Microstrip directional coupler and radio frequency transmitting module

Abstract

The invention discloses a microstrip directional coupler and a radio frequency transmitting module, and the microstrip directional coupler comprises a dielectric substrate, a transmission microstrip line, a coupling microstrip line, a first filtering microstrip line, a second filtering microstrip line, a resistor, and a first ground layer. Wherein the transmission microstrip line, the coupling microstrip line, the first filtering microstrip line, the second filtering microstrip line, the resistor and the first ground layer are arranged on a first surface of the dielectric substrate; two ends of the transmission microstrip line are respectively provided with an input port and an output port; two ends of the coupling microstrip line are respectively provided with a coupling port and an isolation port, the isolation port is electrically connected with the first ground layer through the resistor, and the coupling microstrip line and the transmission microstrip line are arranged at an interval; the first filtering microstrip line is electrically connected with the position, close to the input port, of the transmission microstrip line; the second filtering microstrip line is electrically connected with the position, close to the output port, of the transmission microstrip line.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of wireless communication, and particularly relates to a microstrip directional coupler and a radio frequency transmitting module. BACKGROUND

[0002] With the rapid development of mobile communication technology, more and more terminal communication users have higher requirements for communication rate, and thus higher requirements are put forward for the design of a radio frequency system. In the transmitting module of the radio frequency system, a filter and a directional coupler are indispensable functional modules. The filter is mainly used to filter out harmonic components generated by a transmitting circuit to meet the authentication standards of various countries and regions. The directional coupler is mainly used to sample or shunt a radio frequency signal in a specified flow direction, and then a DPD (Digital Predistortion) compensation technology is used to ensure that the EVM (Error Vector Magnitude) index of the signal reaches the optimum and to improve the efficiency of a radio frequency PA (Power Amplifier).

[0003] In the related art, a filter and a directional coupler need to be separately arranged in the transmitting module of the radio frequency system to realize corresponding functions, and more materials are used and a larger area is occupied. SUMMARY

[0004] The application aims to provide a microstrip directional coupler and a radio frequency transmitting module, which can reduce the occupied area.

[0005] In a first aspect, the application discloses a microstrip directional coupler, which comprises a dielectric substrate, a transmission microstrip line, a coupling microstrip line, a first filter microstrip line, a second filter microstrip line, a resistor and a first ground layer. The transmission microstrip line, the coupling microstrip line, the first filter microstrip line, the second filter microstrip line, the resistor and the first ground layer are arranged on a first surface of the dielectric substrate. Two ends of the transmission microstrip line are respectively provided with an input port and an output port. Two ends of the coupling microstrip line are respectively provided with a coupling port and an isolation port. The isolation port is electrically connected to the first ground layer through the resistor. The coupling microstrip line is arranged at intervals with the transmission microstrip line. The first filter microstrip line is electrically connected to a position on the transmission microstrip line close to the input port. The second filter microstrip line is electrically connected to a position on the transmission microstrip line close to the output port.

[0006] In a second aspect, the application discloses a radio frequency transmitting module, which comprises the microstrip directional coupler of the first aspect.

[0007] The embodiment of the present application provides a microstrip directional coupler, which comprises a dielectric substrate, a transmission microstrip line, a coupling microstrip line, a first filter microstrip line, a second filter microstrip line, a resistor and a first ground layer, the transmission microstrip line, the coupling microstrip line, the first filter microstrip line, the second filter microstrip line, the resistor and the first ground layer are arranged on a first surface of the dielectric substrate, two ends of the transmission microstrip line are respectively provided with an input port and an output port, two ends of the coupling microstrip line are respectively provided with a coupling port and an isolation port, the isolation port is electrically connected to the first ground layer through the resistor, the coupling microstrip line is arranged at intervals with the transmission microstrip line, the first filter microstrip line is electrically connected to a position on the transmission microstrip line close to the input port, and the second filter microstrip line is electrically connected to a position on the transmission microstrip line close to the output port. Since the microstrip directional coupler of the present application has the functions of coupling and filtering at the same time, compared with the scheme in the related art that a filter and a directional coupler are separately arranged to realize the functions of filtering and coupling, the microstrip directional coupler of the present application can reduce the use of materials and the occupied area.

