CN218448408U - Directional coupler - Google Patents
Directional coupler Download PDFInfo
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- CN218448408U CN218448408U CN202222518347.8U CN202222518347U CN218448408U CN 218448408 U CN218448408 U CN 218448408U CN 202222518347 U CN202222518347 U CN 202222518347U CN 218448408 U CN218448408 U CN 218448408U
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Abstract
The utility model relates to a directional coupler, directional coupler's surface is formed with conformal shielding layer except that the port pad, conformal shielding layer forms for conducting material. The directional coupler includes a directional coupler circuit including a primary transmission line, a first amplitude balancing network, a first isolation resistor, a first secondary transmission line and/or a second amplitude balancing network, a second isolation resistor, a second secondary transmission line. The utility model discloses an adopt conformal shielding design, under the prerequisite that need not shield cover or keep apart the chamber, reduce the interference between the external radiation interference of directional coupler and the adjacent device in the directional coupler, saved the processing and the equipment cost in shield cover or isolation chamber, reduced PCB's area and equipment inner space simultaneously.
Description
Technical Field
The utility model relates to a radio frequency circuit design field, more specifically relates to a directional coupler.
Background
The directional coupler is a radio frequency device widely used in radio frequency system, and its essence is to distribute the power of radio frequency signal according to a certain proportion, and couple out a part of the radio frequency signal transmitted in the main transmission line for power detection. The directional coupler is generally a four-port network, the first port is an input end, the second port is a straight-through end, and a transmission line between the first port and the second port is a main transmission line; the other transmission line is a sub-transmission line (i.e., a coupled line), a port of the sub-transmission line adjacent to the first port is a coupled end, and the other port is an isolated end.
The technical indexes of the directional coupler mainly include coupling degree, working bandwidth, insertion loss, flatness of the coupling degree and directivity. The prior art has the following defects: although the size of the coupled microstrip line directional coupler using miniaturization technology is small, when the coupled microstrip line directional coupler is integrated with a detection circuit, a shielding case or an isolation cavity is often required to be added to eliminate electromagnetic interference.
SUMMERY OF THE UTILITY MODEL
The present invention is directed to overcome at least one of the above-mentioned drawbacks (disadvantages) of the prior art, and provides a directional coupler for reducing the external radiation interference of the directional coupler and the interference between the adjacent devices in the directional coupler without a shielding case or an isolation cavity.
The utility model provides a technical scheme be, a directional coupler, directional coupler's surface is formed with conformal shielding layer except that the port pad.
The mode of adopting conformal shielding can effectively reduce the external radiation interference of directional coupler and the interference between inside adjacent device, need not to set up the shield cover in addition or keep apart the chamber simultaneously, has saved the processing and the assembly cost in shield cover or keep apart the chamber, has reduced PCB's area and equipment inner space simultaneously.
Further, the conformal shielding layer is formed of a conductive material. At present, the main flow processes of conformal shielding include three types of electroplating, spraying and sputtering, the used materials are conductive materials, and the conductive materials are metals with conductive effects. Optionally, the conductive material is copper-clad gold immersion.
Furthermore, the directional coupler comprises a directional coupler circuit, the directional coupler circuit comprises a main transmission line, a first amplitude equalization network, a first isolation resistor and a first auxiliary transmission line, two ports of the main transmission line are respectively an input port and a straight port of the directional coupler, and the main transmission line and the first auxiliary transmission line form a first coupling strip line; one end of the first amplitude equalization network is connected with the coupling end of the first coupling strip line, and the other end of the first amplitude equalization network is a first coupling port of the directional coupler; one end of the first isolation resistor is connected to the isolated end of the first coupling stripline, and the other end thereof is grounded.
The directional coupler is realized by adopting a coupling strip line and an amplitude equalization network, and the size of the directional coupler can be greatly reduced.
Further, the directional coupler circuit further comprises a second amplitude equalization network, a second secondary transmission line, and a second isolation resistor; the main transmission line and the second auxiliary transmission line form a second coupling strip line; one end of the second amplitude equalization network is connected with the coupling end of the second coupling strip line, and the other end of the second amplitude equalization network is a second coupling port of the directional coupler; one end of the second isolation resistor is connected to the isolated end of the second coupling stripline, and the other end is grounded.
The first amplitude balance network, the first isolation resistor, the first auxiliary transmission line and the main transmission line form a forward unidirectional coupler; the second amplitude balance network, the second isolation resistor, the second auxiliary transmission line and the main transmission line form a reverse single-directional coupler. The forward single directional coupler and the reverse single directional coupler share the main transmission line to form a double directional coupler, and can sample forward signals and reverse signals simultaneously.
