JP4630891B2 - Filter circuit and wireless communication device - Google Patents

Description

  The present invention relates to a filter circuit used in, for example, a wireless communication device and a wireless communication device using the same.

  A communication device that performs wireless or wired information communication includes various high-frequency components such as an amplifier, a mixer, and a filter. Among these, a band-pass filter (BPF: band-pass filter) has a function of arranging a plurality of resonators and passing only signals in a specific frequency band. In today's communication systems, from the viewpoint of effective use of frequencies, it is desirable that the filter characteristics have a sharp cutoff characteristic so that the available bandwidth can be used to the maximum. Furthermore, because of the demand for miniaturization of communication equipment, a smaller filter size is desirable.

In order to realize the filter characteristics, it is necessary to couple a plurality of resonators to each other by an electromagnetic field, and the circuit constants of the filter are the resonance frequency f _i of each resonator, the coupling between resonators M _ij , and the outside. The combination Qe.

FIG. 17 is a circuit diagram of a conventional filter circuit. Reference numeral 901 denotes an input terminal, 902 denotes an output terminal, 903 (1) to (n) denote resonators, and 904 (1) to (n-1) denote coupling circuits. This filter circuit is configured by cascading resonators 903 (1) to (n) as shown in the figure. The equivalent circuit of the resonance circuit of FIG. 17 includes an inductor L and a capacitor C, and a resistor is also added when the effect of loss is taken into consideration. The resonance frequency of the resonance circuit when there is no resistance is given by the following equation.

f ₀ = 1 / sqrt (L * C)

Here, L and C are the inductance and capacitance of the resonator, respectively. In the filter circuit of FIG. 17, the resonators are connected in cascade, and the inter-resonator coupling coefficients M _ij (m ₁₂ , m ₂₃ ,..., M _n−1 , _{n in} FIG. 17 represent the coupling amounts of the respective resonant circuits. ) And the value of the external Q (Qe in FIG. 17) representing the amount of excitation of the resonator at the input / output unit, the pass frequency range and stopband attenuation as the filter circuit can be determined. In a filter in which resonators are connected in cascade, current propagates to each resonator, so that currents of all frequency components flow through the resonator. Therefore, when a resonator is configured using a material that has a limit on the current value that can be passed, such as a superconductor, a large amount of power is passed as a filter, so the power durability of the resonator is an important parameter. Then, a method for improving the power durability by taking measures to prevent the current from concentrating by using a disk shape or a wide line for the resonator has been studied. However, since the unloaded Q value is very high in the superconducting resonator, the current concentration in the resonator becomes large. For this reason, there is a problem that it is not possible to obtain a large power durability only by designing the resonator shape.

FIG. 18 is a circuit diagram of a conventional filter circuit. As shown in the circuit diagram of FIG. 18, there is a method of configuring a filter circuit by connecting resonators 913 (1) to (n) in parallel as a method for realizing filter characteristics by dispersing power passing through the resonator. . This improves the overall power resistance characteristics by distributing the power input to each resonator 913 by the parallel configuration of the resonators 913 (1) to (n). In order to configure the resonators in parallel, each resonator is configured to have a different frequency (f ₁ , f ₂ ,..., F _{n in} FIG. 18), and resonators having adjacent resonance frequencies are in reverse phase. The filter characteristics are realized by synthesizing such that In FIG. 18, “−” in “−m ₂ ” represents a reverse phase bond. There is a method of combining a superconducting filter and a normal conducting filter with a filter configuration using this principle (Patent Document 1).

  In Patent Document 1, a superconducting filter and a normal conducting filter are arranged in parallel. However, when a large amount of power comes to the input, the power is not distributed as it is. That is, power is input to each filter and only separated into reflected power and passing power, and this configuration has a problem that the superconducting filter also requires a large power resistance.

  Further, when the filter circuit is actually made as a prototype, the resonance frequency, the coupling coefficient, and the external Q may deviate from the design values due to various factors such as variations in the thickness of the substrate used. For this reason, it is necessary to adjust these parameters later. As such a filter adjusting method, a method of adjusting with a dielectric plate, a dielectric trimmer or a metal rod as described in Patent Documents 2 and 3, or a metal wall is inserted between the resonant elements as described in Patent Document 4 A method for adjusting the amount of binding is disclosed.

Further, as a tuning method of the filter characteristic, there is a method of tuning the position of one attenuation pole by inserting a conductor piece between input and output lines as in Patent Document 5 and varying the amount of coupling between input and output. It is disclosed.
Japanese Patent No. 3380165 JP 2002-204102 A JP 2005-209911 A JP 2001-102809 A Japanese Patent Laid-Open No. Sho 62-131602

  As described above, a filter using a superconductor having a steep passage characteristic has a problem that the power durability cannot be increased due to the critical current density characteristic of the superconductor. Also, characteristic adjustment is indispensable when manufacturing the filter circuit, and the filter characteristic adjustment method in the prior art has only corrected the deviation from the design parameter.

