阅读说明：本技术 一种滤波器及无线电收发设备 (Filter and radio transceiver ) 是由 朱琦 孙旗 于 2020-12-18 设计创作，主要内容包括：本发明提供的滤波器,包括六个谐振器、七个耦合装置、用于输入输出信号的端口和用于连接端口的端口加载装置,通过使每四个谐振器及每四个耦合装置构成一个耦合结构,使得该滤波器包括具有两个相同的谐振器和一个相同的耦合装置的两个耦合结构,每个耦合结构中,通过使任意一个耦合装置的极性或相位与其余三个耦合装置的极性或相位相反,实现了在滤波器受结构限制而必须采用对应拓扑结构时,具有四个通带外的传输零点的技术效果,其中两个位于滤波器通带外低频段,另外两个位于滤波器通带外高频段,从而大大改善滤波器的带外抑制,方便滤波器的设计和制造,端口位置不固定,结构灵活多变；本发明还提供具有该滤波器的无线电收发设备。(The filter provided by the invention comprises six resonators, seven coupling devices, a port for inputting and outputting signals and a port loading device for connecting the port, wherein every four resonators and every four coupling devices form a coupling structure, so that the filter comprises two coupling structures with two same resonators and one same coupling device, and in each coupling structure, the technical effect of having four transmission zeros outside a passband when the filter is limited by the structure and must adopt a corresponding topological structure is realized by enabling the polarity or the phase of any one coupling device to be opposite to the polarity or the phase of the other three coupling devices, wherein two coupling devices are positioned at a low frequency band outside the passband of the filter, and the other two coupling devices are positioned at a high frequency band outside the passband of the filter, thereby greatly improving the out-of-band rejection of the filter and facilitating the design and the manufacture of the filter, the position of the port is not fixed, and the structure is flexible and changeable; the invention also provides a radio transceiver device with the filter.)

1. A filter, the filter comprising:

the six resonators are respectively a first resonator, a second resonator, a third resonator, a fourth resonator, a fifth resonator and a sixth resonator;

the coupling device comprises a first coupling device, a second coupling device, a third coupling device, a fourth coupling device, a fifth coupling device, a sixth coupling device and a seventh coupling device, every two resonators are connected through one coupling device, and the coupling device is used for realizing signal coupling between the two resonators;

ports including a first port for inputting/outputting a signal to/from the filter, a second port for outputting/inputting a signal from/to the filter;

the port loading devices are arranged in one-to-one correspondence with the ports and comprise first port loading devices and second port loading devices;

the method is characterized in that:

the first port is coupled to any one of the six resonators through the first port loading device, and the second port is coupled to any one of the other five resonators through the second port loading device;

the third resonator, the fourth resonator, the fifth resonator, the sixth resonator, the third coupling device, the fourth coupling device, the fifth coupling device, and the sixth coupling device form a first coupling structure; the first resonator, the second resonator, the third resonator, the sixth resonator, the first coupling device, the second coupling device, the sixth coupling device, and the seventh coupling device form a second coupling structure; the first coupling structure and the second coupling structure share the sixth coupling means;

in said third, fourth, fifth and sixth coupling means, the polarity or phase of any one of said coupling means is opposite to the polarity or phase of the remaining three of said coupling means; in the first, second, sixth and seventh coupling means, the polarity or phase of any one of the coupling means is opposite to the polarity or phase of the remaining three of the coupling means;

the filter is provided with four transmission zeros outside the passband, wherein two transmission zeros are positioned at the low-frequency end outside the passband of the filter, and the other two transmission zeros are positioned at the high-frequency end outside the passband of the filter.

2. The filter of claim 1, wherein: in the first coupling structure, the third resonator and the fourth resonator are connected through the third coupling device, the third resonator and the sixth resonator are connected through the sixth coupling device, the fourth resonator and the fifth resonator are connected through the fourth coupling device, and the fifth resonator and the sixth resonator are connected through the fifth coupling device; in the second coupling structure, the first resonator and the second resonator are connected by the first coupling device, the first resonator and the sixth resonator are connected by the seventh coupling device, the second resonator and the third resonator are connected by the second coupling device, and the third resonator and the sixth resonator are connected by the sixth coupling device.

