JP2004214414A - Spiral inductor, method for manufacturing the same, and microwave integrated circuit equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sharply reduce insertion loss, and to maintain miniaturization. <P>SOLUTION: The upper face of a strip line 11 formed on a semi-insulating substrate 10 is laminated with a through-hole formation line 12 formed with a plurality of through-holes formed at predetermined intervals from the upper face to the vertical direction, and the upper face of the through-hole formation line 12 is laminated with a strip line 13 so that a two-layer structure can be constituted. Furthermore, the strip lines 11 and 13 are spirally shaped so that signal currents in a high frequency state can be made to uniformly flow through the strip lines 11 and 13. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spiral inductor used in, for example, an RF (radio frequency) circuit, a method of manufacturing the spiral inductor, and a microwave integrated circuit provided with the spiral inductor.
[0002]
[Prior art]
In recent years, microwave communication has been actively developed to be applicable to mobile communication and the like. In this type of communication system, particularly, downsizing of the communication device is strongly required.
[0003]
Therefore, a communication device has been proposed in which an inductor used in an RF (Radio Frequency) circuit of the communication device is replaced with an inductor having a spiral structure to reduce the size of the device (for example, Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-046101.
[0005]
[Problems to be solved by the invention]
However, since the conductor (strip line) of the spiral structure is arranged directly on a semi-insulating substrate such as GaAs (gallium arsenide), current concentrates on the conductor end in a high frequency state. The problem that insertion loss becomes large arises.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a spiral inductor and a method of manufacturing the spiral inductor, which can suppress insertion loss as much as possible and can be downsized, and a microwave integrated circuit provided with the spiral inductor.
[0007]
[Means for Solving the Problems]
The present invention is configured as follows to achieve the above object.
[0008]
A first strip line having a spiral shape formed on a semi-insulating substrate and allowing a signal current input from one end to pass to the other end; a first strip line laminated on an upper surface of the first strip line; A first through-hole forming line having a plurality of through holes formed at predetermined intervals in a vertical direction from the upper surface of the first strip line along the shape of the first strip line, and forming the first through hole A second strip line having a spiral shape that is stacked on the upper surface of the line and conforms to the shape of the first strip line.
[0009]
According to the configuration of (1), the second strip line is provided on the upper surface of the first strip line formed on the semi-insulating substrate via the through-hole formed line, and further has the two-layer structure. Since the second strip line and the second strip line are formed in a spiral shape, current in a high-frequency state flows through the first and second strip lines and concentrates on two strip line ends. Therefore, the insertion loss can be reduced to about half as compared with the case where one conventional strip line is provided, and further downsizing can be maintained.
[0010]
(2) A plurality of through holes stacked on the upper surface of the second strip line and having a plurality of through holes formed at predetermined intervals in the vertical direction from the upper surface of the second strip line along the shape of the second strip line. 2 through-hole formed line, and a third strip line spirally formed along the shape of the second strip line and stacked on the upper surface of the second through-hole formed line. .
[0011]
According to the configuration of (2), a three-layer structure in which the second through-hole forming line is stacked on the upper surface of the second strip line, and the third strip line is stacked on the upper surface of the second through-hole forming line. As a result, the current in the high frequency state is distributed to the first, second, and third strip lines, respectively, so that the insertion loss can be further reduced as compared with the configuration (1). .
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0013]
(1st Embodiment)
FIG. 1 is a plan view of a spiral inductor according to a first embodiment of the present invention as viewed from above, and FIG. 2 is a front view of the spiral inductor shown in FIG. 1 (as viewed from line AA ′ in FIG. 1). FIG. FIG. 3 is an exploded perspective view of the spiral inductor shown in FIG.
[0014]
In FIG. 1, reference numeral 1A denotes a spiral inductor, in which a strip line 11 is formed on a semi-insulating substrate 10 made of, for example, GaAs (gallium arsenide). The slip line 11 is made of, for example, gold and has a spiral shape, and guides a signal current input to the input terminal 11a to the output terminal 11b.