Furthermore, the first amplitude balance network, the first auxiliary transmission line, the first isolation resistor, the second amplitude balance network, the second auxiliary transmission line and the second isolation resistor are arranged on two sides of the main transmission line in a centrosymmetric manner. The first coupling strip line and the second coupling strip line share one main transmission line, and the length of the main transmission line can be halved, so that the insertion loss of the main transmission line is reduced.
Further, the first amplitude equalization network and/or the second amplitude equalization network are/is an equalization network composed of lumped elements.
Further, the first amplitude equalization network comprises a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, an inductor L1, and an inductor L2; after the resistor R2 and the inductor L2 are connected in parallel, one end of the resistor R2 is connected with the first coupling port of the directional coupler, the other end of the resistor R2 is connected with one end of the inductor L1, one end of the capacitor C1 and one end of the capacitor C2 in series respectively, the other end of the inductor L1 is connected with the coupling end of the first coupling strip line, the other end of the capacitor C1 is grounded, the other end of the capacitor C2 is connected with one end of the resistor R1 in series, and the other end of the resistor R1 is grounded; and/or the second amplitude equalization network comprises a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, an inductor L3 and an inductor L4, wherein after the resistor R5 and the inductor L3 are connected in parallel, one end of the second amplitude equalization network is connected with the second coupling port of the directional coupler, the other end of the second amplitude equalization network is respectively connected with one ends of the inductor L3, the capacitor C3 and the capacitor C4 in series, the other end of the inductor L3 is connected with the coupling end of the second coupling strip line, the other end of the capacitor C3 is grounded, the other end of the capacitor C4 is connected with one end of the resistor R4 in series, and the other end of the resistor R4 is grounded.
Through reasonably configuring the resistance values of the resistors R1 and R2 in the equalization network, the capacitance values of the capacitor C1 and the capacitor C2 and the inductance values of the inductors L1 and L2, the transmission characteristic curve of the first amplitude equalization network can be changed according to a monotone decreasing rule, and then a signal acquired by the first coupling strip line is equalized by the first amplitude equalization network to finally obtain a flat output signal; by reasonably configuring the resistance values of the resistors R4 and R5 in the equalization network, the capacitance values of the capacitor C3 and the capacitor C4, and the inductance values of the inductors L3 and L4, the transmission characteristic curve of the second amplitude equalization network can be changed according to a monotone decreasing rule, and then the signal acquired by the second coupling stripline is equalized by the second amplitude equalization network to finally obtain a flat output signal.
Further, the resistor R1 and the resistor R4 have the same resistance value, the resistor R2 and the resistor R5 have the same resistance value, the first isolation resistor and the second isolation resistor have the same resistance value, the capacitor C1 and the capacitor C3 have the same capacitance value, the capacitor C2 and the capacitor C4 have the same capacitance value, the inductor L1 and the inductor L3 have the same inductance value, and the inductor L2 and the inductor L4 have the same inductance value. This setting can make the utility model discloses an index such as reverse unidirectional coupler that directional coupler formed is the same with unidirectional coupler's degree of coupling of forward, isolation, and this symmetrical structure has guaranteed no matter the flow direction of signal can both realize the same degree of coupling at the coupling end, keeps apart the end and realizes the same isolation.
Further, the first isolation resistor and/or the second isolation resistor is a fixed resistor. The forward unidirectional coupler and/or the reverse unidirectional coupler can obtain better directivity by preferably selecting the resistance value of the first isolation resistor and/or the second isolation resistor.
Compared with the prior art, the utility model, following advantage and beneficial effect have:
the utility model discloses a conformal shielding design, furthest reduces the coupler and disturbs to external radiation, reduces and adjacent device interference within a definite time, and the device is horizontal increases for zero with vertical size, has saved the processing and the assembly cost of shield cover, has reduced PCB's area and equipment inner space simultaneously.
Drawings
Fig. 1 is a circuit diagram of a directional coupler according to embodiment 1 of the present invention.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the invention. For a better understanding of the following embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
Example 1
The embodiment provides a directional coupler, wherein a conformal shielding layer is formed on the outer surface of the directional coupler except for a port pad; the conformal shielding layer is made of a conductive material; the conductive material is metal with a conductive effect. Optionally, the conductive material is copper-clad gold immersion.
