KR20220112936A - Multiplexer - Google Patents

Abstract

A multiplexer according to the present invention comprises a plurality of filters connected to an antenna to pass signals of different frequency bands, wherein each of the plurality of filters comprises a lowpass filter, a bandpass filter, and a highpass filter, the highpass filter is configured with at least one first inter digital transducer (IDT) capacitor and at least one first inductor, and the lowpass filter is configured with a surface acoustic wave (SAW) resonator, one or more second IDT capacitors, and one or more second inductors. Therefore, the present invention is capable of shortening a manufacturing process time of the multiplexer.

Description

Multiplexer {Multiplexer}

The present invention relates to a multiplexer, and more particularly, to a multiplexer including a plurality of filters connected to an antenna to pass signals of different frequency bands.

Currently, mobile communication terminals tend to have communication functions of multiband and multimode, and therefore, a multiplexer is essential in the RF front-end module.

A multiplexer is typically connected to an antenna and includes a plurality of filters that pass signals of different frequency bands, and these plurality of filters include a lowpass filter, a bandpass filter, or a highpass filter ( highpass filter).

However, the existing multiplexers consisted of only an LC filter implemented with an inductor and a capacitor, a SAW filter using a surface acoustic wave (SAW) device, or a LC filter and a SAW filter.

Republic of Korea Patent Publication No. 10-2018-0121075 (published on November 7, 2018)

The technical problem to be achieved by the present invention is to provide a multiplexer configured using an IDT capacitor and a first inductor without using a lumped element.

A multiplexer according to an embodiment of the present invention for solving the above technical problem includes a plurality of filters connected to an antenna to pass signals of different frequency bands, and the plurality of filters are low-pass filters, band-pass filters, respectively. a filter and a high-pass filter, wherein the high-pass filter includes at least one first inter digital transducer (IDT) capacitor and at least one first inductor, the low-pass filter comprising a surface acoustic wave (SAW) resonator; It is characterized in that it is composed of at least one or more second IDT capacitors and at least one or more second inductors.

In the high-pass filter, at least one or more of the first IDT capacitors are connected in a ladder form, one end of at least one of the first inductors is connected in series to the first IDT capacitor, and the other end of the first inductor is grounded. characterized by having

The first inductor is embedded in a package.

The low-pass filter is characterized in that the second IDT capacitor and the second inductor are connected in parallel.

The second inductor is embedded in the package.

A multiplexer according to another embodiment of the present invention for solving the technical problem, a high-pass filter including only at least one first IDT capacitor and at least one or more first inductors connected in parallel to the first IDT capacitor; a lowpass filter comprising at least one first SAW resonator, at least one second IDT capacitor, and at least one second inductor; and a bandpass filter comprising at least one or more second SAW resonators and at least one or more third inductors, wherein the first inductor, the second inductor and the third inductor are all embedded in a package substrate. .

According to the present invention described above, by configuring the low-pass filter and the high-pass filter using the IDT capacitor and the first inductor without using a lumped element, the material cost for the configuration of the multiplexer can be reduced and , since the surface mount technology (SMT) process can be omitted, the manufacturing process time of the multiplexer can be shortened.

1 is a circuit configuration diagram of a multiplexer according to an embodiment of the present invention.
FIG. 2 is a circuit diagram illustrating a high-pass filter constituting the multiplexer shown in FIG. 1 .
FIG. 3A is a plan structural diagram of a multiplexer according to an embodiment of the present invention, and FIG. 3B is a side structural diagram of a multiplexer according to an embodiment of the present invention.
FIG. 4 is a graph of an example for evaluating the performance of the high-pass filter shown in FIG. 2 .
FIG. 5 is a circuit diagram illustrating a low-pass filter constituting the multiplexer shown in FIG. 1 .
6 is a graph of an example for evaluating the performance of the low-pass filter shown in FIG. 5 .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and the accompanying drawings, substantially the same components are denoted by the same reference numerals, so that redundant descriptions will be omitted. In addition, in the description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted.

1 is a circuit configuration diagram of a multiplexer 100 according to an embodiment of the present invention.

The multiplexer 100 according to an embodiment of the present invention includes a plurality of filters connected to an antenna to pass signals of different frequency bands. The multiplexer 100 has a structure having a plurality of outputs when the antenna side is an input, and has a plurality of inputs when the antenna 100 side is an output.

1, the multiplexer 100 according to the present embodiment is connected to an antenna and passes signals of different frequency bands through a high-pass filter (110: highpass filter, HPF), a low-pass filter (120: lowpass filter, LPF), and a bandpass filter 130 (bandpass filter, BPF).

However, the multiplexer 100 of the present invention is exemplary, and may be composed of two filters connected in parallel (referred to as a diplexer or a duplexer), or may be composed of four filters connected in parallel. (referred to as a quadplexer), and may further consist of five filters connected in parallel (referred to as a quintplexer) or more filters.