[0015]
On the upper surface of the strip line 11, a through-hole forming line 12 is laminated. As shown in FIG. 3, the through hole forming line 12 is provided with a plurality of through holes 121 penetrating vertically from the strip line 11 side. The plurality of through holes 121 are provided at intervals smaller than (2/3) λ (wavelength) of the signal current in a high frequency state, for example.
[0016]
A strip line 13 is stacked on the upper surface of the through-hole forming line 12. The strip 13 is made of, for example, gold, has the same shape as the strip line 11, and guides a signal current input to the input terminal 11a to the output terminal 11b.
[0017]
In FIG. 1, an intersection 11b of the strip line 11 is located on the first line 11-1 of the strip line 11 and the first line 13-1 of the strip line 13, and the second line 11-2 and the strip line 13 of the strip line 11. Of the second line 13-2. At this time, the second line 11-2 of the strip line 11 and the second line 13-2 of the strip line 13 do not contact the first line 11-1 of the strip line 11 and the first line 13-1 of the strip line 13. To be configured.
[0018]
Next, the operation of the spiral inductor 1A configured as described above will be described.
[0019]
In the known spiral inductor 2, as shown in FIG. 4, a strip line 21 is disposed on a semi-insulating substrate 20, and the strip line 21 is formed so as to form a spiral structure as shown in FIG.
[0020]
However, in the spiral inductor 2, the current concentrates on the strip line 21 in a high frequency state, and as a result, the insertion loss increases.
[0021]
Therefore, in the first embodiment, the strip line 13 is connected to the upper portion of the strip line 11 via the through-hole forming line 12. If a spiral is formed in this state, a signal current in a high frequency state flows through both of the strip lines 11 and 13.
[0022]
Therefore, compared with the spiral inductor 2 in which only the strip line 21 is disposed on the semi-insulating substrate 20, the insertion loss in a high frequency state is about half.
[0023]
By the way, the spiral inductor 1A in the first embodiment is applied to the RF circuit shown in FIG. This RF circuit is used, for example, in a communication device that performs microwave communication.
[0024]
That is, the field effect transistor (FET) 3 is connected to the input terminal 11a of the spiral inductor 1A, and the capacitor 4 and the output terminal 5 are connected to the output terminal 11b. The input terminal 6 is connected to the FET 3.
[0025]
The high-frequency signal current, that is, the microwave signal current input to the input terminal 6 is supplied to the spiral inductor 1 after being turned on and off by the FET 3. The spiral inductor 1A distributes the inputted microwave signal current evenly to the strip lines 11 and 13. The output microwave signal current of the spiral inductor 1A is output to the output terminal 5 after being stored in the capacitor 4.
[0026]
As described above, in the first embodiment, the through-hole forming line 12 is laminated on the upper surface of the strip line 11 formed on the semi-insulating substrate 10, and the strip line 13 is formed on the upper surface of the through-hole forming line 12. Since the strip lines 11 and 13 are formed in a spiral shape in a stacked two-layer structure, a signal current in a high frequency state flows through the strip lines 11 and 13. Therefore, the insertion loss can be reduced to about half as compared with the case where a single strip line 21 is provided in the related art, and downsizing of the entire device using the spiral inductor 1A can be maintained.
[0027]
(Second embodiment)
FIG. 7 is a sectional view of a spiral inductor 1B according to a second embodiment of the present invention as viewed from the front. In FIG. 7, the same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description will be omitted.
[0028]
That is, in the second embodiment, the through-hole forming line 14 is stacked on the upper surface of the strip line 13, and the strip line 15 is stacked on the upper surface of the through-hole forming line 14. The strip line 15 is made of, for example, gold and has a spiral shape, and guides the signal current input to the input terminal 11a to the output terminal 11b.
