A dynamic impedance self-balancing dual-path bridge single-switch phase shifter

Abstract

The application discloses a kind of dynamic impedance self-balancing double-path bridge type single-switch phase shifter, it is related to microwave radio frequency integrated circuit technical field.The phase shifter includes main path and controlled compensation path across between input end and output end, forms double-path full-bridge connection topological structure;The main path is by microstrip line, capacitor and the inductance in parallel with it collectively constitute bridge sub-network;The controlled compensation path is by microstrip line, inductance and capacitor in series in order to constitute, and controlled compensation path is equipped with the switching unit across inductance and capacitor two ends.The application utilizes double-path full-bridge connection structure, and the insertion loss under switching double state is optimized to 0.2dB within, with extremely strong impedance self-balancing ability and matching consistency in 3.2GHz-3.8GHz frequency band, can be widely used in 5G communication and radar phased array system.

Description

Technical Field

[0001] This invention relates to the field of microwave radio frequency integrated circuit technology, and in particular to a dynamic impedance self-balancing dual-path bridging single-switch phase shifter. Background Technology

[0002] Phase shifters, as core components of phased array radar, satellite communications, and fifth-generation / sixth-generation (5G / 6G) mobile communication systems, play a crucial role in controlling the electromagnetic beam direction and achieving precise beam scanning. With the development of modern communication systems towards higher frequencies, higher efficiency, and large-scale integration, extremely stringent requirements are placed on the insertion loss, phase accuracy, and impedance stability of phase shifters during state transitions. Especially in the Sub-6GHz and millimeter-wave bands, the loss of the phase shifter directly affects the noise figure and transmit power efficiency of the entire front-end system.

[0003] Currently, commercially available phase shifter structures mainly include switching line type, reflective type, and loaded line type. Among them, the loaded line type phase shifter is widely favored for small-angle phase shift applications due to its simple structure and compact size. The loaded line phase shifter achieves phase shift by connecting controlled reactance elements in parallel to the main transmission line. Although simple in structure, it has significant limitations: Firstly, when a large phase shift angle (e.g., above 20°) is required, the strong susceptance introduced by the parallel elements causes the main transmission line impedance to deviate significantly from the 50Ω standard impedance, resulting in high reflection loss and insertion loss typically exceeding 0.5dB. Secondly, there is the imbalance problem during state switching. When the switch switches between open and closed states, the circuit admittance changes drastically, leading to extremely poor gain consistency across different phase shift states. This technical dilemma of "high loss" and "large fluctuation" severely restricts the industrialization process of high-performance phased array antenna systems.

[0004] Furthermore, existing technologies often require complex cascaded matching networks or multi-stage resonant circuits to address impedance matching issues. This not only increases the physical size of the circuit and introduces additional parasitic parameters, but also makes the device extremely sensitive to process variations. Particularly when using high-impedance microstrip lines to reduce size, the initial mismatch reflections caused by the high-impedance lines are extremely difficult to eliminate. While some improvement solutions exist in the industry, most cannot simultaneously achieve low loss and impedance self-balancing between states on a minimally simplistic single-switch platform. This has become a major obstacle restricting the advancement of RF front-end modules towards ultra-high performance and ultra-high integration.

[0005] Therefore, there is an urgent need in this field for a breakthrough phase shifter topology that can utilize the circuit's own electrical performance characteristics to achieve dynamic impedance self-compensation, fundamentally solving the contradiction between large-angle phase shift and low loss and high matching stability, thereby meeting the pursuit of ultimate performance of radio frequency devices in modern communication systems. Summary of the Invention

[0006] The purpose of this invention is to propose a dynamic impedance self-balancing dual-path bridging single-switch phase shifter to solve the problems of severe impedance mismatch, excessive insertion loss and poor state stability of traditional single-switch phase shifters when switching at large angles, so as to meet the requirements of high-performance RF front-end for low loss and high phase consistency.

[0007] To achieve the above objectives, this invention proposes a dynamic impedance self-balancing dual-path bridged single-switch phase shifter, comprising a main path and a controlled compensation path. Both the main path and the controlled compensation path are connected between the input and output terminals, forming a dual-path full-bridge topology. The main path is formed by a first microstrip line and a second capacitor connected in series, and a first inductor connected in parallel with the first microstrip line and the second capacitor is also connected between the input and output terminals, forming a bridge sub-network. The controlled compensation path is composed of a third microstrip line, a second inductor, and a first capacitor connected in series. The controlled compensation path includes a switching unit connected across the second inductor and the first capacitor. The series resonant frequency of the second inductor and the first capacitor is lower than the operating center frequency of the circuit, causing the controlled compensation path to exhibit inductive admittance when the switching unit is disconnected, thereby compensating for the impedance mismatch susceptance of the main path.