3. The filter of claim 1, wherein: the sixth coupling means has a polarity or phase opposite to that of the first, second, third, fourth, fifth, and seventh coupling means.

4. The filter of claim 1, wherein: two of the first, second, third, fourth, fifth, sixth, and seventh coupling means have polarities opposite to those of the other five coupling means, and the two coupling means with opposite polarities or phases are located in the first coupling structure S1 and the second coupling structure S2, respectively; the two coupling means of opposite polarity or phase are not located at the common sixth coupling means K6 of the first coupling structure S1 and the second coupling structure S2.

5. The filter of claim 1, wherein: the filter comprises a dielectric filter, a coaxial cavity filter, a waveguide filter and a microstrip filter.

6. The filter of claim 1, wherein: the coupling device comprises a magnetic coupling device, an electric coupling device, a positive coupling device, a negative coupling device, an inductive coupling device and a capacitive coupling device; the magnetic coupling, the positive coupling or the inductive coupling are three names of coupling devices with the same principle; the electric coupling, the negative coupling or the capacitive coupling are three names of coupling devices with the same principle.

7. Radio transceiver apparatus, characterized by: comprising a filter according to any one of claims 1 to 6.

Technical Field

The present invention relates to the field of electronic communication devices, and in particular, to a filter and a radio transceiver.

Background

With the development of the mobile communication industry, radio devices in various frequency bands are more and more, so that spectrum resources are more and more in short supply, different systems need to work near the frequency bands with similar frequencies, and the radio devices are more easily interfered by radio signals transmitted by other radio devices in adjacent frequency bands; therefore, a filter with better out-of-band rejection and higher rectangular coefficient is required to filter the interference signal to ensure the normal operation of the radio device.

Conventionally, a sixth-order filter can generate at most four controllable cross-coupling zeros, as shown in fig. 1, the entire filter topology is an up-down symmetric structure, in which the coupling devices K1, K2, K3, K4, and K5 are magnetic couplings, and respectively connect two adjacent resonators; the cross coupling device K6 is electrically coupled and connects the non-adjacent resonators R2 and R5; the cross coupling device K7 is a magnetic coupling and connects non-adjacent resonators R1 and R6; after entering a resonator R1 through a loading device C1 from a port P1, a signal is divided into three paths, and a first transmission path passes through R1, R2, R2, R3, R4, R5 and R6 and then reaches the port P2; the second transmission path passes through the resonators R1, R2, R5 and R6 and then reaches the port P2; the third transmission path passes through the resonator R1, R6 and reaches the port P2. Resonators R2, R3, R4 and R5 and coupling devices K2, K3, K4 and K6 form a first coupling structure S1, and a transmission zero is generated at the low-frequency end and the high-frequency end outside the passband of the filter; resonators R1, R2, R5 and R6 and coupling devices K1, K5, K6 and K7 form a second coupling structure S2, and transmission zeros are generated at the low-frequency end and the high-frequency end outside the passband of the filter respectively; as shown in fig. 2, the filter topology results in a total of four transmission zeros.

However, when the position of the filter port is changed, the filter topology structure shown in fig. 1 cannot be applied, as shown in fig. 3, after the filter port is moved, the filter topology structure loses the symmetry of the upper and lower parts or the left and right parts, and only one coupling structure S1 can be formed by the resonators R3, R4, R5 and R6 and the coupling devices K3, K4, K5 and K6, so that only one transmission zero can be generated at each of the low-frequency end and the high-frequency end outside the pass band of the filter; as shown in fig. 4, the filter topology can only generate two transmission zeros, the rectangular coefficient is reduced, and the out-of-band rejection capability is deteriorated.

It is known from the disclosure of chinese patent CN200410101528.4 that a general filter can be analyzed by using a coupled resonant circuit. The resonators in the filter may be equivalent to parallel LC resonant circuits with the following transmission characteristics:

(1) the amplitude characteristic is that for signals at the frequency point of the resonator, all the signals pass through, the signal part at the non-resonant frequency point passes through, and the more the frequency of the signals deviates from the resonant frequency point of the resonator, the less the energy passes through the resonator.

(2) Phase characteristics: signals with a frequency below the resonance frequency of the resonator are transmitted with a phase of +90 deg., and signals with a frequency above the resonance frequency of the resonator are transmitted with a phase of-90 deg..

