JP2003234605A - Non-reciprocal circuit element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-reciprocal circuit element in which an amount of attenuation on the outside of a frequency band is increased and unwanted radiation is reduced while the price increase and the enlargement of the element are avoided. <P>SOLUTION: In the non-reciprocal circuit element, a DC magnetic field is impressed by a magnet 6 to a magnetic assembly 4 composed by arranging in a ferrite 7 a plurality of center electrodes 8, 9 and 10 so as to cross each other, one end of each of the center electrodes 8-10 is connected to the ground, capacitors 12a-12c for matching are connected to the other ends, and a serial circuit 20 composed of an inductor L1 and a capacitor C1 is connected to the input port P1 of the center electrode 8. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reciprocal circuit device used in a microwave band, such as an isolator or a circulator.

[0002]

2. Description of the Related Art Generally, non-reciprocal circuit elements such as lumped-constant type isolator and circulator have a characteristic that a forward signal has a small amount of attenuation and a backward signal has a large amount of attenuation. For example, it is used in a transmission circuit section of a communication device such as a mobile phone.

By the way, there is linear distortion in the amplifier incorporated in the above-mentioned communication equipment, and this is a cause of generation of unnecessary radiation (spurious, especially the second and third harmonics of the fundamental wave). Since this unnecessary radiation causes interference and abnormal operation of the power amplifier, it is required to be below a certain level. In order to prevent the generation of this unwanted radiation, an amplifier with excellent linearity may be adopted, or a separate filter may be employed to attenuate the unwanted waves.

[0004]

However, an amplifier with good linearity is expensive, and if a filter is separately adopted, the cost increases as the number of parts increases, and the size of the entire communication device increases. Occurs. For this reason, it is difficult to use it in mobile phones, etc. where there is a strong demand for downsizing and price reduction.

Here, an isolator or a circulator is used in communication equipment for the purpose of stable operation and protection of an amplifier. In particular, the lumped-constant type isolator and the circulator function as a bandpass filter in terms of their forward characteristics, and thus have a feature that attenuation is large even in the forward direction in a frequency band away from the passband.

It is conceivable to use such a characteristic outside the band to attenuate unnecessary waves. However, since the above isolator is not originally intended to obtain attenuation outside the band, there is a limit in exhibiting its performance.

The present invention has been made in view of the above circumstances, and provides a nonreciprocal circuit device capable of reducing unnecessary radiation by increasing the amount of attenuation outside the frequency band while avoiding an increase in price and size. It is intended to be provided.

[0008]

According to a first aspect of the present invention, there is provided a nonreciprocal circuit device in which a DC magnetic field is applied by a magnet to a magnetic assembly formed by arranging a plurality of center electrodes in a ferrite. While connecting one end of each center electrode to the ground, connect the matching capacitor to the other end,
A feature is that a series circuit including an inductor and a capacitor is connected to the input port of the center electrode.

According to a second aspect of the present invention, in the same nonreciprocal circuit device as the first aspect, one end of each center electrode is connected to ground and a matching capacitor is connected to the other end, and the output port of the center electrode is connected. It is characterized in that a series circuit consisting of an inductor and a capacitor is connected to.

According to a third aspect of the present invention, in the same nonreciprocal circuit device as the first aspect, one end of each center electrode is connected to ground and a matching capacitor is connected to the other end, and the input port of the center electrode is connected. Also, a series circuit including an inductor and a capacitor is connected to the output port and the output port, respectively.

According to a fourth aspect of the present invention, in any one of the first to third aspects, a terminating resistor is connected to at least one port of the center electrodes.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 3 are views for explaining a lumped constant isolator according to an embodiment (first embodiment) of the invention of claims 1 and 4, and FIG. 1 is an exploded perspective view of the isolator. 2A is a plan view of an inductor formed on a dielectric substrate, FIG. 2B is a perspective plan view of electrodes formed on the back surface of the dielectric substrate, and FIG. 3 is an equivalent circuit diagram of an isolator.

In FIG. 1, reference numeral 1 denotes a lumped-constant type isolator, in which a terminal block 3 is arranged on a bottom surface 2a of a case 2 made of magnetic metal, and a magnetic assembly 4 is arranged on the terminal block 3. A box-shaped cap 5 also made of a magnetic metal is attached to the case 2, and a rectangular permanent magnet 6 is attached to the inner surface of the cap 5 to form a magnetic circuit. It is configured to apply a DC magnetic field to the assembly 4.

In the magnetic assembly 4, the three central conductors 8, 9 and 10 are arranged on the upper surface of the disk-shaped ferrite 7 so as to intersect each other at an angle of 120 degrees with an electrically insulating sheet (not shown) interposed. And the ground portion 11 of each of the central conductors 8 to 10 is in contact with the bottom surface of the ferrite 7.

