CN117080701A - Heterogeneous integrated LTCC coaxial cavity band-pass filter and radio frequency front-end circuit - Google Patents

Heterogeneous integrated LTCC coaxial cavity band-pass filter and radio frequency front-end circuit Download PDF

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Publication number
CN117080701A
CN117080701A CN202311042734.1A CN202311042734A CN117080701A CN 117080701 A CN117080701 A CN 117080701A CN 202311042734 A CN202311042734 A CN 202311042734A CN 117080701 A CN117080701 A CN 117080701A
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China
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metal
dielectric
layer
coaxial cavity
metal layer
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CN202311042734.1A
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Chinese (zh)
Inventor
徐金旭
尤博怀
章秀银
李慧阳
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South China University of Technology SCUT
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South China University of Technology SCUT
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Priority to CN202311042734.1A priority Critical patent/CN117080701A/en
Publication of CN117080701A publication Critical patent/CN117080701A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/212—Frequency-selective devices, e.g. filters suppressing or attenuating harmonic frequencies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/202—Coaxial filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/207—Hollow waveguide filters
    • H01P1/208—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure

Abstract

The application discloses a heterogeneous integrated LTCC coaxial cavity band-pass filter and a radio frequency front-end circuit, which are manufactured by adopting an LTCC process and are composed of multiple dielectric layers with different dielectric constants, wherein a short-circuited end of a coaxial cavity resonator is filled with a low-dielectric constant medium, and an open-circuited section of the coaxial cavity resonator is filled with a high-dielectric constant medium, and the low-dielectric constant filter comprises side metal, bottom metal, a signal input port, a signal output port and a plurality of resonators. The coaxial cavity band-pass filter designed through the heterogeneous integrated LTCC process has the advantages of small size, low insertion loss, good roll-off performance and capability of effectively inhibiting higher harmonic waves, and can well meet the requirements of a radio frequency front-end circuit on miniaturization, high integration and low loss of a filter device.

