CN212257645U - Embedded multimode coupler, radio frequency module and communication equipment - Google Patents

Abstract

The embodiment of the application provides an embedded multimode coupler, a radio frequency module and communication equipment, the embedded multimode coupler comprises a substrate, the substrate comprises a first layer and a second layer which are stacked, an input port, a through port and a main line conductor are arranged on the first layer, a coupling port, an isolation port and a secondary line conductor are arranged on the second layer, the input port and the through port are respectively connected with two ends of the main line conductor, the coupling port and the isolation port are respectively connected with two ends of the secondary line conductor, the secondary line conductor comprises a convex structure, the length extending direction of the top of the convex structure is consistent with the length extending direction of the main line conductor, and the top is overlapped with the main line conductor under a overlooking angle. The embedded multimode coupler has the characteristics of high directivity, wide frequency response, small size, low insertion loss in a multi-frequency passband, good frequency response flatness and the like.

Description

Embedded multimode coupler, radio frequency module and communication equipment

Technical Field

The application relates to the technical field of couplers, in particular to an embedded multimode coupler, a radio frequency module and communication equipment.

Background

With the continuous development of the WIFI technology and the wireless communication broadband technology, a new modulation mode (such as QAM and QPSK) is adopted to improve the spectrum utilization rate, the requirement on the linearity performance of the power amplifier is high, and the radio frequency closed loop system, as a loop system of the linearization technology, especially as an important device of closed loop feedback, needs higher performance requirement. However, the conventional coupler technology has problems of directivity, wide frequency response, and flatness in the frequency response band, and in order to solve the problems, it is necessary to increase the design cost.

SUMMERY OF THE UTILITY MODEL

In view of the above, an object of the present application is to overcome the deficiencies of the prior art and to provide an embedded multimode coupler, an rf module and a communication device.

An embodiment of the application provides an embedded multimode coupler, which comprises a substrate, the base plate is including range upon range of first layer and second floor, be equipped with input port, through port and mainline conductor on the first layer, be equipped with coupling port, isolation port and auxiliary line conductor on the second floor, the input port with through port connects respectively the both ends of mainline conductor, the coupling port with it connects respectively to keep apart the port the both ends of auxiliary line conductor, wherein, the auxiliary line conductor includes protruding type structure, the length extending direction at the top of protruding type structure with the length extending direction of mainline conductor is unanimous, the top with the mainline conductor overlaps under the depression angle degree.

In one embodiment, the main line conductor and the auxiliary line conductor have the same length and take a quarter wavelength of a central frequency point of an operating frequency band.

In one embodiment, the in-line multimode coupler further comprises: the length of the main line conductor and the length of the auxiliary line conductor are respectively a quarter wavelength of a central frequency point of the lowest working frequency band in the plurality of available working frequency bands.

In one embodiment, the in-line multimode coupler further comprises: and in a top view, the distances from the top of the convex structure to the two ends of the main line conductor are equal.

In one embodiment, the input port and the through port are each for connection to a load matched to the characteristic impedance of the main line conductor.

In one embodiment, the in-line multimode coupler further comprises: the input port and the through port are respectively connected with the corresponding coupling capacitors, and each coupling capacitor is used for connecting an external object.

In one embodiment, the coupling port and the isolation port are each used to connect a 50 ohm matched load through a corresponding blind hole.

In one embodiment, the in-line multimode coupler further comprises: and the coupling port and the isolation port are respectively connected to the corresponding matching microstrip lines through corresponding blind holes, and each matching microstrip line is used for connecting an external object. Further, the matching microstrip line adopts a microstrip transmission line with characteristic impedance of 50 ohms.

In one embodiment, the main line conductor is a microstrip line and the sub-line conductor is a strip line.

In one embodiment, the substrate further includes a third layer stacked on the second layer, and the third layer is provided with a reference ground corresponding to the microstrip line.

Another embodiment of the present application provides a radio frequency module including the embedded multimode coupler.

Another embodiment of the present application provides a communication device, including the above radio frequency module.

