Lange coupler and receiver
By optimizing the transmission line and substrate structure in the Lange coupler, so that the phase difference between the through-end and coupling ends at the third harmonic is 90°±5°, the existing Lange coupler cannot effectively isolate the third harmonic reflection, and a better reflection third harmonic suppression effect is achieved.
Patent Information
- Application Number
- CN202420833990.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-22
- Publication Date
- 2025-03-25
- Estimated Expiration
- 2034-04-22
AI Technical Summary
The existing Lange coupler has large phase differences at the third harmonics, and the reflected waves cannot be effectively isolated and absorbed, resulting in unhelpful emission.
A Lange coupler is designed, with the phase difference between the triple frequency signal at the straight-through end and the triple frequency signal at the coupling end being 90°±5°. By optimizing the substrate material and transmission line structure, the difference in phase velocity between the parity modes is reduced and the isolation effect of reflected third harmonics is improved.
Effectively suppressing the reflection of the third harmonics, improving the reflection third harmonic suppression system of the Lange coupler, avoiding unhelpful emissions, and not reducing the sensitivity of the receiver.
Smart Images
Figure CN222673281U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of wireless communication technology, and in particular to a Lange coupler and a receiver. Background Art
[0002] The general structure of the currently commonly used balanced limiting low noise amplifier design is: the received signal is divided into two paths through a Lange coupler and input into two symmetrical limiting low noise amplifiers respectively, wherein the Lange coupler is in the form of a microstrip line, and the limiting low noise amplifier includes a limiter and a low noise amplifier.
[0003] When a high-power signal is input to a limiting low-noise amplifier through a receiving antenna, the PIN tube in the limiter and the amplifier tube in the low-noise amplifier (amplifier tube such as HEMT FET) will generate harmonics due to the nonlinearity of the PIN tube in the limiter and the amplifier tube in the low-noise amplifier, among which the third harmonic is the most serious.
[0004] The existing Lange coupler has a large phase difference at the third harmonic, and the reflected wave cannot be well absorbed by the isolation end, so it is reflected back to the input port, causing useless emission.
[0005] How to suppress the reflection of the third harmonic without reducing the sensitivity of the receiver is a technical problem to be solved by this application. Utility Model Content
[0006] The purpose of the present application is to provide a Lange coupler and a receiver to suppress the reflection of the third harmonic without reducing the receiving sensitivity.
[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions.
[0008] In a first aspect, an embodiment of the present application provides a Lange coupler, comprising a substrate and a transmission line; the transmission line is located on one side of the substrate or inside the substrate; the transmission line comprises a through end and a coupling end, and the Lange coupler is used to make the phase difference between the tripled frequency signal of the through end and the tripled frequency signal of the coupling end 90°±5°.
[0009] Optionally, the transmission line is located on one side of the substrate, and a relative dielectric constant of the substrate is less than 3.
[0010] Optionally, the substrate includes a first substrate and a second substrate; the Lange coupler further includes a first metal layer;
[0011] The first metal layer is located on the first surface of the first substrate, the transmission line is located on the second surface of the first substrate, and the second substrate is located on the second surface of the first substrate and covers the transmission line;
[0012] The second substrate and the first substrate have the same relative dielectric constant to reduce the difference in phase velocity between odd and even modes.
[0013] Optionally, the thickness of the second substrate is greater than or equal to the thickness of the first substrate.
[0014] Optionally, a second metal layer is provided on a side of the second substrate away from the first metal layer to form a stripline structure, and the first metal layer and the second metal layer prevent the coupled electric field between the stripline structure from being transmitted outside the stripline structure, so that the waveform transmitted by the transmission line is close to a transverse electromagnetic wave, thereby reducing the difference in phase velocity between odd and even modes.
[0015] Optionally, the Lange coupler further includes a connecting line layer, which is located between the first metal layer and the second metal layer and is not in the same plane as the transmission line; the connecting line layer and the transmission line are connected through a via to form a Lange bridge.
[0016] Optionally, the transmission line is made of a material having an electrical conductivity higher than or equal to that of gold.
[0017] Optionally, the transmission line includes a through-end transmission line and a coupled-end transmission line; the line width of the through-end transmission line and the line width of the coupled-end transmission line are designed asymmetrically so that the phase difference between the tripled frequency signal of the through-end and the tripled frequency signal of the coupled-end is 90°±5°.
[0018] Optionally, the line width of the through-end transmission line is greater than the line width of the coupled-end transmission line.
[0019] In a second aspect, an embodiment of the present application provides a receiver, comprising the Lange coupler described in the first aspect.
