JP3033704B2 - Microwave circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave circuit mainly utilizing electromagnetic coupling of a plurality of coupling lines.

[0002]

2. Description of the Related Art Conventionally, in a microwave circuit of this type, a plurality of coupling lines, a lead-out line, and a bonding wire have been used as a type of configuration utilizing electromagnetic coupling of a plurality of coupling lines. Are known, an interdigital capacitor comprising a plurality of coupling lines and lead-out lines, or a Marchand balun comprising a plurality of coupling lines, lead-out lines and ground via holes.

FIG. 11 shows a basic configuration of a conventional Lange coupler type microwave circuit.
FIG. 1B is related to a plan view, and FIG. 2B is related to a cross-sectional side view taken along line AA ′ in FIG.

This microwave circuit has a ground conductor 1
A plurality (three in this case) of quarter-wavelength coupling lines 4,
Two 1/8 wavelength coupling lines 5 and a plurality (four in this case) of bonding wires 7 are respectively formed, and four lead-out lines 6 outside the range of the dimension l.
a to 6d are formed, and the lead-out lines 6a to 6d are connected to terminals 8a to 8d, respectively.

That is, in this Lange coupler type microwave circuit, the coupling lines 4 and 5 and the lead lines 6a to 6d are formed on the dielectric substrate 2 having a uniform thickness h, and the terminal 8d is connected to a resistance of 50Ω. When power is input from the terminal 8a after terminating at the terminal 8a, the output is distributed to the terminal 8b as a direct terminal and the terminal 8c as a coupling terminal with a phase difference of 90 degrees. The absolute values of the transmission coefficients in these two directions depend on the thickness h of the dielectric substrate 2 and the coupling line interval s of the wavelength. Therefore, as the thickness h of the dielectric substrate 2 is larger, or as the coupling line interval s is smaller, the absolute value of the transmission coefficient to the coupling terminal increases, and conversely, the absolute value of the transmission coefficient to the direct terminal decreases. . Therefore, the thickness h of the dielectric substrate 2 and the coupling line spacing s are designed such that the transmission coefficient to the direct terminal is equal to the absolute value of the transmission coefficient to the coupling terminal.

FIG. 12 shows the basic configuration of a conventional microwave circuit of the interdigital capacitor type. FIG. 12 (a) relates to a plan view thereof and FIG. 12 (b).
FIG. 4A relates to a cross-sectional side view taken along line AA ′ in FIG.

In this microwave circuit, a plurality (four in this case) of quarter-wavelength coupling lines 4 in a range of a dimension l are provided on a dielectric substrate 2 having a thickness h and a ground conductor 1 on the back surface.
Are formed, and two lead-out lines 6a and 6b are formed outside the range of the dimension l.
a and 6b are connected to terminals 8a and 8b, respectively.

That is, in this microwave circuit of the interdigital capacitor type, the 1/4 wavelength coupling line 4 and the lead line 6 are formed on the dielectric substrate 2 having a uniform thickness. The absolute value of the transmission coefficient from the terminal 8a to the terminal 8b depends on the thickness h of the dielectric substrate 2 and the coupling line interval s between the 1/4 wavelength coupling lines 4, and the thickness of the dielectric substrate 2 The transmission coefficient increases as h increases and as the coupling line interval s decreases.

FIG. 13 shows the basic structure of a conventional merchant balun type microwave circuit. FIG. 13 (a) relates to a plan view thereof, and FIG. 13 (b) relates to A of FIG. It relates to a cross-sectional side view taken along line -A '.

This microwave circuit has a ground conductor 1 on the back surface.
The two quarter-wavelength coupling lines 4 and the two lead-out lines 6b and 6c are formed on the dielectric substrate 2 having the thickness h and having two dimensions l on the same straight line. A half-wavelength coupling line 10 and a lead-out line 6a are formed in a direction along the dimension l, and ground ends having via holes 11 at the ends of the two quarter-wavelength coupling lines 4 respectively. Pads 12 are connected, and lead-out lines 6a-6c are connected to terminals 8a-8, respectively.
c. Here, the 波長 wavelength coupling line 10 and the two １ ／ wavelength coupling lines 4 are electromagnetically coupled to each other at a portion having a length of 波長 wavelength.

