terminal T_ANT, and the other end of the second filter F2 is connected to the second sub-filter SF2.

The second filter F2 supports cellular communication in a second frequency band, specifically, a 4.4 GHz to 5.0 GHz band (n79 band) of the Sub-6 GHz band.

The second filter F2 operates as a band pass filter. For example, the second filter F2 may include a band pass filter having a pass band of 4.4 GHz to 5.0 GHz, and a lower limit frequency of 4.4 GHz and an upper limit frequency of 5.0 GHz.

5 shows a process of deriving a second filter according to an embodiment of the present invention.

5(a) shows an example of a circuit diagram of a Chebyshev filter in which the resonance part is arranged in a T shape.

The Chebyshev filter of FIG. 5A may have a predetermined transfer-function. The Chebyshev filter of FIG. 5(a) includes a first series resonance part including a first capacitor C1/first inductor L1 connected in series with each other, and a second capacitor C2/second inductor L2 connected in parallel with each other. A parallel resonator may include a second series resonator including a third capacitor C3/third inductor L3 connected in series with each other.

The first series resonance part and the second series resonance part are disposed between the first terminal Tx and the second terminal Ty, and the parallel resonance part is disposed between a node between the first series resonance part and the second series resonance part and a ground.

FIG. 5(b) shows an example of a circuit diagram in which a J-Inverter technique is applied to the Chebyshev filter of FIG. 5(a).

Referring to FIG. 5(b), the filter of FIG. 5(b) includes a capacitor C01, a capacitor C12, a capacitor C23, and a capacitor C34 arranged in series between the terminal Tx and the terminal Ty.

In addition, the filter of FIG. 5(b) is disposed at the node between the capacitor C01 and the capacitor C12 and at the ground, and is connected in parallel with the first capacitor C1/first inductor L1, and the node between the capacitor C12 and the capacitor C23 and at the ground. A second capacitor C2/second inductor L2 disposed and connected in parallel with each other, a third capacitor C3/third inductor L3 disposed at a node between the capacitor C23 and the capacitor C34 and a ground, and connected in parallel with each other. have.

The filter of FIG. 5(b) may be derived by applying a J-Inverter technique to the filter of FIG. 5(a).

A third capacitor connected in series with the first capacitor C1/first inductor L1 connected in series with each other in FIG. 5(a) by applying a J-inverter technique to the filter of FIG. 5(a) The C3/third inductor L3 is converted into a form connected in parallel, and is disposed between the ground and different nodes of the terminal Tx and the terminal Ty.

Meanwhile, in order to satisfy the transfer-function of the Chebyshev filter of FIG. 5A, a capacitor C01, a capacitor C12, a capacitor C23, and a capacitor C34 having high-pass filter characteristics are additionally disposed.

6 shows a process of deriving a second filter according to another embodiment of the present invention.

6(a) shows an example of a Chebyshev filter in which the resonance part is arranged in a ð shape.

The Chebyshev filter of FIG. 6A may have a predetermined transfer-function.

The Chebyshev filter of FIG. 5(a) includes a first parallel resonator including a first capacitor C1/first inductor L1 connected in parallel with each other, and a second capacitor C2/second inductor L2 connected in series with each other. A series resonator may include a second parallel resonator including a third capacitor C3/third inductor L3 connected in parallel with each other.

The series resonance part is disposed between the terminal Tx and the terminal Ty, the first parallel resonance part is disposed between the terminal Tx and the series resonance part and the node between the ground, and the second parallel resonance part is between the terminal Ty and the series resonance part and the ground. It is placed between.

6(b) shows an example of a circuit diagram in which a K-Inverter technique is applied to the Chebyshev filter of FIG. 6(a).

Referring to FIG. 6(b), the filter of FIG. 6(b) includes a first capacitor C1/first inductor L1 connected in series with each other sequentially disposed between a terminal Tx and a terminal Ty, and a first capacitor C1 connected in series with each other. A second capacitor C2/second inductor L2, and a third capacitor C3/third inductor L3 connected in series may be included.

In addition, the filter of FIG. 6(b) includes an inductor L01 disposed between a terminal Tx and a first capacitor C1/first inductor L1 connected in series with each other, a first capacitor C1/first inductor L1 connected in series with each other. Inductor L12 disposed between the second capacitor C2 / second inductor L2 connected in series, between the second capacitor C2 / second inductor L2 connected in series and the third capacitor C3 / third inductor L3 connected in series with each other An inductor L23 disposed at, and an inductor L34 disposed between the third capacitor C3/third inductor L3 and the terminal Ty connected in series with each other may be further included.