[0008] Preferably, the characteristic impedance of the first microstrip line in the main path is 90Ω-100Ω, and the electrical length is 40°-50°.

[0009] Preferably, the characteristic impedance of the third microstrip line in the controlled compensation path is 60Ω-70Ω, and the electrical length is 5°-10°.

[0010] Preferably, the inductance of the first inductor is 8.5nH-10.5nH, and the inductance of the second inductor is 17nH-20nH.

[0011] Preferably, the capacitance of the first capacitor is 4.5pF-5.5pF, and the capacitance of the second capacitor is 8.5pF-9.5pF.

[0012] Preferably, within the operating frequency range of 3.2GHz-3.8GHz, the impedance points of the switch unit in the open and closed states are located on both sides of the center of the Smith chart, and the insertion loss is less than 0.2dB and the return loss is better than -13dB.

[0013] This invention also provides a method for using a dual-path bridged single-switch phase shifter based on dynamic impedance self-balancing, the specific steps of which are as follows: Step S1: Connect the phase shifter to the radio frequency signal link and control the phase shift state by opening and closing the switching unit; Step S2: When the switching unit is disconnected, the controlled compensation path provides inductive compensation admittance, which converges the system impedance to the inductive region of the Smith chart, achieving low-loss output in the first phase state. Step S3: When the switching unit is closed, the controlled compensation path reduces the topology, drives the system impedance to jump to the capacitive region of the Smith chart, and achieves the preset phase shift. Step S4: During the above dual-state switching process, the impedance is dynamically balanced between the inductive and capacitive matching regions by using the dual-path full-bridge topology, thereby achieving consistent insertion loss during the phase shifting process.

[0014] Therefore, this invention proposes a dynamic impedance self-balancing dual-path bridging single-switch phase shifter, which has the following advantages: (1) This invention is the first to adopt a "dual-path full-bridge" topology, which utilizes the inductive susceptance provided by the controlled compensation path in the non-resonant region to actively repair the mismatch reflection caused by the high impedance design of the main path. Through this "reflection vector cancellation" and "admittance compensation mechanism", the reflected energy is re-injected into the transmission link without changing the phase shift reference, so that the insertion loss of the phase shifter at the 3.5GHz frequency point is significantly optimized from 0.4dB to less than 0.2dB, achieving a step improvement in performance.

[0015] (2) This invention possesses excellent dynamic impedance self-balancing capability. By switching the action of the jumper switch, the admittance of the main path and the compensation path is redistributed, so that the impedance trajectory of the circuit in different phase shift states always achieves cross-quadrant convergence within the preferred interval on both sides of the matching center of the Smith chart. This effectively solves the problem of amplitude jitter caused by drastic impedance changes during state switching of traditional phase shifters, and ensures the beam stability of the phased array system during the scanning process.

[0016] (3) The design of this invention is compact and has high parameter tolerance. By using a non-resonant design that deviates from the resonant point, it avoids the stringent requirements of the resonant sensitive area on the processing tolerance, effectively broadening the working bandwidth of the device (3.2GHz-3.8GHz). Moreover, it can achieve high-precision manufacturing by relying on mature microstrip circuit processing technology, which has significant cost advantages and large-scale industrial application prospects.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the circuit topology of a dynamic impedance self-balancing dual-path bridged single-switch phase shifter according to the present invention. Figure 2The diagram shows the equivalent circuit in the embodiment of the present invention; wherein, (a) is the equivalent circuit diagram of the main path, and (b) is the equivalent circuit diagram of the controlled compensation path. Figure 3 This is a graph showing the transmission coefficient of the phase shifter in two states: ON and OFF, according to an embodiment of the present invention. Figure 4 This is a diagram showing the reflection coefficient of the phase shifter in two states: ON and OFF, according to an embodiment of the present invention. Figure 5 This is a graph showing the phase shift of the phase shifter in two states and the phase difference between the two states of the phase shifter as a function of frequency in an embodiment of the present invention. Figure 6 This is a graph showing the phase shift of the phase shifter as a function of frequency when the switch is open (ON) and when only the main path is used, according to an embodiment of the present invention. Figure 7 This is a transmission coefficient curve of the phase shifter in an embodiment of the present invention when the switch is open (ON), there is only the main path, and there is no bridging inductor in the main path. Figure 8 This is a graph showing the reflection coefficient of the phase shifter in an embodiment of the present invention with the switch open (ON), with only the main path, and with no bridging inductance in the main path. Figure 9 A schematic diagram of the Smith chart trajectory of the impedance evolution of the phase shifter at 3.5 GHz in an embodiment of the present invention.

