Directional coupler and radio frequency chip

Abstract

The utility model provides a directional coupler and a radio frequency chip, the directional coupler comprises a first microstrip line and a second microstrip line coupled with the first microstrip line, and two ends of the first microstrip line are respectively provided with a radio frequency input port and an antenna output port. Two ends of the second microstrip line are respectively provided with an isolation port and a coupling output port; the directional coupler further comprises a first filtering unit, a second filtering unit, a first inductor and a first resistor. The first end of the first filtering unit is respectively connected with the isolation port and the first end of the first inductor, the second end of the first inductor is grounded, the second end of the first filtering unit is connected with the first end of the first resistor, and the second end of the first resistor is grounded. According to the directional coupler provided by the utility model, the isolation and directivity of the coupler can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of wireless communications, in particular to a directional coupler and a radio frequency chip. Background Art

[0002] With the rapid development of the domestic economy, people's demand for consumer electronic products is increasing. As the core component of consumer electronic products, the performance of RF front-end chips directly affects the consumer experience. RF front-end chips mainly include power amplifiers (PA), filters, RF switches, and couplers. The main function of the coupler is to monitor the power of the RF signal input to the antenna. If the signal power is too low, feedback will be provided to increase the input power of the PA to ensure that the output power meets the requirements, thereby preventing the user's communication quality from being affected. If the signal power is detected to be too high, the input power of the PA will be reduced to prevent the device from being damaged due to excessive power. At the same time, it can reduce energy consumption and improve product endurance. As can be seen from the above, the quality of the coupler design has a huge impact on the performance of the product.

[0003] Currently, microstrip couplers are commonly used in consumer electronics, such as Figure 1 As shown in the figure, Port 3 is the signal input port. Port 4 is the signal output port, connected to the antenna. Port 1 is the coupling port, used to monitor signal power. Port 2 is the isolation port, typically connected to a 50Ω resistor and then to ground. Couplers generally have three important specifications: coupling coefficient, isolation coefficient, and directivity. The coupling coefficient is the ratio of the power at the coupling port to the power at the input port, the isolation coefficient is the ratio of the power at the isolation port to the power at the input port, and the directivity is the difference between the coupling coefficient and the isolation coefficient. Directivity is a key indicator of coupler performance. Traditional microstrip couplers typically have poor directivity. Even with optimized design or special circuitry, high directivity cannot be achieved over a wide bandwidth.

[0004] Therefore, the performance of the above-mentioned directional coupler is poor and the directivity improvement effect is low. Utility Model Content

[0005] In view of the above deficiencies in the prior art, the present invention proposes a directional coupler and a radio frequency chip to solve the problems of poor performance and low directivity improvement effect of the existing directional coupler.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a directional coupler, comprising a first microstrip line and a second microstrip line coupled to the first microstrip line, wherein the first microstrip line has an RF input port and an antenna output port at both ends, and the second microstrip line has an isolation port and a coupling output port at both ends; the directional coupler also comprises a first filtering unit, a second filtering unit, a first inductor and a first resistor; the first end of the first filtering unit is respectively connected to the isolation port and the first end of the first inductor, the second end of the first inductor is grounded, the second end of the first filtering unit is connected to the first end of the second filtering unit, the second end of the second filtering unit is connected to the first end of the first resistor, and the second end of the first resistor is grounded.

[0008] Preferably, the first filtering unit includes a second inductor and a first capacitor, the first end of the first capacitor is connected to the first end of the second inductor, the second end of the first capacitor is connected to the second end of the second inductor, the first end of the first capacitor serves as the first end of the first filtering unit, and the second end of the first capacitor serves as the second end of the first filtering unit.

[0009] Preferably, the second filtering unit includes a third inductor and a second capacitor, the first end of the third inductor is connected to the first end of the second capacitor, and the second end of the third inductor is connected to the second end of the second capacitor; the first end of the second capacitor serves as the first end of the second filtering unit, and the second end of the second capacitor serves as the second end of the second filtering unit.

[0010] Preferably, the directional coupler further includes a third capacitor, a first end of the third capacitor is connected between the first capacitor and the second capacitor, and a second end of the third capacitor is grounded.

[0011] In a second aspect, the present invention provides a radio frequency chip, which includes the above-mentioned directional coupler.

[0012] Compared with the related art, in an embodiment of the present invention, by providing an RF input port and an antenna output port at both ends of the first microstrip line, and providing an isolation port and a coupling output port at both ends of the second microstrip line; the directional coupler further includes a first filtering unit, a second filtering unit, a first inductor, and a first resistor; the first end of the first filtering unit is respectively connected to the isolation port and the first end of the first inductor, the second end of the first inductor is grounded, the first end of the first filtering unit is respectively connected to the isolation port and the first end of the first inductor, the second end of the first inductor is grounded, the second end of the first filtering unit is connected to the first end of the second filtering unit, the second end of the second filtering unit is connected to the first end of the first resistor, and the second end of the first resistor is grounded; adding the first filtering unit, the second filtering unit, the first inductor, and the first resistor to the isolation port can effectively suppress energy transmission to the isolation end within a wide bandwidth, improve isolation without changing the coupling degree, and thus improve directivity. In practical applications, surface mount devices (SMDs) can be reserved on the substrate, and optimal directivity can be achieved by optimizing the capacitance and inductance values ​​during actual debugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be described in detail below with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made with reference to the following drawings.

