JP4293118B2 - Non-reciprocal circuit device and communication device - Google Patents

Description

  The present invention relates to a nonreciprocal circuit device, and more particularly to a nonreciprocal circuit device and a communication device used in a microwave band.

  In general, a two-port isolator, which is a nonreciprocal circuit element, has a function of passing a signal only in the transmission direction and blocking transmission in the reverse direction, and is used for mobile communication devices such as automobile phones and mobile phones. Used in the transmission circuit section.

  As this type of two-port type isolator (isolator having two center electrodes, a first center electrode and a second center electrode), the one described in Patent Document 1 is known. A two-port isolator 300 shown in FIG. 17 includes a ferrite 303, two center electrodes 301 and 302 disposed on the top surface of the ferrite 303, matching capacitors 304 and 305, and a resistor 306. Between the first port P1 and the ground, the inductance L1 of the first center electrode 301 and the electrostatic capacitance C1 of the matching capacitor 304 constitute a parallel resonance circuit. Between the second port P2 and the ground, the inductance L2 of the second center electrode 302 and the capacitance C2 of the matching capacitor 305 constitute a parallel resonance circuit. In FIG. 17, reference numeral 311 denotes an input terminal, and 312 denotes an output terminal.

  The two-port isolator 300 is advantageous in that since the first and second center electrodes 301 and 302 are orthogonal to each other, a high attenuation can be obtained even outside the use frequency band, and broadband isolation can be obtained. A major feature of the structure of the two-port isolator 300 is that one end of the first center electrode 301 is a first port P1, one end of the second center electrode 302 is a second port P2, and the first and second center electrodes 301 are. , 302 is connected to the ground at the other end (common end), and a resistor 306 is connected between the first port P1 and the second port P2.

  18 includes a ferrite 323, two center electrodes 321 and 322 disposed on the top surface of the ferrite 323, matching capacitors 324 and 325, and a resistor 326. The two-port isolator 320 shown in FIG. Yes. Between the first port P1 and the third port P3, the inductance L1 of the center electrode 321, the electrostatic capacitance C1 of the matching capacitor 324 and the resistor 326 constitute a parallel resonance circuit. Between the second port P2 and the third port P3, the inductance L2 of the center electrode 322 and the electrostatic capacitance C2 of the matching capacitor 325 constitute a parallel resonance circuit. In FIG. 18, reference numeral 331 is an input terminal, 332 is a ground terminal, and 333 is an output terminal.

  A major feature of the structure of the two-port isolator 320 is that one end of the first center electrode 321 is a first port P1, and the other ends (common ends) of the first and second center electrodes 321 and 322 are a third port P3. One end of the second center electrode 322 is the second port P2. In the 2-port isolator 320, when a signal propagates from the input terminal 331 to the output terminal 333, a resonance circuit (a resonance circuit including the inductance L1 and the capacitance C1) between the first port P1 and the third port P3 is There is no resonance, and only one resonance circuit (resonance circuit composed of an inductance L2 and a capacitance C2 connected between the third port P3 and the second port P2) resonates, which greatly increases the insertion loss. Can be improved.

By the way, in recent years, a two-port isolator used in mobile communication devices is required to have a high attenuation in a frequency band (twice frequency) twice as high as a pass band and a frequency band (times third frequency). Has been. This is to eliminate the need for a filter element used in a mobile communication device or to simplify the circuit elements constituting the filter element, thereby realizing a reduction in price and loss.
JP-A-9-232818

  Accordingly, an object of the present invention is to provide a non-reciprocal circuit element and a communication device capable of increasing the attenuation in a frequency band (twice wave) twice as high as a pass band and a frequency band (triple wave) that is three times higher than the pass band. It is to provide.

In order to achieve the above object, a non-reciprocal circuit device according to the present invention comprises:
(A) a permanent magnet;
(B) a ferrite to which a DC magnetic field is applied by a permanent magnet;
(C) a first center electrode disposed on the ferrite, having one end electrically connected to the first port and the other end electrically connected to the third port;
(D) a second center that is electrically insulated from the first center electrode and is disposed on the ferrite; one end is electrically connected to the second port and the other end is electrically connected to the third port; Electrodes,
(E) a first matching capacitor electrically connected between the first port and ground;
(F) a second matching capacitor electrically connected between the second port and ground;
Equipped with a,
More specifically, a resistor is electrically connected between the third port and the ground, and the first port and the second port are input / output ports, respectively. Alternatively, a resistor is electrically connected between either the first port or the second port and the ground, and the first port or the second port and the third port to which the resistor is not connected are input / output. It is characterized as a port.

