JP3598965B2 - Non-reciprocal circuit device and communication device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-reciprocal circuit device such as an isolator and a circulator used in a microwave band and the like, and a communication device including the same.
[0002]
[Prior art]
Mainly, as a non-reciprocal circuit element used in the microwave band, in a resin case having an input / output terminal and an earth terminal, a center conductor electrically connected to the input / output terminal and the earth terminal, and close to the center conductor. Conventionally, a ferrite core, a permanent magnet for applying a static magnetic field to the ferrite core, and a resistor as a terminating resistor arranged at a terminating port of the center conductor are incorporated in a metal case.
[0003]
Further, in such a non-reciprocal circuit device, several specifications have been devised for an input port, an output port, and a termination port of a center conductor according to the application.
[0004]
The non-reciprocal circuit device of each specification will be described with reference to FIGS.
FIG. 5A is an equivalent circuit diagram of a non-reciprocal circuit device in which a parallel capacitor is connected to all of the ports, and FIG. 5B is a diagram in which a parallel capacitor is connected to all of the ports and a series capacitor is connected. FIG. 5C is an equivalent circuit diagram of a non-reciprocal circuit device in which a coil and a capacitor are inserted, and FIG. 5C shows a non-reciprocal circuit device in which a parallel capacitor is connected to all of the ports and a series capacitor is inserted. It is an equivalent circuit diagram.
[0005]
FIG. 6A is a non-reciprocal circuit device diagram in which a parallel capacitor is connected to all of the ports and a series coil and a capacitor are inserted only in the input-side port, and FIG. Is a non-reciprocal circuit device diagram in which a parallel capacitor is connected to all of the ports, and a series coil is inserted only into the input side port, and a parallel capacitor is connected to the input end of the coil, FIG. (C) is a non-reciprocal circuit device diagram in which a parallel capacitor is connected to all of the ports, and a series coil and a capacitor are inserted only on the terminal side.
[0006]
A non-reciprocal circuit device in which the inductance is changed by changing the shape of a plurality of input / output ports and the input impedances are respectively different is disclosed in (1) Japanese Utility Model Application Laid-Open No. 59-91007.
[0007]
A non-reciprocal circuit device in which a parallel capacitor is connected to all ports and a series coil is inserted is disclosed in (2) JP-A-48-3461.
[0008]
Further, a non-reciprocal circuit device in which parallel capacitors are connected to all ports and a series coil is inserted only in the input port is disclosed in (3) Japanese Patent Application Laid-Open No. H11-298205.
[0009]
A non-reciprocal circuit device in which parallel capacitors are connected to all ports, a series coil and a variable capacitor are inserted in the input and output ports, and only a series variable capacitor is inserted in the termination port. (4) is disclosed in JP-A-50-17949.
[0010]
[Problems to be solved by the invention]
However, such a conventional non-reciprocal circuit device has the following problems to be solved.
[0011]
In the non-reciprocal circuit device shown in FIG. 5A, the non-reciprocal circuit device is configured to have low loss and small size with a simple matching circuit, but the characteristic impedance is fixed.
[0012]
In the non-reciprocal circuit device shown in FIG. 5B, a non-reciprocal circuit device having a wide range of characteristics such as insertion loss, isolation characteristics, and reflection loss is formed in all ports. The increase greatly increases the cost, increases the loss at each port, and makes it difficult to reduce the size.
[0013]
In the non-reciprocal circuit device shown in FIG. 5C, a non-reciprocal circuit device capable of arbitrarily setting the characteristic impedance is formed in all ports. However, the loss at each port is increased by increasing the number of components. Increase.
[0014]
In addition, if a circuit is to be constructed with a predetermined low-resistance input impedance and an output impedance of 50Ω, the external dimensions of the series capacitor on the output side port become large, and it is difficult to reduce the size when incorporated in a non-reciprocal circuit device. . For example, assuming that the input impedance is 12Ω and the output impedance is 50Ω, the capacitance values of the respective capacitors are: input port side series capacitor: 7 pF, input port side parallel capacitor: 3 pF, output port side series capacitor: 50 pF, output port side parallel capacitor: 12 pF. Therefore, a large external capacitor is required for the series capacitor on the output port side, which makes it difficult to incorporate the series capacitor in the nonreciprocal circuit device.