[0008] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0009] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which: Figure 1 A structure schematic diagram of a microstrip directional coupler disclosed by the embodiment of the present application; Figure 2 An equivalent circuit diagram of a microstrip directional coupler disclosed by the embodiment of the present application; Figure 3 A size schematic diagram of a microstrip directional coupler disclosed by the embodiment of the present application; Figure 4 A PCB laminated structure schematic diagram corresponding to a microstrip directional coupler disclosed by the embodiment of the present application; Figure 5 A coupling characteristic diagram of a coupling part in a microstrip directional coupler disclosed by the embodiment of the present application; Figure 6 A filter characteristic diagram of a filter part in a microstrip directional coupler disclosed by the embodiment of the present application. DETAILED DESCRIPTION

[0010] Embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are used for the purpose of explanation only, and are not to be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0011] The terms "first", "second" in the description and claims of the present application can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally means that the front and rear associated objects are in an "or" relationship.

[0012] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "connected" should be understood broadly, for example, it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0013] As shown in Figure 1 The present application discloses a microstrip directional coupler, which comprises a dielectric substrate 110, a transmission microstrip line 120, a coupling microstrip line 130, a first filter microstrip line 140, a second filter microstrip line 150, a resistance 160 and a first ground layer 170, wherein: the transmission microstrip line 120, the coupling microstrip line 130, the first filter microstrip line 140, the second filter microstrip line 150, the resistance 160 and the first ground layer 170 are arranged on the first surface of the dielectric substrate 110; both ends of the transmission microstrip line 120 are respectively provided with an input port 121 and an output port 122; both ends of the coupling microstrip line 130 are respectively provided with a coupling port 131 and an isolation port 132, the isolation port 132 is electrically connected with the first ground layer 170 through the resistance 160, and the coupling microstrip line 130 is arranged apart from the transmission microstrip line 120; the first filter microstrip line 140 is electrically connected with the position on the transmission microstrip line 120 close to the input port 121; and the second filter microstrip line 150 is electrically connected with the position on the transmission microstrip line 120 close to the output port 122.

[0014] In the present application, the input port 121 is on the same side as the coupling port 131, and the output port 122 is on the same side as the isolation port 132. The coupling port 131 feeds back the coupling signal to the chip. The resistance 160 can be 50 ohms.

[0015] The microstrip directional coupler of the present application comprises a directional coupling part and a filtering part, realizing the integrated design of filtering and coupling functions, wherein, Figure 1 The upper half part (including the coupling microstrip line 130 and the transmission microstrip line 120) is the directional coupling part, and the lower half part (including the transmission microstrip line 120, the first filtering microstrip line 140 and the second filtering microstrip line 150) is the filtering part. The directional coupling part and the filtering part share the transmission microstrip line 120.

[0016] The equivalent circuit of the directional coupling part is shown in the left half part of Figure 2 , which is equivalent to a coupler. The coupler comprises an input port 121, an output port 122, a coupling port 131 and an isolation port 132. The transmission microstrip line 120 is used as the main transmission line, and the coupling microstrip line 130 is used as the coupling transmission line. The transmission microstrip line 120 is used for transmitting radio frequency energy. The energy loss on the transmission microstrip line 120 is the insertion loss. The transmission characteristics of the transmission microstrip line 120 can be calculated according to the formula , wherein, and are the characteristic impedances of the even mode and the odd mode of the coupling microstrip line, respectively, and are the electrical lengths of the even mode and the odd mode of the coupling microstrip line, respectively, is the characteristic impedance of the port. The decibel value of the ratio of the power on the coupling port 131 to the power on the input port 121 is called the coupling degree, which can be calculated according to the formula . The calculated transmission characteristics and coupling degree can be used to obtain the characteristic impedance and length of the coupling microstrip line 130. With the aid of radio frequency simulation software, the required size of the coupling microstrip line 130 can be obtained. The decibel value of the ratio of the power on the isolation port 132 to the power on the input port 121 minus the coupling degree is called the directivity.

[0017] The equivalent circuit of the filtering part is shown in the right half part of Figure 2 , which is equivalent to a filter. The filter comprises an input port 121 and an output port 122. The transmission microstrip line 120 is used as the main transmission line and is equivalent to an inductor at the same time. The transmission microstrip line 120 is used for transmitting radio frequency energy. The energy loss on the transmission microstrip line 120 is the insertion loss. The transmission microstrip line impedance can be calculated according to the formula , wherein, is a constant, is the microstrip line length, is the characteristic impedance of the microstrip line, is the load impedance, the equivalent inductance value can be calculated by the calculated impedance point, and the required transmission microstrip line 120 size can be obtained by simulation with the assistance of radio frequency simulation software. is the load impedance, the equivalent inductance value can be calculated by the calculated impedance point, and the required transmission microstrip line 120 size can be obtained by simulation with the assistance of radio frequency simulation software.

