KR100288964B1 - multi-layered transformer for high frequency - Google Patents

Abstract

In the high frequency multilayer transformer of the present invention, a plurality of first ceramic sheets are formed with via holes filled with conductive paste, respectively, and first coil patterns connected with the via holes to form a first inductor, respectively. In addition, a first capacitor pattern connected to the first coil pattern of the first ceramic sheet is formed on the second ceramic sheet, a second capacitor pattern is formed on the third ceramic sheet, and the second and third ceramic sheets It is formed at a predetermined interval from each other to form a first capacitor. Via holes are formed in the plurality of fourth ceramic sheets, respectively, and second coil patterns for forming a second inductor are formed through the via holes, and the second coil patterns are second capacitor patterns of the third ceramic sheet. Connected with In addition, a third capacitor pattern connected to the second coil pattern is formed on the fifth ceramic sheet, a fourth capacitor pattern is formed on the sixth ceramic sheet, and the fifth and sixth ceramic sheets are spaced apart from each other. Formed to form a second capacitor. Since the multilayer transformer uses a capacitor, a high impedance conversion rate can be obtained even by using a low capacitance inductor, can be manufactured compactly, and the manufacturing process is simple.

Description

Multi-layered transformer for high frequency

The present invention relates to a transformer, and more particularly, to a transformer for high frequency formed in a stacked form.

In general, a transformer is an apparatus that receives alternating current power in one circuit and supplies power to another circuit by an electromagnetic induction action, and is also called a transformer or a transformer. Transformers can be classified into various types, such as stacked type and winding type, depending on the structure. Among them, the stacked type is widely used.

Hereinafter, a structure of a conventional multilayer transformer will be described with reference to the accompanying drawings.

1 shows the structure of a conventional stacked transformer.

As shown in FIG. 1, the conventional multilayer transformer includes a first inductor L10 and a second inductor L20 that are sequentially formed.

The first inductor L10 is used to form a coil between two ceramic (ferrite or low dielectric constant) sheets 20 and 60 having a terminal pattern formed thereon, and the ceramic sheets 20 and 60. A plurality of ceramic sheets 30, 40, and 50 on which metal patterns (hereinafter referred to as coil patterns) are formed.

The second inductor L2 also includes two ceramic sheets 70 and 150 having a terminal pattern formed thereon, and a plurality of ceramic sheets 80, 90,... 140 having a coil pattern formed between the ceramic sheets 70 and 150. .

Each sheet 20 to 150 of the first and second inductors L1 and L2 are sequentially stacked, and ceramic sheets 10 and 160 having no metal patterns are formed on both sides thereof.

In the first and second inductors L1 and L2, the ceramic sheets 20, 60, 70, and 150 have terminal patterns 21, 61, 71, 151, and coil patterns 22, 62, for electrically connecting to an external circuit. 72 and 152 are formed, respectively, and via holes 23, 63, 73 and 153 are formed at the end of the coil pattern.

In the ceramic sheets 30, 40, 50, 80, 90, ..., 140, coil patterns 31, 41, 51, 81, 91, ..., 141 are formed along edges, respectively. Via holes 32, 42, 52, 82, 92, ..., 142 are formed, respectively.

Since these via holes are filled with a conductive paste, the patterns formed on the sheets are connected through the conductive paste. That is, the coil patterns formed on the sheets 20 to 60 of the first inductor L10 are connected to each other through the conductive paste, and the coil patterns formed on the sheets 70 to 150 of the second inductor L20 are conductive. It is connected to each other through the paste.

Accordingly, by forming the coil patterns connected through the via holes, respectively, inductance values of the first and second inductors L120 and L20 are realized. At this time, the value of the inductance is determined by the length of the coil pattern, the number of turns of the coil, and the width (area) of the coil pattern.

In a conventional stacked transformer having such a structure, when an electrical signal is applied to the terminal terminal from the outside, a magnetic field is formed in the coil of the inductor of the input side, for example, the first inductor L10. As a change in the magnetic lines of the magnetic field formed in the first inductor L10 causes a current change in the inductor on the output side, for example, the second inductor L20, an impedance change is obtained.