[0015]
In addition, when a multilayer capacitor is used for miniaturization, the Q value becomes low in a microwave band of 1 GHz or more, and the insertion loss increases. For example, the Q value of the multilayer capacitor (50 pF) at 1 GHz is about 10, and the insertion loss deteriorates by about 0.05 dB.
[0016]
In addition, when using the nonreciprocal circuit element for the connection to the antenna, which is the main application, when the antenna is connected to the output terminal, the series capacitor and the parallel capacitor of the output port due to surge voltage of induced lightning etc. A large amount of static electricity may accumulate, causing the capacitor to burn out and break down beyond the withstand voltage. As a method for preventing this, a resistor, an RF choke coil, or a surge absorber may be connected between the output terminal and the ground terminal. However, the loss increases, the cost increases, and miniaturization becomes difficult. .
[0017]
Further, in the non-reciprocal circuit device, in the manufacturing process, a confirmation test of the high-frequency characteristics of the center conductor, the input / output terminal, and the ground terminal is performed, but since the measurement time is long, the confirmation test is performed. In a pre-process to be performed, a connection state inspection by DC conduction between the center conductor and the input / output terminal is performed. However, if a series capacitor is inserted between the center conductor and the input / output terminals, DC open detection cannot be performed, so that all nonreciprocal circuit elements must be inspected for high-frequency characteristics, increasing man-hours and increasing costs. Become. In addition, when performing a high-frequency characteristic test, the center conductor is pressed against the input / output terminal and the ground terminal, and the test is performed. However, the housing is distorted due to the pressing, and the opening between the center conductor and each terminal is originally an open defect. In some cases, the parts are connected even though they are unstable, and flow out to the subsequent process, which may cause a delay to occur. Originally, the open failure can be detected by inspection by applying a direct current. However, as described above, in the nonreciprocal circuit device shown in FIG. 5C, since a series capacitor is inserted in each port, It becomes difficult to prevent the outflow of defective products by detecting the delay occurrence failure.
[0018]
In the non-reciprocal circuit device shown in FIG. 6A, the return loss characteristic of the input side port has a wide band, and a non-reciprocal circuit device for attenuating a signal outside the target band is configured. Therefore, a magnetic path is required to prevent the Q value from deteriorating. Therefore, a space for securing the magnetic path is required around the coil, and the non-reciprocal circuit element itself inevitably becomes large.
[0019]
In the non-reciprocal circuit device shown in FIG. 6B, a non-reciprocal circuit device for attenuating an unnecessary signal outside the target band (especially on the high frequency side) is formed, but the non-reciprocal circuit device shown in FIG. The provision of the coil as in the case of the reversible circuit element makes it difficult to reduce the size.
[0020]
The non-reciprocal circuit device shown in FIG. 6 (C) constitutes a non-reciprocal circuit device having a low loss and a wide isolation characteristic, but the non-reciprocal circuit device shown in FIG. 6 (A). The provision of the coil in the same manner as the element makes it difficult to reduce the size.
[0021]
In the nonreciprocal circuit element of (1), the characteristic impedance can be arbitrarily set for each port, but since all ports have reactance, loss increases and miniaturization becomes difficult.
[0022]
In the nonreciprocal circuit element of (2), any characteristic impedance can be set in all ports. However, the increase in the number of components increases the loss at each port and makes it difficult to reduce the size. When a coil is used, the characteristic impedance can be set in a wide range, but the element itself becomes large and it is difficult to further reduce the size.
[0023]
In the nonreciprocal circuit device of (3), a signal outside the target band can be attenuated. However, since the device is provided with a coil, the device itself becomes large and it is difficult to reduce the size.
[0024]
In the non-reciprocal circuit element of (4), input / output matching can be performed in a wide band, and impedance matching is easy. However, since a coil is provided and the number of elements is large, the loss increases and the size is reduced. It becomes difficult to do.
[0025]
An object of the present invention is to provide a small non-reciprocal circuit device which can set an arbitrary input impedance and has low loss as a whole, and a communication device having the same.