The embodiment of the application has the following advantages:

according to the embedded multimode coupler, the secondary line conductor and the main line conductor microstrip line are overlapped in parallel, the secondary line conductor is designed by adopting the rotary coupling main line conductor, and the embedded multimode coupler is low in insertion loss and good in frequency response flatness in a multi-frequency passband, has good frequency response selectivity, and has the advantages of being good in directivity, wide in frequency response, small in size and the like.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

FIG. 1 is a schematic diagram of an embodiment of an in-line multimode coupler;

FIG. 2 shows an equivalent circuit diagram of an in-line multimode coupler according to an embodiment of the present application;

FIG. 3 is a schematic diagram of an application of the embedded multimode coupler of the embodiment of the application to a directional coupler;

FIG. 4 is a schematic diagram showing a multilayer laminated structure of an in-line multimode coupler according to an embodiment of the application;

fig. 5 a-5 i show simulation diagrams of S-parameters of an in-line multimode coupler according to an embodiment of the application.

Detailed Description

Reference will now be made in detail to the embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the templates is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, the present embodiment provides a multimode coupler, which adopts an embedded structure design and can be applied to radio frequency communication systems and products, etc., and the coupler can improve the relatively large fluctuation of the feedback signal in the passband, so as to maximize the linearization of the output radio frequency signal, thereby improving the quality of the whole system, etc. The embedded multimode coupler is described in detail below.

In this embodiment, the embedded multimode coupler is a four-port network that will be located at different layers of the substrate. Exemplarily, as shown in fig. 1, the multimode coupler includes a substrate including a first layer and a second layer stacked, wherein the first layer is provided with an input port P1, a through port P2, and a main line conductor, and the second layer is provided with a coupling port P3, an isolation port P4, and a sub line conductor. On the first layer, the input port P1 and the through port P2 are connected to both ends of the main line conductor, respectively. On the second layer, a coupling port P3 and an isolation port P4 are connected to both ends of the sub-line conductor, respectively.

Unlike conventional parallel coupling designs, the coupler is called an in-line multimode coupler because the secondary line conductor and the main line conductor are disposed in different layers, usually the layer where the main line conductor is located is the top layer, and the secondary line conductor is located in a second layer below the top layer, and the secondary line conductor is in an in-line structure with respect to the top layer. When it is desired to use the coupling port P3 and the isolation port P4, the two ports of the second layer can be introduced to the top layer of the substrate by using blind vias, or can be introduced to other layers below in a buried via manner, and so on.

In this embodiment, the secondary line conductor and the primary line conductor form a new overlapped parallel coupling structure by adopting the bending structure. Exemplarily, as shown in fig. 1, the secondary line conductor includes a convex structure, a length extending direction of a top of the convex structure coincides with a length extending direction of the main line conductor, and the top overlaps the main line conductor at a top view angle. The main line conductor adopts a microstrip line, and the auxiliary line conductor adopts a strip line. Usually, the main line conductor adopts a linear microstrip line structure, the length extending direction of the main line conductor is the connecting direction of the input port P1 and the through port P2, and the length extending direction of the top of the convex structure is the same as the connecting direction of the input port P1 and the through port P2, that is, the top of the convex structure of the main line conductor and the secondary line conductor is parallel. Furthermore, the upper left corner and the upper right corner of the second section of conductor and the turning part of the third section of conductor are designed by adopting a corner cutting structure.

In one embodiment, the secondary line conductor comprises a convex structure, as shown in fig. 1, the convex structure comprises a first section of conductor, a second section of conductor and a third section of conductor which are connected in sequence, wherein the second section of conductor is located between the first section of conductor and the third section of conductor, the first section of conductor and the third section of conductor are in mirror symmetry along a center line of the second section of conductor, the other end of the first section of conductor is provided with a coupling port P3, and the other end of the third conductor is provided with an isolation port P4. It should be understood that the division of the second conductor segment is not limited to the middle segment region which is the top of the convex structure, and in some other embodiments, the second conductor segment may also include two perpendicular segment regions which are 90 degrees from the middle segment region, and the like, and also have the mirror symmetry property.

