JP2006081212A - Diode switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized diode switch applied for a high-frequency switch circuit, for switching signal transmission channel in a high-frequency circuit, such as a digital mobile telephone. <P>SOLUTION: The diode switch for connecting to a first circuit, a second circuit, and a third circuit and for switching between the connection to the first circuit, and the connection between the third circuit and a connection to the second circuit and the third circuit comprises a first diode, connected between the first circuit and the third circuit, a transmission line connected between the third circuit and the second circuit, and a second diode connected to the second circuit side of the transmission line and connected to the ground via a condenser. The transmission line is formed by a line electrode incorporated in a laminated element body and formed in at least two layers, and the line electrode is connected via a through hole electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a switch circuit, and more particularly to a diode switch applied to a high-frequency switch circuit for switching a signal transmission path in a high-frequency circuit such as a digital cellular phone.

  For example, a switch circuit such as a digital cellular phone is used to switch the transmission path between the antenna and the reception circuit and the transmission path between the transmission circuit and the antenna, as shown in FIG.

  This switch circuit is also used to switch the transmission path between the reception circuit and the first antenna and the transmission path between the reception circuit and the second antenna in a telephone or the like adopting the reception diversity system. The Similarly, in the case of a mobile phone base station adopting the transmission diversity system, it 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.

  In addition, this switch circuit is used for switching between internal circuits such as a mobile phone having a terminal for external connection with an in-vehicle booster or the like and a route to the above terminal, and switching of a plurality of channels such as a base station for a mobile phone. Is also used.

  A detailed description will be given below using the switch circuit shown in FIG. This switch circuit is connected to the antenna ANT, the transmission circuit TX, and the reception circuit RX. The transmission circuit TX is connected to the anode of the first diode D1 via the first capacitor C1, and is connected to the antenna ANT via the third capacitor C3 to the cathode of the first diode D1. The antenna ANT is connected to the receiving circuit RX via a series circuit of a third capacitor C3, a second transmission line TL2, and a fourth capacitor C4. 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. The anode of the second diode D2 is connected between the second transmission line TL2 and the fourth capacitor 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 applied from the control circuit VC1 and a voltage of 0 is applied from the control circuit VC2. The positive voltage supplied from the control circuit VC1 is cut in the DC component by the first to fifth capacitors, and is applied only to the circuit including the first diode D1 and the second diode D2. The first diode D1 and the second diode D2 are 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 lowered and connected. On the other hand, the second transmission line TL2 is resonated by being grounded at a high frequency by the second diode D2 and the fifth capacitor which are turned on, and the cathode of the first diode D1 and the third capacitor C3 are resonated. The impedance when the receiving circuit RX side is viewed from the connection point between the antenna ANT 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 and the receiving circuit RX are connected, a positive or 0 voltage is applied from the control circuit VC2 and a 0 voltage is applied from the control circuit VC1, so that the first diode D1 and the second diode D2 are applied. Is turned off. When the first diode D1 is turned off, the impedance of the transmission path between the transmission circuit TX and the antenna ANT is increased, and the first diode D1 is not connected. Further, the transmission path between the antenna ANT and the receiving circuit RX is connected via the second transmission line TL2 by the second diode D2 in the OFF state. 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, by controlling the voltages supplied from the control circuit VC1 and the control circuit VC2, the switch circuit can be switched to perform transmission / reception.

  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, and includes a first line electrode 31 to be a first transmission line TL1, a second line electrode 32 to be a second transmission line TL2, and a first line via a dielectric. The first ground electrode 41 and the second ground electrode 11 as well as the many lands and the uppermost dielectric layer 50 are sandwiched between the electrode 31 and the second line electrode 32, and the first diode D1 is included. Surface mount components are placed.

  This switch circuit requires two transmission lines having a length of ¼ of the wavelength of a transmission signal or a reception signal as the first line electrode 31 and the second line electrode 32. As disclosed in 7-202502, 7-202504 and the like, they are respectively formed on the same layer in the laminated body. Although depending on the dielectric constant of the laminated body, the transmission line has a size of about several tens of millimeters, so that there is a limit to downsizing.