  According to the present invention, the impedance of the third port can be made lower than the impedance of the first port and the impedance of the second port, and in the pass band, while realizing the same characteristics as the conventional one, the frequency band (2 Harmonic), a non-reciprocal circuit element and a communication device capable of increasing the attenuation in the triple frequency band (third harmonic) can be obtained.

  Embodiments of a non-reciprocal circuit device and a communication device according to the present invention will be described below with reference to the accompanying drawings.

[First embodiment, FIGS. 1 to 8]
FIG. 1 shows an exploded perspective view of an embodiment of a non-reciprocal circuit device according to the present invention. The 2-port type isolator 1 is a lumped constant type isolator. As shown in FIG. 1, the two-port isolator 1 generally includes a metal case including a metal upper case 4 and a metal lower case 8, a resin case 3, a permanent magnet 9, a ferrite 20, and a center electrode. A center electrode assembly 13 composed of 21 and 22 and a laminated substrate 30 are provided.

  The metal lower case 8 has left and right side walls 8a and a bottom wall 8b. The lower case 8 is integrally formed with the resin case 3 by an insert molding method. Two ground terminals 16 extend from a pair of opposing sides of the bottom wall 8b of the lower case 8 (the two ground terminals on the back side are not shown). In order to form a magnetic circuit, the metal upper case 4 and the metal lower case 8 are made of, for example, a material made of a ferromagnetic material such as soft iron, and Ag or Cu is plated on the surface thereof.

  The center electrode assembly 13 has two sets of first and second center electrodes 21 and 22 arranged on the upper surface of the disk-shaped microwave ferrite 20 so as to intersect each other with an insulating layer (not shown) interposed therebetween. ing. The crossing angle of the two center electrodes 21 and 22 is adjusted to an angle different from 90 degrees. In the first embodiment, the center electrodes 21 and 22 are composed of two lines whose outermost widths are parallel to each other. However, the center electrodes 21 and 22 may be composed of one or three or more lines. It may be a center electrode. Both end portions 21 a, 21 b, 22 a, 22 b of the first center electrode 21 and the second center electrode 22 extend on the lower surface of the ferrite 20. The end portions 21b and 22b form one common end portion, and the end portions 21a and 22a are separated from each other.

  The center electrodes 21 and 22 may be wound around the ferrite 20 using copper foil, or may be formed by printing a silver paste on or inside the ferrite 20. Alternatively, it may be formed of a laminated substrate as described in JP-A-9-232818. However, since the printed electrodes have higher positional accuracy of the center electrodes 21 and 22, the connection with the laminated substrate 30 is stabilized. In particular, when the connection is made with the small center electrode connection electrodes 51 to 53 (described later) as in the present case, it is more reliable and workable if the center electrodes 21 and 22 are formed by printing.

  As shown in FIG. 2, the multilayer substrate 30 includes a center electrode connection electrodes 51 to 53, a dielectric sheet 41 provided with capacitor electrodes 56, 57 and a resistor 27 on the back surface, and a dielectric provided with a ground electrode 58 on the back surface. The body sheet 42 is used. The center electrode connection electrode 51 is a first port P1, the center electrode connection electrode 52 is a second port P2, and the center electrode connection electrode 53 is a third port P3.

The laminated substrate 30 is manufactured as follows. That is, the dielectric sheets 41 and 42 are mainly composed of Al ₂ O _{3 and} are composed of SiO ₂ , SrO, CaO, PbO, Na ₂ O, K ₂ O, M.
It is made of a low temperature sintered dielectric material containing one or more of gO, BaO, CeO ₂ and B ₂ O ₃ as subcomponents.

  Furthermore, the shrinkage suppression sheets 46 and 47 that suppress firing firing shrinkage in the substrate plane direction (XY direction) of the laminated substrate 30 are produced without firing under the firing conditions of the laminated substrate 30 (particularly, a firing temperature of 1000 ° C. or less). The material of the shrinkage suppression sheets 46 and 47 is a mixed material of alumina powder and stabilized zirconia powder. The thickness of the sheets 41, 42, 46, 47 is about 10 μm to 200 μm.

