JP3838386B2 - Compound switch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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.
[0002]
[Prior art]
For example, a switch circuit such as 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.
[0003]
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.
[0004]
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.
[0005]
As a conventional switch circuit, there is one disclosed in JP-A-6-197040. A circuit diagram of this conventional example is shown in FIG. This switch circuit is connected to the antenna ANT, the transmission circuit TX, and the reception circuit RX. The transmitter circuit TX is connected to the anode of the first diode D101 via the first capacitor C101, and the cathode of the first diode D101 is connected to the antenna ANT via the third capacitor C103.
[0006]
The antenna ANT is connected to the receiving circuit RX through a series circuit of the third capacitor C103, the second transmission line SL2, and the fourth capacitor C104. The anode of the first diode D101 is grounded via a series circuit of the first transmission line SL1 and the second capacitor C102. Further, a control circuit T1 is connected between the first transmission line SL1 and the second capacitor C102 via a resistor R101. The anode of the second diode D102 is connected between the second transmission line SL2 and the fourth capacitor C104, and the cathode of the second diode D102 is grounded.
[0007]
The transmission line and the capacitor are formed in the laminated body, and a diode, a capacitor, and a resistor are mounted on the laminated body.
[0008]
[Problems to be solved by the invention]
When a filter component or the like is connected to the switch circuit, the switch circuit and the filter component are separated and combined. For this reason, there is a problem that a mounting area is large and an impedance matching circuit has to be added. The same applies to other parts.
[0009]
There is a strong demand for miniaturization in a digital cellular phone or the like in which this switch circuit is used. Accordingly, an object of the present invention is to provide a composite switch circuit component having a small size and high performance, to which a new function is added.
[0010]
[Means for Solving the Problems]
The present invention includes a switch circuit including a transmission line and a diode, a low-pass filter circuit including an inductor and a capacitor, and a coupler circuit including a coupling line coupled to the transmission line constituting the inductor. The circuit includes a first diode connected between a first circuit (transmission circuit) and a second circuit (antenna), and a first transmission connected between the first circuit and ground. A second transmission line connected between the line, the second circuit and the third circuit (receiving circuit), and a second diode connected between the third circuit and the ground. The low-pass filter circuit includes a capacitor connected between the first diode and the first transmission line, and connected between the third transmission line and the ground. Comprising the coupler circuit Comprising a coupling line for coupling said third transmission line, a composite switch including a low pass filter circuit and a coupler circuit have.
[0011]
The present invention includes a first or second transmission lines of the switching circuit, the third transmission line and the capacitor of the low pass filter, the coupling line of the coupler circuit, the laminate formed by laminating a plurality of dielectric layers It is comprised by the formed electrode pattern.
[0012]
In the present invention, the electrode constituting the capacitor of the low-pass filter is disposed above the mounting surface of the transmission line of the switch circuit in the laminate.
[0013]
In the present invention, the transmission line of the switch circuit formed in the laminated body is sandwiched between ground electrode layers arranged above and below, and the capacitor of the low-pass filter circuit is sandwiched between the upper ground electrode layer sandwiching the transmission line. And an electrode opposed thereto.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the switch circuit, the low-pass filter circuit, and the coupler circuit are formed as a single component, and a small composite switch circuit component is configured by forming a laminated structure. An equivalent circuit diagram of one embodiment according to the present invention is shown in FIG. According to this equivalent circuit diagram, a low-pass filter circuit comprising L3, C2, C3, and C4 is inserted between the first diode D1 and the first transmission line L1 of the antenna switch circuit, and coupled to L3. A coupling line L4 is provided.
[0015]
In the present invention, in the laminated structure, the switch circuit portion is disposed on the lower side with respect to the mounting surface of the composite switch circuit component, and the low-pass filter circuit portion is disposed on the upper side. A coupler circuit is arranged on the upper side. In the present invention, the transmission line for the switch circuit is sandwiched from above and below by the ground electrode, and the conductive pattern of the capacitor for the low-pass filter circuit is formed further above the ground electrode on the upper side. With this structure, a composite switch circuit component having a small size and good characteristics can be obtained.
[0016]
In the present invention, a low-pass filter circuit is inserted between the anode of the first diode in the switch circuit and the first transmission line. In the equivalent circuit of this embodiment, an equivalent circuit when the transmission circuit TX and the antenna ANT are connected is shown in FIG. In this equivalent circuit, the diode is in the ON state, so it has a low resistance and is ignored. As shown in FIG. 4, according to the present invention, the symmetry of the equivalent circuit is good. For this reason, it is possible to obtain a broadband and low-loss characteristic.