[0014] Figure 1 Schematic diagram of the structure of a traditional directional coupler;

[0015] Figure 2 for Figure 1 Schematic diagram of simulation results of coupling coefficient and isolation coefficient;

[0016] Figure 3 for Figure 1 Schematic diagram of simulation results of directivity coefficient;

[0017] Figure 4 This is a schematic structural diagram of a directional coupler according to an embodiment of the present utility model;

[0018] Figure 5 for Figure 4 Schematic diagram of simulation results of coupling coefficient and isolation coefficient;

[0019] Figure 6 for Figure 4 Schematic diagram of simulation results of the coupling coefficient and isolation coefficient of the adjusted capacitance and inductance;

[0020] Figure 7 for Figure 4 Schematic diagram of simulation results of the adjusted directivity coefficients of capacitance and inductance.

[0021] Among them, 100 is a directional coupler, 1 is a first microstrip line, 2 is a second microstrip line, 3 is a first filtering unit, and 4 is a second filtering unit. DETAILED DESCRIPTION

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of the application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0023] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example 1

[0026] See also Figure 4As shown, an embodiment of the present invention provides a directional coupler 100, which includes a first microstrip line 2 and a second microstrip line 3 coupled to the first microstrip line 2. The first microstrip line 2 is provided with a radio frequency input port (Port3) and an antenna output port (Port4) at both ends, and the second microstrip line 3 is provided with an isolation port (Port2) and a coupling output port (Port1) at both ends. The directional coupler 100 also includes a first filtering unit 3, a second filtering unit 4, a first inductor L1, and a first resistor R1. The first end of the first filtering unit 3 is connected to the isolation port and the first end of the first inductor L1, respectively, and the second end of the first inductor L1 is grounded. The second end of the first filtering unit 3 is connected to the first end of the second filtering unit 4, and the second end of the second filtering unit 4 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is grounded. By adding the first filtering unit 3, the second filtering unit 4, the first inductor L1, and the first resistor R1 to the isolation port, energy transmission to the isolation port can be effectively suppressed within a wide bandwidth, and the isolation degree is improved without changing the coupling degree, thereby improving the directivity. In practical applications, surface mount devices (SMDs) can be reserved on the substrate, and during the actual debugging process, optimal directionality can be achieved by optimizing the capacitance and inductance values.

[0027] In this embodiment, the first filtering unit 3 includes a second inductor L2 and a first capacitor C1. The first end of the first capacitor C1 is connected to the first end of the second inductor L2, and the second end of the first capacitor C1 is connected to the second end of the second inductor L2. The first end of the first capacitor C1 serves as the first end of the first filtering unit 3, and the second end of the first capacitor C1 serves as the second end of the first filtering unit 3. By adding the second inductor L2 and the first capacitor C1 after the isolation port of the directional coupler 100 to suppress energy transmission to the isolation port, the performance of the directional coupler 100 can be flexibly adjusted and its directivity and isolation can be improved. Furthermore, in practical applications, surface mount devices (SMDs) can be reserved on the substrate, and the values ​​of the first capacitor C1 and the second inductor L2 can be optimized during the debugging process to achieve optimal directivity.

[0028] In this embodiment, the second filtering unit 4 includes a third inductor L3 and a second capacitor C2. The first end of the third inductor L3 is connected to the first end of the second capacitor C2, and the second end of the third inductor L3 is connected to the second end of the second capacitor C2. The first end of the second capacitor C2 serves as the first end of the second filtering unit 4, and the second end of the second capacitor C2 serves as the second end of the second filtering unit 4. By adding the third inductor L3 and the second capacitor C2 after the first filtering unit 3 to suppress energy transmission to the isolated port, the performance of the directional coupler 100 can be flexibly adjusted and its directivity and isolation can be improved.

[0029] In this embodiment, the directional coupler 100 further includes a third capacitor C3 , a first end of the third capacitor C3 is connected between the first capacitor C1 and the second capacitor C2 , and a second end of the third capacitor C3 is grounded.