  The electrodes 51-53, 56-58 are formed on the back surfaces of the sheets 41, 42, 46 by a method such as pattern printing. As the material of the electrodes 51 to 53 and 56 to 58, Ag, Cu, Ag—Pd, or the like that has a low resistivity and can be fired simultaneously with the dielectric sheets 41 and 42 is used.

  The resistor 27 is formed on the back surface of the dielectric sheet 41 by a method such as pattern printing. As the material of the resistor 27, cermet, carbon, ruthenium or the like is used. The resistor 27 may be formed on the upper surface of the multilayer substrate 30 by printing, or may be formed by a chip resistor.

  The via hole 60 and the side via hole 65 are formed by previously forming a via hole hole in the dielectric sheets 41 and 42 by laser processing, punching process, or the like, and then filling the via hole hole with a conductive paste.

  The capacitor electrodes 56 and 57 constitute the matching capacitors 25 and 26, respectively, facing the capacitor electrode 58 with the dielectric sheet 42 interposed therebetween. The matching capacitors 25 and 26 and the resistor 27 together with the electrodes 51 to 53 and the via holes 60 and 65 constitute an electric circuit inside the multilayer substrate 30.

  The above dielectric sheets 41 and 42 are laminated, and further sandwiched between shrinkage suppression sheets 46 and 47 from the upper and lower sides of the laminated body of dielectric sheets 41 and 42, and then fired. Thereby, a sintered body is obtained, and then the unsintered shrinkage suppression sheets 46 and 47 are removed by an ultrasonic cleaning method or a wet honing method to obtain a laminated substrate 30 as shown in FIG.

  As shown in FIG. 1, the resin case 3 has a bottom portion 3a and two side portions 3b. The bottom wall 8b of the metal lower case 8 is exposed in a wide area on the bottom 3a. An input terminal 14 (see FIG. 4) and an output terminal 15 are insert-molded in the resin case 3. One end of each of the input terminal 14 and the output terminal 15 is exposed on the outer surface of the resin case 3, and the other end is exposed on the bottom portion 3 a of the resin case 3 to be an input extraction electrode 14 a and an output extraction electrode (not shown). Yes. Each of the ground terminals 16 is led out from the opposite outer surface of the resin case 3.

  The above components are assembled as follows. That is, as shown in FIG. 1, the end portions 21 a to 22 b of the center electrodes 21 and 22 of the center electrode assembly 13 are soldered to the center electrode connection electrodes 51 to 53 formed on the surface of the multilayer substrate 30. The central electrode assembly 13 is mounted on the multilayer substrate 30 by being electrically connected. The center electrodes 21 and 22 and the center electrode connection electrodes 51 to 53 may be soldered efficiently to the laminated substrate 30 in the mother board state.

  The laminated substrate 30 is accommodated in a resin case 3 that is integrally formed with the metal lower case 8. Furthermore, the center electrode assembly 13 and the permanent magnet 9 are stacked thereon. The ground electrode 58 disposed on the lower surface of the multilayer substrate 30 is connected and fixed to the bottom wall 8b by solder, and the two side via holes 65 disposed on the end surface of the multilayer substrate 30 are respectively input lead electrodes by solder. 14a and the output extraction electrode are connected and fixed. Simultaneously with the soldering, the metal lower case 8 and the metal upper case 4 are joined with solder or the like to form a metal case, which also functions as a yoke. That is, the metal case forms a magnetic path that surrounds the permanent magnet 9, the center electrode assembly 13, and the laminated substrate 30. The permanent magnet 9 applies a DC magnetic field to the ferrite 20.

  In this way, the two-port isolator 1 shown in FIG. 3 is obtained. FIG. 4 is an electrical equivalent circuit diagram of the isolator 1. One end 21a of the first center electrode 21 is electrically connected to the input terminal 14 via the first port P1 (center electrode connection electrode 51). One end 22a of the second center electrode 22 is electrically connected to the output terminal 15 via the second port P2 (center electrode connection electrode 52). The other end 21 b of the first center electrode 21 and the other end 22 b of the second center electrode 22 are electrically connected to the ground terminal 16 via the third port P 3 (center electrode connection electrode 53) and the resistor 27. ing. The matching capacitor 25 is electrically connected between the first port P1 and the ground. The matching capacitor 26 is electrically connected between the second port P2 and the ground.