It can be understood that the secondary line conductor and the main line conductor microstrip line are designed in a parallel overlapping mode, the coupling capacitance between the secondary line conductor and the main line conductor microstrip line is increased, namely, the capacitance at two coupling ends is increased, the difference of the even mode phase velocity and the odd mode phase velocity of the microstrip line can be compensated, the odd mode phase velocity and the even mode phase velocity are the same, the purpose of increasing the directivity is achieved, and the problem of the flatness of multi-frequency response can be solved. The auxiliary line conductor and the main line conductor form a rotary coupling structure by adopting a bending design, so that the amplitude-frequency characteristic of the output end can be kept flat in a band to obtain good frequency response selectivity, an angle is formed between the auxiliary line conductor and the main line conductor, the auxiliary line conductor adopts the rotary structure, and the discontinuity exists at the connection position between the auxiliary line conductor and the main line conductor, so that the amplitude of a signal reflected by the coupling port P3 is the same as that of a signal emitted by the input port P1 and leaked to the isolation port P4, the phase is opposite, the port power can be eliminated, and the directivity and the frequency response are improved greatly.

Further, the embedded multimode coupler further comprises: in a top view, distances from the top of the convex structure to two ends of the main line conductor are equal, that is, the convex structure is overlapped with the center of the main line conductor and symmetrically distributed at two ends of the center of the main line conductor, so that the coupling coefficient and the like can be further improved.

In this embodiment, the main line conductor and the sub line conductor have the same length and take a quarter wavelength of a central frequency point of the working frequency band. Exemplarily, if the in-line multi-mode coupler is used as a directional coupler, for example, the working frequency band is 2412-2482 MHz, the lengths of the main line conductor and the secondary line conductor may be a quarter wavelength corresponding to the center frequency point of 2412-2482 MHz. It will be appreciated that by multi-mode is meant that the coupler is capable of being adapted to a plurality of operating frequencies within the designed operating band.

Further, if the coupler is suitable for multiple working frequency bands, the length of the main line conductor and the auxiliary line conductor is a quarter wavelength of a central frequency point of the lowest working frequency band in the multiple available working frequency bands. For example, if the design frequency is 2412 to 2482MHz and 5180 to 5850MHz, the length of the coupler will be one-quarter wavelength of the center frequency point of the 2412 to 2482MHz band.

It will be appreciated that when the length of the coupler is one quarter wavelength of the operating signal, the phase difference between the through port P2 and the coupled port P3 is approximately 90 degrees, thereby improving the isolation between the input port P1 and the isolated port P4. In addition, the power of the signal coupled to the coupling port P3 is maximized, and the coupler has a small size and a low transmission loss.

Exemplarily, the input port P1 and the through port P2 will be used for connecting a load matched to the characteristic impedance of the main line conductor, respectively. For example, a load having a characteristic impedance of 50 ohms or the like may be directly connected. Of course, in some other embodiments, the in-line multimode coupler further comprises: the coupling capacitors located in the first layer, the input port P1 and the through port P2 are connected to corresponding coupling capacitors, respectively, and further, each coupling capacitor is used to connect to external objects such as other elements. Fig. 2 shows an equivalent circuit of an embedded multimode coupler. The inductance L1 is an equivalent inductance of the main line conductor microstrip line, the inductance L2 is an equivalent inductance of the sub line conductor microstrip line, the capacitance C4 and the capacitance C3 are equivalent coupling capacitances of the main line conductor and the sub line conductor, respectively, the capacitance C1 and the capacitance C2 are equivalent parasitic capacitances of the main line conductor and the reference ground, respectively, and the capacitance C5 and the capacitance C6 are equivalent parasitic capacitances of the sub line conductor and the reference ground, respectively. And TL1, TL2, TL3 and TL4 respectively represent characteristic impedance 50 ohm microstrip lines for connection with the respective ports of the coupler.