Adopt conformal shielding's mode can effectively reduce the external radiation interference of directional coupler and the interference between inside adjacent device, need not to set up the shield cover in addition or keep apart the chamber simultaneously, saved the processing and the assembly cost in shield cover or keep apart the chamber, reduced PCB's area and equipment inner space simultaneously.
In the specific implementation process, the directional coupler can adopt a PCB (printed Circuit Board) and a device on the PCB is pasted, so that the whole production process is simple and the cost is low.
The directional coupler provided by the embodiment comprises a directional coupler circuit, wherein the directional coupler circuit comprises a main transmission line, a first amplitude equalization network, a first isolation resistor and a first auxiliary transmission line, two ports of the main transmission line are respectively an input port and a straight port of the directional coupler, and the main transmission line and the first auxiliary transmission line form a first coupling strip line; one end of the first amplitude equalization network is connected with the coupling end of the first coupling strip line, and the other end of the first amplitude equalization network is a first coupling port of the directional coupler; one end of the first isolation resistor is connected to the isolated end of the first coupling stripline, and the other end thereof is grounded.
The directional coupler circuit provided by the present embodiment further includes a second amplitude equalization network, a second isolation resistor, and a second secondary transmission line; the main transmission line and the second auxiliary transmission line form a second coupling strip line; one end of the second amplitude equalization network is connected with the coupling end of the second coupling strip line, and the other end of the second amplitude equalization network is a second coupling port of the directional coupler; one end of the second isolation resistor is connected to the isolated end of the second coupling stripline, and the other end thereof is grounded.
The first amplitude equalization network, the first isolation resistor, the first auxiliary transmission line and the main transmission line provided by the embodiment form a forward unidirectional coupler; the second amplitude balance network, the second isolation resistor, the second auxiliary transmission line and the main transmission line form a reverse single-directional coupler. The forward single directional coupler and the reverse single directional coupler are directly connected to form a double directional coupler, and the forward signal and the reverse signal can be sampled simultaneously.
The first amplitude balance network, the first auxiliary transmission line, the first isolation resistor, the second amplitude balance network, the second auxiliary transmission line, and the second isolation resistor provided in this embodiment are arranged on two sides of the main transmission line in a centrosymmetric manner, that is, symmetrically arranged on two sides of the main transmission line after being rotated 180 ° along the normal center of the main transmission line.
The first amplitude equalization network and the second amplitude equalization network are equalization networks formed by lumped elements. Specifically, as shown in fig. 1, the first isolation resistor is a resistor R3, and the second isolation resistor is a resistor R6. The first amplitude equalization network comprises a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, an inductor L1 and an inductor L2; after the resistor R2 and the inductor L2 are connected in parallel, one end of the resistor R2 is connected with the first coupling port of the directional coupler, the other end of the resistor R2 is connected with one end of the inductor L1, one end of the capacitor C1 and one end of the capacitor C2 in series respectively, the other end of the inductor L1 is connected with the coupling end of the first coupling strip line, the other end of the capacitor C1 is grounded, the other end of the capacitor C2 is connected with one end of the resistor R1 in series, and the other end of the resistor R1 is grounded; the second amplitude equalization network comprises a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, an inductor L3 and an inductor L4, wherein one end of the resistor R5 and the inductor L3 are connected in parallel and then connected with the second coupling port of the directional coupler, the other ends of the resistor R5 and the inductor L3 are respectively connected with one ends of the inductor L3, the capacitor C3 and the capacitor C4 in series, the other end of the inductor L3 is connected with the coupling end of the second coupling strip line, the other end of the capacitor C3 is grounded, the other end of the capacitor C4 is connected with one end of the resistor R4 in series, and the other end of the resistor R4 is grounded.
The resistor R1 and the resistor R4 have the same resistance value, the resistor R2 and the resistor R5 have the same resistance value, the first isolation resistor and the second isolation resistor have the same resistance value, the capacitor C1 and the capacitor C3 have the same capacitance value, the capacitor C2 and the capacitor C4 have the same capacitance value, the inductor L1 and the inductor L3 have the same inductance value, and the inductor L2 and the inductor L4 have the same inductance value. The arrangement can ensure that indexes such as coupling degree and isolation degree of the reverse single-directional coupler and the forward single-directional coupler formed by the directional coupler in the embodiment are the same, and the same coupling degree and isolation degree can be realized at the coupling end and the isolation end no matter the flow direction of signals.
