KR101126676B1 - Filter for multi-band antenna switching module - Google Patents

Abstract

PURPOSE: A filter for a multiband antenna switching module is provided to improve characteristics of frequency attenuation, separation, and blocking by forming a capacitor between an input terminal and an output terminal. CONSTITUTION: A first circuit pattern(S10) printed on a first substrate, that is one arbitrary substrate of multilayer circuit boards, is connected to an input terminal receiving an input signal. A second circuit pattern(S20) printed on the first substrate is connected to an output terminal outputting a filtered input signal. A third circuit pattern(S30) printed on the second substrate is connected to the output terminal through a via hole. A fourth capacitor is formed by using the first circuit pattern and the third circuit pattern as opposing electrodes. A fourth circuit pattern(S40) is printed on the third substrate which is contiguous to the second substrate. A third capacity is formed by using the third circuit pattern and the fourth circuit pattern as the opposing electrodes.

Description

Filter for Multi-band Antenna Switching Module

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter used in addition to an input / output terminal of a product in order to selectively pass, block, separate, or attenuate a signal desired by a user in an electric and electronic field such as a communication device, and in particular, a filter used in a multiband antenna switching module. It is about.

In general, a band pass filter, a high pass filter, and a low pass filter are used to separate transmission and reception and to prevent crosstalk between frequency bands. Also, a multiband that pursues miniaturization by implementing a switching element and a filter circuit on a multilayer board. Antenna switching modules are being utilized. The present invention relates to a filter used in a multiband antenna switching module as described above.

More specifically, in order to improve the frequency attenuation, separation, and blocking characteristics, a filter circuit suitable for this is configured, and the configured filter circuit is implemented by utilizing the space of the integrated multilayer board usefully. That is, the present invention relates to a filter circuit having excellent frequency attenuation, separation, or blocking, and to realize a filter having such excellent characteristics, a multi-band antenna switching module that can be miniaturized and reduced in weight by utilizing a multilayer board used in the existing filter circuit. It relates to a filter for.

Due to the development of information and communication technology, change of life style, and economic growth, the form of communication culture is changing rapidly, and in the era of information, it is needed regardless of time and place. Mobile communication systems that can receive communication services in marine and mountainous areas, etc. are becoming an important communication medium indispensable in daily life.

As the number of subscribers joining such a mobile communication system increases explosively, a new communication system and a new communication system using a new frequency band are being made to accommodate all of these subscribers. In addition, the mobile communication terminal satisfies various communication methods that pursue mobility, which is one of the main characteristics of mobile communication terminals carried by subscribers, and the demand for mobile communication terminals that can make calls using signals of various frequency bands increases. Doing.

In Europe, we are roaming with existing operators to expand service coverage. In this process, the necessity of a terminal that can be used in different ways, that is, both GSM and Universal Mobile TelecommunicatiHIGHs (UMTS), and can be used at all frequencies used, has been highlighted. According to these needs, a miniaturized and highly integrated antenna switching module that can be used in multiple bands such as UMTS and GSM has been required.

FIG. 1 is a diagram illustrating a front end 1000 including an antenna switching module included in a conventional communication terminal, and FIG. 2 is a filter 200 for a module 200 according to the related art shown in FIG. 1. It means the circuit which is provided in front of the transmitting stage of the antenna switching module and the passive elements are arranged in series and in parallel so as to have excellent frequency separation or blocking characteristics.In particular, it means a low pass filter. A detailed circuit diagram is shown. As shown in FIG. 1, the front end 1000 is provided at the front end of the switching module 100 and the switching module 100 and includes a module filter 200 and an antenna for passing, blocking or blocking a specific frequency. . The switching module 100 selects multiple bands such as GSM / DCS / PCS according to a frequency band and selects a transmission / reception mode according to a transmission / reception signal. Each of the ports connected to the filter module 200 is provided. The module filter 200 removes the high frequency noise present in the transmission signal of the GSM / DCS / PCS band and outputs the noise to the switching module 100.

However, due to the miniaturization and high integration of the front end, problems such as coupling and cross talk between integrated transmission lines occur. Therefore, the conventional pattern design has a very small area due to the above problems. It was difficult to implement the necessary functions.

In addition, according to the module filter 200 according to the related art shown in FIG. 2, there is a problem that the high frequency noise present in the signal output from the transmitting end to the antenna switching module cannot be sufficiently removed.

The present invention is to solve the above-mentioned problems of the prior art, an object of the present invention by implementing a capacitor using a coupling phenomenon generated between the input and the output of the filter for the module, the frequency attenuation, separation and blocking characteristics The present invention provides a filter for a multi-band antenna switching module that can be improved and can be miniaturized while improving high frequency noise cancellation.