In this two-port isolator 1, as shown in FIG. 5, when the resistance loaded on the first port P1 is Z1, the resistance loaded on the second port P2 is Z2, and the mutual inductance is ignored, the following relational expression is obtained. You can be consistent if you are satisfied.
Z1 · Z2 / (Z1 + Z2) = (R + jωL1 · L2 / (L1 + L2)) / (1 + jω (C1 + C2) R−ω ² L1 · L2 / (L1 + L2) · (C1 + C2)) ... (1)

If this circuit is resonating under the condition of ω ² L1 · C1 = 1 and ω ² L2 · C2 = 1, the relational expression is
Z1 · Z2 / (Z1 + Z2) = 1 / (jω (C1 + C2)) + L1 · L2 / (L1 + L2) / (R (C1 + C2))
It becomes. Therefore,
R = L1 · L2 / (L1 + L2) · (Z1 + Z2) / (Z1 · Z2) / (C1 + C2)
The real part can be matched. In the above equation, the imaginary part is shifted by 1 / (jω (C1 + C2)). However, in the case of an actual isolator, there is a mutual inductance, which is considered to be canceled.

  In the above equation, L1 = L2 = 0.75 nH, C1 = C2 = 21.5 pF, and normally, 50 Ω strip lines are connected to the first port P1 and the second port P2, so Z1 and Z2 are respectively If 50Ω, R is about 1Ω. Thereby, the impedance of the third port P3 can be made lower than the impedance of the external circuit connected to the first port P1 and the second port P2.

  Thus, since the impedance of the third port P3 can be made lower than the impedances of the first port P1 and the second port P2, the 2-port isolator 1 with a wide isolation can be obtained. Table 1 is a table showing an example of circuit constants and electrical characteristics of the 2-port isolator 1. For comparison, Table 1 also shows circuit constants and electrical characteristics of a conventional two-port isolator 300 (see FIG. 17), which is known as an isolator having a wide band of isolation. The ferrites 20 and 303 are both disk-shaped having a diameter of 1.5 mm and a thickness of 0.3 mm, a saturation magnetization of 85 mT, and ΔH of 2400 A / m. The input reflection loss, insertion loss, and isolation are the worst values in the pass band 893 to 958 MHz, the second harmonic is the worst value in the 1786 to 1916 MHz band, and the third harmonic is the worst value in the 2679 to 2874 MHz band.

  From Table 1, the first example is slightly inferior to the first comparative example, but there is no problem because it is 25 dB or more in the passband. The input reflection loss and the insertion loss are equivalent to each other, and the attenuation amount of the second harmonic and the third harmonic is better in the first embodiment. 6 is a graph showing the input reflection loss characteristic, FIG. 7 is a graph showing the isolation characteristic, and FIG. 8 is a graph showing the insertion loss characteristic. 6, 7, and 8, the solid line indicates the characteristic of the first example, and the dotted line indicates the characteristic of Comparative Example 1.

  The reason why the 2-port isolator 1 can increase the attenuation at the second harmonic and the third harmonic while achieving the same characteristics as the conventional one in the passband is considered to be as follows. When the impedance (input / output matching impedance) of the first port P1 and the second port P2 of the 2-port isolator 1 is 50Ω, the impedance of the third port P3 is about 1Ω. For this reason, the resistance value R of the terminating resistor 27 is as very low as 1Ω, and the third port P3 is close to a state where it is short-circuited to the ground. Therefore, it can be considered that the resistor 306 of the conventional 2-port isolator 300 of FIG. Accordingly, the 2-port isolator 1 can cut the signal that has been propagated through the conventional resistor 306, achieves the same characteristics as the conventional one in the pass band, and doubles the frequency band (double wave) of the pass band. ) It is possible to increase the attenuation in the triple frequency band (third harmonic).

  When the inductors of the center electrodes 21 and 22 of the 2-port isolator 1 are increased, all the impedances of the first, second, and third ports P1, P2, and P3 are increased. Further, when the inductors of the center electrodes 21 and 22 are made smaller, all the impedances of the first, second and third ports P1, P2 and P3 are lowered. Further, when a load having an impedance higher than 50Ω is connected to the first port P1, the impedance of the third port P3 is lowered. Even when a load having an impedance higher than 50Ω is connected to the second port P2, the impedance of the third port P3 is lowered.