Also, the multiplexer 100 may include an impedance matching element. The impedance matching device may include an inductor and/or a capacitor according to impedance to be matched, and may transmit a signal of maximum power through impedance matching. The impedance matching element may be connected between the antenna and the ground, or alternatively or additionally, may be connected between the antenna and each of the filters to match the impedance.

In an embodiment of the present invention, at least one of the plurality of filters uses an LC filter, and at least one of the plurality of filters uses a SAW filter. The LC filter is suitable for implementing a wide passband, but has a limit in improving skirt characteristics. On the other hand, the SAW filter has an advantage in that it is difficult to implement a wider passband than the LC filter due to its characteristics, but has a good skirt characteristic. The skirt characteristic refers to how well the pass band and the stop band are distinguished. A good skirt characteristic means that the slope of the transition band between the pass band and the stop band is steep. .

Therefore, if the LC filter and the SAW filter are used together in consideration of the pass bandwidth required for each filter and the interval between the pass bands, the advantages of both the LC filter and the SAW filter can be utilized.

For example, an LC filter may be used for a frequency band having a relatively large pass bandwidth, and a SAW filter may be used for a frequency band having a relatively small pass bandwidth. In addition, when the interval between two neighboring passbands is large, the LC filter may be used, and when the interval between the two neighboring passbands is small, one or both of the two neighboring passbands may use the SAW filter.

For example, the low-pass filter 120 may be a GPS band filter, the band-pass filter 130 may be a 2.4 GHz Wi-Fi band filter, and the high-pass filter 110 may be a 5 GHz Wi-Fi band filter.

Since the GPS band and the 2.4 GHz Wi-Fi band have relatively small passbands and a narrow interval therebetween, a SAW filter is used as the low-pass filter 120 and the band-pass filter 130, and the 5 GHz Wi-Fi band is relatively small with the 2.4 GHz Wi-Fi band. Since they are separated from each other and have a large passband, an LC filter can be used as the high pass filter 110 .

The high-pass filter 110 is a filter that passes only a frequency component higher than a cut-off frequency among frequency components of the input signal and blocks a frequency component lower than that as much as possible.

The low-pass filter 120 is a filter that passes only a frequency component lower than the cutoff frequency from among the frequency components of the input signal, and blocks a frequency component higher than that as much as possible.

The bandpass filter 130 is a filter that passes only a frequency component between the lower cutoff frequency and the upper cutoff frequency among the frequency components of the input signal, and blocks a frequency component lower than the lower cutoff frequency or an upper cutoff frequency component as much as possible.

Hereinafter, the high-pass filter 110 and the low-pass filter 120, which are the main features of the present invention, will be mainly described.

The high-pass filter 110 of the present invention may be composed of at least one first IDT capacitor and a first inductor. In the high-pass filter 110, at least one first IDT capacitor is connected in a ladder form, one end of the at least one first inductor is connected in series to the first IDT capacitor, and the other end of the first inductor may be grounded. .

FIG. 2 is a circuit diagram illustrating the high-pass filter 110 constituting the multiplexer 100 shown in FIG. 1 .

The high-pass filter 110 shown in FIG. 2 includes at least two or more series-connected first IDT capacitors (C1) and at least two or more parallel-connected first IDT capacitors (C2).

The first IDT capacitors C1 connected in series and the first IDT capacitors C2 connected in parallel may be referred to as a first group of IDT capacitors G1. The IDT capacitor is a chip formed by rotating the SAW resonator 90 degrees. That is, the IDT capacitor rotates the direction of the comb electrode (IDT) of the SAW resonator by 90 degrees, and unlike the SAW resonator, the IDT capacitor is a component that does not use a reflector. In addition, when mounted on the same chip as the SAW resonator, the direction of the comb electrode of the SAW resonator and the comb electrode of the IDT capacitor forms a 90 degree angle.

In addition, the high-pass filter 110 includes at least two or more first inductors, wherein the two or more first inductors L1 are connected in series between the first IDT capacitors C2 and the ground, respectively. Each of these first inductors L1 constituting the first inductor group G2 may be embedded in the package PKB.

3A is a plan structural diagram of the multiplexer 100 according to an embodiment of the present invention, and FIG. 3B is a side structural diagram of the multiplexer 100 according to an embodiment of the present invention.

Referring to FIG. 3A , the capacitor constituting the high-pass filter 110 is exemplified by the IDT capacitor, and referring to FIG. 3B , the first inductors constituting the high-pass filter 110 in the package PKG. (L1) is exemplified embedded. The first inductors L1 are connected to the ground GND in the package and the inductor, which is a component of the notch filter constituting the low-pass filter 120 to be described later.

4 is a graph of an example for evaluating the performance of the high-pass filter 110 shown in FIG.