The present invention has been made in consideration of the above-described circumstances, and the object of the present invention is to achieve both steep passage characteristics and power durability when a signal having maximum power is input near the center frequency. It is possible to provide a filter circuit capable of adjusting the pass characteristic to a desired characteristic and a radio communication apparatus using the filter circuit.

The filter circuit of one embodiment of the present invention includes an input terminal that inputs a signal having a maximum power near a center frequency, a signal received from the input terminal at the terminal A, and a signal received by the terminal A and the terminals B and A first four-terminal element that is sent out from C and synthesizes the signals given to the terminals B and C and is sent out from the terminal D; and the center frequency of the signal inputted from the input terminal is a stop band. A first band rejection filter for reflecting a signal within the stopband included in a signal transmitted from the terminal B to the terminal B and allowing a signal outside the stopband to pass therethrough, and the first band rejection A second band stop having the same stop band as the stop band of the filter and reflecting a signal within the stop band included in a signal transmitted from the terminal C to the terminal C and passing a signal outside the stop band A filter, a first resonator group circuit that passes a signal in a desired band from a signal that has passed through the first band rejection filter using the first plurality of resonators, and each of the first plurality of resonators, A second resonator group circuit that passes a signal in the desired band from a signal that has passed through the second band rejection filter using a plurality of second resonators having the same resonance frequency, and a signal sent from the terminal D A second four-terminal element that divides the signal received at terminal E and sends it out from terminal F and terminal G, and synthesizes the signals given to terminal F and terminal G and sends them out from terminal H And having the same stopband as the first bandstop filter, passing the signal of the first path that has passed through the first resonator group circuit to the terminal F, and sending the signal transmitted from the terminal F to the terminal F Reflected to terminal F A band-stop filter, having the same stopband as the first band-stop filter, passing the signal of the second path that has passed through the second resonator group circuit to the terminal G, and is transmitted from the terminal G A filter circuit comprising: a fourth band rejection filter that reflects a signal to the terminal G; and an output terminal that outputs a signal transmitted from the terminal H. The first band rejection filter and the first resonator group A first phase adjusting mechanism for adjusting a phase difference between a signal passing through the first resonator group circuit and a signal passing through the second resonator group circuit, sandwiched between circuits, the second band rejection filter, and the A second phase adjustment mechanism for adjusting a phase difference between a signal passing through the first resonator group circuit and a signal passing through the second resonator group circuit, sandwiched between the second resonator group circuits; Bandstop filter and first resonator A third phase adjusting mechanism that adjusts a phase difference between a signal that passes through the first resonator group circuit and a signal that passes through the second resonator group circuit, sandwiched between circuits, the fourth band rejection filter, and the At least one of the fourth phase adjusting mechanisms for adjusting the phase difference between the signal passing through the first resonator group circuit and the signal passing through the second resonator group circuit sandwiched between the second resonator group circuits. A filter circuit having two phase adjustment mechanisms.

  Here, at least one of the first phase adjustment mechanism and the third phase adjustment mechanism is provided, and at least one of the second phase adjustment mechanism and the fourth phase adjustment mechanism is provided. It is desirable to have.

  Here, it is desirable to have the first phase adjusting mechanism, the second phase adjusting mechanism, the third phase adjusting mechanism, and the fourth phase adjusting mechanism.

  Here, it is desirable that the transmission lines in the first and second resonator group circuits are composed of superconductors.

  Here, it is desirable that the first and second four-terminal elements are magic Ts.

  Here, the path between the first 4-terminal element and the first and second resonator group circuits, and the path between the second 4-terminal element and the first and second resonator group circuits It is desirable to have a 90 degree delay circuit.

  A wireless communication device of one embodiment of the present invention includes the above-described filter circuit of one embodiment of the present invention.

  According to the present invention, it is possible to provide both a steep pass characteristic and power durability, and a filter circuit capable of adjusting the pass characteristic to a desired characteristic and a wireless communication apparatus using the filter circuit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic block diagram of a filter circuit according to a first embodiment of the present invention. As shown in FIG. 1, the filter circuit includes an input terminal 102 for inputting a signal.

