JP2008227006A - Balun transformer, amplifier, and method for manufacturing the transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a balun transformer capable of easily adjusting a conversion frequency band, and corresponding to significant adjustment, and to provide an amplifier, and a balun transformer manufacturing method. <P>SOLUTION: The balun transformer 30 includes: a first transmission line part 31 formed on the first surface 10a of a substrate 10; having a serpentine shape with a plurality of bent parts 39a-41a, and including two balanced terminals 33 at one end; a second transmission line part 32 formed on the second surface of the substrate 10, i.e., the backside of the first surface 10a, having a serpentine shape with a plurality of bent parts 39a-41a, and including an unbalanced terminal 36 at one end; and a conductive member 43 capable of changing a conversion frequency by electrically connecting the mutually separated two points among the bent parts 39a-41a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to, for example, a balun transformer used in an amplifier constituting a high-frequency module, an amplifier including the balun transformer, and a method of manufacturing the balun transformer.

  In a balun transformer used for an amplifier or the like constituting a high frequency module, a technique for forming transmission line portions 51 and 52 on a front surface 50a and a back surface 50b of a substrate 50 is known as shown in FIG. As shown in FIGS. 12 and 13, C-shaped transmission line portions 51 and 52 are formed at positions corresponding to each other on the front surface 50 a and the back surface 50 b, respectively. One end of the transmission line portion 51 on the front surface 50 a is a balanced terminal 53 and the other end is a ground terminal 54, one end of the transmission line portion 52 on the back surface 50 b is an unbalanced terminal 56, and the other end is a ground terminal 57. The terminals of the transmission line portions 51 and 52 are connected through a through hole or the like. The frequency band that can be converted by the balun transformer 5 depends on the lengths of the transmission line portions 51 and 52. For example, as shown in FIG. 15E, the center frequency is about 430 MHz. When adjusting the center frequency in the balun transformer 5, as shown in FIG. 14, a method of changing the frequency by attaching an adjustment pattern 58 made of metal metal such as copper foil to the transmission line portions 51 and 52, respectively. It has been known. According to this adjustment, as shown by (f) in the graph of FIG. 15, the conversion frequency band changes and the center frequency becomes low. The variable width in this case is about 20 MHz.

Although there is provided a method for adjusting the conversion frequency of the winding type balun transformer (see, for example, Patent Document 1), when the winding type is used, the conversion loss increases as the transmission frequency increases, and several tens of MHz are used. It is a limit. Moreover, in a phase shifter etc., although the adjustment system (for example, refer patent document 2) which can adjust the length of a transmission line part in a stepless manner is provided, this adjustment system is not applied to the balun transformer. .
JP-A-4-286410 JP-A-11-31902

  As described above, the balun transformer that adjusts the frequency by adding the adjustment pattern to the C-shaped pattern has the following problems. That is, the length of the adjustment pattern that can be added is limited, and it is not possible to cope with a case where the adjustment width is large. Therefore, when the adjustment width is large, it is necessary to provide a substrate having a transmission line portion having a different length.

  Therefore, an object of the present invention is to provide a balun transformer, an amplifier, and a balun transformer manufacturing method that can easily adjust a conversion frequency band and can cope with a large adjustment.

  A balun transformer according to an aspect of the present invention is formed on a first surface of a substrate, has a meandering shape having a plurality of curved portions, and includes a first transmission line portion including two balanced terminals at one end, A second transmission line portion formed on a second surface on the back side of the first surface of the substrate, having a meandering shape having a plurality of curved portions, and having an unbalanced terminal at one end; And a conductive member capable of changing the conversion frequency band by electrically connecting two points separated from each other.

  A balun transformer according to one aspect of the present invention is formed on a first surface of a substrate, and includes a first transmission line portion including a balanced terminal at one end, and a second surface on the back side of the first surface of the substrate. And a second transmission line portion having an unbalanced terminal at one end, and the first and second transmission line portions have a plurality of U-shaped line portions having different lengths. The balun transformer according to claim 1.

  An amplifier according to an aspect of the present invention includes the two balun transformers and a transistor in which the balanced terminals of the two balun transformers are connected to an input side and an output side, respectively.

  A method for manufacturing a balun transformer according to one aspect of the present invention includes a first transmission line unit that is formed on a first surface of a substrate and includes two balanced terminals at one end, and a back side of the first surface of the substrate. And a second transmission line portion having an unbalanced terminal at one end, and the first and second transmission line portions have a plurality of curved portions. A balun transformer having a frequency adjustment step of adjusting a conversion frequency band by electrically connecting two points spaced apart from each other with the curved portion interposed therebetween.