Referring to Figure 4, when the capacitor of the high-pass filter 110 is composed of a general capacitor and an IDT capacitor, respectively, in the case of the IDT capacitor, spurious occurs at 2200 to 2300 [MHz], but this corresponds to a non-spec band and , since the remaining bands exhibit the same characteristics, even if the capacitor of the high-pass filter 110 is configured as an IDT capacitor instead of a general capacitor, the same performance as the high-pass filter is exhibited.

Meanwhile, the low-pass filter 120 of the present invention may include notch filters that block a specific frequency band.

FIG. 5 is a circuit diagram illustrating the low-pass filter 120 constituting the multiplexer shown in FIG. 1 .

Referring to FIG. 5 , the low-pass filter 120 may include a first notch circuit 120-1 and a second notch circuit 120-2, and SAW resonators 120-3.

The low-pass filter 120 is a band (1710-2200 MHz) of the band-pass filter 130 except for the frequency of 617-960 [MHz] and the band (2300-2690 MHz) of the high-pass filter 110 (attenuation) ) may be configured with notch circuits as shown in FIG. 5 as needed.

In the first notch circuit 120 - 1 , the second IDT capacitor C3 and the second inductor L2 may be connected in parallel. The first notch circuit 120-1 is a filter for frequency attenuation of 1710 to 2200 [MHz], which is the band of the bandpass filter 130 .

The second IDT capacitor C3 is formed in the form of a chip in which the SAW resonator is rotated by 90 degrees. That is, the second IDT capacitor (C3) rotates the direction of the comb electrode (IDT) of the SAW resonator by 90 degrees, there is no reflector, and when mounted on the same chip as the SAW resonator, the comb electrode of the SAW resonator and the second IDT capacitor (C3) ), the direction of the comb electrode forms an angle of 90 degrees.

Also, the second inductor L2 may be embedded in the package PKG. The second inductor L2 is connected to the first inductors L1 constituting the above-described high-pass filter 110 and the ground GND in the package.

The second notch circuit 120-2 is a filter for frequency attenuation of 2300-2690 [MHz], which is the band of the high-pass filter 110, and is connected in series to the first notch circuit 120-1. The second notch circuit 120 - 2 may have a capacitor C and an inductor L connected in parallel, and both the capacitor C and the inductor L may be embedded in a package.

The SAW resonators 120 - 3 are connected in parallel with the first notch circuit 120 - 1 and are also grounded (GND). Here, the resonant frequency of the SAW resonators 120 - 3 is located in the band (1710 to 2200 MHz) of the bandpass filter 130 .

6 is a graph of an example for evaluating the performance of the low-pass filter 120 shown in FIG.

Referring to FIG. 6 , the low-pass filter 120 includes the first notch circuit 120-1, the second notch circuit 120-2, and the SAW resonators 120-3, so that It can perform a notch function.

6, the frequency of the first notch circuit 120-1 attenuates 200 the frequency band of 1710-2200 [MHz], which is the band of the bandpass filter 130, and the second notch circuit 120-2) The frequency of is shown to attenuate 210 a frequency band of 2300 to 2690 [MHz], which is a band of the high-pass filter 110 . In addition, the frequency of the SAW resonators 120 - 3 shows that the frequency band of 1200 [MHz] corresponding to the band of the bandpass filter 130 is attenuated 220 .

So far, the present invention has been looked at with respect to preferred embodiments thereof. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

100: multiplexer
110: high pass filter
120: low-pass filter
130: bandpass filter

Claims (6)

It is connected to the antenna and includes a plurality of filters that pass signals of different frequency bands,
Each of the plurality of filters includes a low-pass filter, a band-pass filter and a high-pass filter,
The high-pass filter includes at least one first inter digital transducer (IDT) capacitor and at least one first inductor,
The low-pass filter is a multiplexer comprising a surface acoustic wave (SAW) resonator, at least one or more second IDT capacitors, and at least one or more second inductors. The method according to claim 1,
The high-pass filter is
At least one or more of the first IDT capacitors are connected in a ladder form, one end of at least one of the first inductors is connected in series to the first IDT capacitor, and the other end of the first inductor is grounded. . 3. The method according to claim 2,
The first inductor is
A multiplexer characterized in that it is embedded within a package. The method according to claim 1,
The low-pass filter is
The multiplexer, characterized in that the second IDT capacitor and the second inductor are connected in parallel. 5. The method according to claim 4,
and the second inductor is embedded in a package. a high-pass filter including only at least one first IDT capacitor and at least one or more first inductors connected in parallel to the first IDT capacitor;
a low-pass filter comprising at least one first SAW resonator, at least one second IDT capacitor, and at least one second inductor; and
a bandpass filter including at least one second SAW resonator and at least one third inductor,
The first inductor, the second inductor, and the third inductor are all embedded in a package substrate.

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