JP2002064310A - Microwave/millimeter wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave/millimeter wave device capable of sufficiently compensating inductance, that a bonding wire has, in a small chip area. SOLUTION: By performing impedance matching by providing a serial transmission line 14 and a stab line 14b in one terminal part, the deterioration of reflection characteristics/transmission characteristics is prevented. Namely, when a characteristic impedance Za of the serial transmission line 14a is 50 Ω, a line length La is 500 μm, a characteristics impedance Zb of the open stub line 14b is 80 Ω and a line length Lb is 610 μm, in a frequency 60 GHz, a gap between an input/output terminal 14 and an input/output terminal 17 matches 50 Ω.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave / millimeter wave device, and more particularly to a microwave / millimeter wave device in which terminals of a high-frequency circuit are connected by a bonding wire or the like.

[0002]

2. Description of the Related Art Conventionally, connection between terminals of a high-frequency circuit formed on a dielectric substrate has been performed by wire bonding in a form as shown in FIG. In FIG. 9, the MIC (Mi) is formed on the first dielectric substrate 62 on which the high-frequency circuit is formed.
CroweIntegrated Circuit
t) or MMIC (MonoliticMicrow)
A second dielectric substrate 68 on which an integrated circuit (ave Integrated Circuit) is formed is mounted, and a terminal 64 composed of a microstrip line provided on the first dielectric substrate 62 and a second dielectric substrate 68 are formed on the second dielectric substrate 68. The terminals 67 made of microstrip lines are connected by bonding wires 66. The signal lines are connected by bonding wires 66, and the ground conductors 60a and 60b are connected by via holes 63.

However, in connection using a bonding wire, the impedance due to the inductance of the bonding wire increases as the frequency increases. Therefore, at high frequencies such as microwaves and millimeter waves, the impedance mismatch increases, and the reflection characteristics and transmission characteristics deteriorate significantly.

In order to solve the above problems, IEICE Technical Report (EDD-95-59, pp. 11-11).
17) discloses a structure as shown in FIG. In FIG. 10, the microstrip lines 72 and 75 are 50Ω wirings, and the bonding pads 73 and 7 are used to compensate for the impedance of the bonding wire 78.
4 is designed to be wider than 50Ω wiring. This is to increase the size of the bonding pad and to compensate for the inductance of the bonding wire as much as possible due to the parasitic capacitance generated between the bonding pad and the ground conductor.

[0005]

However, in this case, as the frequency becomes higher, the area of the bonding pad must be increased, so that the chip area increases and the chip cost increases.

[0006] Further, since the compensation range is small only by the capacity of the bonding pad, the millimeter wave band (20 GHz to 30 GHz) is used.
At a high frequency such as 0 GHz, sufficient compensation could not be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a microwave / millimeter wave device capable of sufficiently compensating for the inductance of a bonding wire with a small chip area.

[0008]

According to the present invention, there is provided a microwave / millimeter wave device comprising a first terminal formed of a transmission line formed on a first substrate and a first terminal formed of a transmission line formed on a second substrate. The two terminals are electrically connected, and a serial transmission line and a stub line are provided in at least one of the terminal portions.

As the substrate, a dielectric substrate can be used. Specifically, a GaAs substrate, a Si substrate, a high resistance S
A semiconductor substrate such as an i-substrate or an insulating substrate such as a PPO substrate, an alumina ceramic substrate, or a glass ceramic substrate can be used.

As a method of electrically connecting the terminals,
Examples include wire bonding or connection using via holes.

By providing a series transmission line and a stub line on at least one of the terminals electrically connected by a bonding wire or the like, impedance of a connection component such as a bonding wire can be compensated.
As a result, wire bonding can be used even at a high frequency such as a millimeter wave band, high-frequency connection between terminals can be easily performed, and mass productivity is excellent.

Further, in the microwave / millimeter wave device of the present invention, the second substrate is made of a semiconductor, the second substrate is stacked on the first substrate, and the second substrate is connected in series on the first substrate. A transmission line and a stub line are provided, and MIC or MMIC is formed on the second substrate.