  Then, the signal input from the input terminal 102 is received at the terminal A, the received signal is divided and sent out from the terminal B and the terminal C, and the signals given to the terminal B and the terminal C are synthesized and the terminal D is combined. A first four-terminal element 106 is provided. Then, the center frequency of the signal input from the input terminal 102 is in the stop band, the signal in the stop band included in the signal transmitted from the terminal B is reflected to the terminal B, and the signal outside the stop band is passed. A first band stop filter (BSF: Band Stop Filter) 110 (1) is provided. A signal outside the stop band has a stop band identical to the stop band of the first band stop filter 101 (1) and reflects a signal in the stop band included in the signal transmitted from the terminal C to the terminal C. The second band rejection filter 110 (2) that allows the signal to pass therethrough is provided.

  Furthermore, a first resonator group circuit 114 that passes a signal in a desired band from a signal that has passed through the first band rejection filter 110 (1) using the first plurality of resonators 112 (1) to 112 (n); The second band rejection filter 110 using the second plurality of resonators 122 (1) to 122 (n) having the same resonance frequency as each of the first plurality of resonators 112 (1) to 112 (n). A second resonator group circuit 124 that passes a signal in a desired band from the signal that passed through (2) is provided.

  Then, the signal transmitted from the terminal D of the first four-terminal element 106 is received at the terminal E, the received signal is divided and transmitted from the terminal F and the terminal G, and given to the terminal F and the terminal G. A second four-terminal element 108 that synthesizes the transmitted signals and sends them out from the terminal H is provided.

  Then, the signal of the first path having the same stop band as the first band stop filter 110 (1) and having passed through the first resonator group circuit 114 is passed to the terminal F of the second four-terminal element 108. The third band rejection filter 110 (3) that reflects the signal transmitted from the terminal F to the terminal F is provided. Then, the second path signal having the same stopband as the first bandstop filter 110 (1) and passing through the second resonator group circuit 124 is passed to the terminal G of the second four-terminal element 108. , And a fourth band rejection filter 110 (4) for reflecting the signal transmitted from the terminal G to the terminal G. And the output terminal 104 which outputs the signal sent out from the terminal H of the 2nd 4 terminal element 108 is provided.

  In addition, a first 90-degree delay circuit 116 (1) is provided between the first band rejection filter 110 (1) and the first resonator group circuit 114. A second 90-degree delay circuit 116 (2) is provided between the terminal C of the first four-terminal element 102 and the second band rejection filter 110 (2). A third 90-degree delay circuit 116 (3) is provided between the terminal F of the second four-terminal element 104 and the third band rejection filter 110 (3). A fourth 90-degree delay circuit 116 (4) is provided between the fourth band rejection filter 110 (4) and the second resonator group circuit 124.

  Further, this filter circuit is sandwiched between the third band rejection filter 110 (3) and the first resonator group circuit 114, and passes the signal passing through the first resonator group circuit 114 and the second resonator group circuit 124. A phase adjustment mechanism 118 (3) that adjusts a phase difference from the signal, a signal that is sandwiched between the fourth band rejection filter 110 (4) and the second resonator group circuit 124 and passes through the first resonator group circuit 114. A phase adjustment mechanism 118 (4) that adjusts the phase difference from the signal passing through the second resonator group circuit 124 is provided.

  The filter circuit according to the present embodiment has the above-described configuration, and divides a signal in a frequency range in which large power near the center frequency comes into two paths using a four-terminal element. The high-power signal reflected by the band rejection filter arranged on the two divided paths propagates the path between the four terminals that does not pass through the resonator group circuit unit. On the other hand, only the power having a signal intensity smaller than the central band is passed through the divided resonator group circuits on the two paths, a delay of 90 degrees is added to the reflected power, and the resonator group circuit unit is further connected. A band rejection filter is connected so as not to pass, and then the signals reflected by the two paths and the band rejection filter are synthesized. As a result, it is possible to protect the resonator of the resonance circuit group including the resonator having high filter performance but inferior power durability.

  Furthermore, by providing a phase adjustment mechanism such as a phase shifter between the band rejection filter that does not pass high power and the resonator group circuit, the phase difference generated between the two paths is adjusted and synthesized to synthesize the filter. It is possible to improve the influence of the interference wave by changing the pass characteristic, tuning to the desired characteristic, and increasing the attenuation amount of the necessary frequency according to the purpose.

In the filter circuit of FIG. 1, the first and second four-terminal elements and the terminals A to D and E to H are defined as having four terminals having S parameters defined by the following equations. .

  As such a four-terminal element, for example, there is a magic T using a waveguide shown in FIG. The arrangement of each terminal is as shown in FIG. Since the frequency band to be matched is wide, it is desirable to apply Magzik T as a 4-terminal element. However, the 4-terminal element is not necessarily limited to the magic T. For example, a rat race circuit using a transmission line as shown in FIG. 4 may be applied.

