A duplexer and communication, sensing apparatus thereof

Abstract

This invention discloses a duplexer, which includes an input port Port1, a low-pass filter structure, a band-pass filter structure, a first output port Port2, and a second output port Port3, wherein the low-pass filter structure and the band-pass filter structure are connected to the input port Port1; the duplexer circuit does not have a matching circuit, but it can still achieve high isolation between the two filtering performances.

Description

Technical Field

[0001] This invention belongs to the field of microstrip circuits, specifically relating to a duplexer and its communication and sensing devices. Background Technology

[0002] Duplexers play a crucial role in radio frequency (RF) systems by isolating the transmit and receive bands and splitting signals, significantly impacting the overall performance of the wireless communication system. Microstrip-based duplexers, due to their ease of integration, are widely used in the RF front-end circuits of communication systems.

[0003] The main performance indicators of a duplexer include insertion loss, VSWR, isolation, and temperature drift. Among these, isolation is a crucial indicator reflecting the degree of interference between the transmitting and receiving signals. When uplink and downlink frequency band resources are limited and the signal spacing is very close, insufficient isolation at the transmitting and receiving ends will directly affect the system performance of the equipment, and in severe cases, render it completely inoperable, impacting the user's wireless communication. Current technologies improve isolation by adding matching circuits to the duplexer; however, with the miniaturization of devices, this method increases the size of the duplexer, failing to meet miniaturization design requirements. Summary of the Invention

[0004] To address the technical problems mentioned in the background section, this invention proposes a duplexer and its communication and sensing devices.

[0005] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0006] A duplexer, characterized in that it comprises an input port Port1, a low-pass filter structure, a band-pass filter structure, a first output port Port2, and a second output port Port3, wherein the low-pass filter structure and the band-pass filter structure are connected to the input port Port1; when the duplexer is operating, low-frequency radio frequency signals pass through the low-pass filter structure, high-frequency radio frequency signals are suppressed by the low-pass filter structure, and high-frequency radio frequency signals pass through the band-pass filter structure, while the suppressed low-frequency radio frequency signals are suppressed by the band-pass filter structure; the band-pass filter structure comprises two half-wavelength open-circuit transmission line resonators and one quarter-wavelength short-circuit transmission line resonator, wherein the quarter-wavelength open-circuit transmission line resonator... A short-circuit transmission line resonator of one wavelength is positioned between two open-circuit transmission line resonators of half wavelength. One of the open-circuit transmission line resonators of half wavelength is connected to the input port Port1, and the other open-circuit transmission line resonator of half wavelength is connected to the first output port Port2. The low-pass filter structure includes a first resonator Res1, a second resonator Res2, capacitor C3, capacitor C4, inductor L3, and inductor L4. The first resonator Res1 is composed of inductor L1 and capacitor C1 connected in parallel. The second resonator Res2 is composed of inductor L2 and capacitor C2 connected in parallel. One end of capacitor C3 is connected to the input port Port1, and the other end of capacitor C3 is connected to one end of the first resonator Res1. The other end of capacitor C3 is also connected to one end of inductor L3. The other end of the first resonator Res1 is connected to one end of the capacitor C4, and the other end of the first resonator Res1 is also connected to one end of the second resonator Res2; the other end of the inductor L3 is connected to one end of the inductor L4, and the other end of the inductor L3 is also connected to the other end of the capacitor C4; the other end of the inductor L4 is grounded; and the other end of the second resonator Res2 is connected to the second output terminal Port3. Preferably, the bandpass filter structure and the low-pass filter structure are respectively disposed on both sides of the input terminal Port1.

[0007] Preferably, the bandpass filter structure consists of two half-wavelength open-circuit transmission line resonators and one quarter-wavelength short-circuit transmission line resonator arranged side by side with spacing between them, and signal transmission is achieved through spatial coupling.

[0008] Preferably, capacitors C1, C2, C3, and C4 are constructed as parallel plate capacitors or interdigital capacitors.

[0009] Preferably, the inductors L1, L2, L3, and L4 may be constructed from metallized transmission lines or metallized vias.

[0010] Preferably, the inductor L4 is implemented using a metallized through-hole.

[0011] Preferably, the quarter-wavelength short-circuit transmission line resonator is grounded through a metallized via.

[0012] Preferably, the quarter-wavelength short-circuit transmission line resonator is configured as a U-shape.

[0013] Preferably, the frequency response of the low-pass filter structure has transmission zeros Tz1, Tz2, and Tz3. The inductor L2 and the capacitor C2 control the frequency of transmission zero Tz1, the inductor L3 and the capacitor C4 control the frequency of transmission zero Tz2, and the inductor L4 controls the frequency of transmission zero Tz3.