The resistor R3 and the resistor R6 are fixed resistors, and the forward unidirectional coupler and the reverse unidirectional coupler can obtain better directivity by optimizing the resistance values of the resistor R3 and the resistor R6.
In a specific implementation process, the resistance values of the resistors R1 and R2 in the first amplitude equalization network, the capacitance values of the capacitor C1 and the capacitor C2, and the inductance values of the inductors L1 and L2 are reasonably configured, so that the transmission characteristic curve of the first amplitude equalization network can change according to a monotone decreasing rule, and further, a signal acquired by the first coupling stripline is equalized by the first amplitude equalization network to finally obtain a flat output signal; similarly, by reasonably configuring the resistance values of the resistors R4 and R5, the capacitance values of the capacitor C3 and the capacitor C4, and the inductance values of the inductors L3 and L4 in the second amplitude equalization network, the transmission characteristic curve of the second amplitude equalization network can be changed according to a monotonically decreasing rule, and then the signal acquired by the second coupling stripline is equalized by the second amplitude equalization network to finally obtain a flat output signal.
For a better understanding of the directional coupler of this embodiment, a specific example is further explained below:
in the directional coupler shown in fig. 1, the resistors R1 and R4 have a value of 12 Ω, the resistors R2 and R5 have a value of 150 Ω, the resistors R3 and R6 have a value of 100 Ω, the capacitors C1 and C3 have a value of 16.4pF, the capacitors C2 and C4 have a value of 15pF, the inductors L1 and L3 have a value of 100nH, and the inductors L2 and L4 have a value of 1500nH, and in the operating frequency range of 30MHz to 678MHz, the coupling degree of the directional coupler is 50dB, the flatness is not greater than ± 1dB, and the directivity is greater than 22dB, so that the overall structural size of the realized dual directional coupler is only 38.1mm × 25.4mm × 3.3mm, and the overall area of the PCB is greatly reduced.
Let Port1 be the input Port of the directional coupler, port2 be the straight Port of the directional coupler, port3 be the first coupling Port of the directional coupler, port4 be the second coupling Port of the directional coupler. The direction of signal transmission from Port1 input to Port2 is defined as forward direction, and the direction of signal transmission from Port2 input to Port1 is defined as reverse direction. In practical use, port1 is connected with a radio frequency output Port of a high-power broadband linear radio frequency power amplifier, and Port2 is connected with a radio frequency input Port of an antenna. When the transmission direction is forward, the sampling mechanism of the forward unidirectional coupler is as follows: when a high-power radio-frequency signal output by a radio-frequency power amplifier is input from a Port1 and transmitted to a Port2 along the main transmission line of the strip line, a first auxiliary transmission line of a first coupling strip line couples out a part of signal energy from the main transmission line through a coupling gap and transmits the signal energy to a first amplitude equalization network, and when the length of a coupling area is less than one tenth of the working wavelength, the amplitude-frequency characteristic curve of the coupled signal changes according to a monotone increasing rule; when the rf input Port of the antenna is reflected due to impedance mismatch, the reflected signal will be input from Port2, traveling along the main transmission line to Port 1. When the propagation direction is reverse, the sampling mechanism of the reverse unidirectional coupler is the same as that of the forward unidirectional coupler described above.
This concrete directional coupling of implementing has integrated passive component and has conformal shielding layer structure, adopts coupling stripline and amplitude balanced network to realize, reduces the size of coupler by a wide margin, simultaneously directional coupler can adopt PCB cloth board printed circuit, and the device adopts pastes dress, and production simple process, cost are lower, and the design furthest of conformal shielding layer reduces the coupler and disturbs to the external radiation, reduces with adjacent device between the interference, the device transversely with vertical size increase be zero, saved the processing and the assembly cost of shield cover, save PCB area and equipment inner space. Furthermore, the directional coupler is provided with a forward single directional coupler and a reverse single directional coupler, the forward single directional coupler and the reverse single directional coupler share the main transmission line to form a double directional coupler, and forward signals and reverse signals can be sampled simultaneously. Meanwhile, by arranging the structures of the components of the forward unidirectional coupler and the reverse unidirectional coupler, the indexes such as the coupling degree, the isolation degree and the like of the reverse unidirectional coupler and the forward unidirectional coupler are the same, the same coupling degree can be realized at the coupling end no matter the flow direction of a signal, and the same isolation degree can be realized at the isolation end.