The filter of FIG. 6(b) may be derived by applying a K-Inverter technique to the filter of FIG. 6(a).

A third capacitor connected in parallel with the first capacitor C1/first inductor L1 connected in parallel with each other in FIG. 6(a) by applying a K-inverter technique to the filter of FIG. 6(a) The C3/third inductor L3 is converted into a form connected in series and is disposed between the terminal Tx and the terminal Ty.

Meanwhile, in order to satisfy the transfer-function of the Chebyshev filter of FIG. 6A, an inductor L01, an inductor L12, an inductor L23, and an inductor L34 having low-pass filter characteristics are additionally disposed.

7 is a graph showing the frequency response of a filter to which a J-transformation (J-Inverter) technique or a K-transformation (K-Inverter) technique is applied.

Referring to FIG. 7, a first graph (graph 1) shows the frequency response of a filter before applying a J-transformation (J-Inverter) technique or a K-transformation (K-Inverter) technique, and a second graph (graph 2) is The frequency response of the filter to which the J-transformation (J-Inverter) is applied is shown, and the third graph (graph 3) shows the frequency response of the filter to which the K-Inverter is applied.

5(a), 5(b) and 7, the capacitor C01, the capacitor C12, the capacitor C23, and the capacitor C34 additionally disposed in FIG. 5(b), compared to the first graph (graph 1). The second graph (graph 2) shows that the low frequency band has more improved attenuation characteristics, and the high frequency band has more deteriorated attenuation characteristics.

In addition, referring to FIGS. 6(a), 6(b), and 7, the first graph (graph 1) by the inductor L01, the inductor L12, the inductor L23, and the inductor L34 additionally disposed in FIG. 6(b). ), the third graph (graph 3) shows that the high-frequency band has more improved attenuation characteristics, and the low-frequency band has more deteriorated attenuation characteristics.

Accordingly, the attenuation characteristics deteriorated in the high frequency band by the capacitor C12, capacitor C23, and capacitor C34 of FIG. 5(b), and the inductor L01, the inductor L12, the inductor L23, and the inductor L34 of FIG. 6(b) deteriorated in the low frequency band. There is a need to improve the attenuation properties.

5(c) is a circuit diagram showing a second filter F2 according to an embodiment of the present invention.

The second filter F2 according to the embodiment of FIG. 5(c) may further include an inductor L21, an inductor L22, and an inductor L23, compared to the filter of FIG. 5(b).

Referring to FIG. 5C, the second filter F2 according to an embodiment of the present invention includes a first parallel LC resonator, a second parallel LC resonator, a third parallel LC resonator, an inductor L21, and an inductor L22. , Inductor L23, capacitor C01, capacitor C12, capacitor C23, capacitor C34.

The first parallel LC resonator is composed of a first capacitor C1/first inductor L1 connected in parallel with each other, and the second parallel LC resonator is composed of a second capacitor C2/second inductor L2 connected in parallel with each other, and a third The parallel LC resonator is composed of a third capacitor C3/third inductor L3 connected in parallel with each other.

The first parallel LC resonator, the second parallel LC resonator, and the third parallel LC resonator are disposed between different nodes of the plurality of nodes between the first terminal Tx and the second terminal Ty and the ground. Each of the first parallel LC resonator, the second parallel LC resonator, and the third parallel LC resonator is disposed between ground and different nodes between the capacitor C01, the capacitor C12, the capacitor C23, and the capacitor C34.

Inductor L21 is disposed between the first parallel LC resonator and ground, inductor L22 is disposed between the second parallel LC resonator and ground, and inductor L23 is disposed between the third parallel LC resonator and ground.

In Fig. 5(c), an inductor is connected to each of the first parallel LC resonator, the second parallel LC resonator, and the third parallel LC resonator, but according to the embodiment, the first parallel LC resonator The inductor may be connected to only one of the second parallel LC resonator and the third parallel LC resonator. In addition, according to an embodiment, two parallel LC resonance units of the first parallel LC resonance unit, the second parallel LC resonance unit, and the third parallel LC resonance unit may be connected to ground through one inductor.