In addition, the magnetic coupling means, or the positive coupling means, or the inductive coupling means between the resonators may be equivalent to an inductive impedance transformer having a transmission phase of-90 °, and the electric coupling means, or the negative coupling means, or the capacitive coupling means between the resonators may be equivalent to a capacitive impedance transformer having a transmission phase of +90 °.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a filter with a variable port position and four transmission zeros outside a passband, the filter has good out-of-band rejection and high rectangular coefficient; the invention also provides a radio transceiver device with the filter.

In order to achieve the above object, the present invention provides a filter, including:

the six resonators are respectively a first resonator, a second resonator, a third resonator, a fourth resonator, a fifth resonator and a sixth resonator;

the coupling device comprises a first coupling device, a second coupling device, a third coupling device, a fourth coupling device, a fifth coupling device, a sixth coupling device and a seventh coupling device, every two resonators are connected through one coupling device, and the coupling device is used for realizing signal coupling between the two resonators;

ports including a first port for inputting/outputting a signal to/from the filter, a second port for outputting/inputting a signal from/to the filter;

the port loading devices are arranged in one-to-one correspondence with the ports and comprise first port loading devices and second port loading devices;

the first port is coupled to any one of the six resonators through the first port loading device, and the second port is coupled to any one of the other five resonators through the second port loading device;

the third resonator, the fourth resonator, the fifth resonator, the sixth resonator, the third coupling device, the fourth coupling device, the fifth coupling device, and the sixth coupling device form a first coupling structure; the first resonator, the second resonator, the third resonator, the sixth resonator, the first coupling device, the second coupling device, the sixth coupling device, and the seventh coupling device form a second coupling structure; the first coupling structure and the second coupling structure share the sixth coupling means;

in said third, fourth, fifth and sixth coupling means, the polarity or phase of any one of said coupling means is opposite to the polarity or phase of the remaining three of said coupling means; in the first, second, sixth and seventh coupling means, the polarity or phase of any one of the coupling means is opposite to the polarity or phase of the remaining three of the coupling means;

the filter is provided with four transmission zeros outside the passband, wherein two transmission zeros are positioned at the low-frequency end outside the passband of the filter, and the other two transmission zeros are positioned at the high-frequency end outside the passband of the filter.

Preferably, in the first coupling structure, the third resonator and the fourth resonator are connected by the third coupling device, the third resonator and the sixth resonator are connected by the sixth coupling device, the fourth resonator and the fifth resonator are connected by the fourth coupling device, and the fifth resonator and the sixth resonator are connected by the fifth coupling device; in the second coupling structure, the first resonator and the second resonator are connected by the first coupling device, the first resonator and the sixth resonator are connected by the seventh coupling device, the second resonator and the third resonator are connected by the second coupling device, and the third resonator and the sixth resonator are connected by the sixth coupling device.

Preferably, the polarity or phase of the sixth coupling means is opposite to the polarity or phase of the first coupling means, the second coupling means, the third coupling means, the fourth coupling means, the fifth coupling means and the seventh coupling means.

Preferably, two of the first, second, third, fourth, fifth, sixth and seventh coupling means have polarities opposite to those of the other five coupling means, and the two coupling means with opposite polarities or phases are respectively located in the first coupling structure S1 and the second coupling structure S2; the two coupling means of opposite polarity or phase are not located at the common sixth coupling means K6 of the first coupling structure S1 and the second coupling structure S2.

Preferably, the filter comprises a dielectric filter, a coaxial cavity filter, a waveguide filter and a microstrip filter.

Preferably, the coupling means comprises magnetic and electrical coupling means, positive and negative coupling means, inductive and capacitive coupling means; the magnetic coupling, the positive coupling or the inductive coupling are three names of coupling devices with the same principle; the electric coupling, the negative coupling or the capacitive coupling are three names of coupling devices with the same principle.