  Further, as disclosed in JP-A-7-202503 and the like, when the first line electrode and the second line electrode are formed on different layers in the laminated body, the first line electrode as shown in FIG. The shield electrode 21 is provided between the dielectric layer 30 on which the first line electrode 31 is formed and the dielectric layer 10 on which the second line electrode 12 is formed so that the 31 and the second line electrode 12 do not interfere with each other. It is necessary to provide the dielectric layer 20 formed with, and as a whole, the number of layers of the laminated body is increased and the production cost is increased.

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

The present invention is connected to the first circuit, the second circuit, and the third circuit, the connection between the first circuit and the third circuit, and the second circuit and the third circuit. A diode switch for switching the connection between the first circuit and the third circuit, and between the third circuit and the second circuit. And a second diode connected to the second circuit side of the transmission line and grounded via a capacitor. The transmission line is incorporated in the multilayer body and is at least 2 The diode switch is formed of a line electrode formed in a layer, and the line electrode is connected through a through-hole electrode.
In the present invention, the line electrodes formed in different layers are preferably arranged in the multilayer body so that the directions of currents are the same. Moreover, it is preferable that adjacent line electrodes have a portion that overlaps when viewed in projection. The transmission line may be shorter than a quarter wavelength of a signal passing through the transmission line.

  In the diode switch of the present invention, the cathode of the first diode is connected to the first circuit side, the anode is connected to the third circuit side, and the cathode of the second diode is connected to the transmission line. Connected to the second circuit side, the anode is grounded via a capacitor, a control circuit is connected between the second diode and the capacitor, and the first diode and the second diode are connected. A diode is connected in series via the transmission line, the first diode and the second diode are turned on by a voltage applied from the control circuit, and the first circuit and the third diode are turned on. It is also characterized by connecting to a circuit.

  According to the present invention, since the line length of the transmission line of the diode switch can be shortened, a small diode switch can be configured. Thereby, miniaturization of the mobile phone or the high frequency circuit to which the switch circuit is attached is achieved. Further, by reversing the diode connection direction compared to the conventional one, a diode switch with improved insertion loss and isolation characteristics can be obtained.

  FIG. 2 shows an equivalent circuit diagram of a diode switch according to one embodiment of the present invention. This diode switch is connected to the antenna ANT, the transmission circuit TX, and the reception circuit RX. The transmission circuit TX is connected to the cathode of the first diode D1 via the capacitor C1, and the anode of the first diode D1 is connected to the antenna ANT via the capacitor C3. A receiving circuit RX is connected to the antenna ANT through a series circuit of a capacitor C3, a second transmission line L2, and a capacitor C4.

  The first transmission line L1 and the capacitor C6 are connected to the cathode of the first diode D1, and they are grounded via the capacitor C2. Further, a control circuit VC1 is connected between the first transmission line L1 and the capacitor C2 via a resistor R1. The cathode of the second diode D2 is connected between the second transmission line L2 and the capacitor C4, and the anode of the second diode D2 is grounded via the capacitor C5. Further, a control circuit VC2 is connected between the anode of the second diode D2 and the 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 of this embodiment, when the transmission circuit TX and the antenna ANT are connected, a positive voltage is applied from the control circuit VC2 and a voltage of 0 is applied from the control circuit VC1. The positive voltage supplied from the control circuit VC2 is cut in the DC component by the first to fifth capacitors, and is applied only to the circuit including the first diode D1 and the second diode D2. The first diode D1 and the second diode D2 are 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 lowered and connected. On the other hand, the second transmission line TL2 is resonated by being grounded at a high frequency by the second diode D2 and the fifth capacitor which are turned on, and the anode of the first diode D1 and the third capacitor C3 are resonated. The impedance when the receiving circuit RX side is viewed from the connection point between the antenna ANT 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 and the receiving circuit RX are connected, a positive or 0 voltage is applied from the control circuit VC1 and a 0 voltage is applied from the control circuit VC2, so that the first diode D1 and the second diode D2 are connected. Is turned off. When the first diode D1 is turned off, the impedance of the transmission path between the transmission circuit TX and the antenna ANT is increased, and the first diode D1 is not connected. Further, the transmission path between the antenna ANT and the receiving circuit RX is connected via the second transmission line TL2 by the second diode D2 in the OFF state. 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, by controlling the voltages supplied from the control circuit VC1 and the control circuit VC2, the switch circuit can be switched to perform transmission / reception.

  In the present invention, the connection direction of the diode is reversed compared to the conventional example. This improved insertion loss and isolation characteristics.