That is, in this merchant balun type microwave circuit, a 1/2 wavelength coupling line 10 and a 1/4 wavelength coupling line 4 are formed on a dielectric substrate 2 having a uniform thickness. One side of the two-wavelength coupling line 10 is connected to the terminal 8a by a lead-out line 6a and the other side is opened, and one side of the quarter-wavelength coupling line 4 is pulled out by the lead-out lines 6b and 6c and the terminals 8b and 8c. And the other side is grounded by a via hole 11 or the like.
The power input from the terminal 8a is output to the terminals 8b and 8c with a phase difference of 180 degrees. The absolute value of the transmission coefficient to these two terminals is determined by the thickness h of the dielectric substrate 2 and 1 /
Depending on the distance s between the two-wavelength coupling line 10 and the quarter-wavelength coupling line 4, the larger the thickness h of the dielectric substrate 2 and the smaller the coupling line distance s, the smaller the distance from the terminal 8a to the terminal 8b, 8
The absolute value of the transmission coefficient to c increases.

Incidentally, well-known techniques relating to such a microwave circuit include, for example, an interdigital filter disclosed in Japanese Utility Model Publication No. 60-16083 and a microwave semiconductor amplifier disclosed in Japanese Patent Application Laid-Open No. 60-220609. And JP-A-63-540.
Microwave distributor disclosed in Japanese Patent Publication No.
No. 43801, the structure of an interdigital filter, the microwave 180-degree hybrid disclosed in Japanese Patent Publication No. 2-22561, or
No. 95902 discloses an interdigital band-pass filter.

[0013]

In the case of the Lange coupler type microwave circuit shown in FIG. 11, the thickness of the dielectric substrate and the distance between the coupling lines depend on the transmission coefficient to the direct terminal and the transmission coefficient to the coupling terminal. Although the absolute value is designed to be equal, the selection of the thickness h of the dielectric substrate and the coupling line interval s is often limited. One of the limitations is that the thickness of the dielectric substrate cannot be made too large in view of the size of the matching circuit (especially in the case of a monolithic integrated circuit, in order to ensure heat dissipation and reduce the diameter of the via hole). (It is necessary to keep the thickness of the substrate small)
And the fact that the coupling line interval s cannot be made smaller than a certain value due to processing accuracy.

Therefore, in the case of the Lange coupler type microwave circuit, there is a problem that such a restriction often causes the absolute value of the transmission coefficient to the coupling terminal to be smaller than the absolute value of the transmission coefficient to the direct terminal. .

Specifically, for example, when the thickness of the dielectric substrate is 4
When fixed to 0 μm, the transmission coefficient S ₂₁ (d
FIG. 14A shows the calculated values of the dependence of the transmission coefficient B ₃₁ and the transmission coefficient S ₃₁ (dB) to the indirect terminal on the coupling line spacing s (μm), as shown in FIG. The dependence of the transmission coefficient S ₂₁ (dB) and the transmission coefficient S ₃₁ (dB) on the dielectric substrate thickness h (μm) at this time is as shown in FIG. However, here, the material of the dielectric substrate is GaAs.
And the length l of the 1/4 wavelength coupling line is l = 45.
0 μm and the width w are w = 5 μm, and the width of the lead-out line is 30 μm. When the coupling line is formed by a gold plating process, the lower limit of the coupling line interval s is about 5 μm. Therefore, if it is desired to set the dielectric substrate thickness h to about 40 μm due to restrictions on via hole diameter and the like, FIG.
As shown in (b), the transmission coefficient S is smaller than the transmission coefficient S _21.
The imbalance that ₃₁ becomes smaller occurs.

Also, in the case of the microwave circuit of the interdigital capacitor type shown in FIG. 12 and the case of the microwave circuit of the Marchand balun type shown in FIG. 13, the dielectric substrate thickness h is reduced for the same reason as described above. There is a problem that the absolute value of the transmission coefficient may not be secured because a sufficiently large absolute value of the transmission coefficient may not be secured because the width cannot be increased excessively and the coupling line interval s has a lower limit.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a technical problem thereof is to provide a coupling line without increasing the thickness of the dielectric substrate and reducing the interval between the coupling lines. It is an object of the present invention to provide a microwave circuit capable of strengthening the coupling between them.