The first and second resonator group circuits 114 and 124 are blocks made of single resonators having different frequencies, and the same block is arranged in the first path and the second path. Resonators 112 (1) to 112 (n), 122 (1) having two or more and N different resonance frequencies _freso-i (i is an integer from 2 to N), which are equal to or less than the power withstand capability _Wreso (W). ) To 122 (n) are connected in cascade with delay circuits 120 (1) to 120 (n) and 130 (1) to 130 (n) to form resonator group circuits 114 and 124. Each resonator and the delay circuit are connected in parallel by a power distribution circuit 132 and a power combining circuit 134. In the delay circuits 120 (1) to 120 (n) and 130 (1) to 130 (n), the resonators having adjacent resonance frequencies are 180 + 360 × k ± 30 degrees (k is an integer of 0 or more). The phase difference condition is set.

As shown in FIG. 1, the respective resonator group circuits 114 and 124 are connected in series between two band-stop filters having the same characteristics. Then, the withstand force _{W bsf} of the band-stop filter 110 (1) -110 (4), each resonator 112 (1) to 112 (n), between the withstand force _{W reso} of 122 (1) to 122 (n) _Have a relationship of W _bsf > W _reso . In addition, between the two resonance frequencies f _bsf1 and f _bsf2 (f _bsf1 <f _bsf2 ) that determine the bandwidth of the reflection characteristic of the band rejection filter and the resonance frequency f _{reso-i of} each resonator, f _{reso− i} < _fbsf1 or _fbsf2 < _freso-i . That is, each resonator has a resonance frequency outside the stop band of the band stop filter, and the resonator group circuits 114 and 124 use such resonators, the power distribution unit 132, and the power combining unit 134. Thus, a signal in a desired band is extracted from signals outside the stop band of the band stop filters 110 (1) to 110 (4).

  The electrical length from the C terminal of the first four-terminal element 106 to the second band rejection filter 110 (2), and the B length of the first four-terminal element 108 to the first band rejection filter 110 (1). There is a 90 degree delay circuit 116 (2) so that the phase difference is 90 degrees. Further, the electrical length from the G terminal of the second 4-terminal element 108 to the fourth band rejection filter 110 (4), and the third band rejection filter 110 (from the F terminal of the second 4-terminal element 108). The electrical length up to 3) has a 90-degree delay circuit 116 (3) so that the phase difference is 90 degrees. Further, the D terminal of the first four-terminal element 106 and the E terminal of the second four-terminal element 108 are connected to each other, and a circuit for obtaining an output from the H terminal of the second four-terminal element is configured.

  By using this configuration, a filter circuit can be configured without impairing the power durability even when a filter having a power durability smaller than that of the band rejection filters 110 (1) to (4) is used. For example, if you want to pass a large amount of power through a bandpass filter that uses a superconductor that has a limit value for the current that can be passed, the filter configuration of the prior art will exceed the critical current value and cannot pass a large amount of power. There was a problem. However, in the case of a signal having a high power density within the stop band of the band stop filters 110 (1) to (4), the filter circuit of FIG. There is an advantage that can be configured. With this configuration, a filter having a large power durability and a steep skirt characteristic can be configured.

  Further, the band rejection filters 110 (3) and 110 (4) on the output side have low power durability when power that is not radiated from the antenna returns according to the situation of the antenna when considering an actual wireless device. It also has a function of avoiding power inflow to the first and second resonator group circuits 114 and 124.

  Here, a phase difference θ generated between the first path and the second path is caused by the phase shifter 118 (3) provided in the first path and the phase shifter 118 (4) provided in the second path. By tuning, it is possible to change the synthesized waveform at the second four-terminal element 108 and tune or change the out-of-band characteristic to a desired characteristic. When the phase by the phase shifter is changed so as to reduce the phase difference, the filter characteristics can be adjusted so as to be close to the ideal designed characteristics. Further, since the loss due to the phase shifter contributes only to the power entering the resonator group circuit, the main signal in the filter central portion is not affected.

  Further, by providing such a phase shifter between the band rejection filter 110 (3) and the resonator group circuit 114 and between the band rejection filter 110 (4) and the resonator group circuit 124, a large signal power is obtained. Since the signal does not pass through the phase shifter, a phase shifter with low power durability can be used. Also, as shown in FIG. 1, by providing phase shifters in both the first path and the second path, the phase difference between the first path and the second path can be controlled independently, so that an ideal filter Characteristics can be obtained. On the other hand, by adjusting the phase of the phase shifter so as to increase the phase difference, the pass characteristics of the combined filter change, and the characteristics can be varied as necessary.

  Here, although the phase shifter is provided in both the first path and the second path, the phase shifter 118 (3) may be provided only in the first path as shown in FIG. I do not care. In this case, although the phase difference tuning range and the degree of freedom of the variable range are reduced as compared with the case where two phase shifters are provided, there is an advantage that the circuit is simplified by reducing the number of components.