Description

Heterogeneous integrated LTCC coaxial cavity band-pass filter and radio frequency front-end circuit
Technical Field
The application relates to the technical field of wireless communication, in particular to a heterogeneous integrated LTCC coaxial cavity band-pass filter and a radio frequency front-end circuit.
Background
With the rapid development of the mobile communication field, the market demand for high-performance radio frequency front-end devices is increasing. The filter is used as one of key devices of the radio frequency front end of the communication system, and is used for selectively passing or inhibiting signals in a specific frequency range, so that wireless communication devices with different standards in different frequency bands are not interfered with each other, and the filter is a component with the largest quantity and demand in the radio frequency front end, and therefore, pursuing high performance and miniaturization of the filter circuit is of great significance to the radio frequency front end device.
The low temperature co-fired ceramic (LTCC) technology uses ceramic layers and metal wire layers to form a multi-layer structure, can realize complex circuit design, has lower loss and higher integration level, and is widely applied to radio frequency front-end circuits. However, with the continuous improvement of the application frequency band of mobile communication, the structure of the radio frequency filter circuit is more and more complex, the requirement on the comprehensive performance index is higher and higher, and the conventional LTCC technology starts to show some limitations. This is mainly due to the limitations of the material properties and the manufacturing process for high performance, as well as losses and coupling effects that may occur in high frequency environments.
In addition, the coaxial cavity resonator adopts a coaxial structure, and is a filter commonly used in a radio frequency microwave band. Common coaxial cavity resonators are cast and burned from metal and face the problem of large volume while possessing a high quality factor and broad stop band rejection.
Disclosure of Invention
In order to overcome the drawbacks and disadvantages of the prior art, the present application is directed to a heterogeneous integrated LTCC coaxial cavity band-pass filter and a radio frequency front-end circuit.
The coaxial cavity filter is combined with a heterogeneous integration process, is designed based on a low temperature co-fired ceramic (LTCC) process, and is composed of a plurality of mediums with different dielectric constants, so that the characteristics of low insertion loss, compact size, high roll-off, high harmonic suppression and the like are obtained, and the coaxial cavity filter is very important for realizing a high-efficiency and reliable mobile communication system.
The aim of the application is achieved by the following technical scheme:
a heterogeneous integrated LTCC coaxial cavity band-pass filter is manufactured by adopting an LTCC process and is composed of multiple dielectric layers with different dielectric constants.
The semiconductor device comprises a substrate, a first dielectric layer, a second dielectric layer, a third dielectric layer and a fourth dielectric layer, wherein the substrate comprises four dielectric layers and four metal layers, the four dielectric layers are sequentially stacked from bottom to top and comprise the first dielectric layer, the second dielectric layer, the third dielectric layer and the fourth dielectric layer, the first dielectric layer, the second dielectric layer and the third dielectric layer are low-dielectric-constant dielectric layers, and the fourth dielectric layer is a high-dielectric-constant dielectric layer;
the four metal layers are respectively a first metal layer, a second metal layer, a third metal layer and a fourth metal layer; four metal layers are sequentially stacked from bottom to top, wherein the first metal layer is arranged on the upper surface of the first dielectric layer, the second metal layer is arranged on the upper surface of the second dielectric layer, the third metal layer is arranged on the upper surface of the third dielectric layer, the fourth metal layer is arranged on the upper surface of the fourth dielectric layer, and signal connection is carried out between different metal layers through metal vias.
Further, the device also comprises a side metal, a bottom metal, a signal input port, a signal output port and a plurality of resonators;
the side metal and the bottom metal are respectively arranged at the periphery and the bottom of the multi-layer dielectric layer to form a cavity;
the resonators are arranged in a straight line, the resonator at the head end is connected with the signal input port through a first microstrip line, and the resonator at the tail end is connected with the signal output port through a second microstrip line.
Further, the resonator comprises a plurality of metal cover plates, wherein the metal cover plates are respectively arranged on the first metal layer, the second metal layer and the third metal layer, and the metal cover plates penetrate through the dielectric layer through metal vias and are in metal connection with the bottom surface.
Further, the signal input port is located in the fourth metal layer, one end of the resonator located at the head end and one end of the first microstrip line are connected to the second metal layer, the other end of the first microstrip line is connected to the signal input port, and the first microstrip line is located in the second metal layer;
the signal output port is located on the fourth metal layer, the second microstrip line is located on the second metal layer, the resonator located at the tail end and one end of the second microstrip line are connected to the second metal layer, and the other end of the second microstrip line is connected with the signal output port.