[0018] The microstrip directional coupler provided by the embodiment of the present application includes a dielectric substrate 110, a transmission microstrip line 120, a coupling microstrip line 130, a first filter microstrip line 140, a second filter microstrip line 150, a resistor 160, and a first ground layer 170. The transmission microstrip line 120, the coupling microstrip line 130, the first filter microstrip line 140, the second filter microstrip line 150, the resistor 160, and the first ground layer 170 are arranged on the first surface of the dielectric substrate 110. The two ends of the transmission microstrip line 120 are respectively provided with an input port 121 and an output port 122. The two ends of the coupling microstrip line 130 are respectively provided with a coupling port 131 and an isolation port 132. The isolation port 132 is electrically connected to the first ground layer 170 through the resistor 160. The coupling microstrip line 130 is arranged apart from the transmission microstrip line 120. The first filter microstrip line 140 is electrically connected to the position on the transmission microstrip line 120 close to the input port 121. The second filter microstrip line 150 is electrically connected to the position on the transmission microstrip line 120 close to the output port 122. Since the microstrip directional coupler provided by the present application has both coupling and filtering functions, compared with the scheme in the related art in which a filter and a directional coupler are separately arranged to realize the filtering and coupling functions, the use of materials and the occupied area can be reduced by using the microstrip directional coupler provided by the present application. Moreover, no additional components are needed by using the scheme provided by the present application.

[0019] Compared with the scheme of using an LTCC (Low Temperature Cofired Ceramic) band-pass filter and an LTCC directional coupler, since the scheme provided by the present application uses a microstrip line design, no additional materials and material costs are increased. Compared with the scheme of using an LC filter and an LC directional coupler, since the scheme provided by the present application uses a microstrip line design, no additional materials are increased. Moreover, since the present application is a PCB wiring design, after the first debugging is completed, it can be applied to other products of the same type, and no subsequent debugging is needed. Compared with the scheme of using a microstrip filter and a microstrip directional coupler, the present application only needs to occupy one device area to realize the same function, and the area of the circuit board can be reduced.

[0020] In an implementation, as shown in Figure 1 and Figure 3 The two ends of the transmission microstrip line 120 can be respectively provided with protrusions 123, and the two ends of the coupling microstrip line 130 can be respectively provided with grooves 133 corresponding to the protrusions 123, which can improve the coupling degree and isolation degree. Exemplarily, the width and height of the protrusion 123 can be 0.15 mm.

[0021] In the embodiment of the present application, the microstrip directional coupler can further include a second ground layer, which is arranged on a second surface of the dielectric substrate 110, wherein the second surface is opposite to the first surface. The second ground layer is a reference ground layer.

[0022] In an implementation, the thickness of the dielectric substrate 110 can be 0.65 mil-8.65 mil. That is, the distance between the transmission microstrip line 120, the coupling microstrip line 130, the first filter microstrip line 140, the second filter microstrip line 150 and the second ground layer can be 0.65 mil-8.65 mil.

[0023] In an implementation, as shown in Figure 3 The length of the transmission microstrip line 120 can be 5 mm, the width of the transmission microstrip line 120 can be 0.2 mm, the distance between the transmission microstrip line 120 and the first ground layer 170 can be 0.2 mm, and the thickness of the transmission microstrip line 120 can be 1.4 mil-2.8 mil.

[0024] In an implementation, as shown in Figure 3 The length of the coupling microstrip line 130 can be 5 mm, the width of the coupling microstrip line 130 can be 0.4 mm, the distance between the coupling microstrip line 130 and the first ground layer 170 can be 0.2 mm, and the thickness of the coupling microstrip line 130 can be 1.4 mil-2.8 mil.

[0025] In an implementation, as shown in Figure 3 The length of the first filter microstrip line 140 can be 2 mm, the width of the first filter microstrip line 140 can be 0.45 mm, the distance between the first filter microstrip line 140 and the first ground layer 170 can be 0.2 mm, and the thickness of the first filter microstrip line 140 can be 1.4 mil-2.8 mil.

[0026] In an implementation, as shown in Figure 3As shown, the length of the second filter microstrip line 150 can be 2 mm, the width of the second filter microstrip line 150 can be 0.45 mm, the distance between the second filter microstrip line 150 and the first ground layer 170 can be 0.2 mm, and the thickness of the second filter microstrip line 150 can be 1.4 mil to 2.8 mil.

[0027] In one implementation, such as Figure 3 As shown, the coupling microstrip line 130 and the transmission microstrip line 120 can be spaced 0.1 mm apart.