  According to the present invention, it is possible to easily adjust the conversion frequency band and cope with a large adjustment.

  Hereinafter, a balun transformer 30 and an amplifier 1 including the balun transformer 30 according to a first embodiment of the present invention will be described with reference to FIGS. In each figure, the configuration is schematically shown by appropriately enlarging, reducing, or omitting it. In the figure, arrows XYZ indicate three orthogonal directions.

  FIG. 1 is a schematic configuration diagram of an amplifier 1 according to the present embodiment, and FIG. 2 is a connection diagram showing an electrical function of the amplifier 1. The amplifier 1 is an electric circuit that obtains an output electric signal having higher power in accordance with an input electric signal. The amplifier 10 includes a substrate 10, a transistor 20 provided on the substrate 10, and a transistor on the substrate 10. 20 balun transformers 30 and 30 provided on the input side and the output side are provided.

  The substrate 10 is made of, for example, a ceramic or resin material and has a dielectric constant of 2 to 10 and a thickness of about 0.1 to 1 mm.

  The balun transformer 30 shown in FIG. 3 and FIG. 4 includes a first transmission line portion 31 and a second transmission line portion 32 on the front surface 10a and the back surface 10b of the substrate 10, respectively. This is a signal conversion element using a balun circuit for conversion into a balun. Note that the output-side balun transformer 30 is configured in the same manner as the input-side balun transformer 30, and a description thereof will be omitted.

  The first and second transmission line portions 31 and 32 are formed from a conductive layer of a metal material for high-frequency signal transmission so that the width W1 is about 0.1 to 10 mm, for example, by a printing method or a plating method. ing.

  The first transmission line unit 31 includes a balanced terminal 33 provided at one end, a ground terminal 34 provided at the other end, and a meandering pattern 35 disposed between these terminals. The second transmission line portion 32 includes an unbalanced terminal 36 provided at one end, a ground terminal 37 provided at the other end, and a meandering pattern 38 disposed between these terminals.

  As shown in FIG. 5, the serpentine pattern 35 on the surface 10 a includes six U-shaped patterns 39 to 41 that open toward the central portion in the Y direction in the drawing. The U-shaped patterns 39 to 41 are arranged in parallel in two rows in the Y direction, three in the X direction in the drawing, and are formed symmetrically in the Y direction. Each of the U-shaped patterns 39 to 41 includes two straight portions 39b to 41b and curved portions 39a to 41a formed between the two straight portions 39b to 41b. The curved portions 39a to 41a are all equal in shape and width W2. The lengths L1, L2, and L3 of the three U-shaped patterns 39 to 41 are different, and L1 is the shortest and L3 is the longest. The lengths L1, L2, and L3 of the U-shaped patterns 39 to 41 are set in advance to dimensions that can obtain a plurality of desired frequencies, for example, 450 MHz, 580 MHz, and 730 MHz when adjusted as described later. In the X direction, the U-shaped pattern 41, the U-shaped pattern 40, and the U-shaped pattern 39 are arranged in order from the longest one toward the ground terminal 34 side at the other end from the balanced terminal 33 side at the other end. . Adjacent U-shaped patterns 39 to 41 are connected between end portions 39d, 40d and 41d (shown in FIGS. 7 to 9) in the Y direction in the figure, and the vicinity of the connecting portion 42 has the same shape as the curved portion. Is formed. Ends 39d, 40d and 41d on the center side of the U-shaped patterns 39 to 41 are arranged in a straight line so as to be aligned with the balanced terminal 33 or the ground terminal 34 in the Y direction.

  As shown in FIG. 6, the meandering pattern 38 on the back surface 10 b side of the substrate 10 includes six U-shaped patterns 39 to 41 and is configured in a shape substantially similar to the meandering pattern 35. It is arranged to correspond. In the meandering pattern 38, the unbalanced terminal 36 and the ground terminal 37 at both ends are both located at the right end in FIG. 6 on the back surface 10b.