In order to achieve the above object, the present invention provides a radio transceiver device including the filter according to any one of the above aspects.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

the filter provided by the invention comprises six resonators, seven coupling devices, a port for inputting and outputting signals and a port loading device for connecting the port, wherein every four resonators and every four coupling devices form a coupling structure, so that the filter comprises two coupling structures with two same resonators and one same coupling device, and in each coupling structure, the technical effect of having four transmission zeros outside a passband when the filter is limited by the shape and the position of the port and must adopt a corresponding topological structure is realized by enabling the polarity or the phase of any one coupling device to be opposite to the polarity or the phase of the other three coupling devices, wherein two transmission zeros are positioned at a low frequency band outside the passband of the filter, the other two transmission zeros are positioned at a high frequency band outside the passband of the filter, and the frequency and the amplitude of the transmission zeros are adjustable, therefore, the out-of-band rejection of the filter is greatly improved, the design and the manufacture of the filter are convenient, the position of a port is not fixed, and the structure is flexible and changeable; the invention also provides a radio transceiver device with the filter.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a prior art filter topology block diagram.

Fig. 2 is an electrical performance diagram of the filter topology shown in fig. 1.

Fig. 3 is a topology diagram of fig. 1 after the position of the filter port is changed.

Fig. 4 is an electrical performance diagram of the filter topology shown in fig. 3.

Fig. 5 is a topology diagram of a first embodiment of the filter according to the present invention.

Fig. 6 is an electrical performance diagram of the filter topology shown in fig. 5.

Fig. 7 is a topology structural diagram of a second embodiment of the filter of the present invention.

Fig. 8 is a topology structural diagram of a third embodiment of the filter of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example one

As shown in fig. 5, the filter provided by the present invention includes: the device comprises six resonators, seven coupling devices, two ports and two port loading devices, wherein the six resonators are a first resonator R1, a second resonator R2, a third resonator R3, a fourth resonator R4, a fifth resonator R5 and a sixth resonator R6 respectively; the seven coupling devices are respectively a first coupling device K1, a second coupling device K2, a third coupling device K3, a fourth coupling device K4, a fifth coupling device K5, a sixth coupling device K6 and a seventh coupling device K7, every two resonators are connected through one coupling device, and the coupling devices are used for realizing signal coupling between the two resonators; the two ports are a first port P1 and a second port P2 respectively, the first port P1 is used for inputting/outputting signals to/from the filter, and the second port P2 is used for outputting/inputting signals to/from the filter; the port loading devices are arranged in one-to-one correspondence with the ports, the two port loading devices are respectively a first port loading device C1 and a second port loading device C2, the first port P1 is coupled with the first resonator R1 through the first port loading device C1, and the second port P2 is coupled with the fifth resonator R5 through the second port loading device C2.

The third resonator R3 and the fourth resonator R4 are connected through a third coupling device K3, the third resonator R3 and the sixth resonator R6 are connected through a sixth coupling device K6, the fourth resonator R4 and the fifth resonator R5 are connected through a fourth coupling device K4, and the fifth resonator R5 and the sixth resonator R6 are connected through a fifth coupling device K5; the first resonator R1 and the second resonator R2 are connected by a first coupling device K1, the first resonator R1 and the sixth resonator R6 are connected by a seventh coupling device K7, the second resonator R2 and the third resonator R3 are connected by a second coupling device K2, and the third resonator R3 and the sixth resonator R6 are connected by a sixth coupling device K6.

The third resonator R3, the fourth resonator R4, the fifth resonator R5, the sixth resonator R6, the third coupling device K3, the fourth coupling device K4, the fifth coupling device K5, and the sixth coupling device K6 form a first coupling structure S1; the first resonator R1, the second resonator R2, the third resonator R3, the sixth resonator R6, the first coupling device K1, the second coupling device K2, the sixth coupling device K6, and the seventh coupling device K7 form a second coupling structure S2; the first coupling structure S1 and the second coupling structure S2 share the third resonator R3, the sixth resonator R6 and the sixth coupling means K6.

In the third coupling means K3, the fourth coupling means K4, the fifth coupling means K5 and the sixth coupling means K6, the polarity or phase of any one coupling means is opposite to the polarity or phase of the other three coupling means; in the first, second, sixth and seventh coupling means K1, K2, K6, K7, the polarity or phase of any one coupling means is opposite to the polarity or phase of the remaining three coupling means.

The polarity or phase position of the sixth coupling means K6 is opposite to the polarity or phase position of the first coupling means K1, the second coupling means K2, the third coupling means K3, the fourth coupling means K4, the fifth coupling means K5 and the seventh coupling means K7.

