Coupler

Abstract

The invention relates to the technical field of wireless communication, and provides a coupler which comprises a substrate layer, a buried oxide layer, a first metal layer, a second metal layer and a third metal layer which are sequentially stacked and fixed. A main transmission line is formed on the third metal layer, the main transmission line is provided with a signal input end and a signal output end, the signal input end is used for accessing a radio frequency signal, and the signal output end is used for accessing an antenna; an auxiliary transmission line is formed on the first metal layer, the auxiliary transmission line is provided with a coupling end and an isolation end, and the main transmission line and the auxiliary transmission line form partial coupling and are coupled and output through the coupling end; the coupler further comprises a substrate, a monitoring circuit, a control circuit and an impedance matching circuit. The monitoring circuit is used for monitoring radio frequency signals output by the power amplifier, and the radio frequency signals are fed back to the power amplifier through the monitoring circuit after being subjected to impedance matching through the impedance matching circuit. The coupler disclosed by the invention is high in power amplifier monitoring precision and good in reliability.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more particularly to a coupler. Background Technology

[0002] In modern radio frequency and microwave systems such as wireless communication and radar detection, the power amplifier, as a core component for energy amplification, directly determines the communication quality, detection accuracy, and operational reliability of the entire system due to the stability of its operating state. To achieve precise control of the power amplifier, it is necessary to monitor its output power, operating efficiency, and load matching status (such as antenna VSWR) in real time. Directional couplers, as crucial non-intrusive sampling devices, are widely connected to the power amplifier output to extract small amounts of forward (output) and reverse (reflection) power signals, providing a precise signal source for the downstream monitoring circuitry. This is a core component for achieving closed-loop system control and fault early warning.

[0003] With the large-scale application of 5G communication technology, the high-frequency upgrade of industrial wireless communication, and the high-precision requirements of radar systems, the application scenarios of mid-to-high frequency band (1400MHz-3GHz) power amplifiers are becoming increasingly widespread, placing more stringent requirements on the performance indicators and integration characteristics of the matching monitoring couplers. However, existing directional coupler solutions still have many technical pain points in practical applications, making it difficult to meet the precise monitoring needs of modern broadband power amplifier systems. Specifically:

[0004] First, they have low integration and occupy a large space. Traditional monitoring couplers are mostly integrated using PCB substrates or dedicated dielectric substrates, resulting in loose device structures and a high area ratio in the RF front-end module. This is not conducive to the development of RF systems towards miniaturization and high-density integration, and makes them difficult to adapt to equipment scenarios with strict space constraints, such as 5G NR base stations and portable radar.

[0005] Secondly, significant directional fluctuations occur over a wide bandwidth. Directivity is a core indicator of a coupler's ability to distinguish between forward and reverse waves, directly determining the measurement accuracy of power and VSWR. While existing couplers (such as branch-line couplers and Lange couplers) can achieve relatively good performance at specific frequencies, directional fluctuations generally exceed 6dB in the 1400MHz-3GHz wideband range. This causes leakage of the forward signal at the reverse coupling end, severely interfering with the accuracy of forward sampling. Especially when the load impedance changes drastically (such as when the antenna shifts due to environmental influences), it can easily trigger false alarms or control malfunctions in the monitoring system.

[0006] Secondly, the insertion loss and temperature stability are poor. The insertion loss of conventional couplers is usually not less than 0.8dB. Excessive energy loss will reduce the overall output efficiency of the power amplifier and increase the system power consumption. At the same time, in the temperature range of -40℃ to 85℃ commonly seen in industrial scenarios, the coupling temperature drift can reach more than ±1.2dB, which is poor temperature adaptability and cannot maintain stable sampling performance in complex industrial environments such as alternating high and low temperatures and humid heat.

[0007] Finally, insufficient port isolation leads to weak anti-interference capability. The port isolation of existing products generally does not exceed 25dB, which is insufficient to effectively shield crosstalk from other RF signals within the system. This can easily cause distortion of monitoring data, affect the accurate judgment of the power amplifier's operating status, and thus reduce the operational reliability of the entire RF system.