As described above, the impedance matching between the input circuit and the output circuit of the transformer is performed by changing the impedance using two inductors having different coil lengths.

Unlike the transformer in which the coil pattern for forming one inductor is formed on a plurality of sheets as described above, in order to further reduce the structure, the coil pattern for forming one inductor is formed on one sheet. Stacked transformers have been developed. 2 shows the structure of such a conventional stacked transformer.

As shown in FIG. 2, another conventional stacked transformer includes two ceramic sheets 200 and 240 having ground terminal patterns 201 and 241 formed therebetween, and an input terminal pattern 211 between the ceramic sheets 200 and 240. ), The ceramic sheet 210 having the first sheet, the ceramic sheet 220 having the first coil pattern 221 formed thereon, the second and third coil patterns 231 and 232, and the first and second output terminal patterns ( Ceramic sheets 230 having 235 and 236 formed thereon are sequentially formed.

In the first coil pattern 221 of the ceramic sheet 220, two first and second patterns 2211 and 2212 are connected in parallel to each other to form one coil. The via hole 222 is formed at the end of the first pattern 2211, and the via hole 212 is also formed at the end of the input terminal pattern 201 of the ceramic sheet 210.

The second and third coil patterns 231 and 232 of the ceramic sheet 230 respectively form one coil, and are formed in parallel with each other. The second and third coil patterns 231 and 232 are separated from each other, and via holes 233 and 234 are formed at one end of the second and third coil patterns 231 and 232, respectively, and the other ends of the first and second coil patterns 231 and 232. It is connected to the output terminal patterns 235 and 236.

The via holes 212, 222, 233, and 234 are also filled with a conductive paste, so that the input terminal pattern 211 of the ceramic sheet 210 is connected to the first coil pattern 221 of the ceramic sheet 220, and the second of the ceramic sheet 230 is formed. And the third coil patterns 232 and 233 are connected to the ground terminal pattern 241 of the ceramic sheet 240.

In the conventional transformer having such a structure, when an electrical signal is applied to the input terminal, a magnetic field is formed in the first coil formed by the first coil pattern 221, and thus the second and third coil patterns 231 and 232 are applied. The current changes occur in the second and third coils formed by the current, thereby changing the impedances of the first and second output terminals. In this case, the inductance value changes according to the length and width of the first, second and third coil patterns 221, 231. 232.

However, in such conventional stacked transformers, miniaturization is difficult when a high impedance conversion ratio is to be obtained. More specifically, in order to obtain high impedance conversion ratios (1: 1, 1: 2, 1: 4, etc.) in a transformer, a relatively high inductance ratio is required, and therefore, a high capacity inductor is required. Therefore, in order to manufacture a high capacity inductor, a large amount of sheets are required to be stacked, which makes it difficult to miniaturize.

In addition, as the size increases due to the implementation of a high capacity inductor, the insertion loss between the input and output of the transformer is increased, the phase change on the output side is increased, and the input and output impedance characteristics are deteriorated.

In addition, in the case where the coil pattern forming one coil is formed on one sheet as in the transformer shown in FIG. 2, the width and length of the coil pattern need to be increased on the sheet having a limited area, thereby increasing the desired high capacity. There is a problem that can not implement the inductor of.

Therefore, an object of the present invention is to provide a high frequency multilayer transformer having high impedance conversion rate and improved insertion loss and phase characteristics.

1 is an exploded perspective view of a conventional stacked transformer.

Figure 2 is an exploded perspective view of another conventional stacked transformer.

3 is an exploded perspective view of a stacked transformer according to an embodiment of the present invention.

4 is an equivalent circuit diagram of a stacked transformer according to an embodiment of the present invention.

5A is a graph illustrating insertion loss characteristics of a multilayer transformer having an impedance conversion ratio of 1: 1 according to an embodiment of the present invention.

5B is a graph showing the reflection loss characteristics of the multilayer transformer having an impedance conversion ratio of 1: 1 according to the embodiment of the present invention.