Since the size of the second substrate on which the MIC or the MMIC is formed, ie, the size of the semiconductor substrate, can be reduced, it is advantageous for improving the yield and reducing the cost, and excellent in mass productivity. In addition, the substrate on which the MIC or the MMIC is formed is often formed by stacking a plurality of dielectric substrates. When the second substrate is thick as described above, the length of the bonding wire increases according to the thickness, Even if the inductance of the bonding wire is large, the present invention can compensate because the compensation range is wide.

Further, the microwave / millimeter wave device of the present invention includes a series transmission line and a stub line at the first terminal, and the first terminal and the second terminal each have a characteristic impedance Z0. In addition, the impedance when the second substrate is viewed from the stub line connection portion is close to Z0 due to the presence of the series transmission line or the stub line.

The impedance of the connection component is compensated by matching or approaching the impedance of the second substrate from the stub line connection to Z0 or approaching Z0.

Further, the microwave / millimeter wave device of the present invention has a series transmission line and a stub line at the first terminal, and the first terminal and the second terminal have characteristic impedances Z01 and Z02, respectively. And the presence of the series transmission line and the stub line,
The impedance when the first substrate is viewed from the second terminal is closer to Z02, and the impedance when the first substrate is viewed from the second terminal is closer to Z02.

Further, in the microwave / millimeter wave device of the present invention, the first terminal is formed by a microstrip line or a coplanar line, and the second terminal is formed by a microstrip line or a coplanar line. Features.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments will be described more specifically with reference to the drawings.

(Embodiment 1) FIG. 1 is a plan view and a side view showing a first embodiment of the present invention.

First dielectric substrate 1 made of a printed circuit board having a relative dielectric constant of 8.9 and a thickness of 150 μm on which MIC is formed.
2 having a thickness of 150 on which an MMIC (not shown) is formed.
A second dielectric substrate 18 of μm GaAs is provided. On the second dielectric substrate 18, an input / output terminal 17 formed of a microstrip line is formed, and has a characteristic impedance Z0 = 50Ω. First dielectric substrate 1
2, an input / output terminal 14 formed of a microstrip line having a characteristic impedance Z0 = 50Ω is formed, and further formed of a microstrip line.
A serial transmission line 14a having a length La and an open stub line 14b having a length Lb are formed.

The input / output terminal 17 is connected to the end of the serial transmission line 14a by a bonding wire 16, and further connected to the input / output terminal 14 via the serial transmission line 14a. Here, the input / output terminals 14 are drawn out of the MIC formed on the printed circuit board 12, and the input / output terminals 17 are drawn out of the MMIC formed on the GaAs substrate 18.

The ground plane 10a of the microstrip line on the GaAs substrate 18 is on the back surface of the GaAs substrate 18, and the ground conductors of the GaAs substrate 18 and the printed circuit board 12 are connected via via holes 13. The via hole 13 of the printed circuit board 12 usually requires only a small grounding inductance, so that excellent grounding at high frequencies is possible.

Hereinafter, the reason why the impedance of the bonding wire is compensated for using the equivalent circuit shown in FIG. 2A showing the form of FIG. 1 will be described.

The equivalent circuit shown in FIG. 2A has an input / output terminal 84 having a characteristic impedance Z0 on a second dielectric substrate.
Is connected to the serial transmission line 82 having a characteristic impedance Za and having a length La provided at a bonding wire connection portion on the first dielectric substrate. In this embodiment, an open stub line 86 having a length Lb having a characteristic impedance Zb is connected, and then connected to an input / output terminal 81 having a characteristic impedance Z0.

In FIG. 2A, the impedance seen to the right from 111-111 'is Z0, and when normalized by the impedance Z0, it corresponds to the center A of the Smith chart shown in FIG. 2B. I do. By connecting the inductance 83 of the bonding wire, 2
The impedance looking right from 22-222 'is Z1 and moves to point B on the Smith chart. Therefore, when the input / output terminals provided on the first dielectric substrate and the input / output terminals provided on the second dielectric substrate are directly connected by bonding wires, impedance mismatch occurs.