The terminal block 3 is made of an electrically insulating resin and has a structure in which a bottom wall 3b is integrally formed on a rectangular frame-shaped side wall 3a, and an insertion hole 3c is formed in the bottom wall 3b. Recesses 3d for accommodating the matching single-plate capacitors 12a to 12c and the single-plate terminating resistor R are formed on the periphery of the insertion hole 3c of the bottom wall 3b. The magnetic assembly 4 is inserted into the insertion hole 3c, and the ground portion 11 of the magnetic assembly 4 is connected to the bottom surface 2a of the case 2.

On the outer surfaces of the left and right side walls 3a of the terminal block 3, surface-mounting input / output terminals 15 and ground terminals 16 are provided.
Is formed, and the input / output terminal 15 is led out to a corner portion of the upper surface of the bottom wall 3b. Also, the above ground terminal 1
Reference numeral 6 is led out to the upper surface of each of the concave portions 3d, and the lower surface electrodes of the capacitors 12a to 12c and one end of the terminating resistor R are connected. The terminals 15 and 16 are formed by insert-molding a part of the terminals 15 and 16.

Input / output ports P1 to P3 of the respective central conductors 8 to 10 are connected to the upper surface electrodes of the capacitors 12a to 12c, of which the tip of the port P1 is the input terminal 15 and the tip of the port P2. Is connected to the output terminal 15, and the tip of the port P3 is connected to the terminating resistor R.

On the upper surface of the magnetic assembly 4, a dielectric substrate 18 having a rectangular plate shape is arranged. This dielectric substrate 1
8 is a case where the cap 5 is attached to the case 2, and at the same time, the magnetic assembly 4 and the terminal block 3 are attached to the case 2 via the permanent magnet 6.
In addition, the ports P1 to P3 of the central conductors 8 to 10 are electrically and mechanically held in the capacitors 12a to 12c, respectively. A hole 18a is formed in the central portion of the dielectric substrate 18 corresponding to the magnetic assembly 4, and a notch 18b is formed in the corner portion corresponding to the terminating resistor R.

The upper surface of the dielectric substrate 18 is shown in FIG.
As shown in FIGS. 2A and 2B, a series inductor L1 as one component of the series circuit 20 is patterned. One end of this inductor L1 is connected to the connection electrode 22 on the back surface via the through-hole electrode 21, and the other end is connected to the input electrode 24 on the back surface via the same through-hole electrode 23.

The connection electrode 22 is the capacitor 12a.
And the input electrode 24 is connected to the input port P of the central conductor 8.
Connected to 1. As a result, the input port P1 is connected to the series inductor L1 which is one of the constituent elements of the series circuit 20.
Has been added. The other component, the series capacitor C1, is formed outside the isolator 1 and is connected to the input port P1.
A series circuit 20 is formed with the capacitor C1 (see the equivalent circuit diagram of FIG. 3).

A dielectric film 25 is interposed between the dielectric substrate 18 and the permanent magnet 6, and the dielectric film 25 is sandwiched between the permanent magnet 6 and the dielectric substrate 18. This dielectric film 25 is used for the permanent magnet 6
It is a quadrangle that covers the entire lower surface of and has a small dielectric constant and a small dielectric loss tangent.

Next, the function and effect of this embodiment will be described.

According to the lumped constant isolator 1 of this embodiment, the inductor L1 is patterned on the dielectric substrate 18, and the inductor L1 and the external capacitor C1 form a bandpass filter. It is possible to increase the amount of attenuation outside the operating frequency band, particularly in the high-frequency band (second harmonic wave, third harmonic wave), and reduce harmonic distortion and unnecessary radiation. Further, since a part of the series circuit 20 is built in the input port P1, a bandpass filter can be formed with a simple structure and at a low cost, and the above-mentioned expensive amplifier and a separate filter are not required, which contributes to downsizing and cost reduction. it can.

The input port P1 of the isolator 1
Since the series circuit 20 including the inductor L1 and the capacitor C1 is connected to, the load fluctuation in the band of the output part of the amplifier in the communication device can be reduced, the current consumption of the amplifier can be reduced, and the operation of the amplifier can be stabilized. , Can contribute to higher performance of communication equipment. That is, in the amplifier, the current consumption easily changes remarkably due to the load fluctuation of the output part of the amplifier,
Therefore, it is necessary to suppress the load fluctuation of the output section within the band as much as possible.

When the inductor L1 is formed on the dielectric substrate 18, there is a concern that the insertion loss of the isolator will increase due to the permanent magnet 6 coming into contact with the inductor L1 of the dielectric substrate 18. On the other hand, in the present embodiment, the dielectric constant between the dielectric substrate 18 and the permanent magnet 6 is
Since the dielectric film 25 having a small dielectric loss tangent is sandwiched, the permanent magnet 6 having a large permittivity and a large dielectric loss tangent can be separated from the inductor L1, which increases the inductance and reduces the insertion loss. Therefore, the insertion loss of the isolator can be reduced.