[0030] In this embodiment, in order to better reflect the performance of the utility model, a traditional coupler is first simulated. The basic structure of the coupler is as follows: Figure 1 As shown in the simulation results, Figure 2-Figure 3 As shown. S(3,1) is the coupling coefficient, and S(3,2) is the isolation coefficient. Calculations show that the directivity is 11.0dB (1.9GHz) and 7.5dB (2.6GHz). Usually, the performance of the coupler cannot be changed after the design is completed. If the measured performance cannot meet the requirements, it needs to be redesigned, which will cost a lot of time and manpower. Therefore, the present invention adds a second inductor L2 and a first capacitor C1 after the isolation end of the directional coupler 100 to flexibly adjust the performance of the directional coupler 100 to achieve the design goal. In addition, as Figure 3 As shown in the figure, the directivity coefficient of the traditional coupler is simulated. It can be seen that the directivity of the traditional microstrip coupler is poor, and the performance cannot be changed after the design is completed. If the measured performance cannot meet the requirements, redesign is required, which will not only increase the product cost, but also extend the product design cycle.

[0031] Secondly, the pad die reserved for the isolation port is connected to the substrate and a matching structure of the first inductor L1 and the first capacitor C1 is added to the substrate. The first capacitor C1, the second capacitor C2, the second inductor L2, and the third inductor L3 resonate to improve the isolation coefficient of the coupler without affecting the coupling coefficient of the coupler, thereby improving the directivity. The first capacitor C1 and the second inductor L2 resonate at the frequency point m1, hindering the transmission of signals near the 1.9GHz band to the isolation end, thereby improving the isolation coefficient of the coupler near the 1.9GHz band. Since the directivity is the difference between the coupling coefficient and the isolation coefficient, the directivity of the coupler near the 1.9GHz band is improved. Similarly, the second capacitor C2 and the third inductor L3 resonate at the frequency point m2, improving the directivity of the directional coupler 100 near the 2.6GHz band.

[0032] In addition, adjusting the first inductor L1 and the third capacitor C3 can improve the isolation coefficient within a wide frequency band, such as Figure 6 As shown in the figure, it can be seen that the isolation coefficient has been improved in a wide frequency band. Figure 5 and Figure 6It can be found that the minimum isolation coefficient before adjustment is 37.5dB and the maximum isolation coefficient is 65.3dB; after adjustment, the minimum isolation coefficient is 66.4dB and the maximum isolation coefficient is 111.6dB. The simulation results of the adjusted directivity coefficient are as follows Figure 7 Compared with the traditional microstrip coupler, it is found that after adding the circuit of the utility model, the directivity of the directional coupler 100 at 1.9GHz and 2.6GHz is 84.6dB and 83.8dB respectively. Figure 3 The directivity of the traditional dual microstrip line coupler in the test was improved by 73.6dB and 76.3dB. The directivity was significantly improved across the entire frequency band, proving the effectiveness of the circuit of the utility model.

[0033] As can be seen from the figure, adding a special matching structure after the isolation port after adding a band-stop filter can significantly improve the performance of the microstrip coupler, allowing for flexible debugging and reducing the risk of redesign. The isolation coefficient and directivity coefficient of the directional coupler 100 are significantly improved.

[0034] Example 2

[0035] The present invention provides a radio frequency chip, which includes the directional coupler 100 of the first embodiment. The technical problems solved and the technical effects produced by the radio frequency chip are the same as those of the directional coupler 100, and are not described in detail here.

[0036] It should be noted that the various embodiments described above with reference to the accompanying drawings are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Those skilled in the art should understand that any modifications or equivalent substitutions to the present invention that do not depart from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include the plural form, and vice versa. Furthermore, unless otherwise specified, all or part of any embodiment may be used in combination with all or part of any other embodiment.

Claims

1. A directional coupler comprising a first microstrip line and a second microstrip line coupled to the first microstrip line, wherein the first microstrip line has a radio frequency input port and an antenna output port at both ends thereof, and the second microstrip line has an isolation port and a coupling output port at both ends thereof; characterized in that: The directional coupler also includes a first filtering unit, a second filtering unit, a first inductor and a first resistor; the first end of the first filtering unit is respectively connected to the isolation port and the first end of the first inductor, the second end of the first inductor is grounded, the second end of the first filtering unit is connected to the first end of the second filtering unit, the second end of the second filtering unit is connected to the first end of the first resistor, and the second end of the first resistor is grounded.

2. The directional coupler according to claim 1, wherein The first filtering unit includes a second inductor and a first capacitor, the first end of the first capacitor is connected to the first end of the second inductor, the second end of the first capacitor is connected to the second end of the second inductor, the first end of the first capacitor serves as the first end of the first filtering unit, and the second end of the first capacitor serves as the second end of the first filtering unit.

3. The directional coupler according to claim 2, wherein: The second filtering unit includes a third inductor and a second capacitor, the first end of the third inductor is connected to the first end of the second capacitor, and the second end of the third inductor is connected to the second end of the second capacitor; the first end of the second capacitor serves as the first end of the second filtering unit, and the second end of the second capacitor serves as the second end of the second filtering unit.

4. The directional coupler according to claim 3, wherein The directional coupler further includes a third capacitor, a first end of the third capacitor is connected between the first capacitor and the second capacitor, and a second end of the third capacitor is grounded.

5. A radio frequency chip, characterized in that: The radio frequency chip includes the directional coupler according to any one of claims 1 to 4.

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