In the present invention, next, by providing a series transmission line having an appropriate characteristic impedance Za and a length La, the impedance seen rightward from 333-333 'is Z2, and the point C on the Smith chart is set. Move up to Next, by providing an open stub line having appropriate characteristic impedance Zb and length Lb, 444
The impedance seen to the right from -444 'can be Z0, and it can be moved from point C to center A on the Smith chart.

That is, by providing the series transmission line and the stub line having appropriate characteristic impedance and line length as described above, the impedance between the terminals can be matched to Z0, and the inductance of the bonding wire can be compensated. .

In this embodiment, since the inductance of the bonding wire is about 0.2 nH, for example, the characteristic impedance Za of the series transmission line 14a is set to 50Ω, the line length La is set to 500 μm, and the characteristic of the open stub line 14b is set. Impedance Zb is 80Ω,
By setting the line length Lb to 610 μm, the frequency 60
At GHz, the distance between the input / output terminal 14 and the input / output terminal 17 was matched to 50Ω. In the present embodiment, the values are set to the above values. In short, the combination may be such that the impedance seen from the connection portion of the stub line 14b to the GaAs substrate side is close to 50Ω, and as a result, the connection portion of the stub line 14b The magnitude of the reflection coefficient at should be 0.3 or less.

In the present embodiment, the first terminal and the second terminal have the same characteristic impedance Z0, but they may be different. When the first terminal and the second terminal have characteristic impedances Z01 and Z02, respectively, the impedance when the second substrate is viewed from the stub line connection portion is Z01, and the second impedance is Z2 because of the presence of the series transmission line and the stub line. The impedance when the first substrate is viewed from the terminal
, The inductance of the bonding wire can be compensated.

In this embodiment, the open stub line is used as the stub line. However, even when a short stub line is used as the stub line, the inductance of the bonding wire is compensated as shown in FIG. Is possible.

In FIG. 3A, the impedance seen to the right from 111-111 'is Z0, and when normalized by the impedance Z0, corresponds to the center A of the Smith chart shown in FIG. 3B. I do. By connecting the inductance 93 of the bonding wire, 2
The impedance looking right from 22-222 'is Z1 and moves to point B on the Smith chart. next,
By providing a series transmission line having an appropriate characteristic impedance Za and a length La, the impedance seen to the right from 333-333 'is Z2, and the impedance is moved to the point C on the Smith chart. Next, by providing a short stub line having an appropriate characteristic impedance Zb and a length Lb, the impedance seen to the right from 444-444 'can be Z0.
It is possible to move from the point to the center A.

Also, compensation can be performed similarly by using a short stub line short-circuited at high frequency by providing a capacitive element such as an MIM capacitor at the tip instead of the open stub line.

The length of the serial transmission line 14a is La =
Although it is set to 500 μm, it may be set to La + n × λg1 / 2 (n is an integer, λg1 is a wavelength of a signal propagating through the serial transmission line 14 a), and the length of the stub line 14 b is L.
Although b = 610 μm, it may be Lb + n × λg2 / 2 (n is an integer, and λg2 is the wavelength of a signal propagating through the stub line 14b).

In addition, for the case of using a plurality of bonding wires, by appropriately selecting the characteristic impedance Za and the line length La of the series transmission line 14a and the characteristic impedance Zb and the line length Lb of the stub line 14b, Compensation can be made. In this case, the inductance of the bonding wire is reduced, and the compensation frequency range can be widened.

In this manner, the distance between the input / output terminal 17 of the GaAs substrate 18 and the input / output terminal 14 on the printed circuit board 12 is matched to 50Ω, and the impedance of the bonding wire is compensated. As shown in FIG. 4, the reflection characteristics and the transmission characteristics between the input / output terminals 14 were improved as compared with the case where the series transmission line 14a and the open stub line 14b were not provided. FIG. 4A shows the reflection characteristics S11 and the transmission characteristics S21 when the series transmission line 14a and the open stub line 14b are not provided, and FIG. 4B shows the case when the series transmission line 14a and the open stub line 14b are provided. The graph shows the reflection characteristic S11 and the transmission characteristic S21, and the reflection loss at a frequency of 60 GHz is greatly improved from 9.5 dB to 20 dB or more.