FIG. 4 is a characteristic diagram showing the measurement result of the insertion loss performed to confirm the effect of the lumped constant isolator. The permanent magnet used in this experiment has a relative permittivity of 25, a dielectric loss tangent of 1 × 10 −2, a dielectric film has a relative permittivity of 3.5, a dielectric loss tangent of 2 × 10 −3, and a thickness Is 50 μm. For comparison, the same measurement was performed for an isolator without a dielectric film (in the figure, the alternate long and short dash line indicates a comparative example, and the solid line indicates this example). As is clear from the figure, it can be seen that the insertion loss can be improved by about 0.05 dB by using the dielectric film.

FIG. 5 is a diagram for explaining a first modification of the above embodiment, FIG. 5 (a) is a plan view of an inductor formed on a dielectric substrate, and FIG. 5 (b) is a dielectric. It is a see-through plan view of the electrode formed on the back surface of the substrate. In the figure, the same reference numerals as those in FIG. 2 indicate the same or corresponding portions.

The first modification is formed by patterning both the series inductor L1 as a series circuit and the first electrode 30a and the second electrode 30b of the series capacitor C1 on the upper surface of the dielectric substrate 18. .

One end of the inductor L1 has a matching capacitor 12 through a through-hole electrode 21 and a connection electrode 22.
connected to a. The other end of the inductor L1 is connected to the first electrode 30a of the series capacitor, and the second electrode 30b of the series capacitor which faces the first electrode 30a with the dielectric substrate 18 in between is connected to the input port P via the input electrode 24.
Connected to 1.

As a result, a series circuit including the series inductor L1 and the series capacitor C1 is added to the input port P1 (see the equivalent circuit diagram of FIG. 6).

Also in the first modification, the dielectric substrate 18 is used.
By sandwiching the dielectric film between the permanent magnet and the permanent magnet, the insertion loss of the isolator can be reduced while preventing the interference and the abnormal operation due to unnecessary radiation, and the same effect as the above embodiment can be obtained. Further, since both the inductor L1 and the capacitor electrode C1 are formed on the dielectric substrate 18, the number of parts can be reduced and the size can be reduced as compared with the case where either one is externally attached.

FIG. 7 is a diagram for explaining a second modification of the above embodiment, in which the same reference numerals as those in FIG. 2 indicate the same or corresponding portions.

In the second modification, the inductor L1 as a series circuit, the connection electrode 22, and the both surfaces of the first dielectric substrate 31 are provided.
The input electrode 24 is formed, and a one-layer second dielectric substrate 32 is formed on the upper surface of the first dielectric substrate 31 with no permanent magnets.

According to the second modification, since the second dielectric substrate 32 is laminated on the first dielectric substrate 31 on which the inductor L1 is formed, the insertion loss of the isolator can be reduced and the same as in the above embodiment. The effect is obtained. Further, the first and second dielectric substrates 31 and 32 can be integrally formed by laminating, and the number of parts can be reduced and the cost can be further reduced as compared with the case where the above-mentioned dielectric film is used.

FIG. 8 is a diagram for explaining a third modification of the above embodiment, in which the same reference numerals as those in FIG. 7 indicate the same or corresponding portions.

In the third modification, the inductor L1 is patterned on the upper surface of the first dielectric substrate 31, and the connection electrode 22 and the input electrode 24 connected to the inductor L1 are formed on the upper surface of the second dielectric substrate 31. This is an example of pattern formation.

In the third modification, since the inductor L1, the connection electrode 22 and the input electrode 24 are formed on the upper surfaces of the first and second dielectric substrates 31 and 32, electrodes are patterned on both surfaces of one substrate. It is easier to manufacture, cost can be further reduced, and an inexpensive and low-loss isolator can be provided.

FIG. 9 is an equivalent circuit diagram for explaining a lumped constant isolator according to an embodiment (second embodiment) of the present invention. In the figure, the same symbols as those in FIG. 3 indicate the same or corresponding portions.

In the second embodiment, one end of each center electrode is connected to the ground, and the other end has a matching capacitor C0.
And a series circuit including a series inductor L2 and a series capacitor C2 is connected to the output port P2 of the center electrode.

According to the second embodiment, the output port P2
Since the series circuit including the series inductor L2 and the series capacitor C2 is connected to the above, the amount of attenuation outside the operating frequency band of the isolator can be increased, harmonic distortion and unnecessary radiation can be reduced, and substantially the same as in the first embodiment. The same effect can be obtained.