[0008] Therefore, existing couplers have poor monitoring accuracy, poor directionality, and poor anti-interference capabilities. Summary of the Invention

[0009] To address the shortcomings of the existing technologies, this invention proposes a coupler to solve the problems of poor monitoring accuracy and poor directionality in existing couplers.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a coupler for monitoring the radio frequency signal output by a power amplifier. The coupler includes a substrate layer, a buried oxide layer, a first metal layer, a second metal layer, and a third metal layer stacked and fixed in sequence. The first metal layer has a first metal via through it, and the second metal layer has a second metal via through it. The first metal layer and the second metal layer are connected through the first metal via, and the second metal layer and the third metal layer are connected through the second metal via. A main transmission line is formed on the third metal layer. The main transmission line has a signal input terminal and a signal output terminal. The signal input terminal is used to receive the radio frequency signal, and the signal output terminal is used to connect to the antenna. A secondary transmission line is formed on the first metal layer. The secondary transmission line has a coupling terminal and an isolation terminal. The main transmission line and the secondary transmission line are partially coupled and output through the coupling terminal. The isolation terminal is used to isolate signal interference. The second metal layer serves as a same-layer jumper layer for the secondary transmission line. The coupler further includes a substrate, a detection circuit disposed on the substrate, a control circuit integrated with the coupling coil of the secondary transmission line, and an impedance matching circuit; the input terminal of the control circuit is connected to the coupling terminal and the isolation terminal respectively, the output terminal of the control circuit is connected to the input terminal of the impedance matching circuit and the monitoring circuit respectively, and the output terminal of the monitoring circuit is fed back to the input terminal of the power amplifier; the control circuit is used to control the conduction and disconnection of the monitoring circuit and the impedance matching circuit respectively; the monitoring circuit is used to monitor the radio frequency signal output by the power amplifier, and after impedance matching by the impedance matching circuit, the signal is fed back to the power amplifier through the monitoring circuit.

[0011] Preferably, the main transmission line includes a first microstrip line, a second microstrip line formed by vertically bending and extending one end of the first microstrip line, a third microstrip line and a fourth microstrip line formed by vertically bending and extending in opposite directions at the end of the second microstrip line away from the first microstrip line; the end of the first microstrip line away from the second microstrip line serves as the signal output terminal, and the end of the third microstrip line away from the fourth microstrip line serves as the signal input terminal; The secondary transmission line includes a first secondary transmission line in a ring shape, a second secondary transmission line extending along a portion of the outer periphery of the first secondary transmission line and spaced apart from each other, a jumper line connecting a first end of the first secondary transmission line and a first end of the second secondary transmission line, a coupling line connected to a second end of the first secondary transmission line, and an isolation line connected to a second end of the second secondary transmission line. Both the first and second auxiliary transmission lines are partially coupled to the main transmission line.

[0012] Preferably, the thickness of the first metal layer is 0.29um ± 0.05um; the thickness of the second metal layer is 0.32um ± 0.05um; and the thickness of the third metal layer is 4um ± 0.005um.

[0013] Preferably, the first microstrip line, the second microstrip line, the third microstrip line, and the fourth microstrip line are integrally formed into a T-shaped structure.

[0014] Preferably, the main transmission line has a four-segment gradient microstrip line structure, wherein the first microstrip line has a width of 40um±5um, the second microstrip line has a width of 20um±1um, the third microstrip line has a width of 45um±5um, and the fourth microstrip line has a width of 20um±5um.

[0015] Preferably, the width of the secondary transmission line is 6um ± 5um, and the distance between the secondary transmission line and the primary transmission line is 3um ± 1um.

[0016] Preferably, the area of ​​the sub-transmission line projected onto the main transmission line is 130 μm. 2 ~150um 2 .

[0017] Preferably, the control circuit includes a first switch, a second switch, a third switch, and a fourth switch; the output terminals of the first switch and the second switch are respectively connected to the coupling line, the control terminal of the first switch is connected to the input terminal of the monitoring circuit, the control terminal of the second switch is connected to the first terminal of the impedance matching circuit, and the second terminal of the impedance matching circuit is grounded; the output terminals of the third switch and the fourth switch are respectively connected to the isolation line, the control terminal of the third switch is connected to the third terminal of the impedance matching circuit, and the control terminal of the fourth switch is connected to the input terminal of the monitoring circuit.

[0018] Preferably, the impedance matching circuit includes a first resistor, a first capacitor, a second capacitor, and a second resistor; the first end of the first resistor is connected to the first end of the first capacitor, the first end of the second capacitor, and the first end of the second resistor, respectively; the second end of the first resistor is connected to the second end of the first capacitor, the second end of the second capacitor, and the second end of the second resistor, respectively; the first end of the first resistor is also connected to the control terminal of the second switch; and the first end of the second resistor is also connected to the control terminal of the third switch.