[0017]
Hereinafter, the present invention will be described in detail according to examples. A perspective view of an embodiment according to the present invention is shown in FIG. Further, FIG. 2 shows an exploded perspective view of this embodiment, and FIG. 3 shows an equivalent circuit diagram thereof. This embodiment is composed of a laminated body 2 of dielectric layers and a semiconductor element 1 in which two diodes are built. In the equivalent circuit diagram, the inside of the broken line is the part of this embodiment, and the capacitors C11, C12, C13, C14 and resistors R1, R2 outside the broken line are connected as external parts on a circuit board or the like. In addition, the external component can be configured in the laminated body or on the laminated body.
[0018]
The internal structure of the laminate 2 is as shown in FIG. A first ground electrode 31 is formed on the lower dielectric layer 21, and a predetermined lead electrode is formed. Then, it is connected to the external electrodes (2), (9) and (10).
[0019]
On the dielectric layer 21, the dielectric layer 22 on which the capacitor electrode 41 that forms the capacitor C <b> 1 is formed opposite to the first ground electrode 31 is laminated. The capacitor electrode 41 is formed with a lead electrode. And it connects to an external electrode (5).
[0020]
On top of this, two dielectric layers 23 and 24 constituting a transmission line are laminated. The transmission line L1 in the equivalent circuit diagram is configured by connecting the line electrode 11 of the dielectric layer 23 and the line electrode 12 of the dielectric layer 24. The two line electrodes are connected through the through-hole electrode 51. Then, extraction electrodes facing the side surfaces of the respective dielectric layers are respectively formed and connected to the external electrodes (3) and (7).
[0021]
The transmission line L2 in the equivalent circuit diagram is configured by connecting the line electrode 13 of the dielectric layer 23 and the line electrode 14 of the dielectric layer 24. The connection between the two line electrodes is made through the through-hole electrode 52. Lead electrodes facing the side surfaces of the respective dielectric layers are formed and connected to the external electrodes (1) and (6).
[0022]
On the dielectric layer 25 thereabove, a second ground electrode 32 is formed, and a predetermined lead electrode is formed. Then, it is connected to the external electrodes (2), (9) and (10).
[0023]
Capacitor electrodes 42 and 43 that form capacitors C2 and C3 are formed on the dielectric layer 26 so as to face the second earth electrode 32. The capacitor electrode 42 is formed with an extraction electrode and connected to the external electrode (3).
[0024]
On the dielectric layer 27 thereabove, a capacitor electrode 44 is formed to face the capacitor electrode 42 and form a capacitor C4. The capacitor electrode 44 is formed with a through-hole electrode 53 and is connected to the lower capacitor electrode 43.
[0025]
On the dielectric layer 28 thereabove, the coil electrode 15 constituting the transmission line L3 is formed. One end of the coil electrode 15 is connected to the external electrode (3), and the other is a through-hole electrode 54 and is connected to the lower-layer through-hole electrode 53.
[0026]
On the dielectric layer 29 thereabove, a line 16 serving as a coupling line L4 is formed so as to be coupled to the coil electrode 15 constituting the transmission line L3. The line 16 is connected to the external electrodes (4) and (8). One through-hole electrode 55 is formed, and this through-hole electrode 55 is connected to the lower through-hole electrode 54.
[0027]
A pattern electrode is formed on the upper surface of the uppermost dielectric layer 30. One pattern electrode 17 is connected to the lower through-hole electrode 55 by a through-hole electrode 56. The pattern electrode 18 is a mark. In addition, pattern electrodes connected to the external electrodes (1), (5), and (6) are formed.
[0028]
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 (1), (2), (3), (4), (5), (6), (7), (8), (9), and (10) on the side surface after firing, and pattern electrodes on the upper surface were formed. The terminals of the semiconductor element 1 incorporating two diodes are connected to the pattern electrodes 16 and (6), (1) and (5), respectively.
[0029]
According to this embodiment, a low-pass filter circuit (LPF) including capacitors C2, C3, C4 and an inductor L3 is formed between the anode of the first diode D1 of the switch circuit and the first transmission line L1. ing. Further, a coupler circuit is configured by coupling L3 and L4.
[0030]
The insertion loss characteristics of this example are shown in FIG. FIG.5 (b) is an enlarged view of the passband part of Fig.5 (a). According to the example of the present invention, the characteristic of an insertion loss of 1 dB or less is obtained at 900 ± 250 MHz, which indicates that the characteristic is excellent.