6A and 6B are graphs showing signal phase characteristics of first and second output terminals of a stacked transformer having an impedance conversion ratio of 1: 1 according to an embodiment of the present invention.

7A and 7B are graphs illustrating insertion loss and return loss characteristics of a multilayer transformer having an impedance conversion ratio of 1: 4 according to an embodiment of the present invention.

In order to achieve this object, the high-frequency multilayer transformer according to the present invention comprises a plurality of first ceramic sheets forming a first inductor, second and third ceramic sheets forming a first capacitor, sequentially formed; A plurality of fourth ceramic sheets forming a second inductor, and fifth and sixth ceramic sheets forming a second capacitor.

Via holes filled with conductive paste are formed in the plurality of first ceramic sheets, respectively, and first coil patterns connected to the via holes to form a first inductor are formed. In addition, a first capacitor pattern connected to the first coil pattern of the first ceramic sheet is formed on the second ceramic sheet, a second capacitor pattern is formed on the third ceramic sheet, and the second and third ceramic sheets It is formed at a predetermined interval from each other to form a first capacitor.

Via holes are formed in the plurality of fourth ceramic sheets, respectively, and second coil patterns forming second inductors are formed through the via holes, respectively, and the second coil patterns are formed by the second capacitor pattern of the third ceramic sheet. Connected. In addition, a third capacitor pattern connected to the second coil pattern is formed on the fifth ceramic sheet, a fourth capacitor pattern is formed on the sixth ceramic sheet, and the fifth and sixth ceramic sheets are spaced apart from each other. Formed to form a second capacitor.

An input terminal pattern connected to the second coil pattern and the first capacitor pattern is formed on one of the plurality of fourth ceramic sheets, and a first output terminal pattern connected to the first capacitor pattern is formed on the second ceramic sheet. The fifth ceramic sheet has a second output terminal pattern connected to the third capacitor pattern.

Therefore, the signal input to the input terminal pattern is converted through the first inductor and the first capacitor and output to the first output terminal pattern, and is also converted through the second inductor and the second capacitor and output to the second output terminal pattern. .

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

3 shows a structure of a stacked transformer according to an embodiment of the present invention, and FIG. 4 shows an equivalent circuit of the stacked transformer according to an embodiment of the present invention.

As shown in FIG. 3, the stacked transformer according to the embodiment of the present invention includes a first inductor L1, a first capacitor C1, a second inductor L2, and a second inductor sequentially formed on the same line. It consists of two capacitors C2.

The first inductor L1 includes a ceramic (ferrite or low dielectric constant) sheet 300 on which a ground terminal pattern 301 and a coil pattern 302 for forming a coil are formed, and below the ceramic sheet 300. Two ceramic sheets 310 and 320 having coil patterns 311 and 321 formed thereon are sequentially formed. Via holes 303, 312, and 322 are formed at the ends of the patterns 302, 311, and 321 of the ceramic sheets 300, 310, and 320.

Two ceramic sheets (1) are sequentially formed under the ceramic sheet (320) of the first inductor (L1) in the first capacitor (C1), and each of the capacitor patterns (331, 341) for forming the capacitor is formed. 330,340. The first output terminal pattern 333 connected to the first capacitor pattern 331 is formed at one side of the ceramic sheet 330, and the via holes 332 and 342 are formed at one side of the capacitor patterns 331 and 341 of the ceramic sheets 330 and 340. ) Are formed respectively.

The second inductor L2 includes a ceramic sheet 350 formed under the ceramic sheet 340 of the first capacitor C1 and having the first input terminal pattern 351 and the coil pattern 352 formed thereon. . Below the ceramic sheet 350, two ceramic sheets 360 and 370 in which coil patterns 361 and 371 are formed are sequentially formed. Via holes 353, 362 and 372 are formed at the ends of the patterns 352, 361 and 371 of the ceramic sheets 350, 360 and 370.