  Further, as shown in FIG. 6, a configuration may be adopted in which a total of four phase shifters 118 (1) to (4) are provided, two in front of and behind each of the first and second resonator group circuits. . In this case, as compared with the case of two phase shifters, the phase difference tuning range and the degree of freedom of the variable range are further increased. Therefore, more ideal filter characteristics can be obtained. Further, the position of the phase shifter when one phase shifter is provided for each of the first path and the second path as shown in FIG. 1 is not necessarily limited to the position of FIG. The position may be 1) and 118 (2), 118 (1) and 118 (4), 118 (2) and 118 (3), or 118 (3) and 118 (4).

7 and 8 show the operation principle of the resonator parallel connection type. As shown in FIG. 7, when the two resonance waveforms of the frequencies ω ₁ and ω ₂ are combined with a delay difference of 180 degrees, the output is the sum of the two resonance waveforms, and a band pass filter can be configured by adjusting the coupling value. . Further, as shown in FIG. 8, when combining with a delay difference of 0, difference combining is performed.

  FIG. 9 is a circuit diagram showing a specific configuration of the filter circuit of FIG. Here, n = 2, and the phase adjustment mechanism has a configuration in which a total of four phase adjustment mechanisms are provided, two in each of the first and second resonator group circuits.

The resonator group circuits 114 and 124 include resonators 112 (1) and 122 (1) having a low-frequency resonance frequency _fL1 and resonators 112 (2) and 122 (1) having a high-frequency resonance frequency _fH1. 2) and the coupling circuit 140 in which the external Q of each resonator is Qe are connected in parallel by the power distribution circuit 132 and the power combining circuit 134, and the phase relationship is 180 degrees when combined with the band rejection filter portion. It consists of a delay line 130 for inversion and synthesis.

  Here, the resonator group circuits 114 and 124 can be made of a conductive material formed on an insulating substrate. The insulating substrate has a ground conductor on one side and a line conductor that is a transmission line on the opposite side. The conductive material includes a metal such as copper or gold, a superconductor such as niobium or niobium tin, and a Y-based copper oxide high-temperature superconductor. As the substrate, magnesium oxide, sapphire, lanthanum aluminate, or the like can be used.

For example, a superconducting microstrip line is formed as a transmission line on a magnesium oxide substrate having a thickness of about 0.43 mm and a relative dielectric constant of about 10. Here, the superconductor of the microstrip line uses a Y-based cuprate high-temperature superconducting thin film having a thickness of about 500 nm, and the line width of the strip conductor is about 0.4 mm. Further, in order to obtain a good Y-based copper oxide superconducting film, a buffer layer may be provided between the substrate and the superconducting film. Examples of the buffer layer include CeO ₂ and YSZ. The superconducting thin film can be formed by a laser deposition method, a sputtering method, a co-evaporation method, a MOD method, or the like. In addition to the microstrip line, the filter structure can be various structures such as a strip line and a coplanar line. Furthermore, not limited to the above, various resonators such as a dielectric resonator and a cavity resonator can be used.

The band rejection filters 110 (1) to 110 (4) include resonators 142 (1) to (4) having a resonance frequency f _c1 and coupling circuits 144 (1) to (4) having an external Q of Qbsf. Therefore, since high power durability is required, a dielectric resonator, a cavity resonator, or the like can be used.

An example of an input signal spectrum to this filter circuit is shown in FIG. Further, the frequency response of the filter circuit is shown in FIG. 301 is a filter characteristic, 302 is a resonance waveform, and 303 is an input signal. The signal input from the input terminal 102 is divided into two powers by the first four-terminal element 106 and output in reverse phase from the terminals C and B, and the resonators 142 (1) and 142 (2) for the band rejection filter The power in the vicinity of the center frequency f _c1 is reflected by the one-stage band rejection filters 110 (1) and 110 (2) including the coupling circuits 144 (1) and 144 (2).

The reflected power returns to the first four-terminal element 106 in the same phase relationship by the delay circuit 116, and is combined with power and output from the D terminal. Next, the signal inputted to the E terminal of the second four-terminal element 108 is divided into two and outputted in the same phase from the F and G terminals, so that the resonators 142 (3) and 142 (4) for the band rejection filter and the coupling circuit 144 are output. (3) The power in the vicinity of the center frequency f _c1 is reflected by the one-stage band rejection filters 110 (3) and 110 (4) composed of 144 (4), and the second phase is also reversed by the delay circuit 116 in the relationship of the second phase. Returning to the 4-terminal element 108, the power is combined and output from the H terminal.