[0020] Compared with the prior art, this application has the following beneficial effects:
[0021] The Lange coupler provided in the embodiment of the present application has a phase difference of nearly 90° between the tripled frequency signal at the through end and the tripled frequency signal at the coupling end, so the reflected third harmonic can be better transmitted to the isolation end and thus absorbed by the isolation end, thereby improving Lange's reflected third harmonic suppression. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0023] Figure 1 A schematic diagram of ports and transmission lines of a Lange coupler in the prior art;
[0024] Figure 2 A schematic diagram of a Lange coupler provided in an embodiment of the present application;
[0025] Figure 3 A schematic diagram of a Lange coupler with a transmission line located inside a substrate provided in an embodiment of the present application;
[0026] Figure 4 A schematic diagram of a Lange coupler including a first substrate and a second substrate provided in an embodiment of the present application;
[0027] Figure 5 A schematic diagram of a Lange coupler with a stripline structure provided in an embodiment of the present application;
[0028] Figure 6 A schematic diagram of a Lange coupler with a connection line layer and vias provided in an embodiment of the present application;
[0029] Figure 7 A schematic diagram of a transmission line from a top view provided in an embodiment of the present application;
[0030] Figure 8 For along Figure 7 A schematic cross-sectional view of the first cross section in FIG.
[0031] Fig. 9 For along Figure 7 A schematic cross-sectional view taken along the second cross section or the third cross section;
[0032] Fig.10 A schematic diagram of an asymmetric transmission line provided in an embodiment of the present application.
[0033] Description of reference numerals:
[0034] 10 Substrate
[0035] 11. First substrate
[0036] 12. Second substrate
[0037] 20 Transmission Line
[0038] 21. Straight-through transmission line
[0039] 22 Coupled end transmission line
[0040] 30 First metal layer
[0041] 40 Second metal layer
[0042] 50 Connection line layer
[0043] 60 Vias
[0044] 701 First Section
[0045] 702 Second Section
[0046] 703 Third Section DETAILED DESCRIPTION
[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described in the drawings here can be arranged and designed in various different configurations.
[0048] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
[0049] In the description of this application, it should be noted that relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium.
[0050] Figure 1 The port and transmission line of a traditional Lange coupler are shown. The four ports are connected by a transmission line. The main design indicators are the line width, line spacing and line length of the transmission line. The line length is λ / 4. The input signal passes through the Lange coupler and is output from the through-end and the coupled end. Under the premise of achieving a 3dB coupling degree, the coupled end will also produce a phase difference that is 90° ahead of the through-end. According to the theoretical analysis of the coupler, as the frequency increases, at the triple frequency, the Lange coupler will still achieve a 3dB coupling degree, but the coupling end will change from leading by 90° to lagging by 90°, so the third harmonic generated by the limiter and the low noise amplifier will be synthesized at the isolation end after reflection, and thus have a better third harmonic suppression degree.
[0051] However, the above analysis assumes that the wave transmitted by the microstrip line is a transverse electromagnetic wave (TEM). When performing odd-mode and even-mode analysis, it is found that in the odd-mode state, the electric field will couple between the transmission lines, and there will be some electric field in the air, which leads to the equivalent dielectric constant in the odd-mode state being lower than that in the even-mode state, so the phase velocity between the odd-mode and the even-mode is different. At the fundamental wave, the line length is only λ / 4, and the influence of the different phase velocities between the odd-mode and the even-mode is not obvious, but as the frequency increases to the third frequency, the influence will become more obvious, and the following problems will occur: 1. The phase difference between the coupling end and the through end is no longer near 90°; 2. The isolation (directivity) of Lange becomes worse. As a result, the reflected third harmonic cannot be well absorbed by the isolation end, and the signal transmitted to the isolation end will also be coupled to the input end due to the poor isolation.
[0052] In order to suppress the reflection of the third harmonic without reducing the sensitivity of the receiver, the embodiment of the present application provides a Lange coupler, which can be found in Figure 2 , Figure 3 The present Lange coupler comprises a substrate 10 and a transmission line 20; the transmission line 20 may be located on one side of the substrate 10 such as Figure 2 , or may be located inside the substrate 10 such as Figure 3 The lower surface of the substrate may be provided with a first metal layer 30 as a ground plane.
[0053] The transmission line 20 includes a through end and a coupled end, and the Lange coupler is used to make the phase difference between the triple frequency signal at the through end and the triple frequency signal at the coupled end 90°±5°. Since the phase difference between the triple frequency signal at the through end and the triple frequency signal at the coupled end is close to 90°, the phase orthogonality of the through end and the coupled end during the triple frequency is optimized, and the reflected third harmonic can be better transmitted to the isolation end, thereby being absorbed by the isolation end, and improving the Lange's reflected third harmonic suppression.