[0026]
[Means for Solving the Problems]
According to the present invention, a magnetic assembly in which a plurality of center conductors are arranged to cross a ferrite and a permanent magnet for applying a static magnetic field to the magnetic assembly are arranged in a metal case, and an output port of the center conductor and A parallel capacitor is connected between the terminal port and the ground terminal, a series capacitor is inserted between the input port of the center conductor and the input terminal, and a parallel capacitor is connected between the input port and the ground terminal. And configure.
[0027]
Further, in the present invention, each of the parallel capacitor and the series capacitor is constituted by a single-plate capacitor.
[0028]
Further, according to the present invention, a parallel capacitor and a series capacitor connected to the center conductor of the input port sandwich the center conductor, and the parallel capacitor and the series capacitor are arranged one above the other.
[0029]
Further, the present invention is configured such that the value of the input impedance of the input-side port is set to 3 to 45Ω so that the input-side port can transfer signals to and from the preceding circuit with low impedance.
[0030]
According to the present invention, a communication device includes the non-reciprocal circuit device.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
The configuration of the isolator according to the first embodiment will be described with reference to FIGS.
1 (A) is an exploded perspective view of the isolator, FIG. 1 (B) is a cross-sectional view taken along a plane passing through an input port of the isolator, and FIG. 1 (C) passes through a terminal port of the isolator. 2 is an equivalent circuit of the isolator, and FIG. 3 is a diagram illustrating frequency characteristics of insertion loss due to a difference in the configuration of the isolator.
[0032]
In FIG. 1A, reference numeral 1 denotes a resin molded body including an input terminal 9, an output terminal 10, and a ground terminal 11 formed on a lower yoke 12. A magnetic assembly 5 including a center conductor 4 and a ferrite 3 adjacent to the center conductor 4, a permanent magnet 6 for applying a static magnetic field to the magnetic assembly 5, a magnetic assembly 5 and a permanent magnet 6 , Capacitors C0, C1, C2, and C3 as matching elements, and a resistor R serving as a terminating resistor are provided. The upper yoke 2 is placed over the resin molded body 1. And an isolator.
[0033]
The equivalent circuit of the isolator is as shown in FIG. With reference to FIGS. 2 and 1, the relationship among the input port 40a of the center conductor 4, the capacitors C0 and C1, the input terminal 9, and the ground terminal 11 will be described.
[0034]
As shown in FIG. 1, a capacitor C0 is arranged on the upper side and a capacitor C1 is arranged on the lower side with the input side port 40a of the center conductor 4 interposed therebetween, and the upper surface of the capacitor C0 and the input terminal 9 are electrically connected. Thus, the connection plate 8 is arranged. The bottom surface of the capacitor C1 is connected to the ground terminal 11 via the lower yoke 12.
[0035]
The terminal 40b of the center conductor 4 is electrically connected to the ground terminal 11 formed on the lower yoke 12 by connecting the capacitor C2 and the resistor R in parallel.
[0036]
The output port 40c of the center conductor 4 is electrically connected to the ground terminal 11 formed on the lower yoke 12 via the output terminal 10 and the capacitor C3.
[0037]
With this configuration, the part that matches the input impedance value while maintaining the equal resistance value by inserting a series capacitor, and the part that matches the input impedance value while maintaining the equal conductance value by connecting a parallel capacitor are connected. In addition, the input impedance can be determined arbitrarily.
[0038]
Further, since the matching element is constituted by the capacitor, the element can be made smaller and the insertion loss can be reduced by about 0.1 dB as compared with a case where a coil having a large outer shape and a low loss is difficult to be realized. Therefore, a compact and low-loss isolator can be configured.
[0039]
In addition, since a series capacitor is inserted only in the input port, the size can be reduced, and the number of components in the entire isolator is reduced.For example, when a series capacitor is inserted in both the input port and the output port. As a result, low loss characteristics, such as a reduction in insertion loss of about 0.03 dB, can be obtained. FIG. 3 shows the loss characteristics due to the difference in the configuration of such elements.