In the present embodiment, the polarities of the coupling devices K1, K2, K3, K4, K5, and K7 are magnetic coupling, positive coupling, or inductive coupling, which are three terms of coupling devices having the same principle. The polarity of the coupling device K6 is an electrical coupling, or a negative coupling, or a capacitive coupling, which are three designations of coupling devices of the same principle. Wherein the coupling device K6 is in the first coupling structure S1 with opposite polarity to the remaining three coupling devices K3, K4, K5; the coupling means K6 are in the second coupling structure S2 opposite in polarity to the remaining three coupling means K1, K3, K7; that is, the first coupling structure S1 and the second coupling structure S2 share a coupling device K6 of opposite polarity.

In the present embodiment, a signal is input to the filter from the first port P1, passes through the first port loading device C1, enters the first resonator R1, and is divided into three transmission paths. The first transmission path reaches the resonator R5 after passing through K1-R2-K2-R3-K3-R4-K4, the second transmission path reaches the resonator R5 after passing through K1-R2-K2-R3-K6-R6-K5, and the third transmission path reaches the resonator R5 after passing through K7-R6-K5. After vector superposition at the resonator R5, the three signals are output to the second port P2 through the second port loading device C2.

Specifically, after a signal with a frequency lower than the passband frequency of the filter enters the filter and passes through a first transmission path K1-R2-K2-R3-K3-R4-K4, the phase change is-90 degrees +90 degrees-90 degrees and is equal to-90 degrees; after passing through a second transmission path K1-R2-K2-R3-K6-R6-K5, the phase change is-90 degrees +90 degrees-90 degrees and is equal to +90 degrees; after passing through the third transmission path K7-R6-K5, the phase change is-90 ° +90 ° -90 ° equal to-90 °. When the signal lower than the passband frequency of the filter enters the filter, the signal passing through the first transmission path and the signal passing through the second transmission path are vector-superposed at the resonator R5, and because the phase difference of the two paths of signals is 180 degrees and the phases are opposite, the signals are mutually offset at the resonator R5, and a transmission zero lower than the passband frequency of the filter is formed; similarly, when the signal passing through the third transmission path and the signal passing through the second transmission path are vector-superposed at the resonator R5, a transmission zero below the pass band frequency of the filter is also formed due to the 180 ° phase difference between the two signals. Thus, a signal with a frequency lower than the pass band of the filter can generate two transmission zeros located at the low frequency end outside the pass band of the filter after entering the filter.

After a signal with a frequency higher than the passband frequency of the filter enters the filter and passes through a first transmission path K1-R2-K2-R3-K3-R4-K4, the phase is changed to-90 degrees and equal to-630 degrees, namely equal to 90 degrees; after passing through a second transmission path K1-R2-K2-R3-K6-R6-K5, the phase change is-90 ° -90 ° -90 ° +90 ° -90 ° -90 ° -90 ° and equal to-450 °, namely equal to-90 °; after passing through the third transmission path K7-R6-K5, the phase change is-90 ° -90 ° -90 ° and is equal to-270 °, i.e., equal to +90 °. After the signal higher than the passband frequency of the filter enters the filter, the signal passing through the first transmission path and the signal passing through the second transmission path are vector-superposed at the resonator R5, and because the phase difference of the two paths of signals is 180 degrees and the phases are opposite, the signals are mutually offset at the resonator R5 to form a transmission zero higher than the passband frequency of the filter; similarly, the signal passing through the third transmission path and the signal passing through the second transmission path are vector-superposed at the resonator R5 with a phase difference of 180 °, also forming a transmission zero above the filter passband frequency. Therefore, a signal with a frequency higher than the passband frequency of the filter can generate two transmission zeros at the high-frequency end outside the passband of the filter after entering the filter.

Therefore, the topology of the filter in this embodiment can generate four transmission zeros outside the passband, where two transmission zeros are located at the low-frequency end outside the passband of the filter, and the other two transmission zeros are located at the high-frequency end outside the passband of the filter, as shown in fig. 6.