Further, the coupling port P3 and the isolation port P4 may be used to connect some compensating elements. Exemplarily, the coupling port P3 and the isolation port P4 of the in-line multi-mode coupler are respectively used for connecting an impedance-matched load through corresponding blind vias. For example, a load having an impedance of 50 ohms or the like may be directly connected. The parasitic capacitance generated by the blind hole can be used for compensating the parasitic reactance generated when the rotating coupling microstrip is rotated, so that the return loss of the port is improved.

Alternatively, in some other embodiments, the in-line multimode coupler further comprises: the coupling port P3 and the isolation port P4 are connected to the matching microstrip lines through corresponding blind holes, and each matching microstrip line is used for connecting an external object. For example, the matching microstrip line may be a microstrip line having a characteristic impedance of 50 ohms. For example, fig. 3 shows a schematic diagram of an application of a directional coupler. Wherein, the main line conductor and the auxiliary line conductor can be respectively connected with an equivalent load Z0 with characteristic impedance of 50 ohms at two ends.

It can be understood that the reserved element compensation of the coupling port P3 and the isolation port P4 can be used to adjust the reflection coefficient of the isolation port P4 to change the amplitude and phase of the reflected signal of the isolation port P4, so that the phase of the reflected signal is opposite to that of the signal of the input port P1, and the power cancellation effect is achieved. On the other hand, by utilizing the slope relation between the module value of the impedance of the resonant circuit and the frequency of the coupler, the module monotone reduction of the impedance is realized when the impedance deviates from a resonant frequency point by selecting a proper circuit topological structure, so that the amplitude-frequency characteristic of the output end of the directional coupler keeps flat and the bandwidth is expanded in a band, and the consistency and the stability of the microstrip line are further achieved.

In practice, the embedded multimode coupler is usually designed as a multilayer structure. For example, if the embedded multimode coupler has a three-layer structure, the substrate may further include a third layer stacked on the second layer, for example, a reference ground corresponding to the microstrip line is disposed on the third layer. For another example, if the embedded multimode coupler has a four-layer structure, for example, the substrate may further include a fourth layer stacked with the third layer, and the fourth layer may be exemplarily provided with a power ground, and the like. In one embodiment, as shown in fig. 4, the first layer D1 is a main line conductor layer, the second layer D2 is a sub line conductor layer, the third layer D3 is a microstrip line reference ground layer, and the fourth layer D4 is a power ground layer. It is understood that the microstrip reference ground layer and the power ground layer are only examples, and for the couplers with three or more layers, the structural design of the third layer and more layers can be set according to actual requirements.

Taking an embedded multimode coupler with a four-layer structure as an example, the two working frequency bands of the coupler are 2412-2482 MHz and 5180-5850 MHz, wherein the substrate is a common FR-4 material-grade copper-clad epoxy glass fiber cloth laminated board, the relative dielectric constant r of the laminated board is 4.5, and the dielectric loss is 0.022. By forming the in-line multimode coupler described above on the substrate, the physical size of the final coupler is only 1.2x0.5mm, which is a reduction of nearly 20% compared to the conventional coupler size. Fig. 5 a-5 i show simulated test curves for a plurality of S-parameters of a coupler, wherein the horizontal axes each represent the frequency of a signal tuning the coupler, the vertical axes of the curves represent different amplitudes or phases, and each m point on the curves is a frequency test point. Wherein S11 (corresponding to S (1,1) in fig. 5 a), S22 (corresponding to S (2,2) in fig. 5 b), S33 (corresponding to S (3,3) in fig. 5 c), and S44 (corresponding to S (4,4) in fig. 5 d) respectively represent parameters of the impedance matching performance of the ports P1, P2, P3, and P4 of the in-line multi-mode coupler; s21 (corresponding to S (2,1) in fig. 5 e) represents the insertion loss of the in-line multimode coupler; s31 (corresponding to S (3,1) in fig. 5 f) represents the degree of coupling of the in-line multimode coupler; s41 (corresponding to S (4,1) in fig. 5 g) represents the isolation of the in-line multimode coupler; d in fig. 5h represents the degree of orientation of the in-line multimode coupler; the ratio in fig. 5i represents the phase difference between the through port and the coupled port of the in-line multimode coupler. As can be seen from the simulation test curves shown in fig. 5a to 5i, the coupler has high directivity and good frequency response selectivity, the amplitude-frequency characteristic of the output end of the coupler is kept flat and wide frequency response in the band, the transmission loss is small, and the like.