It is obvious that the above embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, and are not limitations to the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims (10)
1. A directional coupler is characterized in that a conformal shielding layer is formed on the outer surface of the directional coupler except for a port pad.
2. A directional coupler according to claim 1, wherein said conformal shielding layer is formed of a conductive material.
3. A directional coupler according to claim 2, wherein said conductive material is copper clad immersion gold.
4. A directional coupler according to any one of claims 1 to 3, characterized in that said directional coupler comprises a directional coupler circuit, said directional coupler circuit comprising a main transmission line, a first amplitude equalizing network, a first isolating resistor and a first auxiliary transmission line, two ports of the main transmission line being an input port and a through port of said directional coupler, respectively, the main transmission line and the first auxiliary transmission line constituting a first coupled stripline; one end of the first amplitude equalization network is connected with the coupling end of the first coupling strip line, and the other end of the first amplitude equalization network is a first coupling port of the directional coupler; one end of the first isolation resistor is connected to the isolated end of the first coupling stripline, and the other end thereof is grounded.
5. A directional coupler according to claim 4, characterized in that said directional coupler circuit further comprises a second amplitude equalizing network, a second isolating resistor and a second secondary transmission line; the main transmission line and the second auxiliary transmission line form a second coupling strip line; one end of the second amplitude equalization network is connected with the coupling end of the second coupling strip line, and the other end of the second amplitude equalization network is a second coupling port of the directional coupler; one end of the second isolation resistor is connected to the isolated end of the second coupling stripline, and the other end is grounded.
6. A directional coupler according to claim 5, wherein said first amplitude equalizing network, first secondary transmission line, first isolation resistor and second amplitude equalizing network, second secondary transmission line, second isolation resistor are arranged on both sides of the primary transmission line in a centrosymmetric manner.
7. A directional coupler according to claim 5 or 6, characterised in that said first and/or said second amplitude equalising network is an equalising network formed from lumped elements.
8. A directional coupler according to claim 5 or 6, characterized in that said first amplitude equalizing network comprises a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, an inductor L1 and an inductor L2; after the resistor R2 and the inductor L2 are connected in parallel, one end of the resistor R2 is connected with the first coupling port of the directional coupler, the other end of the resistor R2 is connected with one end of the inductor L1, one end of the capacitor C1 and one end of the capacitor C2 in series respectively, the other end of the inductor L1 is connected with the coupling end of the first coupling strip line, the other end of the capacitor C1 is grounded, the other end of the capacitor C2 is connected with one end of the resistor R1 in series, and the other end of the resistor R1 is grounded;
and/or the second amplitude equalization network comprises a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, an inductor L3 and an inductor L4, wherein after the resistor R5 and the inductor L3 are connected in parallel, one end of the second amplitude equalization network is connected with the second coupling port of the directional coupler, the other end of the second amplitude equalization network is respectively connected with one ends of the inductor L3, the capacitor C3 and the capacitor C4 in series, the other end of the inductor L3 is connected with the coupling end of the second coupling strip line, the other end of the capacitor C3 is grounded, the other end of the capacitor C4 is connected with one end of the resistor R4 in series, and the other end of the resistor R4 is grounded.
9. A directional coupler according to claim 8, wherein the resistor R1 and the resistor R4 have the same resistance value, the resistor R2 and the resistor R5 have the same resistance value, the first isolation resistor and the second isolation resistor have the same resistance value, the capacitor C1 and the capacitor C3 have the same capacitance value, the capacitor C2 and the capacitor C4 have the same capacitance value, the inductor L1 and the inductor L3 have the same inductance value, and the inductor L2 and the inductor L4 have the same inductance value.
10. A directional coupler according to claim 5 or 6, characterized in that the first and/or second isolation resistor is a fixed resistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222518347.8U CN218448408U (en) | 2022-09-19 | 2022-09-19 | Directional coupler |
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| CN202222518347.8U CN218448408U (en) | 2022-09-19 | 2022-09-19 | Directional coupler |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117517769A (en) * | 2024-01-08 | 2024-02-06 | 深圳市瀚强科技股份有限公司 | Debug circuit, control method of debug circuit and radio frequency power detection circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117517769A (en) * | 2024-01-08 | 2024-02-06 | 深圳市瀚强科技股份有限公司 | Debug circuit, control method of debug circuit and radio frequency power detection circuit |
| CN117517769B (en) * | 2024-01-08 | 2024-04-09 | 深圳市瀚强科技股份有限公司 | Debug circuit, control method of debug circuit and radio frequency power detection circuit |
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