The inductor L21, the inductor L22, and the inductor L23 connected to each of the first parallel LC resonator, the second parallel LC resonator, and the third parallel LC resonator form an additional attenuation region, and J-transformation (J-Inverter) When the technique is applied, the attenuation characteristics deteriorated in the high frequency band can be improved by additionally disposed capacitors C01, C12, C23, and C34.

Due to the attenuation region formed by the inductor L21, the inductor L22, and the inductor L23, the second filter F2 can secure sufficient attenuation characteristics for the 5.15GHz to 5.95GHz band (Wi-Fi 5GHz band).

6(c) is a circuit diagram showing a second filter F2 according to another embodiment of the present invention.

Referring to FIG. 6(c), the second filter F2 according to the embodiment of FIG. 6(c) is compared with the second filter F2 according to the embodiment of FIG. 6(b), a capacitor Cz1 and a capacitor. It may further include Cz2 and a capacitor Cz3.

6(c), the second filter F2 according to an embodiment of the present invention includes a first series LC resonator, a second series LC resonator, a third series LC resonator, a capacitor Cz1, and a capacitor Cz2. , And a capacitor Cz3, an inductor L01, an inductor L12, an inductor L23, and an inductor L34.

The first series LC resonator is composed of a first capacitor C1/first inductor L1 connected in series with each other, the second series LC resonator is composed of a second capacitor C2/second inductor L2 connected in series with each other, and a third The series LC resonator is composed of a third capacitor C3/third inductor L3 connected in series with each other.

The first series LC resonance part, the second series LC resonance part, and the third series LC resonance part are disposed between the first terminal Tx and the second terminal Ty. The first series LC resonator, the second series LC resonator, and the third series LC resonator may be disposed between the inductor L01, the inductor L12, the inductor L23, and the inductor L34.

The capacitor Cz1 is connected in parallel with the first series LC resonator, the capacitor Cz2 is connected in parallel with the second series LC resonator, and the capacitor Cz3 is connected in parallel with the third series LC resonator.

In FIG. 6(c), a capacitor is connected to each of the first series LC resonator, the second series LC resonator, and the third series LC resonator, but according to an embodiment, the first series LC resonator The capacitor may be connected only to one of the second series LC resonator and the third series LC resonator. A capacitor Cz1, a capacitor Cz2, and a capacitor Cz3 connected to each of the first series LC resonator, the second series LC resonator, and the third series LC resonator form additional attenuation zones, so that inductor L01, inductor L12, inductor L23, Inductor L34 can improve the attenuation characteristics deteriorated in the low frequency band.

Due to the attenuation band formed by the capacitor Cz1, the capacitor Cz2, and the capacitor Cz3, the second filter F2 can secure sufficient attenuation characteristics for the 3.3GHz to 4.2GHz band (n77 band).

Again, referring to FIG. 4A, the second sub-filter SF2 is disposed between the second filter F2 and the second terminal T2. One end of the second sub-filter SF2 is connected to the second filter F2, and the other end of the second filter F2 is connected to the second terminal T2.

The second sub-filter SF2 operates as a band-stop filter. The second sub-filter SF2 may be composed of a SAW filter or a BAW filter having high attenuation characteristics. The second sub-filter SF2 is disposed in a signal path between the second terminal T2 and the antenna terminal T_ANT, so that the attenuation characteristic of the second filter F2 may be supplemented.

For example, when the second filter F2 is configured according to the embodiment of FIG. 5(c), the second sub-filter SF2 has a stop band of 4.0 GHz to 4.2 GHz band, a lower limit frequency of 4.0 GHz and A band-stop filter having an upper limit frequency of 4.2 GHz may be included. The second sub-filter SF2 may sufficiently supplement the attenuation characteristic of the second filter F2 for the 3.3 GHz to 4.2 GHz band (n77 band). Accordingly, the second filter F2 according to the embodiment of FIG. 5(c) is based on the attenuation band formed by the inductor L21, the inductor L22, and the inductor L23, for the 5.15GHz to 5.95GHz band (Wi-Fi 5GHz band). Sufficient attenuation characteristics can be secured, and sufficient attenuation characteristics for the 3.3 GHz to 4.2 GHz band (n77 band) can be secured by the stop band of the 4.0 GHz to 4.2 GHz band of the second sub-filter SF2.