[0019] Preferably, the substrate layer is made of silicon, the buried oxide layer is made of an insulating material, the first metal layer is made of copper, the second metal layer is made of copper, and the third metal layer is made of aluminum.

[0020] Compared with related technologies, in the embodiments of the present invention, the coupling architecture of the mid-to-high frequency coupler is realized by sequentially stacking and fixing a substrate layer, a buried oxide layer, a first metal layer, a second metal layer, and a third metal layer; the first metal layer and the second metal layer are connected through a first metal via, and the second metal layer and the third metal layer are connected and interconnected through a second metal via; the mid-to-high frequency coupling is achieved through different metal layers of the secondary transmission line and the main transmission line; these coupling branches couple energy from the main transmission line through electromagnetic fields; due to the different projected areas and positions, the signals coupled out are in phase and superimposed at a specific port (such as the forward port), while canceling out phase at another port (such as the reverse port); the input of the control circuit... The input terminals are connected to the coupling terminal and the isolation terminal, respectively. The output terminal of the control circuit is connected to the input terminals of the impedance matching circuit and the monitoring circuit, respectively. The output terminal of the monitoring circuit is fed back to the input terminal of the power amplifier. The control circuit is used to control the conduction and disconnection of the monitoring circuit and the impedance matching circuit, respectively. The monitoring circuit is used to monitor the RF signal output by the power amplifier. After impedance matching by the impedance matching circuit, the signal is fed back to the power amplifier through the monitoring circuit. In this way, an adjustable impedance adjustment circuit is introduced at the circuit node of the secondary transmission line. It can be used to accurately compensate for the phase and amplitude errors caused by distributed parameters and boundary effects in a wide frequency range, and further suppress forward signal leakage on the reverse port, thereby significantly improving directivity in a wide frequency range. Attached Figure Description

[0021] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings: Figure 1 A schematic diagram of the multilayer structure of the coupler provided in an embodiment of the present invention; Figure 2 A three-dimensional structural diagram of the coupler provided in an embodiment of the present invention; Figure 3 A top view of the coupler provided in an embodiment of the present invention; Figure 4 The equivalent circuit diagram of the coupler provided in the embodiments of the present invention; Figure 5 This is a measured diagram of the directionality of the coupler on the module provided in an embodiment of the present invention; Figure 6 Temperature stability curve of coupling coefficient at 25°C for a coupler provided in an embodiment of the present invention; Figure 7 Temperature stability curve of coupling coefficient at 85°C for a coupler provided in an embodiment of the present invention; Figure 8 Temperature stability curve of coupling coefficient at -40℃ for a coupler provided in an embodiment of the present invention; Figure 9 The insertion loss curve of the coupler provided in the embodiment of the present invention.

[0022] Among them, 100 is the coupler, 1 is the substrate, 2 is the buried oxide layer, 3 is the first metal layer, 4 is the second metal layer, 5 is the third metal layer, 6 is the first metal via, 7 is the second metal via, 8 is the main transmission line, 81 is the first microstrip line, 82 is the second microstrip line, 83 is the third microstrip line, 84 is the fourth microstrip line, 9 is the sub-transmission line, 91 is the first sub-transmission line, 92 is the second sub-transmission line, 93 is the jumper line, 94 is the coupling line, 95 is the isolation line, 10 is the substrate, 11 is the control circuit, SW1 is the first switch, SW2 is the second switch, SW3 is the third switch, SW4 is the fourth switch, 12 is the impedance matching circuit, 13 is the monitoring circuit; and 20 is the power amplifier. Detailed Implementation