[0031]
In this embodiment, the first transmission line L1 and the second transmission line L2 are arranged between the first ground electrode 31 and the second ground electrode 32. The switch circuit is disposed on the mounting surface side of the composite switch circuit component. A low-pass filter circuit is configured above the switch circuit.
[0032]
Since the low-pass filter circuit portion is arranged on the upper side of the switch circuit portion, in the capacitors C2 and C3 inserted between the grounds of the low-pass filter circuit, the conductive patterns 42 and 43 constituting the capacitance are The opposing second ground electrode 32 has a lead portion connected to the ground on the actual substrate. In this embodiment, the external electrode (2) corresponds to this. The external electrode (2) functions as a line electrode, and is regarded as a circuit in which an inductor L is connected in series to the capacitors C2 and C3. This equivalent circuit diagram is as shown in FIG. 6, and is effective in reducing harmonics by the series resonance of the capacitor C2 and the inductor L4 and the series resonance of the capacitor C3 and the inductor L5.
[0033]
The transmission lines L1 and L2 are both formed in a spiral shape and are divided into two layers. By using this spiral shape and further providing an overlapping portion, the line length could be shortened.
[0034]
According to the present invention, the switch circuit incorporating the low-pass filter circuit and the coupler circuit can be integrated and downsized. In addition, it has excellent characteristics such as wide band characteristics, low loss, and high harmonic suppression effect. In this embodiment, the transmitting circuit, the antenna, and the receiving circuit are described as switching circuits. However, it is needless to say that the switching circuit can be used as a switching circuit of three circuits (first circuit, second circuit, and third circuit). Further, it is within the scope of the present invention to be used as a switch for other circuits.
[0035]
【The invention's effect】
According to the present invention, a switch circuit having a low-pass filter circuit and a coupler circuit, which is small in size and excellent in characteristics, can be configured. In addition, a transmission line, a low-pass filter circuit, and a coupler circuit can be formed in a laminated body of dielectric layers to constitute a small composite switch circuit component.
[Brief description of the drawings]
FIG. 1 is a perspective view of an embodiment according to the present invention.
FIG. 2 is an exploded perspective view of the laminated body of the embodiment shown in FIG.
FIG. 3 is an equivalent circuit diagram of the embodiment according to the present invention shown in FIG.
FIG. 4 is an equivalent circuit diagram when the transmission circuit TX of the embodiment according to the present invention and the antenna ANT are connected.
FIG. 5 is a graph showing insertion loss characteristics of an embodiment according to the present invention.
FIG. 6 is a part of an equivalent circuit of an embodiment according to the present invention.
FIG. 7 is an equivalent circuit diagram of a conventional switch circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Semiconductor element 2 Laminate body 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 Dielectric layer 31 1st earth electrode 11, 12, 13, 14, 15, 16 Line electrodes 51, 52 , 53, 54, 55, 56 Through-hole electrode 32 Second ground electrode 41, 42, 43, 44 Capacitor electrode

Claims (4)

A switch circuit including a transmission line and a diode, a low-pass filter circuit including an inductor and a capacitor, and a coupler circuit including a coupling line coupled to the transmission line constituting the inductor ;
The switch circuit includes a first diode connected between a first circuit (transmission circuit) and a second circuit (antenna), and a first diode connected between the first circuit and ground. Transmission line, a second transmission line connected between the second circuit and the third circuit (receiving circuit), and a second connection connected between the third circuit and ground. Including a diode,
The low-pass filter circuit includes a capacitor that connects a third transmission line between the first diode and the first transmission line, and that is connected between the third transmission line and the ground,
The coupler circuit includes a coupling line coupled to the third transmission line,
A composite switch characterized by combining a low-pass filter circuit and a coupler circuit. The first or second transmission lines of the switching circuit, the third transmission line and the capacitor, the coupling line of the coupler circuit, a plurality of dielectric layers electrode patterns formed in the laminated body obtained by laminating the low-pass filter The composite switch according to claim 1, comprising:   3. The composite switch according to claim 2, wherein an electrode constituting the capacitor of the low-pass filter is disposed above the mounting surface with respect to the transmission line of the switch circuit in the multilayer body.   The transmission line of the switch circuit formed in the laminated body is sandwiched between upper and lower ground electrode layers, and the capacitor of the low-pass filter circuit includes an upper ground electrode layer sandwiching the transmission line and an electrode opposed thereto. The composite switch according to claim 2, wherein the composite switch is formed by:

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