JPH10135703A - Diode switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact diode switch by forming at least one of 1st and 2nd transmission lines set in a layered product in a spiral shape and also at least in two layers. SOLUTION: At least one of 1st and 2nd transmissions lines set in a layered product is formed in a spiral shape and also at least in two layers. The line electrodes 107 and 108 are overlapping each other when the upper and lower layers are viewed in terms of projection at a spiral overlapping part (oblique line part) 121. When another spiral overlapping part is added, the length of the transmission line can be shortened. In this example, a diode switch of 900MHz is used and the overlapping rate is set at 13% against the total length. As a result, a 1/4λ transmission line of about 30mm can be reduced down to about 21mm, that is, the length of the transmission line can be reduced to the 70% length of the 1/4λ line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit, and more particularly to a high-frequency circuit such as a digital cellular phone.
The present invention relates to a diode switch applied to a high-frequency switch circuit for switching a signal transmission path.

[0002]

2. Description of the Related Art For example, as shown in FIG. 6, a switch circuit of a digital cellular phone is used to switch a transmission path between an antenna and a reception circuit and a transmission path between a transmission circuit and an antenna.

Further, this switch circuit is used for switching a transmission path between a reception circuit and a first antenna and a transmission path between a reception circuit and a second antenna in a telephone or the like employing a reception diversity system. Is also used. Similarly, in the case of a base station for a mobile phone adopting the transmission diversity system, the base station is used to switch the transmission path between the transmission circuit and the first antenna and the transmission path between the transmission circuit and the second antenna. Is done.

Further, this switch circuit switches between an internal circuit such as a mobile phone having a terminal for external connection to a vehicle-mounted booster or the like and a path to the terminal, and a plurality of channels such as a base station for a mobile phone. Also used for switching.

Hereinafter, using the switch circuit shown in FIG.
This will be described in detail. This switch circuit includes an antenna AN
T, the transmission circuit TX, and the reception circuit RX. An anode of a first diode D1 is connected to the transmission circuit TX via a first capacitor C1, and the first diode D1
One cathode is connected to the antenna ANT via a third capacitor C3. The antenna ANT is connected to a receiving circuit RX via a series circuit of a third capacitor C3, a second transmission line TL2, and a fourth capacitor C4. Further, the anode of the first diode D1 is grounded via a series circuit of the first transmission line TL1 and the second capacitor C2. Further, a control circuit VC1 is connected between the first transmission line TL1 and the second capacitor C2 via a resistor R1. Also, the second transmission line TL
The anode of the second diode D2 is connected between the second and fourth capacitors C4, and the cathode of the second diode D2 is grounded via the fifth capacitor C5. Further, a control circuit VC2 is connected between the cathode of the second diode D2 and the fifth capacitor C5 via a resistor R2. Here, the control circuit VC1 connected via the resistor R1 and the control circuit VC2 connected via the resistor R2 are circuits for switching the switch circuit.

In the switch circuit shown in FIG. 7, when the transmission circuit TX and the antenna ANT are connected, a positive voltage is supplied from the control circuit VC1 to the control circuit VC2.
From 0 is applied. The positive voltage supplied from the control circuit VC1 is cut off the DC component by the first to fifth capacitors, and the first diode D1
And a first diode D1 and a second diode D2.
Is turned on. When the first diode D1 is turned on, the impedance of the transmission path between the transmission circuit TX and the antenna ANT is reduced and the connection is established. On the other hand, the second transmission line TL2 is grounded at a high frequency and resonated by the second diode D2 and the fifth capacitor which are turned on, and the first diode D2 is turned on.
The impedance when the receiving circuit RX side is viewed from the connection point CP between the first cathode, the third capacitor C3, and the second transmission line TL2 becomes very large, and the transmission path between the antenna ANT and the receiving circuit RX is not connected. At this time, the transmission signal from the transmission circuit TX is transmitted to the antenna ANT without leaking to the reception circuit RX.