The embedded multimode coupler provided by the embodiment has the advantages that the secondary line conductor and the main line conductor microstrip line are designed in a parallel overlapping mode, so that the coupling capacitance between the secondary line conductor and the main line conductor microstrip line is increased, the problems of directivity and multi-frequency response flatness of the coupler can be effectively solved, a wider coupling coefficient can be obtained, and the defects that the coupling coefficient is strong and the process is difficult in the conventional parallel coupling mode are overcome; and the secondary line conductor adopts the design of a rotary coupling main line conductor microstrip line, namely forms an angle with the main line conductor, so that the amplitude-frequency characteristic of the output end can be kept flat in a band, and wider frequency response selectivity is obtained, thereby improving the frequency response amplitude in the passband of a feedback signal, greatly improving the linearity of a radio frequency system, the system communication quality and the like.

The present application also proposes a radio frequency module exemplarily including the in-line multi-mode coupler and the like in embodiment 1 described above. In a wireless communication product, the embedded multi-mode coupler has the characteristics of wide frequency response, low insertion loss, good multi-frequency selectivity, good flatness in a pass band, high isolation, good directivity and the like.

The application also provides a communication device, such as a wireless telephone, a mobile phone and the like. The communication device exemplarily comprises the radio frequency module, wherein the radio frequency module comprises an embedded multi-mode coupler. By using the embedded multimode coupler structure, the problem of the traditional parallel coupler can be solved, and the signal linearization maximization is obtained in the application of a radio frequency closed loop system, so that the signal quality of the whole system is improved, and the like.

In all examples shown and described herein, any particular value should be construed as merely exemplary, and not as a limitation, and thus other examples of example embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

The above examples are merely illustrative of several embodiments of the present application, and the description is more specific and detailed, but not to be construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application.

Claims (10)

1. An embedded multimode coupler is characterized by comprising a substrate, wherein the substrate comprises a first layer and a second layer which are laminated, an input port, a through port and a main line conductor are arranged on the first layer, a coupling port, an isolation port and a secondary line conductor are arranged on the second layer, the input port and the through port are respectively connected with two ends of the main line conductor, the coupling port and the isolation port are respectively connected with two ends of the secondary line conductor, the secondary line conductor comprises a convex structure, the length extending direction of the top of the convex structure is consistent with the length extending direction of the main line conductor, and the top of the convex structure is overlapped with the main line conductor under a depression angle.

2. The in-line multimode coupler of claim 1 wherein the main line conductor and the secondary line conductor are of equal length and are of a quarter wavelength at a center frequency of an operating band.

3. The in-line multimode coupler of claim 2, further comprising: the length of the main line conductor and the length of the auxiliary line conductor are respectively a quarter wavelength of a central frequency point of the lowest working frequency band in the plurality of available working frequency bands.

4. The in-line multimode coupler according to any of claims 1-3, further comprising: and in a top view, the distance from the top of the convex structure to the two ends of the main line conductor is equal.

5. The in-line multimode coupler of claim 1, further comprising: the input port and the through port are respectively connected with the corresponding coupling capacitors, and each coupling capacitor is used for connecting an external object.

6. The in-line multimode coupler of claim 1 or 5, further comprising: and the coupling port and the isolation port are respectively connected to the corresponding matching microstrip lines through corresponding blind holes, and each matching microstrip line is used for connecting an external object.

7. The in-line multimode coupler of claim 1 wherein the main line conductor is a microstrip line and the secondary line conductor is a stripline.

8. The in-line multimode coupler of claim 7, wherein the substrate further comprises a third layer stacked with the second layer, the third layer being provided with a reference ground corresponding to a microstrip line.

9. A radio frequency module comprising the in-line multimode coupler of any of claims 1 to 8.

10. A communication device comprising the radio frequency module of claim 9.

Images