  In the conventional two-port isolator 300 shown in FIG. 17, both ends of the resistor 306 are connected to the first port P1 and the second port P2, and are not connected to a metal case with good heat dissipation. On the other hand, the two-port isolator 1 of the first embodiment connects the resistor 27 to a metal case with good heat dissipation, and can improve power resistance.

[Second Embodiment, FIGS. 9 to 15]
As shown in FIG. 9, the two-port isolator 1A of the second embodiment uses a laminated substrate 30A instead of the laminated substrate 30 in the structure shown in FIG. 1, the terminal 14 is an output terminal, and the terminal 15 is an input. A terminal is connected to a resistor 27 to form a terminal terminal. FIG. 10 is an exploded perspective view of the multilayer substrate 30A.

  FIG. 11 is an electrical equivalent circuit diagram of the isolator 1A. One end 21a of the first center electrode 21 is electrically connected to the output terminal 14 via the first port P1 (center electrode connection electrode 51). One end 22 a of the second center electrode 22 is electrically connected to the ground terminal 16 via the second port P <b> 2 (center electrode connection electrode 52) and the resistor 27. The other end 21b of the first center electrode 21 and the other end 22b of the second center electrode 22 are electrically connected to the input terminal 15 via the third port P3 (center electrode connection electrode 53). The matching capacitor 25 is electrically connected between the first port P1 and the ground. The matching capacitor 26 is electrically connected between the second port P2 and the ground.

  Thus, the 2-port isolator 1A having a wide input reflection loss and a low insertion loss is obtained. Table 2 is a table showing an example of circuit constants and electrical characteristics of the 2-port isolator 1A. For comparison, Table 2 also shows circuit constants and electrical characteristics of a conventional two-port isolator 320 (see FIG. 18), which is known as an isolator with low insertion loss. The ferrites 20 and 323 are both disk-shaped with a diameter of 1.5 mm and a thickness of 0.3 mm, a saturation magnetization of 85 mT, and ΔH of 2400 A / m. The input reflection loss, output reflection loss, insertion loss, and isolation are the worst values in the pass band 893 to 958 MHz, the second harmonic is the worst value in the 1786 to 1916 MHz band, and the third harmonic is the worst in the 2679 to 2874 MHz band. Value.

  From Table 2, the second embodiment has the same isolation, input reflection loss, output reflection loss, and insertion loss as the second embodiment, and the second and third harmonic attenuations are the same as those of the second embodiment. Is better. 12 is a graph showing the input reflection loss characteristic, FIG. 13 is a graph showing the output reflection loss characteristic, FIG. 14 is a graph showing the isolation characteristic, and FIG. 15 is a graph showing the insertion loss characteristic. In FIG. 12, FIG. 13, FIG. 14 and FIG. 15, the solid line indicates the characteristic of the second embodiment, and the dotted line indicates the characteristic of the comparative example 2.

  The reason why the 2-port isolator 1A can increase the attenuation at the second harmonic and the third harmonic while realizing the same characteristics as the conventional one in the passband is considered as follows. In the conventional two-port isolator 320, a matching capacitor 324 is connected between the first port P1 and the third port P3. Therefore, the parallel resonance circuit formed by the capacitance C1 of the matching capacitor 324 and the inductance L1 of the first center electrode 321 becomes a high-pass circuit, and high frequency easily passes. On the other hand, in the two-port isolator 1A of the second embodiment, the matching capacitor 25 is connected between the first port P1 and the ground. Therefore, the parallel resonant circuit formed by the capacitance C1 of the matching capacitor 25 and the inductance L1 of the first center electrode 21 is a low-pass circuit, and it is difficult for high frequencies to pass through. As a result, the amount of attenuation at the second harmonic and the third harmonic is better in the isolator 1A of the second embodiment than in the conventional isolator 320.

  The input impedance of the conventional 2-port isolator 320 (impedance of the first port P1) is 50Ω, whereas the input impedance of the 2-port isolator 1A of the second embodiment (impedance of the third port P3). ) Is 1Ω. Therefore, when the external circuit connected to the input terminal 15 has a low impedance, the 2-port isolator 1A is suitable.