A filter for a multi-band antenna switching module according to the present invention is a module filter which passes, blocks or attenuates an input signal according to a frequency range and is formed on a multilayer circuit board, wherein the module filter inputs the input signal. A first circuit pattern S10 connected to a receiving input terminal and printed on a first substrate which is any one of the multilayer circuit boards, and connected to an output terminal to which the input signal is filtered and output and printed on the first substrate The third circuit pattern S30 is connected to the output terminal through a second circuit pattern S20 and a via hole, and is printed on a second substrate adjacent to the first substrate so as to face the first circuit pattern. It is configured to include, characterized in that the fourth capacitor (C4) is formed using the first circuit pattern (S10) and the third circuit pattern (S30) as the counter electrode. The first substrate and the second substrate referred to in the present invention may be present at any position of the multilayer circuit board, and the third substrate to be described later may be present at any position of the multilayer circuit board.

The module filter may further include a fourth circuit pattern S40 printed on a third substrate adjacent to the second substrate and grounded, wherein the third circuit pattern S30 and the fourth circuit pattern ( The third capacitor C3 is formed using S40 as the counter electrode.

In addition, the third capacitor C3 and the fourth capacitor C4 have the third circuit pattern S30 as a common electrode.

In the filter for a multi-band antenna switching module according to the present invention, the module filter is formed on a multi-layer circuit board by passing, blocking or attenuating an input signal according to a frequency range, wherein the module filter is a filter input. A first inductor (L1) connected to the terminal, one end is connected to the first inductor (L1) and the other end is connected in parallel with the second inductor (L2), the second inductor (L2) connected to the output terminal to form a parallel circuit A first capacitor C1, one end of which is connected between the first inductor L1 and the second inductor L2 and the other end of which is grounded second capacitor C2, one end of the second inductor L2 and an output A third capacitor C3 connected between the terminals and the other end of which is grounded; a first circuit pattern S10 printed on a first substrate connected to the input terminal and being one of any of the multilayer circuit boards, and the output terminal; Connected to the substrate and printed on a second substrate adjacent to the first substrate. 3 circuit is formed by the pattern (S30) to the counter electrode is characterized in that comprises a fourth capacitor (C4).

In addition, the third capacitor C3 and the fourth capacitor C4 have a common electrode.

The module filter may include a switching module of a front end of a mobile communication system that selects a transmission / reception signal according to a frequency band from a mobile communication antenna and connects it to a mobile communication transmission / reception terminal, and a transmission terminal receiving a transmission signal from the transmission terminal. It is characterized in that the arrangement.

As described in detail above, according to the filter for a module or the filter for a multi-band antenna switching module according to the present invention, a capacitor is formed between an input terminal and an output terminal, thereby improving frequency attenuation, separation and blocking characteristics, and increasing passive elements. Nevertheless, it is possible to achieve miniaturization and weight reduction by utilizing a multilayer board used in the existing filter circuit implementation.

1 is a diagram illustrating a front end provided in a communication terminal.
FIG. 2 is a detailed circuit diagram of a conventional filter for a module included in the front end of FIG. 1.
3 is a circuit diagram of a filter for a module according to the present invention.
4A is a diagram illustrating frequency characteristics of an embodiment of a conventional filter circuit for modules.
4B is a diagram illustrating frequency characteristics of an embodiment of a module filter circuit according to the present invention.
5 is a diagram illustrating an embodiment in which the coupling circuit 220 of the filter 200 for a module according to the present invention is formed on a multilayer board.
6 is a cross-sectional view taken along the line AA in FIG.
7A to 7C are diagrams showing respective layers of some multilayer substrates shown in FIG.

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

3 is a detailed circuit diagram of a module filter 200 ′ according to the present invention. Referring to FIGS. 1 and 3, a GSM / DCS / PCS transmitting end (hereinafter, And a switching module 100 are connected to an output side, and a low pass filter 210 and a coupling circuit 220 are connected in parallel between the transmitting end and the switching module 100.

Here, the low pass filter 210 means a known low pass filter that passes only a frequency below a specific frequency.

Specifically, the input terminal 230 of the filter 200 'for the module (terminal present on the input side of the filter for the module) is connected to the transmitting end, and the output terminal 240 for the module 200' for the module 200 is for the module. The switching module 100 is connected to the terminal present at the output side of the filter.

In addition, the module filter 200 ′ is connected to the first inductor L1 connected to the input terminal 230, one end of which is connected to the first inductor L1, and the other end of the second inductor L2 connected to the output terminal 240. The first capacitor C1 is connected in parallel with the second inductor L2 to form a parallel circuit, and one end is connected between the first inductor L1 and the second inductor L2 and the other end is grounded (to the chassis ground). A second capacitor C2 grounded or chassis common line, one end of which is connected between the second inductor and the output terminal 240 and the other end of which is grounded (grounded to the chassis ground or chassis common line), and a third capacitor C3 ) And a fourth capacitor C4 formed using the input terminal 230 and the output terminal 240 as counter electrodes. As an example, the fourth capacitor C4 uses the first circuit pattern S10 connected to the input terminal 230 and the third circuit pattern S30 connected to the output terminal 240 as counter electrodes. Can be formed.