[0014] Preferably, the duplexer further includes a dielectric substrate, wherein the input port Port1, the low-pass filter structure, the band-pass filter structure, the first output port Port2, and the second output port Port3 are formed on the surface of the dielectric substrate or inside the dielectric substrate.

[0015] A communication device comprising the duplexer described above.

[0016] A sensing device comprising the duplexer described above.

[0017] The beneficial effects of adopting the above technical solution are as follows:

[0018] This patent proposes a duplexer that, despite lacking a matching circuit, still achieves high isolation between the two filtering paths. This is primarily due to the strong high-frequency suppression capability of the low-frequency band filter structure and the strong low-frequency suppression capability of the high-frequency band filter structure. The high-frequency band filter physical structure consists of two half-wavelength open-circuit transmission lines and a quarter-wavelength short-circuit transmission line, achieving signal transmission through spatial coupling. Its filtering response exhibits strong suppression capability at low frequencies. The low-frequency band filter physical structure implements a low-pass topology using parallel-plate capacitors or interdigital capacitors as capacitors and metal transmission lines or metallized vias as inductors. Because this filtering response has three transmission zeros at high frequencies, it possesses strong suppression capability for high-frequency signals. Attached Figure Description

[0019] Figure 1 This is a diagram of the duplexer architecture;

[0020] Figure 2 This is a diagram of the physical structure of a duplexer;

[0021] Figure 3 This is a performance diagram of a duplexer. Detailed Implementation

[0022] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] This invention proposes a duplexer and its communication and sensing devices. Figure 1 This is an architecture diagram of a miniaturized, high-isolation millimeter-wave duplexer. As shown in the diagram, the duplexer consists of a low-pass filter structure and a band-pass filter structure. The function of the low-pass filter structure is to allow RF signals to pass through in the low-frequency band and suppress them in the high-frequency band; the function of the high-frequency band filter structure is to allow RF signals to pass through in the high-frequency band and suppress them in the low-frequency band.

[0024] The duplexer includes an input port (Port1), a low-pass filter structure, a band-pass filter structure, a first output port (Port2), and a second output port (Port3). The low-pass filter structure and the band-pass filter structure are connected to the input port (Port1). When the duplexer is working, low-frequency radio frequency (RF) signals pass through the low-pass filter structure, while high-frequency RF signals are suppressed by the low-pass filter structure. High-frequency RF signals pass through the band-pass filter structure, and the suppressed low-frequency RF signals are suppressed by the band-pass filter structure. The band-pass filter structure includes two half-wavelength open-circuit transmission line resonators and one quarter-wavelength short-circuit transmission line resonator. The transmission line resonator is positioned between two half-wavelength open-circuit transmission line resonators. One half-wavelength open-circuit transmission line resonator is connected to the input port Port1, and the other half-wavelength open-circuit transmission line resonator is connected to the first output port Port2. The low-pass filter structure includes a first resonator Res1, a second resonator Res2, capacitor C3, capacitor C4, inductor L3, and inductor L4. The first resonator Res1 is composed of inductor L1 and capacitor C1 connected in parallel. The second resonator Res2 is composed of inductor L2 and capacitor C2 connected in parallel. One end of capacitor C3 is connected to the input port Port1, and the other end of capacitor C3 is connected to one end of the first resonator Res1. The other end of capacitor C3 is also connected to one end of inductor L3. The other end of the first resonator Res1 is connected to one end of the capacitor C4, and the other end of the first resonator Res1 is also connected to one end of the second resonator Res2; the other end of the inductor L3 is connected to one end of the inductor L4, and the other end of the inductor L3 is also connected to the other end of the capacitor C4, the other end of the inductor L4 is grounded, and the other end of the second resonator Res2 is connected to the second output terminal Port3.

[0025] The low-pass filter architecture employs a lumped-parameter filter design. Because this filter response has three transmission zeros at high frequencies, it exhibits strong suppression capabilities for high-frequency signals. Specifically, L 2 and C 2. Control transmission zero point Tz1, L 3 and C4. Control transmission zero point Tz2, L 4. Control transmission zero point Tz3.

[0026] The bandpass filter structure employs a distributed parameter filter design, utilizing two half-wavelength open-circuit transmission line resonators and one quarter-wavelength short-circuit transmission line resonator arranged in parallel, achieving a third-order Chebyshev filter response through spatial coupling. This filter response exhibits high suppression in the low-frequency band.

