JPH08162853A - Slot line type single balance mixer - Google Patents

Abstract

PURPOSE: To improve the frequency characteristic of a conversion loss of a mixer while keeping shield performance of the mixer circuit and shield performance to an external device. CONSTITUTION: A mixer circuit is formed on a 1st layer 41 and a 4th layer 44 of a 4-layer printed circuit board and GND patterns to shield the mixer circuit are formed on 2nd, 3rd and 4th layers 42, 43, 44, the GND patterns are connected by GND conversion throughholes 52 for GND conversion. In the slot line single balance mixer as above, the 1st GND pattern 21 is formed on the entire face of the 2nd layer 42 and the 2nd 3rd GND patterns 31, 32 where a length (l) from the GND conversion throughhole 52 is regulated to be L<λ/8 (λ is an effective wavelength of a frequency handled by the mixer) are formed respectively on the 3rd and 4th layers 43, 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slot line type single balance mixer for a microwave frequency converter, and more particularly to a slot line type single balance mixer which can improve the frequency characteristic of the conversion loss of the mixer.

[0002]

2. Description of the Related Art A multilayer printed circuit board has an advantage that a circuit to be mounted can be formed by separating each layer and a plane area of the circuit can be reduced. Focusing on such advantages, a slot line type single balance mixer configured on a multilayer printed circuit board is used.

A conventional slot line type single balance mixer constructed on a conventional multilayer printed circuit board will be described below with reference to the drawings. FIG. 6 is a side sectional view showing a slot line type single balance mixer configured on a conventional four-layer printed circuit board. 7A to 7D are plan views showing respective layers of the slot line type single balance mixer.

In these drawings, the conventional slot line type single balance mixer is shown in FIG.
First to fourth layers 14 by superimposing 10, 120 and 130
1, 142, 143, 144 are formed, mixer circuits are provided in the first layer (top layer) 141 and the fourth layer (bottom layer) 144, and the first and second layers 142, 143 are provided with these mixer circuits. The GND pattern for preventing the interference between the layer 141 and the fourth layer 144 is formed.

That is, as shown in FIG. 7A, the first layer 141 has a strip line 1 for inputting a local oscillation source.
11 and a strip line 112 for transmitting and receiving a signal are formed, and as shown in FIGS. 7B to 7D, the second layer 142, the third layer 143, and the fourth layer 144 have a first layer. The first to third GND patterns 121, 131 and 132 are formed respectively. Then, as shown in FIG. 7D, a slot line 133 is formed in the central portion of the third GND pattern 132, and this slot line 133 is used for frequency conversion as shown in FIG. Two diodes 134 and 135 were connected.

Here, in order to secure the shielding properties of the first layer 141 and the fourth layer 144, the first and second GND patterns 121 and 131 are all conductors on both sides of the substrate corresponding to the strip lines 111 and 112. The third GND pattern 13 is provided in order to secure the shielding property to the outside.
2 stripline 111 and stripline 11
Both sides of the board corresponding to 2 were also solid earth. Then, these first to third GND patterns 121, 131,
132 is a side metal (short end surface) 171 formed on the end surface of the four-layer printed circuit board 110, 120, 130.
They were connected to 172 and were at the same potential.

[0007] Further, near the one end of the strip line 111 for inputting the local oscillation source and the slot line 133 and near the other end of the strip line 112 for transmitting and receiving the signal and the other end of the slot line 133, there are through holes for signals respectively. 1
They were connected by 51 and 151. Furthermore, in order to prevent the impedance characteristics of the strip lines 111, 112, etc. from changing, the GND patterns 121, 13 are
1, 132 are connected by a plurality of through holes 152 for GND conversion to perform the GND conversion. Furthermore, these GND conversion through holes 152 divide the four-layer printed circuit boards 110, 120, and 130 into three, forming a local oscillation signal propagation area 161, a mixer area 162, and a transmission / reception signal propagation area 163.

[0008]

However, in the above-mentioned conventional slot line type single balance mixer, as shown in FIGS. 6 and 7C and 7D, the second and third GND patterns 131 and 132 are formed. Since the portion corresponding to the local oscillation signal propagation area 161 and the transmission / reception signal propagation area 163 (outside the through hole 152 for GND conversion) is made of a conductor, the second and third GNDs are used.
There is a problem that the impedance of the patterns 131 and 132 becomes discontinuous and the conversion loss of the mixer at a specific frequency becomes abnormally large.

That is, the second and third GND patterns 1
31, 132 are four-layer printed circuit boards 110, 120, 1
It is connected to the side metals 171 and 172 formed on the end face of 30, and is in an electrically shorted state. Therefore, this second and third GND patterns 131, 13
The local oscillation signal propagation area 161 and the transmission / reception signal propagation area 163 of No. 2 are GND conversion through holes 152.
For, it works as if a short stub is connected.