  On the other hand, the signal in the frequency band that passes through the band rejection filter passes the composite wave of the resonance waveform in the resonator group circuits 114 and 124, and is in phase by the delay circuit 116 and has the F terminal and G terminal of the second four-terminal element 108. Are combined and output from the H terminal. Further, a signal that does not pass through the resonator group circuits 114 and 124 is returned to the first four-terminal element 106 by the delay circuit 116 in an opposite phase relationship, is combined with power, output from the A terminal, and returned to the input terminal 102.

Here, a large power in the vicinity of the center frequency f _c of the filter because it does not pass through the resonator group circuit 114 and 124 of the superconducting performs both the filter characteristic having a steep filter characteristic and high power durability using superconductors be able to.

  Here, the phase difference between the phase on the input side of the first path as seen from the first resonator group circuit 114 and the phase on the input side of the second path as seen from the second resonator group is made close to zero. The phase shifter 118 (1) between the input side band rejection filter 110 (1) and the first resonator group circuit 114 and between the input side band rejection filter 110 (2) and the second resonator group circuit 124. ), 118 (2). Similarly, the phase difference between the phase on the output side of the first path as seen from the first resonator group circuit 114 and the phase on the output side of the second path as seen from the second resonator group circuit 124 is set to 0. Thus, the phase shifter 118 is provided between the output side band rejection filter 110 (3) and the first resonator group circuit 114, and between the output side band rejection filter 110 (4) and the second resonator group circuit 124. (3) and 118 (4) are provided. As a result, unnecessary signals that do not pass through the first and second resonator group circuits and are reflected can be synthesized in the same phase by the first four-terminal element 106 and returned to the input side. It is possible to improve the characteristics and bring them closer to the desired characteristics. Although the degree of freedom of adjustment is lowered, even if one of the phase shifters 118 (1) and 118 (3) and one of the phase shifters 118 (2) and 118 (4) are provided. I do not care.

  Further, in the first path that passes through the C terminal of the first four-terminal element 106 and the second path that passes through the B terminal of the first four-terminal element 106, the band rejection filter portion and the resonator group circuit, respectively. It is also possible to perform waveform synthesis by generating a phase difference θ between each path by a phase shifter provided between 114 and 124.

  FIG. 11 shows changes in frequency characteristics when the phase difference is changed. By providing a phase difference between the two paths, the combined result of the waveform passing through the band rejection filter is distorted, and the filter waveform when combined with the reflected wave of the band rejection filter is also asymmetric. Therefore, by changing the phase shifter to positively give the phase difference, the position of the attenuation pole of the filter can be changed, and a specific signal can be attenuated sharply.

(Second Embodiment)
FIG. 12 is a circuit diagram of a filter circuit according to the second embodiment of the present invention. The resonator group circuits 114 and 124 of this filter circuit include two resonators 112 (11) and 112 (12), 112 (21) and 112 (22), 122 (11) sandwiched between the coupling circuits 140, and 122 (12), 122 (21), and 122 (22), which are configured by cascading delay circuits, respectively, and a coupling circuit 150 having a coupling coefficient M _j (j is an integer of 1 or more) between the resonators. (1), it is connected by 150 (2), each of the resonators have the same resonance frequency as the center frequency f ₀ of the filter circuit.

These resonators have a power _tolerance W _reso (W), the number of which is an even number of 2 or more, and each resonator has a resonance frequency f ₀ . The delay circuit satisfies the phase difference condition in the range of 180 + 360 × k ± 30 degrees (k is an integer of 0 or more) between resonators having degenerate resonance frequencies due to coupling between adjacent resonators. Resonator group circuits 114 and 124 are configured in parallel using a power combining circuit 134. This filter has a relationship of W _bsf > W _{reso and} a relationship of f _bsf2 −f _bsf1 <M _j × f ₀ .

The frequency response of this filter circuit is shown in FIG. A filter characteristic 301 is realized by synthesizing the input signal 303 with a superposition of the resonance waveform 302 in which the degeneracy is solved. In addition, as the inter-resonator coupling coefficient M _j increases, the degenerate frequency difference increases.

  In this filter circuit, as in the first embodiment, the phase adjustment mechanisms 118 (1) to 118 (4) are provided between the band rejection filter and the resonator group circuit, and the phase difference between the signals of the two paths The filter waveform can be varied by combining the two, or providing the phase difference θ between the two paths.

  According to the present embodiment, in addition to the effects of the first embodiment, a resonator having the same characteristics can be applied as a resonator of a resonator group circuit, so that there is an advantage that parts can be shared. In addition, compared with four resonators in parallel in the resonator group circuit, since the circuit can be configured in two parallels, an effect of reducing the circuit area of the filter circuit such as the number of synthesis circuits can be obtained.