As shown in FIG. 2, the low pass filter 210 includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, and a second inductor L2. Has a shape of π type connected in series or in parallel, and since the first capacitor C1 and the second inductor L2 form a parallel resonant circuit to form a stop band for blocking a frequency for a predetermined band, It prevents the frequency inflow of the band.

Here, the frequency to be blocked may be a harmonic frequency having a frequency of multiplication of the transmission signal and forming noise with respect to the transmission signal. Here, the harmonic frequency is a frequency having a multiple of the transmission frequency, that is, a frequency of 2 times, 3 times, 4 times, etc., and refers to a frequency that forms noise with respect to the transmission signal.

Meanwhile, as illustrated in FIG. 5, the coupling circuit 220 faces the first circuit pattern S10 connected to the input terminal 230 and the third circuit pattern S30 connected to the output terminal 240. It refers to the fourth capacitor C4 formed as an electrode, which is formed by using a coupling phenomenon generated due to the integration of the switching module.

By adding the coupling circuit 220 generated by the coupling phenomenon of the input terminal and the output terminal to the low pass filter 210 as described above, the frequency attenuation, separation, and blocking characteristics are improved. In addition, the additional coupling circuit 220 and the first inductor L1 form an additional parallel resonant circuit, thereby additionally eliminating harmonic frequencies of other multiplications that form noise with respect to the transmission signal. . The additionally generated stopband may be changed by adjusting values of the first inductor L1 and the fourth capacitor C4.

Hereinafter, the effects of the present invention will be described by comparing the input / output characteristics of the present invention with the coupling circuit 220 and the conventional filter without the coupling circuit 220.

4A is a diagram illustrating a frequency characteristic of an exemplary embodiment of a conventional modular filter 200 (hereinafter, referred to as a conventional filter) in which a coupling circuit 220 does not exist. On the other hand, Figure 4b is a gain value of the modular filter 200 according to the present invention, the coupling circuit 220 is present (hereinafter referred to as the "it filter"). Looking at the gain value of m1 and m2 near the pass frequency This is almost the same, it can be seen that the frequency pass characteristics of the conventional filter and this filter are similar to each other.

However, looking at the gain values of m3 and m4, respectively, which represent 1.6 GHz stopbands, it shows a 6 to 10 dB reduction in gain near 1.6 GHz compared to conventional filters. Through the addition of the coupling circuit 220, it can be seen that the attenuation characteristics and noise characteristics for the first harmonic frequency formed by the resonance of the first capacitor C1 and the second inductor L2 are improved.

In addition, m5 and m6 representing the stop band of 2.4 GHz, the attenuation characteristics of about 30 dB around 2.4 GHz was improved due to the parallel resonance of the coupling circuit 220 and the first inductor (L1), which appears in the conventional filter It was found that additional stopbands were formed.

That is, the addition of the coupling circuit 220 not only maintains the pass characteristic of the pass frequency of 800 MHz, but also improves the attenuation and blocking characteristics of the first harmonic frequency of 1.6 GHz, and the second harmonic frequency of 2.4 Ghz. It can be seen that the noise characteristics are improved by forming the stop band additionally.

FIG. 5 is a cross-sectional view illustrating a part of a multilayer substrate in which a coupling circuit 220 is formed in the filter 200 'for a module according to the present invention. FIG. 6 is a cross-sectional view illustrating a cross section AA of FIG. 5. 5 is a diagram showing each layer of the multilayer substrate shown in FIG. Of course, these drawings are only for the purpose of describing the embodiments of the present invention, and various modifications are possible in the range that can be designed by those skilled in the art in consideration of the characteristics of the low pass filter even in the embodiment described in the present invention.

In the present invention, for convenience, FIG. 7A is defined as a first layer, FIG. 7B is a second layer, and FIG. 7C is a third layer. This is for convenience of description only and the present invention is not limited thereto. It will be apparent that the first layer, the second layer and the third layer can be implemented by selecting any layer of the multilayer printed circuit board. Hereinafter, the division of layers such as the first layer is the same point of view.

Further, L1, L2, C1, C2, which are not shown in Figs. 5, 6 and 7A to 7C, may be formed on any part of the multilayer substrate in consideration of electrical signal characteristics. Devices mounted on different layers of the multilayer board may be electrically connected to each other by via holes and metals filled in the via holes, and may be fixed circuit values (resistance values, reactance values, capacitor values) or variable as necessary. It can have a circuit value.