Further, it should be noted that the filter is a two-terminal reciprocal element, and the signal can be input to the filter from the second port P2, and after entering the fifth harmonic resonator R5 through the second port loading device C2, the signal is divided into three transmission paths. The first transmission path reaches the resonator R1 after passing through K4-R4-K3-R3-K2-R2-K1, the second transmission path reaches the resonator R1 after passing through K5-R6-K6-R3-K2-R2-K1, and the third transmission path reaches the resonator R1 after passing through K5-R6-K7. After vector superposition at the resonator R1, the three signals are output to the first port P1 through the first port loading device C1. Because the three signal transmission paths are the same as the input and output ports before interchange and only the transmission directions are opposite, the phase difference generated by signal transmission is the same as the calculated value, the transmission curve of the filter generated after port interchange is the same as that in fig. 6, four transmission zeros can still be generated, two transmission zeros are respectively positioned at the low-frequency end outside the filter passband, and two transmission zeros are positioned at the high-frequency end outside the filter passband.

Example two

As shown in fig. 7, in the present embodiment, the position of the second port P2 is changed, and the second port P2 is coupled to the fourth resonator R4 through the loading device C2. In the present embodiment, the polarities of the coupling devices K1, K2, K3, K4, K5 and K7 are electric coupling, negative coupling or capacitive coupling, and the polarity of the coupling device K6 is magnetic coupling, positive coupling or inductive coupling. Wherein the coupling means K6 is in the first coupling structure S1 with opposite polarity to the coupling means K3, K4, K5; the coupling means K6 are in the second coupling structure S2 with opposite polarity to the coupling means K1, K2, K7; that is, the first coupling structure S1 and the second coupling structure S2 share a coupling device K6 of opposite polarity.

In the second embodiment, the signal is input to the filter from the first port P1, passes through the first port loading device C1, enters the first resonator R1, and then is split into three transmission paths. The first transmission path reaches the resonator R4 after passing through K1-R2-K2-R3-K3, the second transmission path reaches the resonator R4 after passing through K7-R6-K6-R3-K3, and the third transmission path reaches the resonator R4 after passing through K7-R6-K5-R5-K4. After vector superposition at the resonator R4, the three signals are output to the second port P2 through the second port loading device C2.

The phase change conditions of the three transmission paths are as follows: when a signal lower than the passband frequency of the filter enters and passes through the first transmission path, the phase change is-90 degrees +90 degrees-90 degrees and equal to-90 degrees; after passing through the second transmission path, the phase change is-90 ° +90 ° +90 ° +90 ° -90 ° equal to +90 °; after passing through the third transmission path, the phase change is-90 ° +90 ° -90 ° equal to-90 °. When the signal which is lower than the pass band frequency of the filter enters the filter, the signal which passes through the first transmission path and the signal which passes through the second transmission path are vector-superposed at the resonator R4, because the phase difference of the two signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R4, and a transmission zero which is lower than the pass band frequency of the filter is formed. When the signal which is lower than the pass band frequency of the filter enters the filter, the signal which passes through the second transmission path and the signal which passes through the third transmission path are vector-superposed at the resonator R4, because the phase difference of the two paths of signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R4, and a transmission zero point which is lower than the pass band frequency of the filter is formed. Thus, a signal having a frequency below the pass band of the filter, after entering the filter, may generate two transmission zeros located at the low frequency end outside the pass band of the filter.

When a signal with the frequency higher than the passband frequency of the filter enters the filter and passes through the first transmission path, the phase change is-90 degrees to-90 degrees; after passing through the second transmission path, the phase change is-90 ° -90 ° +90 ° -90 ° -90 ° equal to +90 °; after passing through the third transmission path, the phase change is-90 ° -90 ° -90 ° -90 ° -90 ° is equal to-90 °. When the signal which is higher than the pass band frequency of the filter enters the filter, the signal which passes through the first transmission path and the signal which passes through the second transmission path are vector-superposed at the resonator R4, because the phase difference of the two paths of signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R4, and a transmission zero point which is higher than the pass band frequency of the filter is formed. When the signal which is higher than the pass band frequency of the filter enters the filter, the signal which passes through the second transmission path and the signal which passes through the third transmission path are vector-superposed at the resonator R4, because the phase difference of the two paths of signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R4, and a transmission zero point which is higher than the pass band frequency of the filter is formed. Therefore, a signal with a frequency higher than the passband of the filter can generate two transmission zeros located at the high frequency end outside the passband of the filter after entering the filter.

Therefore, the filter topology structure in this embodiment may generate four transmission zeros, where two transmission zeros are located at the low-frequency end outside the filter passband, and two transmission zeros are located at the high-frequency end outside the filter passband, as shown in fig. 6.