  In the present invention, the transmission line has a spiral shape. The transmission line has the following differences between the meander shape and the spiral shape. First, in the case of a meander shape, as shown in the schematic diagram in FIG. For this reason, the magnetic fields between adjacent transmission lines are weakened, and the transmission lines appear as if they are shortened. In addition, if an attempt is made to increase the length of a transmission line 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 a spiral shape, the current directions of adjacent transmission lines are the same as shown in the schematic diagram of FIG. For this reason, the magnetic fields between adjacent transmission lines are strengthened, 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. As described above, when the transmission line is formed in a spiral shape, the transmission line appears to be long, so that the actual line length can be shortened.

  Further, in the case of the meander shape, when there is a space for forming two 1 / 4λ transmission lines on one layer, the positions of the start point and end point of the transmission line are highly flexible and easy to design. However, in an era when miniaturization is required, sufficient space cannot be secured. For example, there is a sufficient interval between the transmission line on the transmission side and the transmission line on the reception side so that interference does not occur. It is necessary to open it and form it in another layer, which is not suitable for miniaturization. In the case of a spiral shape, there is a relationship of drawing out, and it is necessary to form a through hole in order to form a transmission line over two or more layers. However, for the reasons described above, it is suitable for downsizing.

  In the present invention, a spiral shape is used as the transmission line, but it is preferably 1 to 5 turns. Further, according to the spiral shape of the present invention, it was possible to form a 1 / 4λ transmission line with a length of about 90%.

  In the present invention, it is desirable that the spiral transmission line formed in two or more layers is formed so that the transmission lines overlap between the upper and lower sides. This means that when the two layers are viewed in projection, the current direction of the transmission line is the same and overlaps. By overlapping line electrodes with the same current direction, that is, close to each other, the magnetic field between the lines is strengthened. As a result, the transmission line appears to be long, and in practice the line length Can be shortened.

  The overlapping of the upper and lower transmission lines can achieve the effect of reducing the line length by overlapping even a part, but it is preferable to overlap 10% or more of the total length. According to the present invention, it was confirmed that the line length can be reduced to 60 to 70% of 1 / 4λ by overlapping 10% to 30%.

Hereinafter, the present invention will be described in detail according to examples.
FIG. 1 shows a perspective view of an embodiment according to the present invention. The diode switch 600 includes a multilayer body 601, a semiconductor element 602 in which two diodes are incorporated, and a chip capacitor 607. An equivalent circuit diagram of this diode switch is as shown in FIG. In FIG. 2, the portion surrounded by a broken line is the diode switch of the embodiment shown in FIG. 1, and other circuit constants are formed on the circuit board on which the diode switch is mounted. It can also be configured on the element body.

  The internal structure of the multilayer body 601 is shown in FIG. A first ground electrode 101 is formed on the lower dielectric layer 100, and a predetermined lead electrode is formed.

  On the dielectric layer 100, several dummy layers are arranged, and two dielectric layers 102 and 103 constituting a transmission line are laminated. The transmission line L1 in the circuit diagram of FIG. 2 is configured by connecting the line electrode 104 of the dielectric layer 103 and the line electrode 105 of the dielectric layer 102. The two line electrodes are connected through the through-hole electrode 106. And the extraction electrode which faces the side surface of each dielectric material layer is formed, respectively.

  Further, the transmission line L2 in the circuit diagram of FIG. 2 is configured by connecting the line electrode 107 of the dielectric layer 103 and the line electrode 108 of the dielectric layer 102. The connection between the two line electrodes is made through the through-hole electrode 109. And the extraction electrode which faces the side surface of each dielectric material layer is formed, respectively.

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

  A pattern electrode is formed on the upper surface of the uppermost dielectric layer 112. This pattern electrode includes pattern electrodes 113, 114, 115 connected to the first ground electrode 101 and the second ground electrode 111, and a pattern electrode 116 connected to the line electrode 104 constituting the first transmission line L1. Similarly, the pattern electrode 117 connected to the line electrode 105 constituting the first transmission line L1, the pattern electrode 118 connected to the line electrode 108 constituting the second transmission line L2, and the second transmission It has a pattern electrode 119 connected to the line electrode 107 constituting the line L2, and a pattern electrode 120 connected to a diode.