FIG. 10 is an equivalent circuit diagram for explaining a lumped constant isolator according to an embodiment (third embodiment) of the invention of claim 3. In the figure, the same reference numerals as those in FIGS. 3 and 9 indicate the same or corresponding portions.

In the third embodiment, a series circuit including a series inductor L1 and a series capacitor C1 and a series circuit including a series inductor L2 and a series capacitor C2 are provided for each of the input port P1 and the output port P2 of the center electrode. It is configured by connecting each.

Also in the third embodiment, since the input and output ports P1 and P2 are connected to the series circuits including the series inductors L1 and L2 and the series capacitors C1 and C2, respectively, substantially the same as the first embodiment. The effect is obtained.

Although the lumped-constant type isolator has been described as an example in each of the above-described embodiments, the present invention can of course be applied to a circulator.

[0046]

As described above, according to the nonreciprocal circuit device according to the present invention, since the series circuit including the inductor and the capacitor is connected to at least one of the input port and the output port of the center electrode, the nonreciprocal circuit is provided. The amount of attenuation of the circuit element outside the operating frequency band can be increased, and harmonic distortion and unwanted radiation can be reduced. Further, it is possible to form a bandpass filter with a simple structure and at a low cost, and it is possible to contribute to downsizing and cost reduction by eliminating the above-mentioned expensive amplifier and a separate filter.

In the present invention, since the series circuit composed of the inductor and the capacitor is connected to the input and output ports of the center electrode, it is possible to reduce the load fluctuation within the band of the output part of the amplifier in the communication equipment, and to reduce the current consumption of the amplifier. It is possible to reduce the power consumption, stabilize the operation of the amplifier, and contribute to the high performance of the communication device.

[Brief description of drawings]

FIG. 1 is an exploded perspective view illustrating a lumped constant isolator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an inductor on a dielectric substrate of the isolator.

FIG. 3 is an equivalent circuit diagram of the isolator.

FIG. 4 is a characteristic diagram showing an effect of the above embodiment.

FIG. 5 is a diagram showing a dielectric substrate according to a first modification of the above embodiment.

FIG. 6 is an equivalent circuit diagram of the isolator of the modified example.

FIG. 7 is an exploded perspective view of a dielectric substrate according to a second modification of the above embodiment.

FIG. 8 is an exploded perspective view of a dielectric substrate according to a third modification of the above embodiment.

FIG. 9 is an equivalent circuit diagram of a lumped constant isolator according to a second embodiment of the present invention.

FIG. 10 is an equivalent circuit diagram of a lumped constant isolator according to a third embodiment of the present invention.

[Explanation of symbols]

1 Lumped constant type isolator (non-reciprocal circuit device) 4 Magnetic assembly 6 permanent magnet 7 Ferrite 8, 9, 10 center conductor 12a to 12c matching capacitors 20 series circuit 31 First Dielectric Substrate 32 second dielectric substrate P1 input port P2 output port L1, L2 inductor C1, C2 capacitors

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Kawanami             Stock number 2 26-10 Tenjin, Nagaokakyo-shi, Kyoto             Murata Manufacturing Co., Ltd. (72) Inventor Takao Nakata             Stock number 2 26-10 Tenjin, Nagaokakyo-shi, Kyoto             Murata Manufacturing Co., Ltd. (72) Inventor Takashi Hasegawa             Stock number 2 26-10 Tenjin, Nagaokakyo-shi, Kyoto             Murata Manufacturing Co., Ltd. F-term (reference) 5J013 EA01 FA03

Claims (4)

[Claims] 1. In a nonreciprocal circuit device in which a DC magnetic field is applied by a magnet to a magnetic assembly in which a plurality of center electrodes are arranged to intersect with a ferrite, one end of each of the center electrodes is connected to ground. At the same time, a matching capacitor is connected to the other end, and a series circuit including an inductor and a capacitor is connected to the input port of the center electrode, which is a nonreciprocal circuit device. 2. A nonreciprocal circuit device in which a DC magnetic field is applied by a magnet to a magnetic assembly in which a plurality of center electrodes are arranged to intersect with ferrite, and one end of each of the center electrodes is connected to ground. At the same time, a matching capacitor is connected to the other end, and a series circuit including an inductor and a capacitor is connected to the output port of the center electrode, which is a nonreciprocal circuit device. 3. A nonreciprocal circuit device in which a DC magnetic field is applied by a magnet to a magnetic assembly in which a plurality of center electrodes are arranged to intersect with a ferrite, and one end of each of the center electrodes is connected to ground. At the same time, a matching capacitor is connected to the other end, and a series circuit including an inductor and a capacitor is connected to the input port and the output port of the center electrode, respectively. 4. The non-reciprocal circuit device according to claim 1, wherein a terminating resistor is connected to at least one port of each of the center electrodes.