The second capacitor C2 includes two ceramic sheets 380 and 390 which are sequentially formed under the ceramic sheet 380 of the second inductor L2 and each of which has the capacitor patterns 381 and 391 formed thereon. A second output terminal pattern 383 connected to the capacitor pattern 381 is formed at one side of the ceramic sheet 380, and a via hole 382 is formed at one side of the capacitor pattern 381. A ground terminal pattern 392 connected to the capacitor pattern 391 is formed at one side of the ceramic sheet 390.

The via hole formed in each sheet is filled with a conductive paste, so that the coil pattern and the capacitor pattern formed in each sheet are connected through the conductive paste.

More specifically, the coil patterns 302, 311 and 321 formed on the ceramic sheets 300 to 320 are connected through the via holes 303, 312 and 322 to form one coil, and the coil patterns 352, 361 and 371 formed on the ceramic sheets 350 to 370 are It is connected through the via holes 353, 362 and 372 to form another coil.

At this time, the capacitor patterns 331 and 341 of the ceramic sheets 330 and 340 are not connected to each other to form a single capacitor at a predetermined interval, and the capacitor patterns 381 and 391 of the ceramic sheets 380 and 390 are also not connected to each other. Spacing is formed to form another capacitor.

In this case, the coil pattern 321 of the ceramic sheet 320 and the capacitor pattern 331 of the ceramic sheet 330 are connected to each other through the via holes 322 and 332, and the capacitor pattern 341 of the ceramic sheet 340 and the capacitor pattern 341. The input terminal pattern 351 of the ceramic sheet 350 is connected through the via hole 342. In addition, the coil pattern 371 of the ceramic sheet 370 and the capacitor pattern 381 of the ceramic sheet 380 are connected to each other through the via holes 372 and 382.

In the multilayer transformer according to the present invention, as the ceramic sheets 300, 310, ..., 390 described above are sequentially stacked, two inductors L1 and L2 and two capacitors C1 and C2 are implemented, respectively. In order to avoid interference, the first inductor L1, the second inductor L2, the first capacitor C1, and the second capacitor C2 are formed at a distance of 100 μm or more from each other.

An equivalent circuit of the stacked transformer according to the embodiment of the present invention having such a structure is as shown in FIG. An input terminal of the stacked transformer is connected to the load R1 on the input side, a first output terminal is connected to the load R2 on the output side, and a second output terminal is connected to the load R3 on the output side.

As such, when an electrical signal is applied to the input terminal of the transformer through the input side load R1 and the stacked transformer according to the exemplary embodiment of the present invention is connected to the input / output side load, the electrostatic energy of the first capacitor C1 is applied. Conversion and electron energy conversion of the first inductor L1 are alternately generated to perform impedance conversion. In addition, the electron energy of the second inductor L2 and the electrostatic energy conversion of the second capacitor C2 are alternately generated to perform impedance conversion.

Accordingly, a corresponding signal according to impedance conversion is output through the first and second output terminals, and signals output through the first and second output terminals have the same magnitude and have a phase difference of about 180 °.

In the multilayer transformer according to the present invention operating as described above, the first and second inductors L1 and L2 and the first and second capacitors C1 and C2 should have appropriate values in order to obtain a predetermined impedance conversion rate.

In order to obtain an impedance conversion ratio of 1: 1 between input and output in a state where the center frequency of the input signal is 900 MHz ± 100 MHz, the capacitance values of the first and second inductors L1 and L2 are 12.5 nH. The capacitance of the first and second capacitors C1 and C2 was set to 2.5 Hz to implement a multilayer high-frequency transformer.

The multilayer transformer for high frequency according to the embodiment of the present invention having an impedance conversion ratio of 1: 1 implemented as described above was manufactured in a size of 3.2 mm in width and 1.6 mm in length. In-band insertion loss characteristics of such a stacked transformer are shown in FIG. 5A, and in-band reflection loss characteristics are shown in FIG. 5B. As shown in Figs. 5A and 5B, in a stacked transformer having an impedance conversion ratio of 1: 1, the insertion loss and reflection loss in the signal band are 1.4 dB (max) and -12 dB (min), respectively.

