High-isolation circuit based on LTCC technology

Abstract

The utility model discloses a high-isolation circuit based on an LTCC technology. The high-isolation circuit comprises an LTCC substrate, a microwave transmission line, a metal floor group and a plurality of metal shielding wire groups, the more than two microwave transmission lines are arranged on the LTCC substrate in parallel, and each microwave transmission line comprises two microstrip lines and an embedded strip line; the embedded strip line is embedded in the LTCC substrate, the two microstrip lines are both printed on the surface of the LTCC substrate and located at the two ends of the embedded strip line respectively, one microstrip line is connected with one end of the corresponding embedded strip line through a transmission line metallization communicating hole, and the other microstrip line is connected with the other end of the corresponding embedded strip line through a transmission line metallization communicating hole. The other microstrip line is connected with the other end of the corresponding embedded strip line through a transmission line metallization communication hole; the metal floor group comprises a plurality of metal floor layers, and the plurality of metal floor layers are arranged on the LTCC substrate in a layered mode and serve as grounding reference planes; the metal shielding line groups are arranged at the tops of the microstrip lines in a one-to-one correspondence mode and play a role in shielding radiation signals of the microstrip lines. According to the utility model, high isolation between circuit channels can be realized.

Description

Technical Field

[0001] This utility model belongs to the field of microwave radio frequency circuit technology, specifically relating to a high isolation circuit based on LTCC technology. Background Technology

[0002] With the rapid development of microwave wireless technology, communication systems are moving towards miniaturization, integration, and multi-functionality. Due to the need for miniaturization, the spacing between transmission lines is getting smaller, resulting in poorer isolation between radio frequency channels. In traditional design methods, shielding is added to the two transmission lines to increase isolation, but this design requires additional structures and is relatively large, making it unsuitable for high-frequency requirements. Utility Model Content

[0003] In view of this, the present invention provides a high isolation circuit based on LTCC technology, which can achieve high isolation between circuit channels and is beneficial to the miniaturization of radio frequency circuit size.

[0004] This utility model is achieved through the following technical solution:

[0005] A high isolation circuit based on LTCC technology includes: an LTCC substrate, two or more microwave transmission lines, a metal ground plane group, and several metal shielding wire groups;

[0006] Two or more microwave transmission lines are arranged in parallel on the LTCC substrate, and each microwave transmission line includes two microstrip lines and an embedded stripline.

[0007] The embedded stripline is embedded in the LTCC substrate. Two microstrip lines are printed on the surface of the LTCC substrate and are located at both ends of the embedded stripline. One microstrip line is connected to one end of the corresponding embedded stripline through a transmission line metallization interconnection hole, and the other microstrip line is connected to the other end of the corresponding embedded stripline through a transmission line metallization interconnection hole.

[0008] The metal ground plane assembly includes several metal ground plane layers, which are layered on the LTCC substrate and serve as a ground reference plane.

[0009] Metal shielding wires are arranged one-to-one on the top of the microstrip line to shield the signals radiated from the microstrip line.

[0010] Furthermore, each group of metal shielded wires includes two metal shielded wires, which are arranged in a cross pattern.

[0011] Furthermore, each group of metal shielding wires includes two or more metal shielding wires, which are arranged side by side, cross by side, or in a grid pattern on top of the microstrip line.

[0012] Furthermore, each group of metal shielding wires includes a metal shielding wire, which is arranged in a wavy or bent cross shape on top of the microstrip line.

[0013] Furthermore, the metal floor assembly includes a top-printed metal floor;

[0014] The top printed metal ground plane is located on top of the LTCC substrate, on the same layer as the microstrip line; the metal shielding line group is bonded to the top printed metal ground plane.

[0015] Furthermore, the metal floor assembly also includes a bottom printed metal floor, a first embedded metal floor, a second embedded metal floor, and a third embedded metal floor;

[0016] A first-layer embedded metal floor, a second-layer embedded metal floor, and a third-layer embedded metal floor are sequentially embedded in the LTCC substrate from top to bottom at intervals.

[0017] The embedded stripline is set on the same layer as the two embedded metal floor layers. Each transmission line metallized interconnection hole is vertically set in the LTCC substrate. The top end of each transmission line metallized interconnection hole is connected to the microstrip line, and the other end passes through the layer where the first embedded metal floor layer is located and is connected to the embedded stripline.

[0018] The bottom printed metal floor is set at the bottom of the LTCC substrate, and the top printed metal floor, the first embedded metal floor, the second embedded metal floor, the third embedded metal floor and the bottom printed metal floor are connected by several metal ground vias.

[0019] Each microstrip line, the top printed metal floor, and one layer of embedded metal floor together form a 50-ohm microstrip line I; the embedded strip line, one layer of embedded metal floor, and three layers of embedded metal floor together form a 50-ohm strip line II.

[0020] One end of a 50-ohm microstrip line I is connected to one end of a 50-ohm stripline II, and one end of another 50-ohm microstrip line I is connected to the other end of a 50-ohm stripline II, forming the microwave transmission line.