[0018]

According to the present invention, a plurality of coupling lines are formed on a dielectric substrate having a ground conductor on the back surface, and the coupling lines are electromagnetically coupled to each other. In the wave circuit, by forming protrusions on the surface or both surfaces of the dielectric substrate, a microwave circuit in which the region where the coupling line is formed is partially thickened can be obtained.

On the other hand, according to the present invention, in a microwave circuit having a Lange coupler composed of a plurality of coupling lines, lead-out lines, and bonding wires formed on a dielectric substrate having a ground conductor on the back surface, By forming protrusions on the surface or both surfaces of the body substrate, a microwave circuit can be obtained in which the region where the coupling line is formed is partially thickened.

On the other hand, according to the present invention, in a microwave circuit in which an interdigital capacitor including a plurality of coupling lines and a lead line is formed on a dielectric substrate having a ground conductor on the back surface, By forming protrusions on the surface or both surfaces of the above, a microwave circuit is obtained in which the region where the coupling line is formed is partially thickened.

In addition, according to the present invention, a merchant balun comprising a plurality of coupling lines, lead lines, and ground via holes formed on a dielectric substrate having a ground conductor on the back surface is formed. In the microwave circuit, by forming projections on the surface or both surfaces of the dielectric substrate, a microwave circuit in which the region where the coupling line is formed is partially thickened can be obtained.

In these microwave circuits, it is preferable that the protruding portions are formed of the same material as the dielectric substrate, or are formed of an insulating film deposited on the front or back surface of the dielectric substrate. .

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The microwave circuit of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a basic configuration of a Lange coupler type microwave circuit having a center frequency of 60 GHz according to a first embodiment of the present invention. FIG. (B) relates to a cross-sectional side view taken along the line AA 'in FIG.

This microwave circuit has a ground conductor 1
A plurality (three in this case) of quarter-wavelength coupling lines 4, and two 1 / 8-wavelength coupling lines 5, in the range of dimension l on the surface of the dielectric substrate 2 having a thickness h having A plurality of (four in this case) bonding wires 7 are formed, and four outgoing lines 6a outside the range of the dimension l.
To 6d are formed, and the lead-out lines 6a to 6d are connected to the terminals 8a to 8d, respectively. In addition, the region where the coupling lines are formed on the surface of the dielectric substrate 2 is partially thickened to form a surface. The projection 9 is formed.

In this Lange coupler type microwave circuit, the ground conductor 1 is made of 20 μm thick gold,
The dielectric substrate 2 is made of GaAs having a thickness of 40 μm, and the surface projection 9 is made of GaAs having a thickness of 10 μm. Also, 1 /
The four-wavelength coupling line 4 has a length l (dimension l) = 450 μm,
The ８ wavelength coupling line 5 is made of gold having a length of 225 μm, a width w = 10 μm and a thickness of 2 μm, and the lead lines 6 a to 6 d are made of a gold having a width w = 10 μm and a thickness of 2 μm.
It is made of gold having a thickness of 0 μm and a thickness of 2 μm. Further, the bonding wire 7 is made of a gold wire having a diameter of 5 μm, and the coupling line interval s is 5 μm.

FIG. 2 shows a basic configuration of a Lange coupler type microwave circuit having a center frequency of 60 GHz according to a second embodiment of the present invention. FIG. 2 (a) relates to a plan view thereof and FIG. (B) relates to a cross-sectional side view taken along the line AA 'in FIG.

This microwave circuit has a ground conductor 1
A plurality (three in this case) of quarter-wavelength coupling lines 4, and two 1 / 8-wavelength coupling lines 5, in the range of dimension l on the surface of the dielectric substrate 2 having a thickness h having A plurality of (four in this case) bonding wires 7 are formed, and four outgoing lines 6a outside the range of the dimension l.
To 6d are formed, and the lead-out lines 6a to 6d are connected to the terminals 8a to 8d, respectively. In addition, the region where the coupling lines are formed on the surface of the dielectric substrate 2 is partially thickened to form a surface. The projection 9 is formed, and the region where the coupling line is formed on the back surface of the dielectric substrate 2 on the ground conductor 1 side is also partially thickened to form the rear projection 3. .