As a result of experiments conducted by the present inventor, the length l of the local oscillation signal propagation area 161 and the transmission / reception signal propagation area 163 of the second and third GND patterns 131 and 132 is (x / 4) λ. When (x = odd number, λ = effective wavelength of the frequency handled by the mixer), this portion acts as a short stub or an open stub, and the impedance of the GND conversion through hole 152 becomes a size that cannot be ignored, and the second and third GND patterns 131, 13
It was found that the discontinuity of the potential occurs in 2 and the conversion loss of the mixer at a specific frequency becomes abnormally large.

In Japanese Patent Laid-Open No. 3-71703, there is disclosed a method for connecting a high frequency circuit having a microstrip line on the first layer of a multilayer printed circuit board, wherein a part of the GND pattern formed on the inner layer of the multilayer printed circuit board is used. There is proposed a method of connecting a multilayer printed circuit board, which can keep the characteristic impedance constant even if the width of the microstrip line is widened midway to provide a solder land by deleting the solder land.

However, according to the method for connecting a multilayer printed circuit board disclosed in Japanese Patent Laid-Open No. 3-71703, the thickness of the printed circuit board is substantially increased and the characteristic impedance is adjusted by deleting a part of the GND pattern of the inner layer. However, such a technique cannot solve the above problems.

Therefore, as a result of further experiments conducted by the present inventor, the local oscillation signal propagation area 161 and the transmission / reception signal propagation area 1 of the second and third GND patterns 131 and 132.
When the length l of the 63 part is set to l <λ / 8 (λ = effective wavelength handled by the mixer), this part does not act as a stub, and thereby the impedance of the GND conversion through hole becomes small and the mixer It has been found that the frequency characteristics of the conversion loss of are good.

The present invention has been made in view of the above-mentioned problems, and while securing the shieldability of the circuits formed in the uppermost layer and the lowermost layer of the multilayer printed circuit board and the shieldability to the outside, the mixer An object of the present invention is to provide a slot line type single balance mixer which can improve the frequency characteristic of conversion loss.

[0015]

In order to achieve the above object, a slot line type single balance mixer according to claim 1 forms a mixer circuit in the uppermost layer and the lowermost layer of a multilayer printed circuit board, and a plurality of inner layers. Form a GND pattern that shields these mixer circuits on the
A slot line type single balance mixer for connecting a D pattern by a GND conversion through hole to perform a GND conversion, and a first GND pattern formed on substantially the entire surface of one of the plurality of inner layers, and the first GND pattern. A second GND pattern formed in an inner layer different from the pattern, wherein the outer length l from the GND conversion through hole is 1 <λ / 8, where λ = effective wavelength of the frequency handled by the mixer. There is.

According to a second aspect of the present invention, there is provided a slot line type single balance mixer having a multilayer printed circuit board in which a mixer circuit is formed in an uppermost layer and a lowermost layer, and one or a plurality of inner layers and the lowermost layer are shielded by the GND circuit.
In a slot line type single balance mixer for forming a pattern, connecting these GND patterns through through holes for GND conversion, and performing GND conversion, a first line formed on substantially the entire surface of one of the one or a plurality of inner layers. A GND pattern and a second GND pattern formed on the bottom layer and having an outer length l from the GND conversion through hole as l <λ / 8, where λ = effective wavelength of a frequency handled by a mixer. It has a different structure.

According to another aspect of the present invention, in a slot line type single balance mixer, a mixer circuit is formed on the uppermost layer and the lowermost layer of a multilayer printed circuit board, and a GND pattern for shielding these mixer circuits is formed on one or a plurality of inner layers. In a slot line type single balance mixer that performs GND conversion by connecting these GND patterns through GND conversion through holes, the length L from the GND conversion through holes to the board end face of the multilayer printed circuit board is L < λ / 8 or nλ / 2−λ / 8 <L <nλ / 2 + λ /
8 where λ = effective wavelength of the frequency handled by the mixer, n =
It is a natural number, and the entire surface of the one or more inner layers is a GND pattern.

[0018]

According to the slot line type single balance mixer having the above structure, the length outside the GND converting through hole of the second GND pattern formed in the inner layer or the lowermost layer of the multilayer printed circuit board. L
l <λ / 8 (λ = effective wavelength of the frequency handled by the mixer)
As a result, the portion outside the GND conversion through hole of the second GND pattern does not act as an open stub on the GND conversion through hole. As a result, in the vicinity of the handled frequency, the GND
The impedance of the conversion through hole is reduced, and the frequency characteristic of the conversion loss of the mixer is improved.

Further, the first GND pattern of the whole conductor is
Since it is formed in one of the plurality of inner layers, the mixer circuits formed in the uppermost layer and the lowermost layer are reliably shielded.