Further, the diameter of the metal cover plate is larger than the diameter of the resonator.
Further, the signal input port and the signal output port adopt a G-S-G structure.
Further, the first dielectric layer, the second dielectric layer and the third dielectric layer are filled with a dielectric constant of 8;
and the fourth dielectric layer is filled with a dielectric constant of 45.
Further, the resonators are specifically five.
A radio frequency front-end circuit comprises the heterogeneous integrated LTCC coaxial cavity band-pass filter.
Compared with the prior art, the application has the following advantages and beneficial effects:
the coaxial cavity filter is realized based on the LTCC heterogeneous integrated process design, and the dielectric layers with different dielectric constants are utilized to obtain larger freedom degree of the filter design, so that the coaxial cavity filter gets rid of the limitation brought by the traditional microwave integrated circuit.
The application fills low dielectric constant medium at the short-circuited end of the coaxial cavity resonator and fills high dielectric constant medium at the open-circuited end of the coaxial cavity resonator. The equivalent inductance in the low-dielectric-constant medium and the equivalent capacitance in the high-dielectric-constant medium are integrated on one resonator at the same time, so that the equivalent inductance with low crosstalk and small loss (the low-dielectric-constant medium loss is usually smaller than the high-dielectric-constant medium loss) and the equivalent capacitance with small size can be obtained at the same time, and the insertion loss of the filter can be effectively reduced.
In addition, the capacitive design in high dielectric constant can provide a larger bandwidth tuning range, thereby increasing the coaxial cavity filter bandwidth. Therefore, the heterogeneous integrated LTCC coaxial cavity band-pass filter and the radio frequency front-end circuit have the characteristics of small size, low loss, high roll-off and the like and have high performance, and can effectively inhibit higher harmonics.
Drawings
Fig. 1 is a schematic structural diagram of a heterogeneous integrated LTCC coaxial cavity bandpass filter according to an embodiment of the present application;
fig. 2 is a side view of a metal layer structure of a heterogeneous integrated LTCC coaxial cavity bandpass filter according to an embodiment of the application;
FIG. 3 is a side view of a dielectric layer structure of a heterogeneous integrated LTCC coaxial cavity band-pass filter according to an embodiment of the present application;
FIG. 4 is a detailed view of S-parameter curves of 0-50GHz according to the embodiment of the application;
FIG. 5 is a detailed view of S-parameter curves of examples 0-80GHz according to the present application.
The figure shows: 1. side metal; 2. a bottom metal; 3. a first metal layer; 4. a second metal layer; 5. a third metal layer; 6. a fourth metal layer; 7. a first resonator; 8. a second resonator; 9. a third resonator; 10. a fourth resonator; 11. a fifth resonator; 12. a signal input port; 13. a signal output port; 14. a first microstrip line; 15. a second microstrip line; 16. a first dielectric layer; 17. a second dielectric layer; 18. a third dielectric layer; 19. and a fourth dielectric layer.
Detailed Description
The present application will be described in further detail with reference to examples, but embodiments of the present application are not limited thereto.
Example 1
As shown in fig. 1-3, a heterogeneous integrated LTCC coaxial cavity bandpass filter combines a coaxial cavity filter with a heterogeneous integration process, and is designed based on a low-temperature co-fired ceramic (LTCC) process, wherein the overall filter is composed of multiple dielectric constant media, a low-dielectric constant medium is filled in a short-circuited end of a coaxial cavity resonator, and a high-dielectric constant medium is filled in an open-circuited section of the coaxial cavity resonator. The filter circuit comprises a side metal 1, a bottom metal 2, a signal input port 12, a signal output port 13 and a plurality of resonators, wherein the filter circuit formed by the resonators is used for connecting the signal input port and the signal output port.
The heterogeneous integrated LTCC coaxial cavity band-pass filter comprises four dielectric layers and four metal layers.
As shown in fig. 3, the four dielectric layers include a first dielectric layer 16, a second dielectric layer 17, a third dielectric layer 18 and a fourth dielectric layer 19, where the first dielectric layer 16, the second dielectric layer 17 and the third dielectric layer 18 are low dielectric constant dielectric layers, are filled with a dielectric having a dielectric constant of 8 (er=8), and the fourth dielectric layer 19 is a high dielectric constant dielectric layer, and are filled with a dielectric having a dielectric constant of 45 (er=45).
As shown in fig. 2, the four metal layers are a first metal layer 3, a second metal layer 4, a third metal layer 5 and a fourth metal layer 6, respectively; four metal layers are sequentially stacked from bottom to top, wherein the first metal layer 3 is etched on the upper surface of the first dielectric layer 16, the second metal layer 4 is etched on the upper surface of the second dielectric layer 17, the third metal layer 5 is etched on the upper surface of the third dielectric layer 18, the fourth metal layer 6 is etched on the upper surface of the fourth dielectric layer 19, and signal connection is performed between different metal layers through metal vias.