In this Lange coupler type microwave circuit, the ground conductor 1 is made of 20 μm thick gold,
The dielectric substrate 2 is made of GaAs having a thickness of 40 μm, the rear projection is made of GaAs having a thickness of 320 μm, and the front projection 9 is made of GaAs having a thickness of 10 μm. The 1/4 wavelength coupling line 4 has a length l (dimension l) = 450 μm and a width w.
= 10 μm, 2 μm thick gold, the １ ／ wavelength coupling line 5 has a length of 225 μm, a width w = 10 μm, and a thickness of 2 μm.
m, and the lead-out lines 6a to 6d have a width of 30 μm.
m, made of gold having a thickness of 2 μm. Further, the bonding wire 7 is made of a gold wire having a diameter of 5 μm, and the coupling line interval s is 5 μm.

FIG. 3 shows a basic configuration of an interdigital capacitor type microwave circuit according to a third embodiment of the present invention. FIG. 3 (a) relates to a plan view thereof, and FIG. FIG. 4A relates to a cross-sectional side view taken along line AA ′ in FIG.

This microwave circuit has a ground conductor 1
Are formed on the surface of the dielectric substrate 2 having a thickness h having a thickness of h and a plurality of (four in this case) quarter-wavelength coupling lines 4 are formed in the range of the dimension l, and two of them are formed outside the range of the dimension l. The lead-out lines 6a and 6b are formed, and the lead-out lines 6a and 6b are connected to the terminals 8a and 8b, respectively. In addition, the area of the surface of the dielectric substrate 2 where the coupling line is formed is partially thick. The surface projection 9 is formed by being formed into a film.

In this microwave circuit of the interdigital capacitor type, the ground conductor 1 has a thickness of 20 μm.
The dielectric substrate 2 is made of GaAs having a thickness of 40 μm.
, And the surface projection 9 is made of GaAs having a thickness of 10 μm. The 1/4 wavelength coupling line 4 has a length l (dimension l).
= 450 μm, width w = 12.5 μm, and thickness 2 μm, and the lead-out lines 6a to 6b are made of gold having a width of 30 μm and a thickness of 2 μm. Further, the coupling line interval s is 5 μm.

FIG. 4 shows a basic configuration of a Marchand balun type microwave circuit according to a fourth embodiment of the present invention. FIG. 4A is related to a plan view thereof, and FIG. It is related to a cross-sectional side view taken along line AA ′ in FIG.

This microwave circuit has a ground conductor 1
Two 1/4 wavelength coupling lines 4 and two lead-out lines 6 in two ranges 1 on the same straight line on the surface of the dielectric substrate 2 having a thickness h having
b and 6c are formed, and a half-wavelength coupling line 10 and a lead-out line 6 are formed in two directions along the dimension l. At the ends of the two quarter-wavelength coupling lines 4, Are connected to ground pads 12 each having a via hole 11 for grounding, and lead-out lines 6a to 6c are connected to terminals 8a to 8c, respectively.
The surface where the coupling line is formed is partially thickened to form a surface projection 9.

In this merchant balun type microwave circuit, the ground conductor 1 is made of 20 μm thick gold, the dielectric substrate 2 is made of 40 μm thick GaAs,
The surface projection 9 is made of GaAs having a thickness of 10 μm. or,
The half-wavelength coupling line 10 has a length of 950 μm and a width w = 3.
The 1/4 wavelength coupling line 4 is made of gold having a thickness of 0 μm and a thickness of 2 μm, and has a length l (dimension l) = 450 μm and a width w = 30 μm.
m, made of gold having a thickness of 2 μm.
c is made of gold having a width of 30 μm and a thickness of 2 μm. Further, the via hole 11 has a side of 30 μm and a depth of 40 μm, and the grounding pad 12 is made of gold having a side of 50 μm and a thickness of 2 μm. In addition, the coupling line interval s is 5 μm.

FIG. 5 is a side cross-sectional view schematically illustrating each step of a manufacturing method for manufacturing the microwave circuit according to the first embodiment, and FIG. FIG. 2 (b) relating to a resist patterning process
FIG. 4C relates to a surface projection forming step, FIG. 5C relates to a line forming step, and FIG. 5D relates to a ground conductor forming step.