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figures 1-3As shown, this embodiment of the invention provides a coupler 100 for monitoring the radio frequency signal output by a power amplifier (PA). The coupler 100 includes a substrate layer 1, a buried oxide layer 2, a first metal layer 3, a second metal layer 4, and a third metal layer 5, which are sequentially stacked and fixed. The first metal layer 3 and the second metal layer 4 are connected through a first metal via 6, and the second metal layer 4 and the third metal layer 5 are connected through a second metal via 7. The third metal layer 5 is used for signal transmission, the second metal layer 4 is used for connecting and interconnecting the signals between the first metal layer 3 and the second metal layer 4, and the first metal layer 3 is used for signal coupling with the third metal layer 5. The mid-to-high frequency coupler 100 is fabricated using SOI (Silicon-On-Insulator) substrates with specific thickness ratios, specifically substrate layer 1, buried oxide layer 2, first metal layer 3, second metal layer 4, and third metal layer 5, applying specific thicknesses and materials for different metal layers. The second metal layer 4 serves as a transition layer, the third metal layer 5 with a gradually widened design serves as a through line, and the first metal layer 3 serves as the coupling line 94 of the coupler 100. The substrate layer 1 provides stable physical support for subsequent layers; the buried oxide layer 2 is an insulating layer that isolates the silicon substrate from the overlying metal circuitry, effectively reducing parasitic capacitance and signal loss. The first metal layer 3 is the coupling portion of the coupler 100, responsible for signal coupling; the second metal layer 4 serves as a transition layer, connecting signals between different layers and acting as a bridge for electrical interconnection; the third metal layer 5 is the through line layer of the coupler 100, featuring a gradually widened design, primarily responsible for transmitting the main signal. The first metal via 6 and the second metal via 7 are used to connect adjacent metal layers, enabling electrical conduction between layers.

[0027] A main transmission line 8 is formed on the third metal layer 5. The main transmission line 8 has a signal input terminal P1 and a signal output terminal P2. The signal input terminal P1 is used to receive the radio frequency signal, and the signal output terminal P2 is used to receive the antenna. A secondary transmission line 9 is formed on the first metal layer 3. The secondary transmission line 9 has a coupling terminal P3 and an isolation terminal P4. The main transmission line 8 and the secondary transmission line 9 are partially coupled and coupled through the coupling terminal P3. The isolation terminal P4 is used to isolate signal interference. The second metal layer 4 serves as a jump layer for the secondary transmission line 9. The coupling of the secondary transmission line 9 and the main transmission line 8 in the mid-to-high frequency band is achieved through different metal layers. These coupling branches couple energy from the main transmission line 8 through electromagnetic fields. Due to the different projected areas and positions, the signals coupled out of them are superimposed in phase at a specific port (such as the forward port) and canceled out in phase at another port (such as the reverse port). The second metal layer 4 serves as a jumper for the secondary transmission lines 9. When two secondary transmission lines 9 on the second metal layer 4 need to cross without touching at a certain point, the crossing problem is solved by jumping to connect other circuits or avoid unnecessary additional coupling areas. For example, a signal jumps from a point on a secondary transmission line 9 to the second metal layer 4 through the first metal via 6. On the second metal layer 4, this secondary transmission line 9 travels laterally for a distance, bypassing the main transmission line 8 on the upper third metal layer 5. After bypassing, the signal jumps to the third metal layer 5 through the second metal via 7 to continue its journey. This makes the whole process resemble an overpass structure, effectively avoiding conflicts caused by planar crossings and facilitating assembly.

[0028] Please combine them together Figure 4As shown, the coupler 100 further includes a substrate 10, a monitoring circuit 13 disposed on the substrate 10, a control circuit 11 integrated with the coupling coil of the secondary transmission line 9, and an impedance matching circuit 12; the input terminal of the control circuit 11 is connected to the coupling terminal P3 and the isolation terminal P4 respectively, the output terminal of the control circuit 11 is connected to the input terminal of the impedance matching circuit 12 and the monitoring circuit 13 respectively, and the output terminal of the monitoring circuit 13 is fed back to the input terminal of the power amplifier 20; the control circuit 11 is used to control the conduction and disconnection of the monitoring circuit 13 and the impedance matching circuit 12 respectively; the monitoring circuit 13 is used to monitor the radio frequency signal output by the power amplifier 20, and after impedance matching by the impedance matching circuit 12, the signal is fed back to the power amplifier 20 through the monitoring circuit 13. The equivalent capacitance C3, which couples the main transmission line 8 and the secondary transmission line 9, is crucial to the coupling coefficient of coupler 100. The partial coupling design between the secondary transmission line 9 and the main transmission line 8 significantly improves the isolation and directivity of coupler 100 under electromagnetic field effects, suppressing forward signal leakage at the reverse port. By employing a specific SOI stack-up process and integrating it within the frequency band selection switch, it has a small area, making it easy to integrate with the power amplifier 20 on the same substrate 10, resulting in a compact structure and ease of integration. Under normal operating conditions, the signal from the power amplifier 20 is input from the signal input terminal P1 of the main transmission line 8, and most of the energy is transferred to the load from the signal output terminal P2 of the main transmission line 8. A small portion of the energy is coupled to the secondary transmission line 9 through the coupling branch, where the impedance matching circuit 12 further absorbs and cancels any residual unbalanced signals, ensuring that the reverse coupling terminal P3 only responds with high sensitivity to the reverse signal reflected from the load.