  This laminate is made by using a dielectric material, forming a sheet with a doctor blade, screen-printing an Ag electrode on this sheet to form a pattern electrode, laminating it, pressing it, and firing it integrally It is. Then, terminal electrodes 603, 604, 605, and 606 on the side surfaces after firing were formed. The terminals of the semiconductor element 602 incorporating two diodes are connected to the pattern electrodes 117, 118, 119, and 120, respectively, and the chip capacitor 607 is connected to the pattern electrodes 116 and 117.

  These transmission lines are all formed in a spiral shape and are divided into two layers. A plan view of this transmission line pattern diagram is shown in FIG. In this embodiment, the line electrodes 107 and 108 constituting the second transmission line are overlapped when the upper and lower layers are projected in the spiral part 121 (shaded portion). By using this spiral shape and further providing an overlapping portion, the line length could be shortened. In this example, a 900 MHz band diode switch was constructed, and the ratio of overlapping portions was 13% of the total line length. As a result, a quarter λ transmission line that required about 30 mm could be formed with about 21 mm. According to this, it can be shortened by 70%.

  FIG. 5 shows a plan view of a pattern diagram of a transmission line of another embodiment. These transmission lines are all formed in a spiral shape and are divided into two layers. In this embodiment, the spirally-shaped portions 121b (shaded portions) of the line electrodes 107b and 108b constituting the second transmission line overlap when the upper and lower layers are viewed in projection. By using this spiral shape and further providing an overlapping portion, the line length could be shortened. In this embodiment, a diode switch for the 800 MHz band is configured, and the ratio of overlapping portions is 25% of the total line length. As a result, a 1 / 4λ transmission line that requires about 33 mm can be formed with about 22 mm. According to this, it was able to shorten 67%.

  According to the present invention, since the line length of the transmission line of the diode switch can be shortened, a small diode switch can be configured. Thereby, miniaturization of the mobile phone or the high frequency circuit to which the switch circuit is attached is achieved. Further, by reversing the diode connection direction compared to the conventional one, a diode switch with improved insertion loss and isolation characteristics can be obtained.

It is a perspective view of one example concerning the present invention. FIG. 2 is an equivalent circuit diagram of a switch circuit using the embodiment shown in FIG. 1. It is a disassembled perspective view of the laminated body of the Example which concerns on this invention shown in FIG. It is a top view of the transmission line pattern of one Example shown in FIG. It is a top view of the transmission line pattern of another Example which concerns on this invention. It is a figure which shows the function of a switch circuit. It is a circuit diagram of the conventional switch circuit. It is a disassembled perspective view which shows the prior art. It is a disassembled perspective view which shows other conventional techniques. It is explanatory drawing of this 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, 118 119, 120 Pattern electrode 121 Overlapping portion 104b, 105b, 107b, 108b Line electrode 121b Overlapping portion 600 Diode switch 601 Multilayer body 602 Semiconductor element 603, 604, 605, 606 Terminal electrode 607 Chip capacitor

Claims (5)

Connected to the first circuit, the second circuit, and the third circuit, and switches the connection between the first circuit and the third circuit and the connection between the second circuit and the third circuit. And a first diode connected between the first circuit and the third circuit, and connected between the third circuit and the second circuit. A transmission line; and a second diode connected to the second circuit side of the transmission line and grounded via a capacitor;
2. The diode switch according to claim 1, wherein the transmission line is formed of line electrodes formed in at least two layers built in a multilayer body, and the line electrodes are connected via through-hole electrodes.   2. The diode switch according to claim 1, wherein the line electrodes formed in different layers are arranged in the multilayer body so that the directions of currents are the same.   The diode switch according to claim 1, wherein adjacent line electrodes have overlapping portions when viewed in projection.   The diode switch according to any one of claims 1 to 3, wherein a line length of the transmission line is shorter than a quarter wavelength of a signal passing through the transmission line.   The first diode has a cathode connected to the first circuit side, an anode connected to the third circuit side, and the second diode has a cathode connected to the second circuit side of the transmission line. Is connected, the anode is grounded via a capacitor, and a control circuit is connected between the second diode and the capacitor, and the first diode and the second diode are connected to the transmission line. Are connected in series, and the first diode and the second diode are turned on by the voltage supplied from the control circuit to connect the first circuit and the third circuit. The diode switch according to any one of claims 1 to 4, wherein:

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