[0028] The PCB (Printed Circuit Board) stack-up structure corresponding to the microstrip directional coupler of this application can be as follows: Figure 4 As shown, in the order from top to bottom, it includes a silkscreen layer, a solder mask layer, an L1 layer, a dielectric substrate, an L2 layer, a solder mask layer, and a silkscreen layer. The thickness of the solder mask layer can be 0.8-1.8 mil. The L1 layer includes a transmission microstrip line 120, a coupling microstrip line 130, a first filter microstrip line 140, a second filter microstrip line 150, a resistor 160, and a first ground layer 170. The thickness of L1 layer can be 1.4mil-2.8mil, the material of L1 layer can be 1 / 2OZ+Copper (electroplated), the thickness of dielectric substrate can be 4.65mil+ / -4mil, the material of dielectric substrate can be Core, the dielectric constant of dielectric substrate can be 4.2, L2 layer can be the second ground layer, the thickness of L2 layer can be 1.4mil-2.8mil, the material of L2 layer can be 1 / 2OZ+Copper (electroplated), and the total thickness of this PCB stack-up structure can be 1.2mm.

[0029] When the microstrip directional coupler of this application is configured with the parameters described above, the coupling characteristics of the coupling portion in the microstrip directional coupler can be as follows: Figure 5 As shown, the filtering characteristics of the filtering section in a microstrip directional coupler can be as follows: Figure 6 As shown.

[0030] It should be noted that the specific data mentioned above are all examples. The length, width, thickness of each microstrip line, the distance between it and the first ground layer 170, the thickness of the dielectric substrate 110, etc. can all be adjusted according to actual needs to obtain a microstrip directional coupler that meets the requirements.

[0031] The embodiment of the present application discloses a radio frequency transmitting module, which comprises the microstrip directional coupler described above. The radio frequency transmitting module comprises the microstrip directional coupler described above, and can simultaneously have the coupling and filtering functions, thereby reducing the use of materials and the occupied area.

[0032] It should be noted that the radio frequency transmitting module can be a transmitting module of a radio frequency system in a terminal.

[0033] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A microstrip directional coupler characterized by, The microstrip directional coupler comprises: a dielectric substrate, a transmission microstrip line, a coupling microstrip line, a first filtering microstrip line, a second filtering microstrip line, a resistor and a first ground layer, wherein: the transmission microstrip line, the coupling microstrip line, the first filtering microstrip line, the second filtering microstrip line, the resistor and the first ground layer are arranged on a first surface of the dielectric substrate; two ends of the transmission microstrip line are respectively provided with an input port and an output port; two ends of the coupling microstrip line are respectively provided with a coupling port and an isolation port, the isolation port is electrically connected to the first ground layer through the resistor, and the coupling microstrip line is arranged apart from the transmission microstrip line; the first filtering microstrip line is electrically connected to a position on the transmission microstrip line close to the input port; the second filtering microstrip line is electrically connected to a position on the transmission microstrip line close to the output port.

2. The microstrip directional coupler of claim 1, wherein, two ends of the transmission microstrip line are respectively provided with protrusions, and two ends of the coupling microstrip line are respectively provided with grooves corresponding to the protrusions.

3. The microstrip directional coupler of claim 1, wherein, The microstrip directional coupler further comprises a second ground layer arranged on a second surface of the dielectric substrate, wherein the second surface is opposite to the first surface.

4. The microstrip directional coupler of claim 3, wherein, The thickness of the dielectric substrate is 0.65 mil-8.65 mil.

5. The microstrip directional coupler of claim 1, wherein, The length of the transmission microstrip line is 5 mm, the width of the transmission microstrip line is 0.2 mm, the distance between the transmission microstrip line and the first ground layer is 0.2 mm, and the thickness of the transmission microstrip line is 1.4 mil-2.8 mil.

6. The microstrip directional coupler of claim 1, wherein, The length of the coupling microstrip line is 5 mm, the width of the coupling microstrip line is 0.4 mm, the distance between the coupling microstrip line and the first ground layer is 0.2 mm, and the thickness of the coupling microstrip line is 1.4 mil-2.8 mil.

7. The microstrip directional coupler of claim 1, wherein The length of the first filtering microstrip line is 2 mm, the width of the first filtering microstrip line is 0.45 mm, the distance between the first filtering microstrip line and the first ground layer is 0.2 mm, and the thickness of the first filtering microstrip line is 1.4 mil-2.8 mil.

8. The microstrip directional coupler of claim 1, wherein, The length of the second filtering microstrip line is 2 mm, the width of the second filtering microstrip line is 0.45 mm, the distance between the second filtering microstrip line and the first ground layer is 0.2 mm, and the thickness of the second filtering microstrip line is 1.4 mil-2.8 mil.

9. The microstrip directional coupler of claim 1, wherein, The coupling microstrip line is spaced apart from the transmission microstrip line by 0.1 mm.

10. A radio frequency transmit module, characterized by The microstrip directional coupler comprises any one of claims 1-9.

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