Further, in this embodiment, the side metal and the bottom metal form a cavity structure, and the bottom metal is located on the lower surface of the first dielectric layer.
Further, the plurality of resonators includes a first resonator 7, a second resonator 8, a third resonator 9, a fourth resonator 10, and a fifth resonator 11, which are arranged in a straight line, and have the same structure.
Specifically, the resonator comprises a metal cover plate, wherein the metal cover plate is respectively arranged on a first metal layer, a second metal layer and a third metal layer, and the metal cover plate of each layer is connected with the bottom surface through a metal via hole and penetrates through a dielectric layer to be grounded.
Further, in this embodiment, the coaxial cavity resonator is manufactured by a low-temperature co-firing ceramic process, the resonator penetrates through multiple layers of media, and a metal cover plate slightly larger than the diameter of the resonator is added to a metal layer above each layer of media, so as to reduce errors caused during the process manufacturing.
The signal input port 12 is located in the fourth metal layer 6, one end of the first resonator 7 and one end of the first microstrip line 14 located at the head end are connected to the second metal layer 4, the other end of the first microstrip line is connected to the signal input port through a metal through hole, and the first microstrip line 14 is located in the second metal layer;
the signal output port 13 is located on the fourth metal layer 6, the second microstrip line 15 is located on the second metal layer, the fifth resonator 11 located at the tail end and one end of the second microstrip line are connected to the second metal layer 4, and the other end of the second microstrip line 15 is connected to the signal output port through a metal through hole.
The signal input port 12 is connected to the first resonator 7 at the second metal layer 4 through a via hole and a first microstrip line, the signal output port 13 is connected to the fifth resonator at the second metal layer through a via hole and a second microstrip line, the second metal layer is located between the second dielectric layer and the third dielectric layer, and both the second metal layer and the third metal layer belong to a low dielectric constant layer, and the low dielectric constant dielectric loss is generally smaller than the high dielectric constant dielectric loss, so that signal input and output to the resonator at the low dielectric constant layer is helpful for reducing the loss caused by signal transmission.
Further, the signal input port 12 and the signal output port 13 are constructed by adopting a G-S-G structure, and the structure is provided with ground wires at both sides of the signal wire, so that the transmission loss and distortion of signals can be effectively reduced, and the G-S-G structure can also provide good common mode rejection capability.
The conductor material in the filter is silver, and the element size and the wiring width are in the micrometer scale.
The heterogeneous integrated LTCC coaxial cavity band-pass filter and the radio frequency front-end circuit are in plane symmetry structures.
It should be noted that: the number of layers of the dielectric plates of the filter is related to the frequency band of application of the filter, and no matter which frequency band is applied to, the basic structure is that the short circuit part of the metal coaxial cavity is positioned on the low dielectric constant dielectric layer, and the open circuit part is positioned on the high dielectric constant dielectric layer.
Referring to fig. 4, an electromagnetic simulation graph of a heterogeneous integrated LTCC coaxial cavity band-pass filter and a radio frequency front-end circuit 0-50GHz is shown in the embodiment of the present application; simulation results show that the passband range of the filter is 23.25GHz-29.5GHz, the total in-band return loss is better than-24 dB, the insertion loss is better than 1.2dB, the filter is suitable for millimeter wave frequency bands, the out-of-band rejection performance is good, the rejection is greater than-40 dB when the frequency is smaller than 20.5GHz, and the rejection is greater than-30 dB when the frequency is greater than 33.5 GHz.
Referring to fig. 5, a 0-80GHz electromagnetic simulation graph of a heterogeneous integrated LTCC coaxial cavity band-pass filter and a radio frequency front-end circuit according to an embodiment of the present application is shown; simulation results show that the filter has good out-of-band rejection performance, can effectively reject high-frequency harmonic waves, and has secondary and third harmonic wave rejection of more than 55dB.
In summary, the filter provided by the embodiment of the application effectively reduces the size of the filter on the premise of ensuring the electrostatic protection capability, reduces the in-band insertion loss through the LTCC heterogeneous integration technology, and improves the out-of-band rejection performance; in addition, the whole filtering scheme is of a transverse plane symmetrical structure, the circuit structure is simple, the design is not limited to millimeter wave frequency band filters, and the filtering scheme can be widely applied to other application frequency bands.
Example 2
The embodiment also provides a radio frequency front-end circuit, which comprises the heterogeneous integrated LTCC coaxial cavity band-pass filter in embodiment 1.
The embodiments described above are preferred embodiments of the present application, but the embodiments of the present application are not limited to the embodiments described above, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the present application should be made in the equivalent manner, and are included in the scope of the present application.