In addition, the multilayer substrate may be a multilayer substrate manufactured using a low temperature calcined ceramic (LTCC) lamination process or a high temperature calcined ceramic (HTCC) lamination process. The substrate may use a conductive metal having excellent conductivity such as gold or silver and capable of firing in an oxidizing atmosphere, and various passive devices such as resistors, capacitors, and inductors may be implemented by printing the conductive metal on the inside of the multilayer substrate. have.

5, 6 and 7A to 7C, the module filter 200 ′ according to the present invention includes an input terminal 230 connected to a transmitting terminal and an output terminal connected to the switching module 100 ( 240, and the input terminal 230 and the output terminal 240 are electrically connected in all layers of the multilayer board through the conductive metal filled in the via holes.

Here, in the first layer illustrated in FIG. 7A, a first circuit pattern S10 connected to an input terminal 230 for receiving a signal to be filtered and a second circuit connected to an output terminal 230 for outputting a filtered signal are provided. The pattern S20 is formed, and the first circuit pattern S10 and the second circuit pattern S20 are printed with a conductive metal.

In addition, in the second layer illustrated in FIG. 7B, the third circuit pattern S30, the first circuit pattern, and the second circuit pattern printed with a conductive metal are opposed to the first circuit pattern S10 and the second circuit pattern S20. Is a common electrode).

Referring to FIG. 6, a dielectric material such as silicon (Si) is interposed between the first circuit pattern S10 connected to the input terminal 230 and the third circuit pattern S30 connected to the output terminal 240. The fourth capacitor C4 is formed to form the coupling circuit 220.

In addition, a grounded fourth circuit pattern S40 may be formed in the third layer illustrated in FIG. 7C, and a dielectric such as silicon may be disposed between the third circuit pattern S30 connected to the output terminal 240. The third capacitor C3 is formed by interposing the material.

On the other hand, the first layer to the third layer specified above may not be located in a specific portion of the multi-layer substrate and may be located in any layer by design change by those skilled in the art.

In the above described exemplary embodiments of the present invention by way of example, as described above, the present invention is applied to the field of filtering to pass or block or attenuate the input signal according to the frequency range, the scope of the present invention is It is not limited only to the specific embodiments as such, those skilled in the art will be able to appropriately change within the scope without departing from the technical gist of the claims of the present invention.

1000: front end 100: switching unit
200 ': module filter 210: low pass filter
220: coupling circuit 230: input terminal
240: output terminal

Claims (6)

A filter for a module which passes, blocks or attenuates an input signal according to a frequency range and is formed on a multilayer circuit board.
The module filter,
A first circuit pattern S10 connected to an input terminal receiving the input signal and printed on a first substrate which is any one of the multilayer circuit boards;
A second circuit pattern S20 connected to an output terminal on which the input signal is filtered and output, and printed on the first substrate;
And a third circuit pattern S30 connected to the output terminal through a via hole and printed on a second substrate adjacent to the first substrate so as to face the first circuit pattern.
A filter for a multi-band antenna switching module, characterized in that the fourth capacitor (C4) is formed using the first circuit pattern (S10) and the third circuit pattern (S30) as the opposite electrode.
The method of claim 1,
The module filter,
A fourth circuit pattern S40 printed on a third substrate adjacent to the second substrate and grounded;
And a third capacitor (C3) formed using the third circuit pattern (S30) and the fourth circuit pattern (S40) as opposed electrodes.
The method of claim 2,
The third capacitor (C3) and the fourth capacitor (C4) is a filter for a multi-band antenna switching module, characterized in that the third circuit pattern (S30) as a common electrode.
A filter for a module which passes, blocks or attenuates an input signal according to a frequency range and is formed on a multilayer circuit board.
The module filter,
A first inductor L1 connected to the input terminal of the filter;
A second inductor L2 having one end connected to the first inductor L1 and the other end connected to the output terminal;
A first capacitor C1 connected in parallel with the second inductor L2 to form a parallel circuit;
A second capacitor C2 having one end connected between the first inductor L1 and the second inductor L2 and the other end grounded;
A third capacitor C3 having one end connected between the second inductor L2 and the output terminal and the other end grounded;
A first circuit pattern S10 connected to the input terminal and printed on a first substrate, which is one of any of the multilayer circuit boards, and a third printed on a second substrate connected to the output terminal and adjacent to the first substrate. And a fourth capacitor (C4) formed by using the circuit pattern (S30) as the counter electrode.
The method of claim 4, wherein
The third capacitor (C3) and the fourth capacitor (C4) is a filter for a multi-band antenna switching module, characterized in that the common electrode.
The method according to any one of claims 1 to 5, wherein
The module filter,
A multi-band arranged between a switching module of a front end of a mobile communication system for selecting a transmission / reception signal according to a frequency band from a mobile communication antenna and connecting to a mobile communication transmission / reception terminal, and a transmission terminal receiving a transmission signal from the transmission terminal; Filter for antenna switching module.

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