  The plurality of U-shaped patterns 39 to 41 are arranged in the order of long, medium, and short from the right side to the left side in the drawing. Also in the meandering pattern 38, the length of each of the U-shaped patterns 39 to 41 is such that the three kinds of frequencies can be obtained when the length is adjusted as will be described later, like the meandering pattern 35. , L2, L3. Further, the unbalanced terminal 36 in the second transmission line portion 32 on the back surface 10b is connected to the front surface 10a side through the through hole 46, and the ground terminal 37 is connected to the front surface 10a side through the through hole 46 and grounded. Yes.

  In the amplifier 1 configured as described above, when a high-frequency signal is input to the unbalanced terminal 36 of the input-side balun transformer 30, the phases differ from each other by 180 degrees from the balanced terminals 33 and 33 of the input-side balun transformer 30. Two balanced signals having the same amplitude are output and input to the transistor 20. When a balanced signal is input from the transistor 20 to the balun transformer 30 on the output side, a high frequency signal is output from the unbalanced terminal 36 of the balun transformer 30 on the output side.

  Next, the frequency adjustment process in the method for manufacturing the balun transformer 30 of the present embodiment will be described. First, the frequency before adjustment in the balun transformer 30 configured as described above is shown in FIG. At this time, the center value of the conversion frequency band is 430 MHz. Here, when the center value of the frequency is increased, as shown in FIG. 7, both end portions 39 d on the center side in the Y direction of the U-shaped pattern 39 are connected by the conductive member 43. The conductive member 43 is, for example, a metal piece such as a copper foil, wire bonding, or the like, and has a function of electrically connecting two separated points. The conductive member 43 has a rectangular shape having the same width as the thickness W1 of the meandering patterns 31 and 32 and the same length as the width W3 of the end portions 39d of the U-shaped pattern 39. By this conductive member 43, the end portions 39d on the center side in the Y direction in FIG. 7 of the U-shaped pattern 39 are connected to each other. Also in the meandering pattern 38 on the back surface 50 b side, the end portions 39 d of the U-shaped pattern 39 are connected by the conductive member 43 in the same manner as the front surface 50 a side.

  W3, which is a linear distance between both end portions 39d of the U-shaped pattern 39, is shorter than the entire length of the U-shaped pattern 39. Therefore, the conductive member 43 shortens the electrical length of the meandering pattern 35 and greatly changes the center value of the converted frequency. The frequency in this case changes as shown in FIG.

  Similarly, as shown in FIG. 8, the frequency when both end portions 40d of the central U-shaped pattern 40 are connected to each other by the conductive member 44 changes as shown in FIG. Further, as shown in FIG. 9, the frequency when both end portions 41d of the right U-shaped pattern 41 are connected to each other by the conductive member 45 changes as shown in FIG. Here, the widths of the conductive members 43 to 45 are all the same as W1, the lengths W3 and W5 of the conductive members 43 and 45 are 1.5 times W2, and the length W4 of the conductive member 44 is Let it be twice W2. The center frequencies in FIGS. 10B, 10C, and 10D are 450 MHz, 580 MHz, and 730 MHz, respectively.

  The balun transformer 30 according to the present embodiment has the following effects. That is, instead of adding an adjustment pattern to increase the substantial length, the conductive member 43 or the like is used to electrically connect two points separated by the curved portions 39a to 41a to shorten the substantial length. The conversion frequency band can be adjusted over a wide range of several MHz to several hundred MHz. Further, since the U-shaped patterns 39 to 41 having different lengths are meanderingly arranged, a plurality of ideal values can be set by one balun transformer 30.

  Moreover, when adjusting the length of the normal transmission line part, it is necessary to add an adjustment pattern to the front surface 10a and the back surface 10b of the substrate in the same manner, and it is difficult to estimate the additional position and the size of the adjustment pattern. However, in the balun transformer 30 of the present embodiment, the position can be easily set by the configuration that is adjusted at the ends of the U-shaped patterns 39 to 41. Therefore, it is possible to adjust to the desired frequency on the front and back surfaces 10a and 10b without using a measuring instrument. In addition, amplifiers are usually composed of semiconductor elements such as FETs, and variations in frequency characteristics due to mounting conditions, variations in element parameters, temperature fluctuations, etc. often occur. By using the balun transformer 30, adjustment for correcting the band fluctuation can be performed.

  Furthermore, it is possible to form a long pattern with respect to the range of the substrate as compared with the case where the entire transmission line portion is C-shaped or configured in a straight line, and the size can be reduced.