[0019] Figure Labels 1. Input terminal; 2. Output terminal; 3. First microstrip line; 4. Second capacitor; 5. First inductor; 6. Second microstrip line; 7. Second inductor; 8. First capacitor; 9. Switching unit; 10. Main path; 11. Controlled compensation path. Detailed Implementation

[0020] To make the technical solutions, advantages, and objectives of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0022] Example 1 like Figures 1-2As shown, the present invention provides a dynamic impedance self-balancing dual-path bridged single-switch phase shifter, including a main path and a controlled compensation path, both of which are synchronously connected between input terminal 1 and output terminal 2, forming a dual-path full-bridge topology.

[0023] The main path 10 consists of a first microstrip line 3 and a second capacitor 4 connected in series, and is connected in parallel with a first inductor 5. In this embodiment, the characteristic impedance of the first microstrip line 3 is selected to be 94Ω, the electrical length is 45.5°, the inductance of the first inductor 5 is 9.32nH, and the capacitance of the second capacitor 4 is 8.87pF.

[0024] In this embodiment, the bridging subnetwork using a high-impedance first microstrip line 3 in conjunction with a parallel first inductor 5 has the following technical advantages: (1) The high-resistivity line design is beneficial for achieving the preset basic phase shift within a smaller physical space; (2) The parallel inductor and the series branch form the initial phase shift framework, but due to the presence of the high resistance line, the path will have a significant capacitive mismatch susceptance at 3.5 GHz, causing the initial impedance to deviate from the 50Ω center point.

[0025] The controlled compensation path 11 is connected across the two ends of the main path 10, and is composed of the second microstrip line 6, the second inductor 7, and the first capacitor 8 connected in series. The switching unit 9 is connected across the second inductor 7 and the first capacitor 8. In this embodiment, the characteristic impedance of the second microstrip line 6 is selected to be 63.2Ω, the electrical length is 6.28°, the inductance of the second inductor 7 is 18.5nH, and the capacitance of the first capacitor 8 is 5pF.

[0026] In this embodiment, setting the resonant frequency of the second inductor 7 and the first capacitor 8 to be far from the operating frequency band has the following technical advantages: (1) It avoids the rapid changes in phase and amplitude near the resonance point, and enhances the robustness of the device in the 3.2GHz-3.8GHz wideband. (2) By utilizing the residual inductive susceptance in the non-resonant state, the impedance mismatch of the main path 10 can be accurately neutralized by the admittance, thereby achieving impedance self-balancing in the dual-state switching.

[0027] Example 2 This invention provides a method for using a dual-path bridged single-switch phase shifter based on dynamic impedance self-balancing, the specific steps of which are as follows: Step S1: Connect the phase shifter to the radio frequency signal link and control the phase shift state by opening and closing the switch unit 9; Step S2: When the switching unit 9 is disconnected, the controlled compensation path 11 provides inductive compensation admittance, which converges the system impedance to the inductive region of the Smith chart, thereby achieving low-loss output in the first phase state. Step S3: When the switch unit 9 is closed, the controlled compensation path 11 drives the system impedance to jump to the capacitive region of the Smith chart through topology reduction, and achieves the preset phase shift. Step S4: During the above dual-state switching process, the impedance is dynamically balanced between the inductive and capacitive matching regions by using the dual-path full-bridge topology, thereby achieving consistent insertion loss during the phase shifting process.

[0028] Example 3 To verify that the phase shifter of the present invention has dynamic impedance self-balancing and low loss effects, its electrical characteristics under different states were analyzed by spectrum simulation. In this embodiment, the first working state is defined as the switch unit 9 being open (ON), and the second working state is defined as the switch unit 9 being closed (OFF).

[0029] Step 1: Basic Mismatch State Analysis (First Microstrip Line 3 and Second Capacitor 4 Only) First, the core phase-shifting components in the main path 10, the first microstrip line 3 and the second capacitor 4, are simulated. For example... Figures 7-8 As shown, because the first microstrip line 3 adopts a high impedance design in exchange for compact phase shift, its return loss is only -7.2dB to -8.4dB in the 3.2GHz-3.8GHz frequency band, and its insertion loss is as high as -0.663dB to -0.905dB; at this time, the circuit is in a state of severe impedance mismatch, and the reflection loss is extremely large.