First, as shown in FIG. 5A, as a photoresist patterning step, a 600 μm thick Ga
A photoresist 14 is patterned on the dielectric substrate 2 made of As by using a lithography technique. Next, as a surface projection forming step, as shown in FIG. 5B, the dielectric substrate 2 is etched using a sulfuric acid-based etchant or the like to form a surface projection 9 having a thickness of 10 μm.

Subsequently, as a line forming step, FIG.
As shown in (c), the coupling line 13 and the lead-out line are formed on the surface projection 9. For example, after removing the photoresist 14 with an organic solvent, a coupling line 13 made of gold having a thickness of 2 μm is formed on the surface projection 9, and at this time, a lead-out line is also formed. This process is Ti / P
a step of forming a metal thin film of about 0.5 μm made of t / Au or the like by sputtering, a lithography step for patterning a coupling line, a step of plating gold serving as a coupling line, and It comprises a step of removing and a step of removing the metal thin film by milling.

Finally, as a ground conductor forming step, if necessary, the thickness of the dielectric substrate 2 is adjusted to, for example, 40 μm by polishing or etching or the like, and then, as shown in FIG. Is formed by plating or the like.

FIG. 6 is a side cross-sectional view for simply explaining each step of another manufacturing method for manufacturing the microwave circuit according to the first embodiment, and FIG. FIG. 1B relates to a process of forming a surface protrusion, and FIG.
FIG. 3C relates to a line forming step, and FIG. 5D relates to a ground conductor forming step.

First, as shown in FIG. 6 (a), as a step of depositing an insulating film and patterning a photoresist,
An insulating film 15 is deposited to a thickness of about 10 μm on a dielectric substrate 2 made of 00 μm GaAs by a plasma CVD method or the like, and a photoresist 14 is formed thereon by lithography.
Is patterned. Next, as a surface projection forming step, as shown in FIG. 6B, the surface projection 9 is formed by etching the insulating film 15 using buffered hydrofluoric acid or the like as an etchant.

Subsequently, as a line forming step, FIG.
As shown in (c), the coupling line 13 and the lead-out line are formed on the surface projection 9. For example, after removing the photoresist 14 with an organic solvent, a coupling line 13 made of gold having a thickness of 2 μm is formed on the surface projection 9, and at this time, a lead line is also formed at the same time. This process is Ti / P
a step of forming a metal thin film of about 0.5 μm made of t / Au or the like by sputtering, a lithography step for patterning a coupling line, a step of plating gold serving as a coupling line, and It comprises a step of removing and a step of removing the metal thin film by milling.

Finally, as a ground conductor forming step, if necessary, the thickness of the dielectric substrate 2 is adjusted to, for example, 40 μm by polishing or etching or the like, and then, as shown in FIG. Is formed by plating or the like.

By the way, in any of the manufacturing methods described with reference to FIGS. 5 and 5, when manufacturing a monolithic integrated circuit, a manufacturing process of a transistor or a passive element is inserted before, after, or between the illustrated processes. Will be.

FIG. 7 shows a microwave circuit according to each embodiment of the present invention, which is a MMIC (Microwave Mono) having a Lange coupler and an interdigital capacitor.
lithic Integrated Circuit
t) is a plan view showing a basic configuration when applied to a balanced upconverter mixer.

This MMIC balanced type up-converter mixer has a ground conductor 1 made of gold having a thickness of 20 μm on the back surface.
A dielectric substrate made of GaAs having a thickness of 40 μm and a rear projection made of GaAs having a thickness of 20 μm
Via hole 11 of 0 μm square, field effect transistor 1
6, Lange coupler 17, interdigital capacitor 18, epitaxial layer and Au / Ge / Ni / Au
A resistor 19 made of ohmic metal, a MIM capacitor 20 using SiN _x as a dielectric film, a ground pad 12 made of gold having a thickness of 2 μm, a bias pad 21, a local signal input pad 22, an intermediate frequency signal input pad 23, It is composed of a transmission signal output pad 24, an input matching stub 25, an output matching stub 26, and a transmission line connecting each component.