[0029] Specifically, power amplifier 20 is mounted on substrate 10. The signal output from power amplifier 20 is transmitted via the transmit link to the signal input terminal P1 of coupler 100, and then via the straight-through line of coupler 100 to the signal output terminal P2. Part of the energy is coupled to the coupling terminal P3 via the main transmission line 8 and the secondary transmission line 9, and then fed back to the input terminal of power amplifier 20 by monitoring circuit 13 (Detector Electronics Corporation, DET) for monitoring of the transmit link signal. After impedance matching by adjusting impedance matching circuit 12, the energy leakage at isolation terminal P4 of coupler 100 is greatly suppressed, thereby ensuring that the reverse coupling terminal P3 only responds with high sensitivity to the reverse signal reflected from the load. Introducing an adjustable impedance adjustment circuit at the circuit node of secondary transmission line 9 can be used to accurately compensate for phase and amplitude errors caused by distributed parameters and boundary effects over a wide frequency range, further suppressing forward signal leakage at the reverse port, thereby significantly improving directivity over a wide frequency range. Meanwhile, through multi-segment coupling and active compensation technology, a directivity exceeding 25dB is achieved in a wide frequency range from 1400MHz to 3GHz, ensuring high accuracy in power and VSWR monitoring. Furthermore, the high directivity minimizes the impact of load impedance variations on the coupler 100 readings, improving the robustness and reliability of the monitoring system. In addition, this coupler 100 is highly suitable for various mid-to-high frequency power amplifier 20 systems requiring closed-loop control of output power or real-time monitoring and protection of antenna VSWR.

[0030] In this embodiment, the main transmission line 8, the secondary transmission line 9, the control circuit 11, and the impedance matching circuit 12 are integrated on the same chip using SOI (Silicon-On-Insulator Integration), resulting in good integration performance.

[0031] The main transmission line 8 and the secondary transmission line 9 are conductors of a certain length. When radio frequency current flows through them, a magnetic field is generated around the conductors, storing magnetic energy and inducing an electromotive force, thus forming an inductance effect. Specifically, the equivalent inductance of the main transmission line 8 is the first inductance L1, and the equivalent inductance of the secondary transmission line 9 is the second inductance L2. The equivalent capacitance C3 of the coupling between the main transmission line 8 and the secondary transmission line 9 represents the energy coupling effect of the two transmission lines through the electric field. Together with the equivalent inductance, it describes the electromagnetic coupling characteristics of the coupler.

[0032] In this embodiment, the main transmission line 8 includes a first microstrip line 81, a second microstrip line 82 formed by vertically bending one end of the first microstrip line 81, a third microstrip line 83 formed by vertically bending the end of the second microstrip line 82 away from the first microstrip line 81 and extending in opposite directions, and a fourth microstrip line 84. The end of the first microstrip line 81 away from the second microstrip line 82 serves as the signal output terminal P2, and the end of the third microstrip line 83 away from the fourth microstrip line 84 serves as the signal input terminal P1. The main transmission line 8 features four segments with varying widths, achieving minimal insertion loss for the coupler 100 and optimal impedance matching between the through-line and the frequency band selection switch, significantly improving the isolation and directivity of the coupler 100. The design of the second microstrip line 82 greatly enhances the overall isolation performance of the coupler 100, while the fourth microstrip line 84 is used to adjust the impedance information of the frequency band switch connected to the coupler 100.

[0033] The secondary transmission line 9 includes a first secondary transmission line 91 in a ring shape, a second secondary transmission line 92 extending along a portion of the outer periphery of the first secondary transmission line 91 and spaced apart from each other, a jumper line 93 connecting the first end of the first secondary transmission line 91 and the first end of the second secondary transmission line 92, a coupling line 94 connected to the second end of the first secondary transmission line 91, and an isolation line 95 connected to the second end of the second secondary transmission line 92. Both the first secondary transmission line 91 and the second secondary transmission line 92 are partially coupled to the main transmission line 8. By encircling the first secondary transmission line 91 and the second secondary transmission line 92, the projected area of ​​the secondary transmission line 9 and the main transmission line 8 is increased, improving coupling performance. The jumper line 93 enables a two-turn coil configuration for the first secondary transmission line 91 and the second secondary transmission line 92, which greatly improves the isolation and directivity performance of the coupler 100 under electromagnetic field effects, suppressing leakage of the forward signal on the reverse port. The jumper line 93 is positioned closer to the main transmission line 8 and spaced apart from it.