[0021] Beneficial effects:

[0022] (1) The high isolation circuit based on LTCC technology provided by this utility model adopts metal shielding wire group 8 to be arranged one-to-one on the top of microstrip line 3, which plays a shielding role on the signal radiated by microstrip line 3. The metal shielding wire group 8 is small in size, which is conducive to the miniaturization of radio frequency circuits and can achieve high isolation between two or more microwave transmission lines.

[0023] (2) The present invention has two metal shielding wires arranged in a cross configuration. The isolation of the circuit is greater than -70dB in the range of 5GHz to 20GHz, thus achieving ultra-wideband high isolation.

[0024] (3) The present invention is provided with five metal floor layers, which can provide a stable current circuit and further reduce electromagnetic radiation. Attached Figure Description

[0025] Figure 1 This is a top view of an ultra-wideband high-isolation circuit;

[0026] Figure 2 yes Figure 1 AA section view;

[0027] Figure 3 This is a schematic diagram of the layer containing the embedded metal floor.

[0028] Figure 4 This is a schematic diagram of the layer containing the embedded metal floor on the second floor;

[0029] Figure 5 This is a schematic diagram of the three-layer embedded metal floor;

[0030] Figure 6 This is a schematic diagram of the layer containing the bottom printed metal floor;

[0031] Among them, 1-LTCC substrate, 21-top printed metal ground plane, 22-bottom printed metal ground plane, 3-microstrip line, 41-first layer embedded metal ground plane, 42-second layer embedded metal ground plane, 43-third layer embedded metal ground plane, 5-embedded stripline, 6-transmission line metallized interconnection hole, 7-metal ground via, 8-metal shielding line group. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] This embodiment provides an ultra-wideband high-isolation circuit based on LTCC technology. See Appendix. Figure 1 and 2 It includes an LTCC (low-temperature co-fired) substrate 1, two or more microwave transmission lines, a metal ground plane group, and several metal shielding line groups 8;

[0034] Two or more microwave transmission lines are arranged in parallel on the LTCC substrate 1, and each microwave transmission line includes two microstrip lines 3 and an embedded stripline 5.

[0035] The embedded stripline 5 is embedded in the LTCC substrate 1. Two microstrip lines 3 are printed on the surface of the LTCC substrate 1 (making the surface where the microstrip line 3 is located the top surface of the LTCC substrate 1), and are located at both ends of the embedded stripline 5 respectively. One microstrip line 3 is connected to one end of the corresponding embedded stripline 5 through the transmission line metallization connection hole 6, and the other microstrip line 3 is connected to the other end of the corresponding embedded stripline 5 through the transmission line metallization connection hole 6.

[0036] The metal ground plane assembly includes several metal ground plane layers, which are layered on the LTCC substrate 1 and serve as a ground reference plane.

[0037] This embodiment provides a high isolation circuit based on LTCC technology, in which metal shielding wire groups 8 are arranged one-to-one on the top of the microstrip line 3 to shield the signals radiated from the microstrip line 3. The metal shielding wire groups 8 are small in size, which is conducive to the miniaturization of radio frequency circuits and can achieve high isolation between two or more microwave transmission lines.

[0038] In one embodiment, each group of metal shielded wires 8 includes two metal shielded wires arranged in a cross configuration. Testing showed that the circuit achieves an isolation level greater than -70dB in the 5GHz to 20GHz range, realizing ultra-wideband high isolation.

[0039] Metal shielding wires can also be set up in other ways, such as two or more metal shielding wires arranged side by side, crossing or in a grid pattern, or a single metal shielding wire arranged in a wavy or bent cross pattern.

[0040] In one embodiment, the metal floor assembly includes five metal floor layers, namely, a top printed metal floor 21, a bottom printed metal floor 22, a first embedded metal floor 41, a second embedded metal floor 42, and a third embedded metal floor 43.

[0041] The top printed metal floor 21 is disposed on the top of the LTCC substrate 1 and is on the same layer as the microstrip line 3; the metal shielding line group 8 is bonded to the top printed metal floor 21 by gold wire bonding technology; the bottom printed metal floor 22 is disposed on the bottom of the LTCC substrate 1.

[0042] A first-layer embedded metal floor 41, a second-layer embedded metal floor 42, and a third-layer embedded metal floor 43 are sequentially embedded in the LTCC substrate from top to bottom at intervals; the top-layer printed metal floor 21, the first-layer embedded metal floor 41, the second-layer embedded metal floor 42, the third-layer embedded metal floor 43, and the bottom-layer printed metal floor 22 are connected by several metal ground vias 7.

[0043] Furthermore, the top printed metal floor 21, the first embedded metal floor 41, the second embedded metal floor 42, the third embedded metal floor 43, and the bottom printed metal floor 22 are arranged at equal intervals from top to bottom.