As another example, when the second filter F2 is configured according to the embodiment of FIG. 6(c), the second sub-filter SF2 has a stop band of 5.15 GHz to 5.35 GHz band, a lower limit frequency of 5.15 GHz and It may include a band stop filter having an upper limit frequency of 5.35GHz. The second sub-filter SF2 may sufficiently supplement the attenuation characteristic of the second filter F2 for the 5.15 GHz to 5.95 GHz band (Wi-Fi 5 GHz band).

Accordingly, the second filter F2 according to the embodiment of FIG. 6(c) is sufficiently attenuated for the 3.3 GHz to 4.2 GHz band (n77 band) by the attenuation band formed by the capacitor Cz1, the capacitor Cz2, and the capacitor Cz3. The characteristics are ensured, and sufficient attenuation characteristics for the 5.15 GHz to 5.95 GHz band (Wi-Fi 5 GHz band) can be secured by the stop band of the 5.15 GHz to 5.35 GHz band of the second sub-filter SF2.

According to an embodiment of the present invention, the second filter F2 is configured in the form of FIGS. 5(c) and 6(c), so that the number of band-stop filters providing attenuation characteristics for adjacent bands is one. Can be reduced.

The third filter F3 is disposed between the antenna terminal T_ANT and the third sub-filter SF3. One end of the third filter F3 is connected to the antenna terminal T_ANT, and the other end of the third filter F3 is connected to the third sub-filter SF3.

The third filter F3 supports Wi-Fi communication in a third frequency band, specifically, a 5 GHz band. For example, the third filter F3 may support Wi-Fi communication in a band of 5.15 GHz to 5.95 GHz.

The third filter F3 operates as a band pass filter. As an example, the third filter F3 may include a band pass filter having a pass band of 5.15 GHz to 5.95 GHz band and a lower limit frequency of 5.15 GHz and an upper limit frequency of 5.95 GHz.

The third filter F3 may be composed of an LC filter. The LC filter of the third filter F3 may be implemented in a Chebyshev filter structure.

The third sub-filter SF3 is disposed between the third filter F3 and the third terminal T3. One end of the third sub-filter SF3 is connected to the third filter F3, and the other end of the third filter F3 is connected to the third terminal T3.

The third sub-filter SF3 operates as a band-stop filter. As an example, the third sub-filter SF3 may operate as a band-stop filter having a lower limit frequency of 4.8 GHz and an upper limit frequency of 5.0 GHz. The third sub-filter SF3 may be composed of a SAW filter or a BAW filter having high attenuation characteristics.

The third sub-filter SF3 is disposed in the signal path between the third terminal T3 and the antenna terminal T_ANT, so that the attenuation characteristics of the third filter F3 for the 4.4 GHz to 5.0 GHz band (n79 band) are obtained. You can secure enough. Meanwhile, according to an embodiment, a capacitor may be disposed in a signal path between the third terminal T3 and the antenna terminal T_ANT. The capacitor provides a high pass characteristic to match the impedance of the 4.4 GHz to 5.0 GHz band (n79 band) and the 5.15 GHz to 5.95 GHz band (Wi-Fi 5 GHz band) located in the high frequency band.

8 shows the frequency response by the first to third filters according to an embodiment of the present invention, and FIG. 9 is a first to third filter and a first to third sub filter according to an embodiment of the present invention. It shows the frequency response by the filter.

Referring to FIG. 8, by implementing the first to third filters as Chebyshev filters, even when the passband has a wide bandwidth of 600 MHz or more, excellent insertion loss characteristics and return loss characteristics can be implemented.

In addition, referring to FIG. 9, each of the first to third sub-filters is connected to each of the first to third filters, so that a 3.3 GHz to 4.2 GHz band (n77 band), and a 4.4 GHz to 5.0 GHz band ( n79 band) and the 5.15GHz to 5.95GHz band (Wi-Fi 5GHz band) can secure sufficient attenuation characteristics for each other.

10 is a block diagram illustrating an example of an amplification unit connected to a filter according to an embodiment of the present invention.

In FIG. 10, the filter F is a configuration corresponding to any one of the first filter F1, the second filter F2, and the third filter F3 of the embodiment of FIG. 4A or the first filter of the embodiment of FIG. 4B. It may be understood as a configuration corresponding to one of the sub-filter SF1, the second sub-filter SF2, and the third sub-filter SF3. In addition, the receiving end (Rx) and the transmitting end (Tx) may be understood as a configuration included in any one of the first terminal (T1) to the fourth terminal (T4) according to various embodiments of the present invention. For example, the first terminal T1 may include a receiving end Rx and a transmitting end Tx.