[0030] Step 2: Self-compensation within the main path (the first microstrip line 3, the second capacitor 4, and the first inductor 5 form the main path 10). The first inductor 5 is connected in parallel across the first microstrip line 3 and the second capacitor 4 to complete the construction of the main path 10. The introduction of the first inductor 5 initially neutralizes some of the capacitive susceptance, such as... Figure 9 As shown in the Smith chart trajectory, the impedance point moves closer to the matching center from the original mismatch point, as... Figures 7-8 As shown, return loss improved to -10.5dB to -11.9dB, and insertion loss was reduced to 0.35dB-0.40dB. Although performance was improved, reflection loss still limited the efficiency of the antenna system under large-angle phase shift requirements.

[0031] Step 3: Dynamic self-balancing of the entire circuit (adding path B) introduces controlled compensation path 11. When switching unit 9 is in the ON state, controlled compensation path 11 is fully connected. Utilizing the non-resonant inductive admittance of the second inductor 7 and the first capacitor 8 outside the operating frequency band, the residual reflection vector of the main path 10 is canceled, and the total impedance is precisely corrected to Z0*(1.284+j0.353), achieving matched convergence of the system in the inductive region. At this time, as... Figure 3 , Figure 4 , Figure 6As shown, the return loss is optimized to around -14dB, the insertion loss is reduced to 0.14dB-0.20dB, and the phase is maintained at -40.8°, achieving a low-loss base state.

[0032] When the switching unit 9 is in the OFF state, the controlled compensation path 11 achieves topology reduction by short-circuiting the second inductor 7 and the first capacitor 8, retaining only the second microstrip line 6. At this time, the impedance point jumps to Z0*(0.826-j0.317), achieving matched convergence of the system in the capacitive region. Although it has crossed from the inductive region to the capacitive region, its magnitude is basically the same distance from the center of the circle diagram. Figures 4-5 As shown, the return loss remains at a high level of -13dB to -15dB, and a phase jump of 22.6° is achieved by utilizing the admittance step.

[0033] This embodiment, through this dual-path full-bridge design, achieves a 22.6° phase shift while cleverly controlling the return loss of both switching states within an excellent range (-13dB to -15dB), solving the problem of large loss fluctuations caused by drastic impedance changes during state switching in traditional single-switch phase shifters.

[0034] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0035] Therefore, this invention provides a dynamic impedance self-balancing dual-path bridged single-switch phase shifter that integrates impedance self-compensation and precise phase control functions. It has a simple design, extremely low insertion loss, and stable operation, effectively solving the problems of severe mismatch and gain jump in traditional solutions. It can be widely used in 5G communication and radar systems.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A dynamic impedance self-balancing dual-path bridging single-switch phase shifter, characterized in that, The circuit includes a main path and a controlled compensation path, both of which are connected between the input and output terminals, forming a dual-path full-bridge topology. The main path is formed by a first microstrip line and a second capacitor cascaded in series, and a first inductor connected in parallel with the first microstrip line and the second capacitor is also connected between the input and output terminals, forming a bridging sub-network. The controlled compensation path is formed by a third microstrip line, a second inductor, and a first capacitor connected in series in sequence. The controlled compensation path includes a switching unit connected across the two ends of the cascaded chain of the second inductor and the first capacitor. The series resonant frequency of the second inductor and the first capacitor is lower than the operating center frequency of the circuit, so that the controlled compensation path exhibits inductive admittance when the switching unit is disconnected, which is used to dynamically compensate for the impedance mismatch susceptance of the main path. The switching unit is configured to switch between an open state and a closed state, causing the phase shifter to generate a phase shift of 22.6°; and within the operating frequency range of 3.2GHz-3.8GHz, the impedance points of the switching unit in the open and closed states are located on opposite sides of the center of the Smith chart, respectively, with insertion loss less than 0.2dB and return loss better than -13dB.

2. The dynamic impedance self-balancing dual-path bridging single-switch phase shifter according to claim 1, characterized in that, The characteristic impedance of the first microstrip line in the main path is 90Ω-100Ω, and the electrical length is 40°-50°.

3. The dynamic impedance self-balancing dual-path bridging single-switch phase shifter according to claim 1, characterized in that, The characteristic impedance of the third microstrip line in the controlled compensation path is 60Ω-70Ω, and the electrical length is 5°-10°.

4. The dynamic impedance self-balancing dual-path bridging single-switch phase shifter according to claim 1, characterized in that, The inductance of the first inductor is 8.5nH-10.5nH, and the inductance of the second inductor is 17nH-20nH.

5. A dynamic impedance self-balancing dual-path bridging single-switch phase shifter according to claim 1, characterized in that, The capacitance of the first capacitor is 4.5pF-5.5pF, and the capacitance of the second capacitor is 8.5pF-9.5pF.

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