EXAMPLE III

As shown in fig. 8, in the present embodiment, the position of the second port P2 is changed, and the second port P2 is connected to the third resonator R3 through the loading device C2. In this embodiment, the polarities of the coupling devices K1, K2, K3, K4, K5 and K7 are electric coupling, negative coupling or capacitive coupling, and the polarity of the coupling device K6 is magnetic coupling, positive coupling or inductive coupling. Wherein the coupling means K6 is in the first coupling structure S1 with opposite polarity to the coupling means K3, K4, K5; the coupling means K6 are in the second coupling structure S2 with opposite polarity to the coupling means K1, K2, K7; that is, the first coupling structure S1 and the second coupling structure S2 share a coupling device K6 of opposite polarity.

In the present embodiment, a signal is input to the filter from the first port P1, passes through the first port loading device C1, enters the first resonator R1, and is divided into three transmission paths. The first transmission path reaches a resonator R3 after passing through K1-R2-K2, the second transmission path reaches a resonator R3 after passing through K7-R6-K6, and the third transmission path reaches a resonator R3 after passing through K7-R6-K5-R5-K4-R4-K3. After vector superposition at the resonator R3, the three signals are output to the second port P2 through the second port loading device C2.

The phase change conditions of the three transmission paths are as follows: when a signal with the frequency lower than the passband frequency of the filter enters and passes through the first transmission path, the phase change is-90 degrees + 90-90 degrees and is equal to-90 degrees; after passing through the second transmission path, the phase change is-90 ° +90 ° +90 ° equal to +90 °; after passing through the third transmission path, the phase change is-90 ° +90 ° -90 ° equal to-90 °. When the signal which is lower than the pass band frequency of the filter enters the filter, the signal which passes through the first transmission path and the signal which passes through the second transmission path are vector-superposed at the resonator R3, because the phase difference of the two signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R3, and a transmission zero which is lower than the pass band frequency of the filter is formed. When the signal which is lower than the pass band frequency of the filter enters the filter, the signal which passes through the second transmission path and the signal which passes through the third transmission path are vector-superposed at the resonator R3, because the phase difference of the two paths of signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R3, and a transmission zero point which is lower than the pass band frequency of the filter is formed. Thus, a signal having a frequency below the pass band of the filter, after entering the filter, may generate two transmission zeros located at the low frequency end outside the pass band of the filter.

When a signal with the frequency higher than the passband frequency of the filter enters and passes through the first transmission path, the phase change is-90 degrees to 90 degrees, and the phase change is +90 degrees; after passing through the second transmission path, the phase change is-90 ° -90 ° +90 ° equal to-90 °; after passing through the third transmission path, the phase change is-90 ° -90 ° -90 ° -90 ° -90 ° -90 ° -90 ° and is equal to-630 °, i.e., +90 °. When the signal which is higher than the pass band frequency of the filter enters the filter, the signal which passes through the first transmission path and the signal which passes through the second transmission path are vector-superposed at the resonator R3, because the phase difference of the two paths of signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R3, and a transmission zero point which is higher than the pass band frequency of the filter is formed. When the signal which is higher than the pass band frequency of the filter enters the filter, the signal which passes through the second transmission path and the signal which passes through the third transmission path are vector-superposed at the resonator R3, because the phase difference of the two paths of signals is 180 degrees, and the phases are opposite, the signals are mutually cancelled at the resonator R3, and a transmission zero point which is higher than the pass band frequency of the filter is formed. Therefore, a signal with a frequency higher than the passband of the filter can generate two transmission zeros located at the high frequency end outside the passband of the filter after entering the filter.

Therefore, the filter topology structure in this embodiment may generate four transmission zeros, where two transmission zeros are located at the low-frequency end outside the filter passband, and two transmission zeros are located at the high-frequency end outside the filter passband, as shown in fig. 6.

In the above embodiments, the resonators R1, R2, R3, R4, R5, and R6 include dielectric filters, coaxial cavity filters, waveguide filters, and microstrip filters.

The invention also provides a radio transceiver device comprising a filter as provided in any of the above embodiments.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing is directed to embodiments of the present application and it is noted that numerous modifications and adaptations may be made by those skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.