In addition, FIG. 6A shows a phase characteristic of a signal output from a first output terminal of a stacked transformer having an impedance conversion ratio of 1: 1, and FIG. 6B shows a phase characteristic of a signal output from a second output terminal. . As shown in FIGS. 6A and 6B, the phase difference between the first and second output terminals is about 180 ° ± 8 °.

In addition, in order to obtain an impedance conversion ratio of 1: 4 between input and output in the state where the center frequency of the input signal is 900 MHz ± 100 MHz, the capacitance values of the first and second inductors L1 and L2 may be changed. A high-frequency multilayer transformer was implemented with 25 nH and capacitance values of the first and second capacitors C1 and C2 of 1.25 GHz.

The high frequency multilayer transformer according to the embodiment of the present invention having an impedance conversion ratio of 1: 4 implemented as described above was manufactured to have a size of 2.0 mm in width and 1.2 mm in length, and it is inserted in a band of the multilayer transformer in FIG. 7A. Loss characteristics are shown, and the return loss characteristics in the band are shown in FIG. 7B.

As shown in FIGS. 7A and 7B, in the high frequency stacked transformer according to the embodiment of the present invention having an impedance conversion ratio of 1: 4, the insertion loss and the reflection loss in the signal band are 1.3 dB (max), −, respectively. 10.3 m (min).

In addition, in the high frequency multilayer transformer according to the embodiment of the present invention, since a capacitor is used unlike a conventional transformer using only an inductor, a capacitor having a small size and a high capacity can be obtained. In order to obtain a high-capacitance capacitor, the thickness between two semaric sheets forming the capacitor should be reduced or the area of the capacitor pattern should be increased. However, the outer dimensions of the stacked transformers are determined, and there is a limit in reducing the gap between the sheets.

Therefore, in another embodiment of the present invention, a plurality of ceramic sheets forming a plurality of capacitors may be connected in parallel to each other to implement a stacked transformer having a high capacity capacitor.

For example, by forming a ceramic sheet with the same structure as the first capacitor C1 described above to form one capacitor, and connecting the formed capacitor in parallel with the first capacitor C1, a high capacity capacitor can be obtained. Can be. As described above, a plurality of capacitors may be formed, and the capacitors may be connected in parallel to each other to implement a stacked transformer having a larger high capacity capacitor.

As described above, in the multilayer transformer according to the exemplary embodiment of the present invention, a capacitor may be used to obtain a high impedance conversion rate even when a low inductor is used.

In addition, a small high frequency multilayer transformer can be manufactured, and the manufacturing process of the high frequency multilayer transformer can be simplified. Thus, the effect of increasing the production yield and mass productivity of the product is provided.

This invention is susceptible to various modifications without departing from the claims set out below.

Claims (3)

A plurality of first ceramic sheets each having a via hole filled with a conductive paste, each having a first coil pattern connected to the via hole to form a first inductor; Second and third ceramic sheets each having a first capacitor pattern and a second capacitor pattern connected to the first coil pattern of the first ceramic sheet, and positioned at a predetermined distance from each other to form a first capacitor; Via holes filled with conductive paste are formed, respectively, and second coil patterns forming second inductors are formed through the via holes, and the second coil patterns are connected to the second capacitor patterns of the third ceramic sheet. A plurality of fourth ceramic sheets; And Third and fourth capacitor patterns connected to the second coil pattern and the fourth capacitor pattern of the fourth ceramic sheet are respectively formed, and are disposed at a predetermined distance from each other to form the second and sixth ceramic sheets. High frequency stacked transformer comprising a. The method of claim 1, A first output terminal pattern connected to the first capacitor pattern is formed on the second ceramic sheet. One of the fourth ceramic sheets has an input terminal pattern connected to the first capacitor pattern and the second coil pattern, The multilayer ceramic transformer of claim 5, wherein a second output terminal pattern connected to the third capacitor pattern is formed on the fifth ceramic sheet. The method of claim 1, Further comprising at least two ceramic sheets, each capacitor pattern is formed, The ceramic sheet is positioned at a predetermined interval from each other two to form a capacitor, each capacitor is a high-frequency multilayer transformer is connected in parallel with the first capacitor or the second capacitor.