[0044] See appendix Figure 2-6 The embedded stripline 5 is disposed on the same layer as the second layer of embedded metal floor 42, and the two ends of the embedded stripline 5 are at the same distance from the end of the corresponding end of the LTCC substrate 1; each transmission line metallized interconnection hole 6 is vertically disposed in the LTCC substrate 1, the top end of each transmission line metallized interconnection hole 6 is connected to the microstrip line 3, and the other end passes through the layer where the first layer of embedded metal floor 41 is located and is connected to the embedded stripline 5.

[0045] Each microstrip line 3, the top printed metal floor 21, and the layer of embedded metal floor 41 together form a 50-ohm microstrip line I; the embedded strip line 5, the layer of embedded metal floor 41, and the three layers of embedded metal floor 42 together form a 50-ohm strip line II.

[0046] One end of a 50-ohm microstrip line I is connected to one end of a 50-ohm stripline II, and one end of another 50-ohm microstrip line I is connected to the other end of a 50-ohm stripline II, forming a microwave transmission line.

[0047] In one embodiment, the LTCC substrate 1 is a multilayer LTCC ceramic plate. The first embedded metal floor 41, the second embedded metal floor 42, and the third embedded metal floor 4 are all grid-type metal floors.

[0048] Working principle: When microwave transmission is performed through a microwave transmission line, electromagnetic interference will occur between microwave transmission lines that are close to each other, and they need to be isolated. In this application, a metal shielding line group 8 is set on the top of the microstrip line 3 in the microwave transmission line. At the same time, the metal shielding line group 8 is small in size, which is beneficial to the miniaturization of radio frequency circuits.

[0049] Isolation test method: The isolation of microwave transmission lines is measured using a test fixture, which is a metal device with an RF connector. The printed metal ground plane 22 is connected to the metal device to test the isolation of two adjacent microwave transmission lines.

[0050] In summary, the above are merely preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A high isolation circuit based on LTCC technology, characterized in that, include: LTCC substrate, two or more microwave transmission lines, metal ground plane assembly, and several metal shielding wire assemblies; Two or more microwave transmission lines are arranged in parallel on the LTCC substrate, and each microwave transmission line includes two microstrip lines and an embedded stripline. The embedded stripline is embedded in the LTCC substrate. Two microstrip lines are printed on the surface of the LTCC substrate and are located at both ends of the embedded stripline. One microstrip line is connected to one end of the corresponding embedded stripline through a transmission line metallization interconnection hole, and the other microstrip line is connected to the other end of the corresponding embedded stripline through a transmission line metallization interconnection hole. The metal ground plane assembly includes several metal ground plane layers, which are layered on the LTCC substrate and serve as a ground reference plane. Metal shielding wires are arranged one-to-one on the top of the microstrip line to shield the signals radiated from the microstrip line.

2. The high isolation circuit based on LTCC technology as described in claim 1, characterized in that, Each set of metal shielded wires consists of two metal shielded wires, which are arranged in a cross pattern.

3. The high isolation circuit based on LTCC technology as described in claim 1, characterized in that, Each group of metal shielded wires includes two or more metal shielded wires, which are arranged side by side, cross by side, or in a grid pattern on top of the microstrip line.

4. The high isolation circuit based on LTCC technology as described in claim 1, characterized in that, Each group of metal shielded wires includes one metal shielded wire, which is arranged in a wavy or bent cross shape on top of the microstrip line.

5. A high isolation circuit based on LTCC technology as described in any one of claims 1-4, characterized in that, The metal floor assembly includes a top-printed metal floor; The top printed metal ground plane is set on top of the LTCC substrate, on the same layer as the microstrip line; The metal shielded wire bond is set on the top printed metal floor.

6. The high isolation circuit based on LTCC technology as described in claim 5, characterized in that, The metal floor assembly also includes a bottom printed metal floor, a first layer of embedded metal floor, a second layer of embedded metal floor, and a third layer of embedded metal floor; A first-layer embedded metal floor, a second-layer embedded metal floor, and a third-layer embedded metal floor are sequentially embedded in the LTCC substrate from top to bottom at intervals. The embedded stripline is set on the same layer as the two embedded metal floor layers. Each transmission line metallized interconnection hole is vertically set in the LTCC substrate. The top end of each transmission line metallized interconnection hole is connected to the microstrip line, and the other end passes through the layer where the first embedded metal floor layer is located and is connected to the embedded stripline. The bottom printed metal floor is set at the bottom of the LTCC substrate, and the top printed metal floor, the first embedded metal floor, the second embedded metal floor, the third embedded metal floor and the bottom printed metal floor are connected by several metal ground vias. Each microstrip line, the top printed metal floor, and the layer of embedded metal floor together form a 50-ohm microstrip line I; The embedded strip, one layer of embedded metal floor, and three layers of embedded metal floor together form the 50-ohm strip II; One end of a 50-ohm microstrip line I is connected to one end of a 50-ohm stripline II, and one end of another 50-ohm microstrip line I is connected to the other end of a 50-ohm stripline II, forming the microwave transmission line.

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