[0027] Figure 2 A schematic diagram of the duplexer's physical structure is provided. As shown in the diagram, the high-frequency and low-frequency filtering structures are positioned on opposite sides of Port 1. The duplexer includes a dielectric substrate. The high-frequency filtering structure is formed on the surface of the substrate and consists of two half-wavelength open-circuit transmission line resonators and one quarter-wavelength short-circuit transmission line resonator arranged side-by-side, with signal transmission achieved through spatial coupling. The half-wavelength open-circuit transmission line resonators are constructed from transmission lines with multiple bends, improving miniaturization. The quarter-wavelength short-circuit transmission line resonator has a U-shaped structure and is grounded through a metallized via. The low-frequency filtering structure uses parallel-plate capacitors or interdigital capacitors to implement a low-pass topology, with inductors implemented using metal transmission lines or metallized vias. Capacitors C1 and C2 are interdigital capacitors, while capacitors C3 and C4 are parallel-plate capacitors. It is worth noting that due to the inductor... L 4. The inductance value is very small in this topology, so metallized vias are used. The input port 1, the first output port 2, and the second output port 3 are formed on the surface of the dielectric substrate or inside the dielectric substrate. The positions of each component are marked on... Figure 2 middle.

[0028] Figure 3 The S-parameter performance curves of the duplexer are shown. The low-frequency band passband return loss is 10 dB, and the isolation from the high-frequency band is 30 dB. The high-frequency band passband return loss is 20 dB, and the isolation from the low-frequency band is 32 dB.

[0029] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0030] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A duplexer, characterized in that, The duplexer includes an input port (Port1), a low-pass filter structure, a band-pass filter structure, a first output port (Port2), and a second output port (Port3). The low-pass filter structure and the band-pass filter structure are connected to the input port (Port1). When the duplexer is working, low-frequency radio frequency (RF) signals pass through the low-pass filter structure, while high-frequency RF signals are suppressed by the low-pass filter structure. High-frequency RF signals pass through the band-pass filter structure, and the suppressed low-frequency RF signals are suppressed by the band-pass filter structure. The band-pass filter structure includes two half-wavelength open-circuit transmission line resonators and one quarter-wavelength short-circuit transmission line resonator. The quarter-wavelength short-circuit... The transmission line resonator is positioned between two half-wavelength open-circuit transmission line resonators. One half-wavelength open-circuit transmission line resonator is connected to the input port Port1, and the other half-wavelength open-circuit transmission line resonator is connected to the first output port Port2. The low-pass filter structure includes a first resonator Res1, a second resonator Res2, capacitors C3 and C4, and inductors L3 and L4. The first resonator Res1 is composed of inductor L1 and capacitor C1 connected in parallel, and the second resonator Res2 is composed of inductor L2 and capacitor C2 connected in parallel. One end of capacitor C3 is connected to the input port Port1.

1. The capacitor C3 is connected to one end of the first resonator Res1, and the other end of the capacitor C3 is also connected to one end of the inductor L3; the other end of the first resonator Res1 is connected to one end of the capacitor C4, and the other end of the first resonator Res1 is also connected to one end of the second resonator Res2; the other end of the inductor L3 is connected to one end of the inductor L4, and the other end of the inductor L3 is also connected to the other end of the capacitor C4, the other end of the inductor L4 is grounded, and the other end of the second resonator Res2 is connected to the second output terminal Port3.

2. A duplexer according to claim 1, characterized in that, The bandpass filter structure and the lowpass filter structure are respectively located on both sides of the input port 1.

3. A duplexer according to claim 1, characterized in that, In the bandpass filter structure, two half-wavelength open-circuit transmission line resonators and one quarter-wavelength short-circuit transmission line resonator are arranged side by side with a gap between them, and signal transmission is achieved through spatial coupling.

4. A duplexer according to claim 1, characterized in that, The capacitors C1, C2, C3, and C4 are all constructed from parallel plate capacitors or interdigital capacitors.

5. A duplexer according to claim 1, characterized in that, The inductors L1, L2, L3, and L4 are all composed of metallized transmission lines or metallized vias.

6. A duplexer according to claim 1, characterized in that, The inductor L4 is a metallized through-hole.

7. A duplexer according to claim 1, characterized in that, The quarter-wavelength short-circuit transmission line resonator is grounded through a metallized via.

8. A duplexer according to claim 1, characterized in that, The quarter-wavelength short-circuit transmission line resonator is configured in a U-shape.

9. A duplexer according to claim 1, characterized in that, The frequency response of the low-pass filter structure has transmission zeros Tz1, Tz2, and Tz3. The inductor L2 and the capacitor C2 control the frequency of transmission zero Tz1, the inductor L3 and the capacitor C4 control the frequency of transmission zero Tz2, and the inductor L4 controls the frequency of transmission zero Tz3.

10. A duplexer according to claim 1, characterized in that, The duplexer also includes a dielectric substrate, and the input port Port1, the low-pass filter structure, the band-pass filter structure, the first output port Port2, and the second output port Port3 are formed on the surface of the dielectric substrate or inside the dielectric substrate.

11. A communication device, characterized in that, Includes the duplexer according to any one of claims 1-10.

12. A sensing device, characterized in that, Includes the duplexer according to any one of claims 1-10.

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