On the other hand, when the antenna ANT is connected to the receiving circuit RX, a positive or zero voltage is applied from the control circuit VC2, and a zero voltage is applied from the control circuit VC1.
Is turned off. When the first diode D1 is turned off, the transmission circuit TX
The impedance of the transmission path between the antenna and the antenna ANT increases, and the antenna is not connected. In addition, the transmission path between the antenna ANT and the reception circuit RX is connected via the second transmission line TL2 by the second diode D2 that has been turned off. At this time, the reception signal from the antenna ANT is transmitted to the reception circuit RX without leaking to the transmission circuit TX. As described above, the control circuit VC
By controlling the voltage supplied from the control circuit 1 and the control circuit VC2, the switch circuit can be switched to perform transmission and reception.

[0008]

FIG. 8 is an exploded perspective view showing an example of a conventional switch circuit having a circuit as shown in FIG. This switch circuit includes a laminated body,
A first line electrode 31 serving as a first transmission line TL1 and a second line electrode 32 serving as a second transmission line TL2;
The first ground electrode 41 and the second ground electrode 11, a large number of lands, and the top dielectric layer 50 are sandwiched between the first line electrode 31 and the second line electrode 32 via a dielectric. Surface mount components including the first diode D1 are arranged.

This switch circuit includes a first line electrode 3
As the first and second line electrodes 32, two transmission lines each having a length of 1/4 of the wavelength of the transmission signal or the reception signal are required.
04, etc., are formed on the same layer in the laminated body. Although depending on the dielectric constant of the laminated body, the size of the transmission line is about several tens of millimeters, and there is a limit to miniaturization.

As disclosed in Japanese Patent Application Laid-Open No. 7-202503, when the first line electrode and the second line electrode are formed on different layers in the laminated body, the first line electrode and the second line electrode are formed as shown in FIG. The dielectric layer 30 on which the first line electrode 31 is formed and the second line electrode 1 are arranged so that the first line electrode 31 and the second line electrode 12 do not interfere with each other.
It is necessary to provide the dielectric layer 20 on which the shield electrode 21 is formed between the dielectric layers 10 on which the second element 2 is formed, which increases the number of layers of the laminated body as a whole and increases the production cost.

An object of the present invention is to solve the above problems and to provide a small diode switch.

[0012]

The present invention comprises a first circuit,
A switch circuit connected to the second circuit and the third circuit for switching the connection between the first circuit and the third circuit and the connection between the second circuit and the third circuit; A first diode having an anode connected to the first circuit, a cathode connected to the third circuit, and a first diode connected to an anode of the first diode.
, A second transmission line connected between the third circuit and the second circuit, and a second transmission line having an anode connected to the second circuit and a cathode connected to ground.
Wherein the first transmission line and the second transmission line are built in a laminated body, and at least one of the first and second transmission lines formed in the laminated body is a spiral. It is a diode switch having a shape and divided into at least two layers.

According to the present invention, the spiral transmission line formed in at least two layers has a portion in which line electrodes constituting the spiral shape are projectedly overlapped between upper and lower layers. is there.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a transmission line has a spiral shape. There is the following difference between the meander shape and the spiral shape of the transmission line. First, in the case of a meandering shape, the directions of currents of adjacent transmission lines are opposite as shown in the schematic diagram of FIG. For this reason,
The magnetic field between adjacent transmission lines weakens, and the transmission line
It looks as if it is shorter. Further, if the length of the transmission line is to be increased in a narrow space, the distance between the adjacent transmission lines is shortened and the weakening of the magnetic field is increased, so that a certain space is required. On the other hand, in the case of the spiral shape, the directions of the currents of the adjacent transmission lines are the same as shown in the schematic diagram of FIG. For this reason, the magnetic field between adjacent transmission lines reinforces each other, and the transmission lines appear to be longer. In the case of this spiral transmission line, there is no problem even if the distance between adjacent transmission lines is shortened. in this way,
When the transmission line is formed in a spiral shape, the transmission line appears to be elongated, and thus the actual line length can be shortened.