Claims (10)

1. A heterogeneous integrated LTCC coaxial cavity band-pass filter is characterized by being manufactured by adopting an LTCC process and being composed of multiple dielectric layers with different dielectric constants.
2. The heterogeneous integrated LTCC coaxial cavity band-pass filter of claim 1, comprising four dielectric layers and four metal layers, wherein the four dielectric layers are sequentially stacked from bottom to top and comprise a first dielectric layer, a second dielectric layer, a third dielectric layer and a fourth dielectric layer, wherein the first dielectric layer, the second dielectric layer and the third dielectric layer are low dielectric constant dielectric layers, and the fourth dielectric layer is a high dielectric constant dielectric layer;
the four metal layers are respectively a first metal layer, a second metal layer, a third metal layer and a fourth metal layer; four metal layers are sequentially stacked from bottom to top, wherein the first metal layer is arranged on the upper surface of the first dielectric layer, the second metal layer is arranged on the upper surface of the second dielectric layer, the third metal layer is arranged on the upper surface of the third dielectric layer, the fourth metal layer is arranged on the upper surface of the fourth dielectric layer, and signal connection is carried out between different metal layers through metal vias.
3. The heterogeneous integrated LTCC coaxial cavity bandpass filter of claim 2, further comprising a side metal, a bottom metal, a signal input port, a signal output port, and a plurality of resonators;
the side metal and the bottom metal are respectively arranged at the periphery and the bottom of the multi-layer dielectric layer to form a cavity;
the resonators are arranged in a straight line, the resonator at the head end is connected with the signal input port through a first microstrip line, and the resonator at the tail end is connected with the signal output port through a second microstrip line.
4. The heterogeneous integrated LTCC coaxial cavity bandpass filter of claim 3, wherein the resonator comprises a plurality of metal cap plates disposed on the first metal layer, the second metal layer, and the third metal layer, respectively, the metal cap plates being in metallic connection with the bottom surface through the dielectric layer.
5. The heterogeneous integrated LTCC coaxial cavity bandpass filter of claim 3 or 4, wherein the signal input port is located in a fourth metal layer, a resonator located at a front end and one end of a first microstrip line are connected to a second metal layer, the other end of the first microstrip line is connected to the signal input port, and the first microstrip line is located in the second metal layer;
the signal output port is located on the fourth metal layer, the second microstrip line is located on the second metal layer, the resonator located at the tail end and one end of the second microstrip line are connected to the second metal layer, and the other end of the second microstrip line is connected with the signal output port.
6. The heterogeneous integrated LTCC coaxial cavity bandpass filter of claim 4, wherein the metal cap plate has a diameter greater than a resonator diameter.
7. The heterogeneous integrated LTCC coaxial cavity bandpass filter of claim 3, wherein the signal input port and the signal output port are in a G-S-G configuration.
8. The heterogeneous integrated LTCC coaxial cavity bandpass filter of claim 2, wherein the first, second, and third dielectric layers are filled with a dielectric having a dielectric constant of 8;
and the fourth dielectric layer is filled with a dielectric constant of 45.
9. A heterogeneous integrated LTCC coaxial cavity bandpass filter according to claim 3 wherein the resonators are in particular five.
10. A radio frequency front-end circuit comprising a heterogeneous integrated LTCC coaxial cavity bandpass filter as claimed in any one of claims 1-9.
CN202311042734.1A 2023-08-17 2023-08-17 Heterogeneous integrated LTCC coaxial cavity band-pass filter and radio frequency front-end circuit Pending CN117080701A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311042734.1A CN117080701A (en) 2023-08-17 2023-08-17 Heterogeneous integrated LTCC coaxial cavity band-pass filter and radio frequency front-end circuit

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Application Number Priority Date Filing Date Title
CN202311042734.1A CN117080701A (en) 2023-08-17 2023-08-17 Heterogeneous integrated LTCC coaxial cavity band-pass filter and radio frequency front-end circuit

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CN117080701A true CN117080701A (en) 2023-11-17

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