The amplification unit AU may include a switch SW, a low noise amplifier (LNA), and a power amplifier (PA).

Referring to FIG. 10, the filter F is connected to one end of the low noise amplifier LNA and one end of the power amplifier PA through the switch SW. The low noise amplifier LNA may be disposed in the reception path Rx_RF of the RF signal, and the power amplifier PA may be disposed in the transmission path Tx_RF of the RF signal. In addition, the other end of the low noise amplifier (LNA) is connected to the receiving end (Rx), and the other end of the power amplifier (PA) is connected to the transmitting end (Tx).

In FIG. 10, it is shown that the low noise amplifier (LNA) is arranged in the reception path (Rx_RF) and the power amplifier (PA) is arranged in the transmission path (Tx_RF), but depending on the need for amplification according to the design, the reception path The low noise amplifier LNA may be removed from (Rx_RF), or the power amplifier PA may be removed from the transmission path Tx_RF.

In the above, the present invention has been described by specific matters such as specific elements and limited embodiments and drawings, but this is provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , Anyone with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations from these descriptions.

Therefore, the spirit of the present invention is limited to the above-described embodiments and should not be defined, and all modifications that are equally or equivalent to the claims as well as the claims to be described later fall within the scope of the spirit of the present invention. I would say.

ANT: antenna
F1: first filter
F2: second filter
F3: third filter
SF1: first sub filter
SF2: second sub filter
SF3: third sub filter

Claims (16)

A first filter having a pass band of a first frequency band;
A second filter having a passband of a second frequency band higher than the first frequency band;
A third filter having a pass band of a third frequency band higher than the second frequency band; And
A sub-filter connected to the second filter and providing an attenuation characteristic for the first frequency band; Including,
The second filter includes a plurality of parallel LC resonance units disposed between different nodes and ground among a plurality of nodes between the first terminal and the second terminal, and a parallel LC resonance unit of any one of the plurality of parallel LC resonance units. A front-end module comprising an inductor to be connected.
The method of claim 1,
The inductor is a front end module that provides an attenuation characteristic for the third frequency band.
The method of claim 1,
The inductor is a front-end module disposed between the parallel LC resonator and the ground.
The method of claim 1,
The second filter includes a plurality of inductors, and each of the plurality of inductors is connected to a different parallel LC resonance unit among the plurality of parallel LC resonance units.
The method of claim 1,
The second filter includes a plurality of capacitors, and each of the plurality of parallel LC resonators is disposed between a different node between the plurality of capacitors and a ground.
The method of claim 1,
The first frequency band is 3.3GHz ~ 4.2GHz band, the second frequency band is 4.4GHz ~ 5.0GHz band, the third frequency band is a 5.15GHz ~ 5.95GHz band front end module.
The method of claim 6,
The sub-filter is a front-end module having a stop band of 4.0GHz to 4.2GHz.
The method of claim 1,
The first filter, the second filter, and the third filter are connected to one antenna terminal.

A first filter having a pass band of a first frequency band;
A second filter having a passband of a second frequency band higher than the first frequency band;
A third filter having a pass band of a third frequency band higher than the second frequency band; And
A sub-filter connected to the second filter to provide attenuation characteristics for the third frequency band; Including,
The second filter includes a plurality of series LC resonators disposed between the first terminal and the second terminal, and a capacitor connected to a series LC resonator of any one of the plurality of series LC resonators.
The method of claim 9,
The capacitor is a front end module that provides an attenuation characteristic for the first frequency band.
The method of claim 9,
The capacitor is a front-end module connected in parallel with the one series LC resonator.
The method of claim 9,
The second filter includes a plurality of capacitors, and each of the plurality of capacitors is connected to a different series LC resonance part among the plurality of series LC resonance parts.
The method of claim 9,
The second filter includes a plurality of inductors, and each of the plurality of series LC resonators is disposed between the plurality of inductors.
The method of claim 9,
The first frequency band is 3.3GHz ~ 4.2GHz band, the second frequency band is 4.4GHz ~ 5.0GHz band, the third frequency band is a 5.15GHz ~ 5.95GHz band front end module.
The method of claim 14,
The sub-filter is a front end module having a stop band of 5.15GHz ~ 5.35GHz.
The method of claim 9,
The first filter, the second filter, and the third filter are connected to one antenna terminal.

Images