According to the slot line type single balance mixer of claim 3, the GND of the multilayer printed circuit board is
The length L from the through hole for conversion to the end face of the substrate is L <
By setting λ / 8 or nλ / 2−λ / 8 <L <nλ / 2 + λ / 8, the length l outside the GND conversion through hole of the GND pattern is also 1 <λ / 8 or nλ / 2−.
λ / 8 <l <nλ / 2 + λ / 8, and the portion outside the GND conversion through hole of the GND pattern does not act as a short stub on the GND conversion through hole. As a result, the impedance of the GND conversion through hole becomes small near the frequency to be handled, and the frequency characteristic of the conversion loss of the mixer becomes good.

Further, since the entire inner layer has the GND pattern, the mixer circuits formed in the uppermost layer and the lowermost layer are reliably shielded.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A slot line type single balance mixer according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a slot line type single balance mixer according to this embodiment. FIG. 2 is a side sectional view of the present slot line type single balance mixer. FIGS. 3A to 3D are plan views showing the layers of the present slot line type single balance mixer. FIG. 4 is a circuit diagram of the slot line type single balance mixer.

As shown in FIGS. 1 and 2, the slot line type single balance mixer according to the present embodiment has a mixer circuit and a GND pattern on a four-layer printed circuit board in which three printed circuit boards 10, 20, 30 are superposed. Is formed.

As shown in FIGS. 1 and 3A, a strip line 11 for inputting a local oscillation source and a strip line 12 for transmitting and receiving a signal are formed on a first layer 41 of a four-layer printed circuit board. There is. Further, as shown in FIGS. 3B to 3D, the second layer 42, the third layer 43, and the fourth layer 44 respectively include the first, second, and third GND patterns 21,
31 and 32 are formed. In addition, these first to third G
The ND patterns 21, 31, and 32 are characteristic parts of the present invention, and will be described in detail later. Fourth layer 44 (third GND pattern 3
At the center of 2), a slot line 33 corresponding to one end sides of the strip lines 11 and 13 is formed.

As shown in FIGS. 1 and 2, the strip line 11 for inputting the local oscillation source and the vicinity of one end of the slot line 33, and the strip line 12 for transmitting and receiving signals.
And the other end of the slot line 33 are connected by signal through holes 51, 51, respectively. Two diodes 34 and 35 for frequency conversion are connected to the slot line 33.

Further, in order to prevent the impedance characteristics of the strip lines 11, 12 and the like from changing, first to
The third GND patterns 21, 31, 32 are used as a plurality of GNDs.
The connection is made through the conversion through hole 52 to perform the GND conversion.

Further, the slot line type single balance mixer is divided into three by the GND conversion through hole 52, and the strip line 11 side for local oscillation source input is the local oscillation signal propagation area 61 and the center is the mixer. Area 62, stripline 1 for transmitting and receiving signals
The transmission / reception signal propagation area 63 is on the second side.

Next, the first to third GND patterns 21, 3
1, 32 will be described with reference to FIGS. As shown in FIG. 3B, the first GND pattern 2
No. 1 has a so-called solid earth structure in which all portions corresponding to the local oscillation signal propagation area 61 and the transmission / reception signal propagation area 63 are conductors.

As shown in FIG. 3C, the second GND pattern 31 is used for the substrate periphery and the GND conversion except the portions corresponding to the local oscillation signal propagation area 61, the mixer area 62 and the transmission / reception signal propagation area 63. The portion corresponding to the through hole 52 is a conductor. Figure 3 (d)
As shown in (3), the third GND pattern 32 has a structure in which the center of the substrate and the peripheral edges of both sides of the substrate are conductors, excluding the portions corresponding to the local oscillation signal propagation area 61 and the transmission / reception signal propagation area 63.

The second and third GND patterns 31 and 32 have a length l outside the GND converting through hole 52 as l <λ / 8. Here, λ is the effective wavelength of the frequency handled by this mixer. The length l
For example, if the frequency handled by the mixer is 6 GHz and the relative dielectric constant of the multilayer printed circuit board is 4, the effective wavelength λ is about 25 mm, and the length l is about 3 mm.

Further, the first to third GND patterns 21,
31 and 32 are side metals (short end faces) 71 and 72 formed on the end faces of the four-layer printed circuit boards 10, 20, and 30.
Are connected to each other and have the same potential.

According to the slot line type single balance mixer of this embodiment having the above structure, the fourth layer 4
Second and third GND patterns 31, 32 formed in FIG.
The portions corresponding to the local oscillation signal propagation area 61 and the transmission / reception signal propagation area 63 are deleted, and the outer length l from the GND conversion through hole 52 of the second and third GND patterns 31 and 32 is changed to l < By setting λ / 8, these second and third GND patterns 31, 32 are
The GND conversion through hole 52 can be prevented from acting as an open stub, and the impedance of the GND conversion through hole 52 can be made sufficiently small.