[0054] In one embodiment, a material with a relatively small relative dielectric constant may be selected as the material of the substrate, for example, a material with a relative dielectric constant less than 3, so that the relative dielectric constant of the substrate is closer to the relative dielectric constant of air, such as Figure 2 , there is air above the transmission line 20, so that the difference in equivalent dielectric constant between odd and even modes is reduced, and the phase velocities of the two are closer, so the phase difference between the tripled frequency signal at the through end and the tripled frequency signal at the coupled end is also closer to 90°, so that the reflected third harmonic can be better transmitted to the isolation port.
[0055] Similarly, in another embodiment, a thicker substrate material may be coated on the surface of the transmission line 20, the goal of which is also to reduce the relative dielectric constant difference between the upper and lower portions of the transmission line 20, thereby reducing the phase velocity difference between the odd and even modes, and optimizing the phase orthogonality of the through end and the coupled end during frequency tripling, such as Figure 4 , the substrate 10 includes a first substrate 11 and a second substrate 12, the first metal layer 30 is located on the first surface of the first substrate 11, the transmission line 20 is located on the second surface of the first substrate 11, and the second substrate 12 is located on the second surface of the first substrate 11 and covers the transmission line 20; the second substrate 12 and the first substrate 11 have the same relative dielectric constant to reduce the difference in phase velocity between odd and even modes, and the phase difference between the triple frequency signal at the through end and the triple frequency signal at the coupling end is also closer to 90°, so that the reflected third harmonic can be better transmitted to the isolation port. The first substrate 11 and the second substrate 12 can be made of the same material. When the thickness of the second substrate 12 is greater than or equal to the thickness of the first substrate 11, it can better ensure that the difference in phase velocity between odd and even modes is small.
[0056] In addition, a material with higher conductivity, such as gold or a material with higher conductivity than gold, may be used as the material of the transmission line 20 . This can reduce the phase shift difference between odd and even modes on the one hand, and reduce loss and improve isolation on the other hand.
[0057] You can also Figure 4 On the basis of the second substrate 12, a second metal layer is provided on a side away from the first metal layer 30 to form a stripline structure, such as Figure 5 The first metal layer 30 and the second metal layer 40 can prevent the coupling electric field between the first metal layer 30 and the second metal layer 40 from being transmitted outside the stripline structure, and have a metal shielding effect, which can more thoroughly solve the problem of partial electric field in the air. Therefore, the waveform transmitted by the transmission line 20 is close to the transverse electromagnetic wave, the phase velocities of the odd and even modes of the stripline are the same, and the phase orthogonality at the triple frequency is better. In addition, this implementation method can make the stripline have no radiation loss.
[0058] exist Figure 5 On the basis of, a connection line layer can be set in the substrate, such as Figure 6 The connection line layer can be set on the first substrate or the second substrate. The connection line layer 50 is located between the first metal layer 30 and the second metal layer 40, and the connection line layer 50 and the transmission line 20 are not in the same plane.
[0059] The connection line layer 50 is used to connect with the transmission line 20 to form a Lange bridge. The connection line layer 50 and the transmission line 20 can be connected by way of a via 60 .
[0060] For the connection method of the Lange bridge, please refer to Figure 7 , Figure 8 and Fig. 9 , Figure 7 This is a schematic diagram of the transmission line from top view. Figure 8 is along Figure 7 A cross-sectional view of the first cross section 701 in FIG. Fig. 9 is along Figure 7 The cross-sectional view taken along the second cross-section 702 or the third cross-section 703 shows five transmission line cross-sections in the transmission line. It can be seen that by setting the shape of the connecting line layer 50 and the position of the via 60, various positions of the transmission line 20 can be connected to form a Lange bridge.
[0061] At this time, there are four metal layers: the upper and lower metal layers (the first metal layer 30 and the second metal layer 40) as the ground plane, and the middle connection line layer 50 and the transmission line 20. The substrate can be GaAs to form a dielectric bridge.
[0062] Figure 7 , Figure 8 and Fig. 9 The transmission line widths of the displayed transmission lines are symmetrical, that is, the transmission line widths are equal.
[0063] The following is an asymmetric transmission line design, refer to Fig.10 In this embodiment, there is no need for the second metal layer 40 or for the transmission line to be placed inside the substrate, nor is there any need to select a substrate material with a relatively small dielectric constant. Fig.10 The transmission line 20 includes a through-end transmission line 21 and a coupled-end transmission line 22; the line width W2 of the through-end transmission line and the line width W1 of the coupled-end transmission line are designed asymmetrically, so that the phase difference between the triple frequency signal at the through-end and the triple frequency signal at the coupled-end is 90°±5°. For example, the line width can be designed so that the line width W2 of the through-end transmission line is greater than the line width W1 of the coupled-end transmission line.
[0064] The design principle of the asymmetric transmission line is explained below.