In this embodiment, the reflection loss is improved to 20 dB or more. However, if it is 10 dB or more, there is no practical problem, and more preferably 15 dB or more. In particular, when connection by wire bonding is applied, it is usually difficult to reduce the reflection loss to 10 dB or more.
By using the method of the present invention, it is possible to easily achieve 20 dB or more, and the effect is large.

(Embodiment 2) FIG. 5 is a plan view and a side view showing a second embodiment of the present invention.

Thickness 60 on which MIC or MMIC is formed
An input / output terminal 27 composed of a coplanar line having a characteristic impedance of 50Ω provided on a dielectric substrate 28 made of 0 μm GaAs, a relative dielectric constant of 8.9, and a thickness of 150 μm
m serial transmission line 24a composed of a microstrip line formed on a dielectric substrate 22 composed of a m printed circuit board.
Are connected by two bonding wires 26, and then
Open stub line 2 consisting of microstrip line
4b was connected to an input / output terminal 24 composed of a microstrip line having a characteristic impedance of 50Ω.

According to the thickness of the GaAs substrate, the length of the bonding wire becomes longer, and the inductance of the two bonding wires is about 0.2 nH. For example, the characteristic impedance Za of the series transmission line 24a is set to 50 Ω. The line length La is set to 500 μm, and the characteristic impedance Zb of the open stub line 24b is set to 8
By setting 0Ω and the line length Lb to 610 μm, the distance between the input / output terminal 24 and the input / output terminal 27 was matched to 50Ω at a frequency of 60 GHz as in the first embodiment.

Here, the ground conductors of the GaAs substrate 28 and the printed circuit board 22 are connected via bonding wires 23 and via holes 29. The ground may be formed by forming a via hole in the GaAs substrate without using a bonding wire and connecting the via hole.

As in the first embodiment, a short stub line may be used instead of an open stub line, and the length La of the serial transmission line 24a and the length Lb of the stub line 24b are La + n × λg1 / 2, Lb
+ N × λg2 / 2.

When the dielectric substrates are stacked and the terminals on the respective dielectric substrates are connected by bonding wires as in the present embodiment, when the thickness of the upper dielectric substrate is increased, the bonding wires Becomes longer, and the inductance of the bonding wire increases.
The present invention having a wide compensation range is effective. In particular, when a coplanar line is formed on the upper dielectric substrate, the thickness of the substrate does not greatly affect the line characteristics, so that the substrate can be made thicker. The method of compensating for the inductance according to the invention is advantageous because it would be large.

In this way, at the frequency of 60 GHz, the impedance between the input / output terminal 27 of the GaAs substrate 28 and the input / output terminal 24 on the printed circuit board 22 is matched to 50Ω, and the impedance of the bonding wire is compensated.
As compared with the case where the serial transmission line 24a and the open stub line 24b were not provided, the reflection characteristics and the transmission characteristics were improved.

(Embodiment 3) FIG. 6 is a plan view and a side view showing a third embodiment of the present invention.

Thickness 60 on which MIC or MMIC is formed
An input / output terminal 37 composed of a coplanar line having a characteristic impedance of 50Ω provided on a GaAs substrate 38 of 0 μm and a length La having a characteristic impedance Za formed on a printed substrate 32 having a relative dielectric constant of 8.9 and a thickness of 600 μm. Series transmission line 34a composed of a coplanar line
Were connected by a bonding wire 36, and then an open stub line 34b formed of a coplanar line having a length Lb having a characteristic impedance Zb was connected to an input / output terminal 34 formed of a coplanar line having a characteristic impedance of 50Ω.

Since the inductance of the bonding wire was estimated to be 0.2 nH, the characteristic impedance of the series transmission line 34a was changed to Za = 50Ω (the center conductor width was 128
μm, slot width 50 μm), length La = 560 μm, and the characteristic impedance of the stub line 34b is Zb = 5.
0 Ω (center conductor width 128 μm, slot width 50 μm),
By setting the length Lb = 770 μm, the first embodiment
Similarly, at a frequency of 60 GHz, the input / output terminals 34
The impedance as viewed from the input / output terminal 37 side was brought close to 50Ω.