As a result, the first layer 4 of the four-layer printed circuit board is obtained.
It is possible to improve the frequency characteristic of the conversion loss of the mixer while ensuring the shieldability of the circuit formed in the first and fourth layers 44 and the shieldability to the outside.

The slot line type single balance mixer of the present invention is not limited to the above embodiment. In the above embodiment, the second and third GND patterns 3
Part of 1, 32 is deleted, and these second and third GND
The length l of the patterns 31 and 32 outside the GND conversion through hole 52 is set to l <λ / 8, but this is not particularly limited, and as shown in FIG. 5, the four-layer printed circuit board 10 is used. , 20 and 30 through holes for GND conversion 5
The outer length L from 2 is L <λ / 8 or nλ / 2−λ /
8 <L <nλ / 2 + λ / 8, and the second and third GND patterns 31 and 32 may be solid earth.

With such a configuration, the second and third G
The portions of the ND patterns 31 and 32 outside the GND conversion through hole 52 do not function as short stubs,
Similar to the above embodiment, the frequency characteristic of the conversion loss of the mixer can be improved.

Further, in the above embodiment, the case where the slot line type single balance mixer of the present invention is applied to the four-layer printed circuit board has been described, but the present invention can be applied to a multilayer printed circuit board having three or more layers. is there.

[0037]

As described above, according to the slot line type single balance mixer of the present invention, an extra G
By deleting a part of the ND pattern, the GND pattern does not act as a stub for the GND conversion through hole, and the impedance of the GND conversion through hole can be reduced. As a result, the frequency characteristics of the conversion loss of the mixer can be improved while ensuring the shieldability of the circuits formed in the uppermost layer and the lowermost layer of the multilayer printed circuit board and the shieldability to the outside.

[Brief description of drawings]

FIG. 1 is a perspective view showing a slot line type single balance mixer according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the present slot line type single balance mixer.

3 (a) to 3 (d) are plan views showing respective layers of the present slot line type single balance mixer.

FIG. 4 is a circuit diagram showing the present slot line type single balance mixer.

FIG. 5 is a side view showing another embodiment of the slot line type single balance mixer of the present invention.

FIG. 6 is a side sectional view of a slot line type single balance mixer according to a conventional example.

7A to 7D are plan views showing respective layers of a conventional slot line type single balance mixer.

[Explanation of symbols]

 10, 20, 30 Printed circuit board 11 Local oscillation source input strip line 12 Signal transmission / reception strip line 21 First GND pattern 31 Second GND pattern 32 Third GND pattern 33 Slot line 35, 35 Diode 41 First layer 42 Second Layer 43 Third layer 44 Fourth layer 51 Signal through hole 52 GND conversion through hole 61 Local oscillation signal propagation area 62 Mixer area 63 Transmission / reception signal propagation area

Claims (3)

[Claims] 1. A mixer circuit is formed on the uppermost layer and the lowermost layer of a multilayer printed circuit board, and GND patterns for shielding these mixer circuits are formed on a plurality of inner layers, and these GND patterns are connected by GND conversion through holes. In a slot line type single balance mixer for performing a GND conversion, a first GND pattern formed on substantially the entire surface of one of the plurality of inner layers, and an inner layer different from the first GND pattern,
A slot line type single balance mixer, characterized in that the length l outside the through hole for ND conversion is l <λ / 8, where λ = the second GND pattern with the effective wavelength of the frequency handled by the mixer. . 2. A mixer circuit is formed on an uppermost layer and a lowermost layer of a multilayer printed circuit board, and GND patterns for shielding these mixer circuits are formed on one or a plurality of inner layers and the lowermost layer, and these GND patterns are converted into a GND pattern. In a slot line type single balance mixer which is connected by a through hole for GND and performs GND conversion, a first GND pattern formed on almost the entire surface of one inner layer of the one or a plurality of inner layers, and formed on the bottom layer, A slot line type single balance, characterized in that the length l outside the through hole for GND conversion is 1 <λ / 8, where λ = the second GND pattern in which the effective wavelength of the frequency handled by the mixer is set. Mixer. 3. A mixer circuit is formed on an uppermost layer and a lowermost layer of a multilayer printed circuit board, and a GND pattern for shielding these mixer circuits is formed on one or a plurality of inner layers,
In a slot line type single balance mixer for connecting these GND patterns through GND conversion through holes to perform GND conversion, a length L from the GND conversion through holes to a board end face of the multilayer printed circuit board is set to L <λ. / 8 or nλ / 2−λ / 8 <L <nλ / 2 + λ /
8 where λ = effective wavelength of the frequency handled by the mixer, n =
A slot line type single balance mixer, characterized in that it is a natural number and the entire surface of the one or more inner layers is a GND pattern.