Among them, the field effect transistor 16 is
Source electrode 28 and drain electrode 30 made of Au / Ge / Ni / Au ohmic metal formed on active layer 27
And a gate electrode 29 made of Ti / Al, and a via hole 11 connecting the source electrode 28 and the ground conductor 1. The Lange coupler 17 has a length of 450 μm,
A 1/4 wavelength coupling line 4 made of gold having a width of 10 μm and a thickness of 2 μm, a ８ wavelength coupling line 5 made of gold having a length of 225 μm, a width of 10 μm and a thickness of 2 μm, and gold having a width of 30 μm and a thickness of 2 μm. And a lead-out line 6. The interdigital capacitor 16 includes the 波長 wavelength coupling line 4 and the extraction line 6. The interdigital capacitor 18 includes a quarter-wavelength coupling line 4 made of gold having a length of 450 μm, a width of 12.5 μm and a thickness of 2 μm, and a quarter-wavelength coupling line 4 made of gold having a length of 225 μm, a width of 10 μm and a thickness of 2 μm. And a lead line 6 made of gold having a width of 30 μm and a thickness of 2 μm.

In this MMIC balanced type up-converter mixer, the local oscillator signal input from the local oscillator input pad 22 is supplied to the unit mixers connected in parallel with a phase difference of 90 degrees via the Lange coupler 17 on the input side. Is entered.

On the other hand, the intermediate frequency signals are input from the two intermediate frequency signal input pads 23 in opposite phases. The local oscillation signal and the intermediate frequency signal are mixed in each unit mixer, and a transmission signal having a sum or a difference between the two frequencies is generated. The transmission signal is synthesized in-phase by the Lange coupler 17 on the output side, and is extracted from the transmission signal output pad 23 to the outside.

On the other hand, the local signal, which is an unnecessary wave, is synthesized in the opposite phase in the Lange coupler 17 on the output side and is canceled.

As described above, when the Lange coupler 17 is formed on the dielectric substrate 2 having a uniform thickness as in the conventional case, there are restrictions on the thickness h of the dielectric substrate 2 and the coupling line interval s. Therefore, there has been a case where the indirect terminal is smaller than the output to the direct terminal.
An imbalance occurs in the input levels to the two unit mixers, and thus the local signal levels combined in opposite phases at the output Lange coupler 17 are not equal. As a result, the suppression ratio of the local oscillation signal, which is an unnecessary wave, becomes insufficient. In such a case, as in the case here, the portion where the Lange coupler 17 is formed is partially thickened by forming a projection, so that the output level to the direct terminal and the indirect terminal is made uniform, A sufficient suppression ratio of the local oscillation signal can be secured.

When the interdigital capacitor 18 is formed on the dielectric substrate 2 having a uniform thickness as in the prior art, the thickness h of the dielectric substrate 2 and the coupling line interval s are limited. A transmission coefficient of a large size could not be obtained, and the conversion gain of the mixer was degraded.
By increasing the thickness of the portion where is formed by forming the protrusions, a sufficiently large transmission coefficient can be secured, and deterioration of the conversion gain can be suppressed.

FIG. 8 shows transmission coefficients S ₂₁ and S ₂₁ of the Lange coupler type microwave circuit of the first or second embodiment shown in FIG. 1 or 2 and the microwave circuit of the conventional structure.
_It shows a frequency (GHz) characteristic of ₃₁ (dB). However, in this case, the terminal 8c is connected to a non-reflection terminal 50Ω.
Shows the frequency characteristic of a transmission coefficient S ₃₁ of the terminal 8a upon terminating the transmission coefficient S ₂₁ and the coupling terminal 8c to direct the terminal 8b in the resistance. The dielectric substrate 2 has a thickness of 40 μm.
The rear projection 3 has a thickness of 20 μm.
aAs, the 1/4 wavelength coupling line 4 has a length l = 4
50 μm, width w = 5 μm, and coupling line spacing s = 5
μm, and the width of the lead-out lines 6a to 6d is 30 μm.

FIG. 8 shows that the conventional structure has a center frequency of 60.
While there is an imbalance of 1 dB or more between the transmission coefficients S ₂₁ and S ₃₁ at GHz, the structure in which the dielectric substrate 2 of the present invention is partially thickened is improved to almost the same level. I understand.