[0040]
In addition, since a series capacitor is inserted only into the input port, even when a lightning surge or the like flows in from an external element such as an antenna connected to the output terminal, no series capacitor is inserted into the output terminal. Therefore, a large amount of static electricity does not accumulate in the capacitor, and problems such as breakage can be prevented.
[0041]
In addition, since a series capacitor is inserted only in the input port, the output terminal is directly connected to the ground terminal via the center conductor, so that the connection state can be confirmed by a DC application continuity test. . Further, by performing the continuity test, inspection can be performed without applying a strong external force to each terminal, deformation of the housing due to the external force can be prevented, and unstable outflow of the isolator at the connection portion can be prevented. it can.
[0042]
Also, since the capacitor itself is cheaper than the coil itself and is easy to mount, an isolator can be formed at low cost. Further, since a capacitor is inserted in series at the input side port 40a, it is possible to eliminate a DC component flowing into the isolator, and it is not necessary to add a capacitor for eliminating a DC component to a pre-stage circuit connected to the isolator. A low-loss and inexpensive circuit element can be configured.
[0043]
Usually, a multilayer capacitor is used as the capacitor for eliminating the DC component. However, in a low impedance circuit (3 to 45Ω), the equivalent series resistance component of the capacitor greatly affects the loss. Therefore, by using a single-plate capacitor having a wider electrode width and a smaller equivalent series resistance component than a multilayer capacitor, a low-loss and inexpensive circuit element can be configured.
[0044]
In addition, a single-plate capacitor can be formed by cutting out a capacitor from a motherboard capacitor several tens to several hundred times as large as a single capacitor in order to obtain a desired capacitance, whereby a capacitor having a desired capacitance can be formed. Therefore, by forming the capacitors C0, C1, C2, and C3 with single-plate capacitors, an isolator having desired characteristics can be manufactured at low cost, quickly, and with high accuracy.
[0045]
In addition, only a single-plate capacitor is used for the input side port to form a low-resistance input impedance circuit, and a series capacitor is not inserted into the output-side port. A small isolator can be configured. For example, when the input impedance is 12Ω and the output impedance is 50Ω, the capacitance values of the respective capacitors are C0 = 7 pF, C1 = 3 pF, and C3 = 10 pF.
[0046]
In addition, the planar area can be reduced by a structure in which the input side port 40a of the center electrode 4 is sandwiched between the capacitor C0 (series capacitor of the input side port 40a) and the capacitor C1 (parallel capacitor of the input side port 40a) and vertically stacked. Moreover, since the capacitors C0 and C1 are formed of single-plate capacitors, they do not increase in the thickness direction even when the capacitors C0 and C1 are stacked, and as a result, the isolator can be downsized.
[0047]
In addition, by setting the input impedance to 3 to 45Ω, which is lower than the normal 50Ω, the configuration of the impedance conversion circuit can be simplified when connecting to a circuit element (power amplifier or the like) requiring a low impedance load resistance. That is, the communication device according to the present invention is driven by a low-voltage power supply such as 3 V, and the transmission and reception of a signal with low impedance is an essential condition. Therefore, a circuit element (power amplifier) having a load impedance of about 3 to 5 Ω If an attempt is made to receive the signal from the active element and convert it to 50Ω, which is the normal input impedance of the isolator, while satisfying the electrical characteristics within the used band, the loss increases, and the low impedance load resistance is required. The matching circuit of the circuit element to be performed is also complicated. Therefore, by setting the input impedance of the isolator to an intermediate predetermined value (for example, 12 Ω) of 3 to 50Ω in advance and transmitting and receiving the power signal, a low-loss circuit configuration can be realized.
[0048]
Next, a communication device according to a second embodiment will be described with reference to FIG. In FIG. 4, ANT is a transmitting / receiving antenna, DPX is a duplexer, BPFa and BPFb are band pass filters, AMPa and AMPb are amplifier circuits, MIXa and MIXb are mixers, OSC is an oscillator, SYN is a frequency synthesizer, and ISO is an isolator. .