  In the case of the conventional 2-port isolator 320 shown in FIG. 18, both ends of the resistor 326 are connected to the first port P1 and the third port P3, and are not connected to a metal case with good heat dissipation. On the other hand, the two-port isolator 1A of the second embodiment has the resistor 27 connected to a metal case with good heat dissipation, and can improve power resistance.

[Third embodiment, FIG. 16]
In the third embodiment, a mobile phone will be described as an example of a communication apparatus according to the present invention.

  FIG. 16 is an electric circuit block diagram of the RF portion of the mobile phone 220. In FIG. 16, 222 is an antenna element, 223 is a duplexer, 231 is a transmission side isolator, 232 is a transmission side amplifier, 233 is a band pass filter for transmission side stages, 234 is a transmission side mixer, 235 is a reception side amplifier, 236 is A reception side interstage bandpass filter, 237 is a reception side mixer, 238 is a voltage controlled oscillator (VCO), and 239 is a local bandpass filter.

  Here, as the transmission-side isolator 231, the two-port type isolators 1, 1 </ b> A of the first or second embodiment can be used. By mounting these isolators, a mobile phone with improved electrical characteristics and high reliability can be realized.

[Other examples]
In addition, this invention is not limited to the said Example, It can change variously within the range of the summary. For example, if the N pole and the S pole of the permanent magnet 9 are reversed, the input port and the output port are switched.

The disassembled perspective view which shows one Example of the nonreciprocal circuit device based on this invention. FIG. 2 is an exploded perspective view of the multilayer substrate shown in FIG. 1. FIG. 2 is an external perspective view of the non-reciprocal circuit device illustrated in FIG. 1. The electrical equivalent circuit schematic of the nonreciprocal circuit device shown in FIG. The equivalent circuit diagram when seeing the inside of the isolator 1 from the 3rd port P3. The graph which shows an input reflection loss characteristic. The graph which shows the isolation characteristic. The graph which shows an insertion loss characteristic. The disassembled perspective view which shows another Example of the nonreciprocal circuit device based on this invention. FIG. 10 is an exploded perspective view of the multilayer substrate illustrated in FIG. 9. The electrical equivalent circuit schematic of the nonreciprocal circuit device shown in FIG. The graph which shows an input reflection loss characteristic. The graph which shows an output reflection loss characteristic. The graph which shows the isolation characteristic. The graph which shows an insertion loss characteristic. The electric circuit block diagram which shows one Example of the communication apparatus which concerns on this invention. The electrical equivalent circuit diagram which shows the conventional nonreciprocal circuit device. Furthermore, the electrical equivalent circuit diagram which shows another conventional nonreciprocal circuit device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A ... 2 port type isolator 4 ... Metal upper case 8 ... Metal lower case 9 ... Permanent magnet 13 ... Center electrode assembly 20 ... Ferrite 21 ... 1st center electrode 22 ... 2nd center electrode 25, 26 ... Matching capacitor 27 ... resistor 220 ... cell phone P1 ... first port P2 ... second port P3 ... third port

Claims (3)

With permanent magnets,
A ferrite to which a DC magnetic field is applied by the permanent magnet;
A first center electrode disposed on the ferrite, having one end electrically connected to the first port and the other end electrically connected to the third port;
A second center electrode which is disposed on the ferrite so as to intersect the first center electrode in an electrically insulated state, and has one end electrically connected to the second port and the other end electrically connected to the third port. When,
A first matching capacitor electrically connected between the first port and ground;
A second matching capacitor electrically connected between the second port and ground;
Equipped with a,
A resistor is electrically connected between the third port and the ground, and the first port and the second port are input / output ports, respectively.
A nonreciprocal circuit device characterized by the above. With permanent magnets,
A ferrite to which a DC magnetic field is applied by the permanent magnet;
A first center electrode disposed on the ferrite, having one end electrically connected to the first port and the other end electrically connected to the third port;
A second center electrode which is disposed on the ferrite so as to intersect the first center electrode in an electrically insulated state, and has one end electrically connected to the second port and the other end electrically connected to the third port. When,
A first matching capacitor electrically connected between the first port and ground;
A second matching capacitor electrically connected between the second port and ground;
With
A resistor is electrically connected between one of the first port and the second port and the ground, and the first port or the second port and the third port to which no resistor is connected are connected. That each was an input / output port,
A nonreciprocal circuit device characterized by the above . A communication apparatus comprising the nonreciprocal circuit device according to claim 1 .

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