FIG. 9 shows the transmission coefficient (dB) frequency (GHz) characteristics of the interdigital capacitor type microwave circuit of the third embodiment shown in FIG. 3 and the conventional microwave circuit. . However, here, the dielectric substrate 2 is made of GaAs having a thickness of 40 μm, the rear projection 3 is made of GaAs having a thickness of 20 μm, and the 1/4 wavelength coupling line 4 has a length 1 = 450 μm and a width w = 7. 5μ
m, the coupling line spacing s = 7.5 μm, and the width of the lead-out lines 6a, 6b is 30 μm.

FIG. 9 shows that the conventional structure has a center frequency of 60.
It can be seen that the transmission coefficient is about 0.3 dB at GHz, whereas the transmission coefficient is improved to 0.1 dB or less in the structure in which the dielectric substrate 2 of the present invention is partially thickened.

FIG. 10 shows the frequency (GH) of the transmission coefficient (dB) of the microwave circuit of the Marchand balun type of the fourth embodiment shown in FIG. 4 and the microwave circuit of the conventional structure.
shows the z) characteristics, FIG. (a) is related to the frequency characteristics of the transmission coefficient S ₂₁ directly to terminal 8b from the terminal 8a, and FIG. (b) is the transmission coefficient from the terminal 8a to the coupling terminal 8c S ₃₁ shows a frequency characteristic of No. ₃₁ . The dielectric substrate 2 is made of GaAs having a thickness of 40 μm,
Is made of GaAs having a thickness of 20 μm, the 波長 wavelength coupling line 4 has a length 1 = 450 μm, the 波長 wavelength coupling line 4 has a length 1 = 950 μm, a width w = 30 μm,
Coupling line spacing s = 5 μm, lead-out lines 6a to 6c
Is 30 μm in width.

FIG. 10 shows that the transmission coefficient S ₂₁ and the transmission coefficient S _{31 of} both the conventional structure and the structure in which the dielectric substrate 2 is partially thickened are 0.2 mm at the center frequency of 60 GHz.
It can be seen that it is improved by about 3 dB.

[0059]

As described above, according to the microwave circuit of the present invention, in the basic configuration in which a plurality of coupling lines formed on a dielectric substrate are electromagnetically coupled to each other, The projections are formed on the surface or both sides of the substrate, and the dielectric substrate in the region where the coupling line is formed is partially thickened, thereby increasing the thickness of the entire dielectric substrate and the coupling line spacing. The coupling between the coupling lines can be strengthened without reducing the size.

[Brief description of the drawings]

FIGS. 1A and 1B show a basic configuration of a Lange coupler type microwave circuit according to a first embodiment of the present invention, wherein FIG. 1A is related to a plan view thereof, and FIG. It relates to a sectional side view at the line.

FIGS. 2A and 2B show a basic configuration of a Lange coupler type microwave circuit according to a second embodiment of the present invention, wherein FIG. 2A is a plan view thereof, and FIG. It relates to a sectional side view at the line.

3A and 3B show a basic configuration of an interdigital capacitor type microwave circuit according to a third embodiment of the present invention, wherein FIG. 3A is a plan view thereof, and FIG. It relates to a cross-sectional side view taken along the line '.

FIG. 4 shows a basic configuration of a Marchand balun type microwave circuit according to a fourth embodiment of the present invention.
(A) is related to the plan view, (b) is A in (a).
It relates to a cross-sectional side view taken along line -A '.

FIGS. 5A and 5B are side cross-sectional views schematically illustrating each step of a manufacturing method for manufacturing the microwave circuit according to the first embodiment shown in FIG. 1; FIG. (B) relates to a surface projection forming step, (c) relates to a line forming step, and (d) relates to a ground conductor forming step.

FIGS. 6A and 6B are side cross-sectional views schematically illustrating steps of another manufacturing method for manufacturing the microwave circuit according to the first embodiment illustrated in FIG. 1; FIG. Related to film deposition and photoresist patterning processes,
(B) relates to a surface projection forming step, (c) relates to a line forming step, and (d) relates to a ground conductor forming step.