[0034] In this embodiment, the thickness of the first metal layer 3 is 0.29um ± 0.05um; the thickness of the second metal layer 4 is 0.32um ± 0.05um; and the thickness of the third metal layer 5 is 4um ± 0.005um. This thickness setting results in a compact overall structure that is easy to integrate.

[0035] In this embodiment, the first microstrip line 81, the second microstrip line 82, the third microstrip line 83, and the fourth microstrip line 84 are integrally formed in a chi-shape. By forming the main transmission line 8, more coupling is achieved between the main transmission line 8 and the secondary transmission line 9, and the overall lateral area of ​​the coupler 100 is also reduced. The four microstrip lines, namely the first microstrip line 81, the second microstrip line 82, the third microstrip line 83, and the fourth microstrip line 84, are different segments of this chi-shape structure. They are integrally formed in one piece without welding or splicing, resulting in better continuity.

[0036] In this embodiment, the main transmission line 8 is a four-segment tapered microstrip line structure. The first microstrip line 81 has a width of 40µm ± 5µm, the second microstrip line 82 has a width of 20µm ± 1µm, the third microstrip line 83 has a width of 45µm ± 5µm, and the fourth microstrip line 84 has a width of 20µm ± 5µm. By appropriately setting the width dimensions of the first microstrip line 81, the second microstrip line 82, the third microstrip line 83, and the fourth microstrip line 84, the overall coupling performance and directivity can be improved. The 20µm narrow line can anchor high-precision coupling, control parasitics, and achieve impedance transition. The 40 / 45µm wide lines can achieve low-loss matching, improve coupling strength, and ensure signal integrity.

[0037] In this embodiment, the width of the secondary transmission line 9 is 6um ± 5um, and the distance between the secondary transmission line 9 and the main transmission line 8 is 3um ± 1um.

[0038] In this embodiment, the area of ​​the orthographic projection of the secondary transmission line 9 onto the main transmission line 8 is 130 μm. 2 ~150um 2 At this area, under electromagnetic field effects, the isolation and directivity performance of coupler 100 are greatly improved, and leakage of forward signals on the reverse port is suppressed. Preferably, the area of ​​the sub-transmission line 9 projected onto the main transmission line 8 is 140 μm. 2 Coupler 100 achieves optimal isolation and directivity performance. The partial projection of the combined and straight-through lines significantly improves isolation. The extension of coupling line 94 and isolation terminal P4 connects perfectly with the other selector switches without affecting the performance of coupler 100.

[0039] In this embodiment, the control circuit 11 includes a first switch SW1, a second switch SW2, a third switch SW3, and a fourth switch SW4. The output terminals of the first switch SW1 and the second switch SW2 are respectively connected to the coupling line 94. The control terminal of the first switch SW1 is connected to the input terminal of the monitoring circuit 13. The control terminal of the second switch SW2 is connected to the first terminal of the impedance matching circuit 12, and the second terminal of the impedance matching circuit 12 is grounded. The output terminals of the third switch SW3 and the fourth switch SW4 are respectively connected to the isolation line 95. The control terminal of the third switch SW3 is connected to the third terminal of the impedance matching circuit 12, and the control terminal of the fourth switch SW4 is connected to the input terminal of the monitoring circuit 13. The impedance matching magnitude and connection can be controlled by the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4. When the first switch SW1 and the fourth switch SW4 are turned on, and the second switch SW2 and the third switch SW3 are turned off, the coupled signal of the coupler 100 is directly transmitted to the monitoring circuit 13 through the secondary transmission line 9. The monitoring circuit 13 then feeds back the signal to the power amplifier 20, thereby ensuring that the reverse coupling terminal P3 only responds with high sensitivity to the reverse signal reflected from the load. When all four switches SW4 are turned on, the frequency band selection switch of the coupler 100 and the output circuit of the coupler 100 are switched. The impedance matching circuit 12 ensures that the access port has no significant impact on the coupler 100. In the design, the second metal layer is used for four-fold access. The impedance matching circuit 12 is implemented by adjustable resistors and adjustable capacitors, resulting in good impedance matching effect.