[0049]
MIXa mixes the input IF signal and the signal output from the SYN, and BPFa allows only the transmission frequency band of the mixed output signal from MIXa to pass, AMPa amplifies the power, amplifies the isolator ISO and Sent from ANT via DPX. The isolator ISO prevents a reflected signal from the DPX or the like to the AMPa to prevent the occurrence of distortion in the AMPa. AMPb amplifies the received signal extracted from DPX. BPFb allows only the reception frequency band of the reception signal output from AMPb to pass. The MIXb mixes the frequency signal output from the SYN and the received signal to output an intermediate frequency signal IF.
[0050]
The isolator shown in the first embodiment is used as the isolator ISO shown in FIG.
[0051]
As described above, by using the non-reciprocal circuit device which is reduced in size with low insertion loss, a small communication device having high power efficiency as a whole is obtained.
[0052]
【The invention's effect】
According to the present invention, by connecting a parallel capacitor between all the ports of the center electrode and the ground electrode, and inserting a series capacitor in the input port, a low-loss and small-size that can arbitrarily select an input impedance is provided. Non-reciprocal circuit elements can be configured at low cost.
[0053]
Also, according to the present invention, by inserting a series capacitor only on the input side port, it is possible to prevent damage to the circuit elements due to the inflow of static electricity from the output terminal outside, and, connected by a direct current output terminal Since the state inspection is possible, man-hours can be reduced, and defects caused by the inspection process can be reduced.
[0054]
Further, according to the present invention, since each capacitor is a single-plate capacitor, a small, high-precision, low-loss non-reciprocal circuit device can be constructed quickly and inexpensively.
[0055]
According to the invention, the DC component flowing into the non-reciprocal circuit device is eliminated by inserting the series capacitor in the input port of the center conductor, and the circuit connected to the input side of the non-reciprocal circuit device In addition, an additional circuit for eliminating a DC component is not required for the element, and a circuit that is inexpensive, small, and has no increase in loss due to the additional circuit can be configured.
[0056]
Further, according to the present invention, a small non-reciprocal circuit device can be configured by a structure in which the series capacitor and the parallel capacitor of the input port of the center conductor are vertically stacked with the center conductor interposed therebetween.
[0057]
Further, according to the present invention, by setting the input impedance to 3 to 45Ω, a low-loss circuit can be configured even when a circuit element requiring a low-impedance load resistance and a non-reciprocal circuit element are connected. .
[0058]
Further, according to the present invention, by providing the non-reciprocal circuit device, a small-sized communication device having excellent communication performance can be obtained at low cost.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view and a sectional view of an isolator according to a first embodiment; FIG. 2 is an equivalent circuit diagram of the isolator according to the first embodiment; FIG. FIG. 4 is a block diagram of a communication device according to a second embodiment. FIG. 5 is an equivalent circuit diagram of a conventional non-reciprocal circuit device. FIG. 6 is an equivalent circuit diagram of a conventional non-reciprocal circuit device. Description】
1-resin molding 2-upper yoke 3-ferrite 4-center conductor 40a-input port 40b-terminal port 40c-output port 5-magnetic assembly 6-permanent magnet 7-spacer 8-connection plate 9-input Terminal 10-output terminal 11-ground terminal 12-lower yoke C-capacitor R-resistor L-coil

Claims (2)

In a non-reciprocal circuit device comprising a magnetic assembly in which a plurality of center conductors are arranged crossing a ferrite and a permanent magnet for applying a static magnetic field to the magnetic assembly,
A parallel capacitor is connected between the output port and the termination port of the center conductor and the ground terminal, and a series capacitor is inserted between the input port and the input terminal only on the input port of the center conductor. A parallel capacitor is connected between the input port and the ground terminal to make the input impedance of the input port 3 to 45Ω , and each of the parallel capacitor and the series capacitor is placed on the opposite surface of the dielectric plate. The input port is formed in a plate shape having the same thickness direction as the thickness direction of the ferrite, and the parallel capacitor and the series capacitor are connected to the input port. , Sandwiching the input port in the thickness direction, and connecting the parallel capacitor and the series capacitor to the input port. Nonreciprocal circuit device, characterized in that arranged one above is the thickness direction. A communication device comprising the non-reciprocal circuit device according to claim 1 .

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