FIG. 7 is a plan view showing a basic configuration when the microwave circuit according to each embodiment of the present invention is applied to an MMIC balanced upconverter mixer having a Lange coupler and an interdigital capacitor.

8 shows the frequency characteristics of the transmission coefficient of the microwave circuit of the Lange coupler type according to the first or second embodiment shown in FIG. 1 or 2 and the microwave circuit of the conventional structure.

9 is a graph showing the frequency characteristics of the transmission coefficient of the microwave circuit of the interdigital capacitor type according to the third embodiment shown in FIG. 3 and the microwave circuit of the conventional structure.

10A and 10B show the frequency characteristics of the transmission coefficient of the microwave circuit of the Marchand balun type according to the fourth embodiment shown in FIG. 4 and the microwave circuit of the conventional structure, and FIG.
7 shows the frequency characteristic of the transmission coefficient from one terminal to the direct terminal, and FIG. 7B shows the frequency characteristic of the transmission coefficient from one terminal to the coupling terminal.

11A and 11B show a basic configuration of a conventional Lange coupler type microwave circuit, in which FIG. 11A is related to a plan view, and FIG. 11B is related to a cross-sectional side view taken along line AA ′ in FIG. Things.

12A and 12B show a basic structure of a conventional microwave circuit of an interdigital capacitor type, in which FIG. 12A is related to a plan view, and FIG. 12B is a sectional side view taken along line AA 'in FIG. It is about.

13A and 13B show the basic configuration of a conventional merchant balun type microwave circuit, in which FIG. 13A is related to a plan view, and FIG. 13B is related to a cross-sectional side view taken along line AA ′ of FIG. Things.

FIG. 14 shows the transmission coefficient characteristics of the Lange coupler type microwave circuit shown in FIG.
(A) relates to the dependence of the transmission coefficient on the coupling line spacing, and (b) relates to the dependence of the transmission coefficient on the thickness of the dielectric substrate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ground conductor 2 dielectric substrate 3 backside projection 4 波長 wavelength coupling line 5 ８ wavelength coupling line 6 a to 6 d extraction line 7 bonding wire 8 a to 8 d terminal 9 surface projection 10 wavelength coupling Line 11 Via hole 12 Grounding pad 13 Coupling line 14 Photoresist 15 Insulating film 16 Field effect transistor 17 Lange coupler 18 Interdigital capacitor 19 Resistor 20 MIM capacitor 21 Bias pad 22 Local signal input pad 23 Intermediate frequency signal input Pad 24 Transmission signal output pad 25 Input matching stub 26 Output matching stub 27 Active layer 28 Source electrode 29 Gate electrode 30 Drain electrode

Claims (6)

(57) [Claims] 1. A microwave circuit in which a plurality of coupling lines are formed on a dielectric substrate having a ground conductor on a back surface, and the coupling lines are electromagnetically coupled to each other. A microwave circuit characterized in that a region in which the coupling line is formed is partially thickened by forming protrusions on both surfaces. 2. A microwave circuit having a Lange coupler comprising a plurality of coupling lines, lead lines and bonding wires formed on a dielectric substrate having a ground conductor on a back surface. Alternatively, a microwave circuit characterized in that a region where the coupling line is formed is partially thickened by forming protrusions on both surfaces. 3. A microwave circuit in which a plurality of coupling lines and an interdigital capacitor composed of a lead-out line are formed on a dielectric substrate having a ground conductor on a back surface, wherein the dielectric substrate has a front surface or both surfaces. A region in which the coupling line is formed is partially thickened by forming a protrusion on the microwave circuit. 4. A microwave circuit in which a merchant balun comprising a plurality of coupling lines, lead lines, and ground via holes formed on a dielectric substrate having a ground conductor on a back surface is formed. Surface of body substrate,
Alternatively, a microwave circuit characterized in that a region where the coupling line is formed is partially thickened by forming protrusions on both surfaces. 5. The microwave circuit according to claim 1, wherein the protrusion is formed of the same material as the dielectric substrate. 6. The microwave circuit according to claim 1, wherein the protrusion is formed of an insulating film deposited on a front surface or a back surface of the dielectric substrate. Microwave circuit.