[0040] In this embodiment, the impedance matching circuit 12 includes a first resistor R1, a first capacitor C1, a second capacitor C2, and a second resistor R2. The first end of the first resistor R1 is connected to the first ends of the first capacitor C1, the second capacitor C2, and the second resistor R2, respectively. The second end of the first resistor R1 is connected to the second ends of the first capacitor C1, the second capacitor C2, and the second resistor R2, respectively. The first end of the first resistor R1 is also connected to the control terminal of the second switch SW2, and the first end of the second resistor R2 is also connected to the control terminal of the third switch SW3. By adjusting the values ​​of the first resistor R1, the second resistor R2, the first capacitor C1, and the second capacitor C2, the impedance of the impedance matching circuit 12 can be adjusted, thereby greatly suppressing the energy leakage at the isolation terminal P4. This ensures that the reverse coupling terminal P3 only responds with high sensitivity to the reverse signal reflected from the load, resulting in high monitoring accuracy.

[0041] In this embodiment, the substrate layer 1 (Silicon) is made of silicon material, the buried oxide layer 2 (BOX) is made of insulating material, the first metal layer 3 is made of copper (Cu) material, the second metal layer 4 is made of copper (Cu) material, and the third metal layer 5 is made of aluminum (Al) material.

[0042] In this embodiment, Figure 5 This is a measured diagram of the directivity of the coupler 100 of this invention on a module. The diagram shows that in the SUB3G high-frequency band (1400MHz-3GHz), the port isolation is greater than or equal to 25dB, making it less susceptible to interference from other RF signals within the system and improving monitoring accuracy. Figure 6-8 This is a temperature stability curve of the coupling coefficient of the coupler 100 of the present invention. It can be seen that the coupler 100 of the present invention has a temperature drift of ≥±0.3dB from -40℃ to 85℃, which is a great advantage in temperature stability.

[0043] like Figure 9 This is an insertion loss curve of the coupler 100 of the present invention. The insertion loss of the coupler 100 of the present invention is within 0.05dBm, which has a minimal impact on the output efficiency of the power amplifier 20 in the overall system.

[0044] In summary, the coupler 100 of the present invention achieves mid-to-high frequency coupling through different metal layers of the secondary transmission line 9 and the main transmission line 8. These coupling branches couple energy from the main transmission line 8 through electromagnetic fields. Due to the different upper and lower projected areas and positions, the signals coupled out of them are superimposed in phase at a specific port and canceled out in phase at the other port. The first end of the first capacitor C1 is connected to the main transmission line 8, and the second end of the first capacitor C1 is connected to the secondary transmission line 9. The input terminal of the control circuit 11 is connected to the coupling terminal P3 and the isolation terminal P4, respectively. The output terminal of the control circuit 11 is connected to the input terminal of the impedance matching circuit 12 and the monitoring circuit 13, respectively. The output of 3 is fed back to the input of the power amplifier 20; the control circuit 11 is used to control the conduction and disconnection of the monitoring circuit 13 and the impedance matching circuit 12 respectively; the monitoring circuit 13 is used to monitor the RF signal output by the power amplifier 20, and after impedance matching by the impedance matching circuit 12, it is fed back to the power amplifier 20 through the monitoring circuit 13; thus, by introducing an adjustable impedance adjustment circuit at the circuit node of the sub-transmission line 9, it can be used to accurately compensate for the phase and amplitude errors caused by distributed parameters and boundary effects in a wide frequency band, further suppress the forward signal leakage on the reverse port, thereby significantly improving the directivity in a wide frequency range.