[0029]
According to the second embodiment, a current in a high frequency state is applied to the strip lines 11, 13, and 15 by the three-layer structure in which the through-hole forming line 14 and the strip line 15 are further laminated on the upper surface of the strip line 13. Since the distribution is performed, the insertion loss can be further reduced as compared with the first embodiment.
[0030]
(Other embodiments)
The present invention is not limited to the above embodiments. For example, the interval between the formation of the through holes is set to be smaller than (2/3) λ of the signal current at a high frequency. However, the interval between the formation of the through holes may be arbitrarily set according to the current to be handled.
[0031]
In the second embodiment, a three-layer structure is used. However, a multi-layer structure of three or more layers may be used. By doing so, the insertion loss in a high frequency state can be further reduced.
[0032]
Further, in each embodiment, an example in which gold is used for the strip line has been described, but a metal having high conductivity other than gold may be used.
[0033]
In addition, the type and structure of the spiral inductor, the type of the through-hole forming line, the microwave integrated circuit such as the RF circuit, and the like can be variously modified without departing from the gist of the present invention.
[0034]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a spiral inductor, a method of manufacturing the spiral inductor, and a microwave integrated circuit including the spiral inductor, which can minimize insertion loss and can be downsized. .
[Brief description of the drawings]
FIG. 1 is a plan view of a spiral inductor according to a first embodiment of the present invention as viewed from above.
FIG. 2 is a sectional view of the spiral inductor according to the first embodiment as viewed from the front;
FIG. 3 is an exploded perspective view of the spiral inductor according to the first embodiment.
FIG. 4 is a sectional view of a conventional spiral inductor viewed from the front.
FIG. 5 is a plan view of the conventional spiral inductor viewed from above.
FIG. 6 is a block diagram when the spiral inductor according to the first embodiment is applied to an RF circuit;
FIG. 7 is a sectional view of a spiral inductor according to a second embodiment of the present invention as viewed from the front.
[Explanation of symbols]
1A, 1B, 2 Spiral inductor, 3 Field effect transistor (FET), 4 Capacitor, 5 Output terminal, 6 Input terminal, 10 Semi-insulating substrate, 11, 13, 15 Strip line, 12 , 14 ... through-hole forming line, 11a ... input end, 11b ... output end, 11c ... intersection, 121 ... through hole.

Claims (6)

A first strip line having a spiral shape formed on a semi-insulating substrate and passing a signal current input from one end to the other end;
A first layer having a plurality of through-holes laminated on the upper surface of the first strip line and formed at predetermined intervals in the vertical direction from the upper surface of the first strip line along the shape of the first strip line. And a through-hole forming line of
A spiral inductor comprising: a second strip line laminated on the upper surface of the first through-hole forming line and having a spiral shape along the shape of the first strip line. 2. The spiral inductor according to claim 1, wherein the first through-hole forming line is formed by forming the through holes at intervals smaller than ２ wavelength of the signal current. 3. A second layer having a plurality of through holes stacked on the upper surface of the second strip line and formed at predetermined intervals in the vertical direction from the upper surface of the second strip line along the shape of the second strip line; And a through-hole forming line of
The spiral inductor according to claim 1, further comprising: a third strip line having a spiral shape that is stacked on the upper surface of the second through-hole formed line and that has a spiral shape along the shape of the second strip line. . The spiral inductor according to claim 1, wherein the first and second strip lines are made of gold. A method for manufacturing a spiral inductor according to claim 1, wherein
A first strip line having a spiral shape is formed on the semi-insulating substrate to pass a signal current input from one end to the other end,
A first through-hole provided with a plurality of through holes formed at predetermined intervals in the vertical direction from the upper surface of the first strip line on the upper surface of the first strip line along the shape of the first strip line. Laminate hole forming lines,
A method of manufacturing a spiral inductor, wherein a second strip line having a spiral shape conforming to the shape of the first strip line is laminated on an upper surface of the first through-hole formed line. A microwave integrated circuit comprising the spiral inductor according to claim 1.

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