[0065] In the design of traditional Lange couplers, the line widths of all transmission lines are the same and consistent. According to the odd-even mode analysis, the equivalent relative dielectric constant of the coupled path is smaller than the relative dielectric constant of the direct path. According to the phase shift velocity formula:
[0066]
[0067] Among them, V p is the phase shift speed, c is the speed of light, ε r is the relative dielectric constant. It can be seen that the phase shift speed of the coupling path is greater than that of the direct path.
[0068] At the fundamental frequency, the phase difference caused by this difference is not large, and the phase difference between the through-end and the coupled end remains close to the orthogonal phase; however, as the frequency increases to triple frequency, the phase difference introduced by the phase velocity difference significantly deteriorates the orthogonality between the through-end and the coupled end, so the third harmonic cannot be well synthesized to the isolated port.
[0069] According to the empirical formula of microstrip lines, different line widths have different equivalent RLC (resistance-capacitance-inductance value), and the equivalent dielectric constants corresponding to different line widths are also different, as shown in the formula:
[0070]
[0071] Among them, ε eff is the equivalent dielectric constant, w is the line width, and h is the substrate thickness.
[0072] It can be seen that the narrower the line width, the larger the equivalent dielectric constant, so the line width of the transmission line in the coupling path can be appropriately reduced to compensate for the low phase velocity at the coupling end. The specific line width size can be simulated and designed using electromagnetic simulation software.
[0073] Therefore, when adopting a design method with different line widths for the coupled path and the straight-through path, different line widths have different phase velocities, which can compensate for the phase difference at the triple frequency caused by the difference in phase velocity between odd and even modes, improve the phase difference at the third harmonic frequency, and optimize the orthogonality of the straight-through port and the coupled port.
[0074] Each feature in the above implementation can be used alone or in combination, which can effectively improve the reflection suppression of the Lange coupler at the third harmonic without deteriorating the receiving path noise.
[0075] Based on the above embodiments, an embodiment of the present application further provides a receiver, comprising the above-mentioned Lange coupler.
[0076] In general, the present application proposes a Lange coupler and a receiver. On the basis of not adding third harmonic suppression branches, the Lange coupler's own three-fold frequency signal at the through end and the three-fold frequency signal at the coupled end are orthogonal to achieve better reflected third harmonic suppression. This method does not increase additional insertion loss, and thus does not deteriorate the receiving path noise.
[0077] The above-described device and system embodiments are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. A person skilled in the art may understand and implement the present embodiment without creative effort.
[0078] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. A Lange coupler, characterized in that: It comprises a substrate and a transmission line; the transmission line is located on one side of the substrate or inside the substrate; the transmission line comprises a through end and a coupling end, and the Lange coupler is used to make the phase difference between the tripled frequency signal of the through end and the tripled frequency signal of the coupling end 90°±5°.
2. The Lange coupler according to claim 1, characterized in that The transmission line is located on one side of the substrate, and the relative dielectric constant of the substrate is less than 3.
3. The Lange coupler according to claim 1, characterized in that The substrate includes a first substrate and a second substrate; the Lange coupler also includes a first metal layer; The first metal layer is located on the first surface of the first substrate, the transmission line is located on the second surface of the first substrate, and the second substrate is located on the second surface of the first substrate and covers the transmission line; The second substrate and the first substrate have the same relative dielectric constant to reduce the difference in phase velocity between odd and even modes.
4. The Lange coupler according to claim 3, characterized in that The thickness of the second substrate is greater than or equal to the thickness of the first substrate.
5. The Lange coupler according to claim 3, characterized in that: A second metal layer is provided on one side of the second substrate away from the first metal layer to form a stripline structure. The first metal layer and the second metal layer prevent the coupled electric field between the stripline structure from being transmitted outside the stripline structure, so that the waveform transmitted by the transmission line is close to a transverse electromagnetic wave.
6. The Lange coupler according to claim 5, characterized in that The Lange coupler also includes a connecting line layer, which is located between the first metal layer and the second metal layer and is not in the same plane as the transmission line; the connecting line layer and the transmission line are connected through vias to form a Lange bridge.
7. The Lange coupler according to claim 1, characterized in that The transmission line is made of a material whose electrical conductivity is higher than or equal to that of gold.
8. The Lange coupler according to claim 1, characterized in that The transmission line includes a through-end transmission line and a coupled-end transmission line; the line width of the through-end transmission line and the line width of the coupled-end transmission line are designed asymmetrically so that the phase difference between the tripled frequency signal of the through-end and the tripled frequency signal of the coupled-end is 90°±5°.
9. The Lange coupler according to claim 8, characterized in that The line width of the through-end transmission line is greater than the line width of the coupled-end transmission line.
10. A receiver, characterized in that: A Lange coupler comprising any one of claims 1 to 9.