[0045] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. A coupler for monitoring the radio frequency signal output by a power amplifier, characterized in that, The coupler includes a substrate layer, a buried oxide layer, a first metal layer, a second metal layer, and a third metal layer stacked and fixed in sequence. The first metal layer has a first metal via through it, and the second metal layer has a second metal via through it. The first metal layer and the second metal layer are connected through the first metal via, and the second metal layer and the third metal layer are connected through the second metal via. A main transmission line is formed on the third metal layer. The main transmission line has a signal input terminal and a signal output terminal. The signal input terminal is used to receive the radio frequency signal, and the signal output terminal is used to connect to the antenna. A secondary transmission line is formed on the first metal layer. The secondary transmission line has a coupling terminal and an isolation terminal. The main transmission line and the secondary transmission line are partially coupled and output through the coupling terminal. The isolation terminal is used to isolate signal interference. The second metal layer serves as a same-layer jumper layer for the secondary transmission line. The coupler further includes a substrate, a monitoring circuit disposed on the substrate, a control circuit integrated with the coupling coil of the secondary transmission line, and an impedance matching circuit; the input terminal of the control circuit is connected to the coupling terminal and the isolation terminal respectively, the output terminal of the control circuit is connected to the input terminal of the impedance matching circuit and the monitoring circuit respectively, and the output terminal of the monitoring circuit is fed back to the input terminal of the power amplifier; the control circuit is used to control the conduction and disconnection of the monitoring circuit and the impedance matching circuit respectively; the monitoring circuit is used to monitor the radio frequency signal output by the power amplifier, and after impedance matching by the impedance matching circuit, the signal is fed back to the power amplifier through the monitoring circuit.

2. The coupler according to claim 1, characterized in that, The main transmission line includes a first microstrip line, a second microstrip line formed by vertically bending and extending one end of the first microstrip line, a third microstrip line and a fourth microstrip line formed by vertically bending and extending in opposite directions at the end of the second microstrip line away from the first microstrip line; the end of the first microstrip line away from the second microstrip line serves as the signal output terminal, and the end of the third microstrip line away from the fourth microstrip line serves as the signal input terminal. The secondary transmission line includes a first secondary transmission line in a ring shape, a second secondary transmission line extending along a portion of the outer periphery of the first secondary transmission line and spaced apart from each other, a jumper line connecting a first end of the first secondary transmission line and a first end of the second secondary transmission line, a coupling line connected to a second end of the first secondary transmission line, and an isolation line connected to a second end of the second secondary transmission line. Both the first and second auxiliary transmission lines are partially coupled to the main transmission line.

3. The coupler according to claim 2, characterized in that, The thickness of the first metal layer is 0.29um ± 0.05um; the thickness of the second metal layer is 0.32um ± 0.05um; and the thickness of the third metal layer is 4um ± 0.005um.

4. The coupler according to claim 2, characterized in that, The first microstrip line, the second microstrip line, the third microstrip line, and the fourth microstrip line are integrally formed into a χ-shaped structure.

5. The coupler according to claim 2, characterized in that, The main transmission line has a four-segment gradient microstrip line structure, wherein the first microstrip line has a width of 40um±5um, the second microstrip line has a width of 20um±1um, the third microstrip line has a width of 45um±5um, and the fourth microstrip line has a width of 20um±5um.

6. The coupler according to claim 5, characterized in that, The width of the secondary transmission line is 6um ± 5um, and the distance between the secondary transmission line and the main transmission line is 3um ± 1um.

7. The coupler according to claim 6, characterized in that, The area of ​​the sub-transmission line projected onto the main transmission line is 130 μm. 2 ~150um 2 .

8. The coupler according to claim 2, characterized in that, The control circuit includes a first switch, a second switch, a third switch, and a fourth switch; the output terminals of the first switch and the second switch are respectively connected to the coupling line, the control terminal of the first switch is connected to the input terminal of the monitoring circuit, the control terminal of the second switch is connected to the first terminal of the impedance matching circuit, and the second terminal of the impedance matching circuit is grounded; the output terminals of the third switch and the fourth switch are respectively connected to the isolation line, the control terminal of the third switch is connected to the third terminal of the impedance matching circuit, and the control terminal of the fourth switch is connected to the input terminal of the monitoring circuit.

9. The coupler according to claim 8, characterized in that, The impedance matching circuit includes a first resistor, a first capacitor, a second capacitor, and a second resistor; the first end of the first resistor is connected to the first end of the first capacitor, the first end of the second capacitor, and the first end of the second resistor, respectively; the second end of the first resistor is connected to the second end of the first capacitor, the second end of the second capacitor, and the second end of the second resistor, respectively; the first end of the first resistor is also connected to the control terminal of the second switch; and the first end of the second resistor is also connected to the control terminal of the third switch.

10. The coupler according to claim 1, characterized in that, The substrate is made of silicon, the buried oxide layer is made of insulating material, the first metal layer is made of copper, the second metal layer is made of copper, and the third metal layer is made of aluminum.

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