Further, in the case of a meandering shape, 1 /
When there is a space for forming two transmission lines of 4λ, the degree of freedom is high at the start point and the end point of the transmission line, and the design is easy. However, in the era when miniaturization is required, it is not possible to secure sufficient space.For example, a sufficient space must be provided between the transmission line on the transmission side and the transmission line on the reception side to prevent interference. It must be opened and formed in another layer, which is not suitable for miniaturization. In the case of the spiral shape, there is also a draw-out relationship, and it is necessary to form a through-hole because the transmission line is formed over two or more layers, but for the above reasons, it is suitable for miniaturization.

In the present invention, the transmission line has a spiral shape, but preferably has 1 to 5 turns.
In addition, according to the spiral shape of the present invention, a transmission line of １ ／ λ can be formed with a length of about 90% thereof.

According to the present invention, in a spiral transmission line formed in two or more layers,
It is desirable that the transmission lines are formed so as to overlap. This means that when the two layers are projected, the transmission lines have the same current direction and overlap. By overlapping or approaching the line electrodes with the same direction of current, the magnetic field between the lines is strengthened, and as a result, the transmission line appears to be longer, and in fact, the line length is longer. Can be shortened.

The duplication of the upper and lower transmission lines is as follows.
By partially overlapping, the effect of reducing the line length can be obtained, but it is preferable to overlap by 10% or more of the entire length. According to the present invention, it was confirmed that the line length can be reduced to 60 to 70% of λλ by overlapping by 10% to 30%.

Hereinafter, the present invention will be described in detail with reference to examples. (Embodiment 1) FIG. 1 is a perspective view of an embodiment according to the present invention. This diode switch 600 includes a laminated element body 60.
A semiconductor element 602 containing one or two diodes,
And a chip capacitor 607. FIG. 2 shows a circuit diagram in which this diode switch is used. In FIG. 2, a portion surrounded by a broken line is the diode switch shown in FIG. 1, and other circuit constants may be formed on a circuit board on which the diode switch is mounted.

FIG. 3 shows the internal structure of the laminated body 601. The lower dielectric layer 100 has a first ground electrode 10
1 is formed, and a predetermined lead electrode is formed.

On the dielectric layer 100, several dummy layers are arranged, and two dielectric layers 1 constituting a transmission line are formed.
02 and 103 are stacked. The transmission line L1 in the circuit diagram of FIG. 2 is configured by connecting a line electrode 104 of the dielectric layer 103 and a line electrode 105 of the dielectric layer 102. The connection between the two line electrodes is performed via a through-hole electrode 106. Then, a lead electrode facing the side surface of each dielectric layer is formed.

The transmission line L2 in the circuit diagram of FIG.
Are the line electrode 107 of the dielectric layer 103 and the dielectric layer 10
It is configured by connecting two line electrodes 108. This 2
The connection of the two line electrodes is performed via the through-hole electrode 109. Then, a lead electrode facing the side surface of each dielectric layer is formed.

Then, a dielectric layer 110 on which a second ground electrode 111 is formed is laminated via several dummy layers.

On the upper surface of the uppermost dielectric layer 112, a pattern electrode is formed. This pattern electrode includes a first ground electrode 101 and a second ground electrode 11.
1 and pattern electrodes 113, 114, 115 connected to
A pattern electrode 116 connected to the line electrode 104 forming the first transmission line L1, a pattern electrode 117 connected to the line electrode 105 also forming the first transmission line L1, and a second transmission line It has a pattern electrode 118 connected to the line electrode 108 forming L2, a pattern electrode 119 connected to the line electrode 107 also forming the second transmission line L2, and a pattern electrode 120 connected to a diode.

This laminated body is formed into a sheet by a doctor blade using a dielectric material, and an Ag electrode is screen-printed on the sheet to form a pattern electrode, which is laminated, pressed and fired integrally. It was done. And
Terminal electrodes 603, 604, 605, 606 on the side surfaces after firing
Was formed. The terminals of the semiconductor element 602 having two built-in diodes are the pattern electrodes 117, respectively.
118, 119 and 120, and a chip capacitor 607 is connected to the pattern electrodes 116 and 117.