Although the ground conductors of the GaAs substrate 38 and the printed circuit board 32 are connected by the bonding wires 33, they may be connected by using via holes.

As in the first embodiment, a short stub line may be used instead of an open stub line, and the length La of the serial transmission line 34a and the length Lb of the stub line 34b are La + n × λg1 / 2, Lb
+ N × λg2 / 2.

In this way, the impedance between the input / output terminal 37 of the GaAs substrate 38 and the input / output terminal 34 on the printed circuit board 32 is adjusted to 50Ω, and the impedance of the bonding wire is compensated. The reflection characteristics and the transmission characteristics were improved as compared with the case where the line 34b was not provided.

(Embodiment 4) FIG. 7 is a plan view and a side view showing a fourth embodiment of the present invention.

Thickness 15 on which MIC or MMIC is formed
An input / output terminal 47 formed of a microstrip line having a characteristic impedance of 50Ω provided on a GaAs substrate 48 of 0 μm and a characteristic impedance Za formed on a printed circuit board 42 having a relative dielectric constant of 8.9 and a thickness of 600 μm.
A series transmission line 44a composed of a coplanar line having a line length La having a characteristic impedance Zb is connected to the series transmission line 44a, and an open stub line 44b composed of a coplanar line having a characteristic length Zb having a characteristic impedance Zb is connected. Connected to an input / output terminal 44 composed of a coplanar line.

In this embodiment, since the inductance of the bonding wire is about 0.2 nH, the characteristic impedance of the serial transmission line 44a is Za = 50Ω (center conductor width 128 μm, slot width 50 μm), and the line length is La.
= 560 μm, the characteristic impedance of the stub line 44b is Zb = 50Ω (center conductor 128 μm, slot width 50 μm), and the line length is Lb = 770 μm, so that the input / output terminals at a frequency of 60 GHz are similar to the first embodiment. The impedance when the input / output terminal 47 was viewed from 44 was approximated to 50Ω matching.

Further, since the ground conductor of the GaAs substrate 48 and the ground conductor of the printed circuit board 42 are directly connected, the high frequency characteristics are excellent.

As in the first embodiment, a short stub line may be used instead of an open stub line, and the length La of the serial transmission line 44a and the length Lb of the stub line 44b are La + n × λg1 / 2, Lb
+ N × λg2 / 2.

In this manner, the impedance between the input / output terminal 47 of the GaAs substrate 48 and the input / output terminal 44 on the printed circuit board 42 is matched to 50Ω, and the impedance of the bonding wire is compensated. As compared to the case where the line 44b was not provided, the reflection characteristics and the transmission characteristics were improved.

(Embodiment 5) FIG. 8 shows a fifth embodiment of the present invention.

The second embodiment is the same as the second embodiment except that the connection between the input / output terminal 54 and the input / output terminal 57 is made by the via hole 56.

The center conductor of the input / output terminal 57 composed of a coplanar line and the serial transmission line 54a composed of a microstrip line formed on the dielectric substrate 52 are connected by a via hole 56. The stub line 54b was connected and connected to the input / output terminal 54 composed of a microstrip line having a characteristic impedance of 50Ω.

Even in the case where the connection is performed by the via hole, the inductance of the via hole 56 can be compensated by providing the series transmission line 54a and the stub line 54b. As compared with the case where the series transmission line 54a and the open stub line 54b were not provided, the reflection characteristics and the transmission characteristics were improved.

[0060]

According to the present invention, it is possible to compensate for the impedance of the connecting parts for connecting the terminals, and to easily perform the high-frequency connection between the terminals in a small area.

According to the second aspect of the present invention, the MI
Since the size of the second substrate on which C or MMIC is formed can be reduced, it is advantageous in yield and cost reduction, and is excellent in mass productivity.

Further, by using a bonding wire or a via hole as a connection component for connecting the terminal on the first substrate and the terminal on the second substrate, the connection can be easily performed, and the mass productivity is excellent.