(Third embodiment)
FIG. 14 is a circuit diagram of a filter circuit according to the third embodiment of the present invention. This filter circuit is a tunable filter in which a frequency adjusting mechanism is provided in each of the resonator of the band rejection filter and the resonator of the resonator group circuit.

Resonators 542 (1) to 542 (4) for the band rejection filter in FIG. 14 resonate at the center frequency f _c1 of the filter. The resonance frequency is varied using a frequency adjustment mechanism that changes the resonance frequency by ± df in this resonator. Similarly, the resonance frequencies of the resonators 512 (1), 512 (2), 522 (1), and 522 (2) of the resonator group circuits 114 and 124 that resonate at f _L1 and f _H1 are set to ± df The resonance frequency is varied using a frequency adjustment mechanism that changes the resonance frequency. By configuring a filter circuit using these resonators and tuning each resonance frequency in the same manner, the resonance frequency of the filter can be varied by ± df. FIG. 15 shows a schematic diagram of changes in filter characteristics when the frequency is varied.

  In this filter circuit, as in the first embodiment, the phase adjustment mechanisms 118 (1) to 118 (4) are provided between the band rejection filter and the resonator group circuit, and the phase difference between the signals of the two paths The filter waveform can be varied by combining the two, or providing the phase difference θ between the two paths.

  According to the present embodiment, in addition to the effects of the first embodiment, the resonance frequency of each resonator can be varied, so that filters having different frequency bands can be obtained using only shared components.

(Fourth embodiment)
FIG. 16 is a schematic block diagram of a wireless communication apparatus according to the fourth embodiment of this invention. A wireless communication apparatus according to the fourth embodiment of the present invention is a wireless transmission apparatus in which the filter circuit described in the previous embodiment is incorporated. Accordingly, detailed description of the filter circuit is omitted below.

  A signal processing circuit 582 to which transmission data 580 is input as a signal, a local signal generator 586 for generating a local signal, and a frequency for multiplying the transmission signal signal-processed by the signal processing circuit 582 with the local signal to perform frequency conversion Converter 584, power amplifier 588 that amplifies the transmission signal frequency-converted by frequency converter 584, band-limiting filter (filter circuit) 590 that band-limits the transmission signal amplified by power amplifier 588, and band limitation An antenna 592 for transmitting the transmitted signal is provided.

  The transmission data 580 is input to the signal processing circuit 582 and subjected to transmission processing such as digital-analog conversion, encoding, and modulation, thereby generating a baseband or intermediate frequency (IF) band transmission signal. The

  The transmission signal generated by the signal processing circuit 582 is input to a frequency converter (mixer) 584 and multiplied by a local signal from the local signal generator 586 to be converted into a radio frequency (Radio Frequency; RF) band signal. Frequency conversion, ie up-conversion. An RF signal output from the mixer 584 is amplified by a power amplifier (PA) 588 and then input to a band limiting filter (transmission filter) 590 to which the filter circuit described in the above embodiment is applied. The RF signal amplified by the power amplifier 588 is subjected to band limitation by the transmission filter 590, and unnecessary frequency components are removed.

  The wireless transmission device of FIG. 16 can achieve both a steep pass characteristic and power durability, and includes a filter circuit that can adjust the pass characteristic to a desired characteristic. It is possible to transmit an RF signal having the above characteristics.

  The embodiments of the present invention have been described above with reference to specific examples. In the description of the embodiment, the description of the filter circuit, the wireless communication device, etc. that is not directly necessary for the description of the present invention is omitted, but the elements related to the required filter circuit, the wireless communication device, etc. Can be appropriately selected and used.

  In addition, all filter circuits and wireless communication devices that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention. The scope of the present invention is defined by the appended claims and equivalents thereof.

1 is a schematic block diagram of a filter circuit according to a first embodiment. The figure which shows the specific example of a 4 terminal element. The figure which shows the terminal number of a 4-terminal element. The figure which shows the specific example of a 4 terminal element. 1 is a schematic block diagram of a filter circuit according to a first embodiment. 1 is a schematic block diagram of a filter circuit according to a first embodiment. Explanatory drawing of the principle of a filter circuit. Explanatory drawing of the principle of a filter circuit. The circuit diagram of the filter circuit of a 1st embodiment. The figure which shows the frequency response of the filter circuit of 1st Embodiment. The figure which shows the frequency response of the filter circuit of 1st Embodiment. The circuit diagram of the filter circuit of a 2nd embodiment. The figure which shows the frequency response of the filter circuit of 2nd Embodiment. The circuit diagram of the filter circuit of a 3rd embodiment. The figure which shows the frequency response of the filter circuit of 3rd Embodiment. The schematic block diagram of the radio | wireless communication apparatus of 4th Embodiment. The circuit diagram of the filter circuit of a prior art. The circuit diagram of the filter circuit of a prior art.