  Moreover, in the said embodiment, although the setting of the length of the U-shaped pattern was set on the basis of the length of the whole meandering pattern 35 and 38 after adjustment, it can also be set based on the value to change. That is, for example, when the ends of one U-shaped pattern are connected, the actual length of the pattern is set to be shortened by a certain fixed value. With this configuration, the actual frequency when the center value of the converted frequency deviates from the design value due to various factors such as design accuracy, variations in dielectric constant and thickness of the dielectric substrate, and variations in processing accuracy. According to the difference between the desired frequency value and the desired frequency value, fine adjustment of the center frequency can be easily performed by connecting necessary portions with an adjustment pattern. Further, when used for an amplifier, it is easy to correct fluctuations in the frequency characteristics of the amplifier.

  The present invention is not limited to the above embodiment. For example, although the U-shaped thing was illustrated as a curved part in the said embodiment, it is not restricted to this shape, For example, you may bend in U shape. Further, the number of music parts is not limited to the above embodiment, and any number of music parts can be applied. Moreover, although the case where the unbalanced terminal 36 and the ground terminal 37 of the second transmission line portion 32 are grounded and connected to the front surface 10a through the through hole 46 has been described, the present invention is not limited to this, and the grounding is performed on the back surface 10b side. , You may connect. Furthermore, although the case where the conductive member 43 is provided in any one of the U-shaped patterns 39 to 41 has been described, adjustment may be performed using the conductive member 43 at a plurality of locations by combining these. Further, the U-shaped patterns 39 to 41 may be set to have the same width so that one type of conductive member 43 can be applied in common to the U-shaped patterns 39 to 41.

  In addition, the present invention can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a plan view showing an amplifier according to an embodiment of the present invention. The connection diagram showing the electrical function of the amplifier. The perspective view which shows the structure of the balun transformer concerning the embodiment. The connection diagram showing the electrical function of the balun transformer. The top view which shows the surface side of the board | substrate of the same balun transformer. The top view which shows the back surface side of the board | substrate of the same balun transformer. The top view which shows the frequency adjustment process concerning the embodiment. The top view which shows the frequency adjustment process concerning the embodiment. The top view which shows the frequency adjustment process concerning the embodiment. The graph which shows the adjustment result of the conversion frequency concerning the embodiment. The perspective view which shows an example of a balun transformer. The top view which shows the surface side of the board | substrate of the same balun transformer. The top view which shows the back surface side of the board | substrate of the same balun transformer. The top view which shows an example of the adjustment method of the conversion frequency of the balun transformer. The graph which shows the adjustment result of the conversion frequency of the balun transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Amplifier 10 ... Board | substrate 10a ... Front surface (1st surface) 10b ... Back surface (2nd surface), 20 ... Transistor, 30 ... Balun transformer, 31 ... 1st transmission line part, 32 ... 2nd Transmission line section, 33 ... balanced terminal, 34 ... ground terminal, 35.38 ... meandering pattern,
36: Unbalanced terminal, 37: Ground terminal, 38: Serpentine pattern,
39, 40, 41 ... U-shaped pattern, 39b-41b ... straight line part,
39a-41a ... curve portion, 42 ... connection pattern, 43, 44, 45 ... conductive member, 44 ... through hole.

Claims (4)

A first transmission line portion formed on the first surface of the substrate, having a meandering shape having a plurality of curved portions, and having two balanced terminals at one end;
A second transmission line portion formed on a second surface on the back side of the first surface of the substrate, having a meandering shape having a plurality of curved portions, and having an unbalanced terminal at one end;
A balun transformer comprising: a conductive member capable of changing a conversion frequency band by electrically connecting two points apart from each other in the curved portion. A first transmission line portion formed on the first surface of the substrate and provided with a balanced terminal at one end;
A second transmission line portion formed on the second surface on the back side of the first surface of the substrate and having an unbalanced terminal at one end;
2. The balun transformer according to claim 1, wherein the first and second transmission line portions include a plurality of U-shaped line portions having different lengths. While comprising two balun transformers according to claim 1 or 2,
An amplifier comprising: transistors having the balanced terminals of the two balun transformers connected to an input side and an output side, respectively. A first transmission line unit formed on the first surface of the substrate and having two balanced terminals at one end, and a second surface on the back side of the first surface of the substrate, and an unbalanced terminal at one end A balun transformer having a meandering transmission line portion, the first and second transmission line portions having a plurality of curved portions,
A balun transformer manufacturing method including a frequency adjustment step of adjusting a conversion frequency band by electrically connecting two points separated from each other with the curved portion interposed therebetween.

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