According to the fourth or fifth aspect of the present invention, by matching the impedance when the second substrate is viewed from the stub line connection portion, it is possible to compensate for the impedance due to the inductance of the bonding wire as a connection component. it can. Wire bonding can be used even at a high frequency such as a millimeter wave band, and mass productivity is excellent.

Further, by forming the terminals by microstrip lines or coplanar lines, it is possible to easily obtain excellent grounding in terms of high frequency.

[Brief description of the drawings]

FIG. 1 is a plan view and a side view showing a first embodiment of the present invention.

FIG. 2 is an equivalent circuit and a Smith chart illustrating the principle of the present invention.

FIG. 3 is an equivalent circuit and a Smith chart illustrating the principle of the present invention.

FIG. 4 is a diagram showing improvements in reflection characteristics and transmission characteristics according to the first embodiment of the present invention.

FIG. 5 is a plan view and a side view showing a second embodiment of the present invention.

FIG. 6 is a plan view and a side view showing a third embodiment of the present invention.

FIG. 7 is a plan view and a side view showing a fourth embodiment of the present invention.

FIG. 8 is a plan view and a side view showing a fifth embodiment of the present invention.

FIG. 9 is a plan view and a side view showing a connection according to the prior art.

FIG. 10 is a plan view and a side view showing compensation according to the prior art.

[Explanation of symbols]

10a, 60a: ground conductor of the second substrate 10b, 20, 50, 60b: ground conductor of the first substrate 12, 22, 32, 42, 52, 62, 71: first substrate 13, 29, 56, 59, 63, 77 ... Via holes 14, 24, 54, 64, 72 ... Microstrip lines 14a, 24a, 34a, 44a, 54a formed on the first substrate ... Series formed on the first substrate Transmission lines 14b, 24b, 34b, 44b, 54b ... stub lines 16, 23, 26, 33, 36, 46, 53, 66, 7 formed on the first substrate
8 Bonding wires 17, 47, 67, 75 Microstrip lines formed on the second substrate 18, 28, 38, 48, 58, 68, 76 Second substrate 27, 37, 57 Second Coplanar lines formed on the first substrate 34, 44 ... Coplanar lines 73, 74 formed on the first substrate Bonding pads

Continued on the front page (72) Inventor Eiji Suematsu 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5E344 AA01 AA23 AA26 BB02 BB06 BB08 BB14 CC09 CD13 DD08 DD16 EE08

Claims (6)

[Claims] A first terminal formed of a transmission line formed on a first substrate and a second terminal formed of a transmission line formed on a second substrate are electrically connected to each other; A microwave / millimeter wave device characterized in that a series transmission line and a stub line are provided at two terminal portions. 2. The second substrate comprises a semiconductor, the second substrate is laminated on the first substrate, a series transmission line and a stub line are provided on the first substrate, 2. The microwave / millimeter wave device according to claim 1, wherein MIC or MMIC is formed on said substrate. 3. The first terminal and the second terminal,
2. The microwave communication system according to claim 1, wherein the microwaves are electrically connected by bonding wires or via holes.
Millimeter wave device. 4. The first terminal portion includes a series transmission line and a stub line, the first terminal and the second terminal each have a characteristic impedance Z0, and the presence of the series transmission line and the stub line. The second connection from the stub line connection
The microwave / millimeter wave device according to any one of claims 1 to 3, wherein the impedance when the substrate is viewed is brought close to Z0. 5. The first terminal portion includes a series transmission line and a stub line, the first terminal and the second terminal have characteristic impedances Z01 and Z02, respectively, and the presence of the series transmission line and the stub line As a result, the impedance when the second substrate is viewed from the stub line connection portion is Z01,
The microwave / millimeter wave device according to any one of claims 1 to 3, wherein the impedance when the first substrate is viewed from the terminal of (1) is closer to Z02. 6. The device according to claim 1, wherein said first terminal is formed by a microstrip line or a coplanar line, and said second terminal is formed by a microstrip line or a coplanar line. The microwave / millimeter wave device according to 1.