Each of the transmission lines is formed in a spiral shape, and is formed in two layers. FIG. 4 shows a plan view of a pattern diagram of this transmission line. In this embodiment, the line electrodes 107 and 10 constituting the second transmission line
Reference numeral 8 denotes a part 121 (hatched portion) of the spiral shape, which overlaps when the upper and lower layers are projected. By adopting this spiral shape and further providing an overlapping portion, the line length could be shortened. In this embodiment, a diode switch for the 900 MHz band is formed, and the ratio of the overlapping portion is set to 13 lines of the total line length.
%. As a result, about 30 mm in the 1 / 4λ transmission line
Necessary items could be constituted by about 21 mm. According to this,
This is a 70% reduction.

FIG. 5 is a plan view of a pattern diagram of a transmission line according to another embodiment. Each of the transmission lines is formed in a spiral shape, and is formed in two layers. In this embodiment, the line electrodes 10 constituting the second transmission line
The spiral portions 121b (shaded portions) of 7b and 108b overlap when the upper and lower layers are projected. By making this spiral shape and further providing an overlapping part,
The line length could be shortened. In this embodiment, 800 MHz
A band diode switch was formed, and the ratio of the overlapping portion was 25% of the entire line length. As a result, a １ ／ λ transmission line requiring about 33 mm can be constituted by about 22 mm.
According to this, it can be reduced by 67%.

[0028]

According to the present invention, the first transmission line and the second transmission line are respectively formed in the laminated body, and the transmission lines are formed in a spiral shape, and are formed in two or more layers. Thus, a small diode switch can be configured. Further miniaturization can be achieved by overlapping the upper and lower transmission lines. As a result, miniaturization of a mobile phone or a high-frequency circuit to which the switch circuit is mounted is achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment according to the present invention.

FIG. 2 is an equivalent circuit diagram of a switch circuit using the embodiment shown in FIG.

FIG. 3 is an exploded perspective view of the laminated body of the embodiment according to the present invention shown in FIG.

FIG. 4 is a plan view of the transmission line pattern of the embodiment shown in FIG.

FIG. 5 is a plan view of a transmission line pattern according to another embodiment of the present invention.

FIG. 6 is a diagram illustrating functions of a switch circuit.

FIG. 7 is a circuit diagram of a conventional switch circuit.

FIG. 8 is an exploded perspective view showing a conventional technique.

FIG. 9 is an exploded perspective view showing another conventional technique.

FIG. 10 is an explanatory diagram of the present invention.

[Explanation of symbols]

100, 102, 103, 110, 112 Dielectric layer 101 First ground electrode 104, 105, 107, 108 Line electrode 106, 109 Through hole electrode 111 Second ground electrode 113, 114, 115, 116, 117, 118 , 1
19, 120 Pattern electrode 121 Overlapping portion 104b, 105b, 107b, 108b Line electrode 121b Overlapping portion 600 Diode switch 601 Stacked element 602 Semiconductor element 603, 604, 605, 606 Terminal electrode 607 Chip capacitor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/46 H05K 3/46 Q

Claims (2)

[Claims] A first circuit connected to a first circuit, a second circuit, and a third circuit; a connection between the first circuit and the third circuit; and a connection between the second circuit and the third circuit. A first diode having an anode connected to the first circuit, a cathode connected to the third circuit, and a first diode connected to an anode of the first diode. A first transmission line, a second transmission line connected between the third circuit and the second circuit,
And a second diode having an anode connected to the second circuit and a cathode connected to the ground, wherein the first transmission line and the second transmission line are built in a laminated body, and At least one of the first and second transmission lines formed in the element body has a spiral shape,
A diode switch characterized by being divided into at least two layers. 2. A transmission line having a spiral shape formed in at least two layers, wherein a line electrode forming a spiral shape is overlapped between upper and lower layers as viewed in projection. Diode switch.