Explanation of symbols

102 input terminal 104 output terminal 106 first four-terminal element 108 second four-terminal element 110 (1) to 110 (4) band rejection filter 112 (1) to 112 (n) first plurality of resonators 114 first 1 resonator group circuit 116 (1) -116 (4) 90 degree delay circuit 118 (1) -118 (4) Phase adjustment mechanism 122 (1) -122 (n) 2nd several resonator 124 2nd resonance Group circuit 130 (1) to 130 (n) delay circuit 132 power distribution circuit 134 power combining circuit 140 coupling circuit 142 (1) to (4) resonator 144 (1) to (4) coupling circuit 150 (1), (2) Coupling circuit 301 Filter characteristic 302 Resonance waveform 303 Input signal 512 (1), (2) Resonator 522 (1), (2) Resonator 542 (1) to (4) Resonator 580 Transmission data 582 Signal processing circuit 88 power amplifier 590 filter circuit 592 antenna

Claims (7)

An input terminal for inputting a signal having the maximum power near the center frequency ;
The signal inputted from the input terminal is received at the terminal A, and the received signal is divided and sent out from the terminal B and the terminal C. The signals given to the terminals B and C are synthesized and sent out from the terminal D. A first four-terminal element;
The center frequency of the signal input from the input terminal is in the stop band, the signal in the stop band included in the signal transmitted from the terminal B is reflected to the terminal B, and the signal outside the stop band is A first band rejection filter to pass;
The stop band is the same as the stop band of the first band stop filter, and the signal within the stop band included in the signal transmitted from the terminal C is reflected to the terminal C and the signal outside the stop band is passed. A second band rejection filter for causing
A first resonator group circuit that passes a signal in a desired band from a signal that has passed through the first band rejection filter using a first plurality of resonators;
A second resonator group that passes a signal in the desired band from a signal that has passed through the second band rejection filter using a plurality of second resonators having the same resonance frequency as each of the first plurality of resonators; Circuit,
The signal sent from the terminal D is received at the terminal E, the received signal is divided and sent from the terminal F and the terminal G, and the signals given to the terminals F and G are synthesized and sent from the terminal H. A second four-terminal element;
The first path signal having the same stopband as the first bandstop filter and passing through the first resonator group circuit is passed to the terminal F, and the signal transmitted from the terminal F is sent to the terminal F A third band rejection filter that reflects to
The signal of the second path having the same stopband as the first bandstop filter and having passed through the second resonator group circuit is passed to the terminal G, and the signal transmitted from the terminal G is passed to the terminal G A fourth band rejection filter that reflects to
An output terminal for outputting a signal transmitted from the terminal H;
In a filter circuit comprising:
A first sandwiched between the first band rejection filter and the first resonator group circuit and adjusting a phase difference between a signal passing through the first resonator group circuit and a signal passing through the second resonator group circuit A phase adjustment mechanism;
A second sandwiched between the second band rejection filter and the second resonator group circuit to adjust a phase difference between a signal passing through the first resonator group circuit and a signal passing through the second resonator group circuit; A phase adjustment mechanism;
A third that is sandwiched between the third band rejection filter and the first resonator group circuit and adjusts a phase difference between a signal passing through the first resonator group circuit and a signal passing through the second resonator group circuit; A phase adjustment mechanism;
A fourth filter for adjusting a phase difference between a signal passing through the first resonator group circuit and a signal passing through the second resonator group circuit, sandwiched between the fourth band rejection filter and the second resonator group circuit. Of the phase adjustment mechanism,
A filter circuit comprising at least one phase adjustment mechanism.   It has at least one of the first phase adjustment mechanism or the third phase adjustment mechanism, and has at least one of the second phase adjustment mechanism or the fourth phase adjustment mechanism. The filter circuit according to claim 1.   The filter circuit according to claim 1, further comprising: the first phase adjustment mechanism, the second phase adjustment mechanism, the third phase adjustment mechanism, and the fourth phase adjustment mechanism.   4. The filter circuit according to claim 1, wherein the transmission lines in the first and second resonator group circuits are made of a superconductor. 5.   The filter circuit according to any one of claims 1 to 4, wherein the first and second four-terminal elements are magic Ts.   90 degrees on the path between the first 4-terminal element and the first and second resonator group circuits, and on the path between the second 4-terminal element and the first and second resonator group circuits 6. The filter circuit according to claim 1, further comprising a delay circuit. A signal processing circuit that performs transmission processing on transmission data to obtain a transmission signal;
A power amplifier for amplifying the transmission signal;
A filter circuit according to any one of claims 1 to 6, which filters the amplified transmission signal;
An antenna that radiates a signal obtained from the filter circuit as a radio wave in space;
A wireless communication device comprising:

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