Radio frequency front-end module with integrated filter, preparation method and wireless communication system

Abstract

The application provides an integrated filter radio frequency front end module, a preparation method and a wireless communication system, wherein the integrated filter radio frequency front end module comprises a multilayer substrate, a filter and a radio frequency chip integrated on the multilayer substrate; wherein a signal transmission line for signal transmission is arranged in the multilayer substrate and penetrates the multilayer substrate; the filter is located between any two layers of the substrate and comprises a signal input port and an output port, a plurality of first ground holes filled with metal are symmetrically arranged around the input port and the output port, the plurality of first ground holes are respectively arranged around the input port and the output port away from the body of the filter, and the signal transmission line is connected with the input port and the output port; the radio frequency chip is assembled on the upper layer of the substrate, the input end of the radio frequency chip is connected with the output port of the filter through the signal transmission line, and the output end is connected with the radio frequency signal outlet through the signal transmission line. The radio frequency front end module provided by the application has high integration.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor chip packaging, and in particular to a radio frequency front-end module with an integrated filter, a preparation method, and a wireless communication system. Background Art

[0002] The RF front-end (RFFE) is a core component of wireless communication systems, responsible for transmitting and receiving RF signals. Key components within the RFFE include filters, which filter out frequencies outside of a specific range. In wireless communication systems, filters are essential for filtering out interference and attenuating noise.

[0003] With the continuous advancement of communication technology, 5G terminals are placing a series of new demands on RF front-ends, such as wide bandwidth, high power, low power consumption, and miniaturization. RF front-end components used in satellites, missiles, and airborne systems are particularly demanding, with a focus on miniaturization, lightweight integration, high-frequency integration, low cost, and high reliability. Low-pass filters, as key passive components in RF front-ends, pose significant challenges to their design and production.

[0004] However, although the current filters can achieve low losses, they cannot meet the needs of miniaturization and lightweighting of the RF front end because they need to use integrated packaging or metal packaging to protect the circuit in the later stage. Summary of the Invention

[0005] The embodiments of the present invention provide a radio frequency front-end module with an integrated filter, a preparation method, and a wireless communication system to solve the current problem of low integration of radio frequency front-ends.

[0006] In a first aspect, an embodiment of the present invention provides a radio frequency front-end module with an integrated filter, comprising: a multi-layer substrate, and a filter and a radio frequency chip integrated on the multi-layer substrate; wherein,

[0007] A signal transmission line is provided in the multi-layer substrate and penetrates the multi-layer substrate for signal transmission;

[0008] The filter is located between any two substrates and includes a signal input port and an output port. A plurality of first grounding holes filled with metal are symmetrically arranged around the input port and the output port. The plurality of first grounding holes are respectively arranged around the input port and the output port on a side away from the filter body. Signal transmission lines are respectively connected to the input port and the output port.

[0009] The RF chip is assembled on the upper substrate. The input end of the RF chip is connected to the output port of the filter through a signal transmission line, and the output end is connected to the RF signal outlet through a signal transmission line.

[0010] In one possible implementation, the filter includes:

[0011] a grounding metal layer, wherein a filter cavity is etched on the grounding metal layer;

[0012] A plurality of coupling lines are interdigitated and arranged in the filter cavity, and one end of each coupling line is connected to the ground metal layer; and

[0013] taps used as input ports and output ports respectively;

[0014] The first grounding hole vertically penetrates the grounding metal layer and forms a quasi-coaxial vertical interconnection structure with the signal transmission line.

[0015] In a possible implementation, the multi-layer substrate comprises, from bottom to top, a first substrate and a second substrate, and the filter is disposed in a first preset area on an upper surface of the first substrate;

[0016] The radio frequency chip is arranged in the second preset area of ​​the uppermost substrate;

[0017] The first preset area and the second preset area do not overlap in a direction perpendicular to the multi-layer substrate.

[0018] In one possible implementation, the multi-layer substrate is a three-layer substrate, the filter is located between a first substrate and a second substrate, a third substrate is provided on an upper surface of the second substrate, and a radio frequency chip is provided on an upper surface of the third substrate;

[0019] The first substrate, the second substrate and the third substrate are all provided with interconnected signal transmission lines for connecting the filter and the radio frequency chip.

[0020] In a possible implementation, a second grounding hole penetrating the first substrate is further provided on the grounding metal layer, and the second grounding hole surrounds the outside of the filter cavity.

[0021] In a possible implementation, multiple RF chips are provided, and the multiple RF chips, as well as the RF chips and the signal transmission lines are connected via bonding wires.

[0022] In a possible implementation, a sealed packaging shell is further provided outside the substrate of the RF chip. The packaging shell includes a packaging tube shell and a cover plate, and is used to package the RF chip.

[0023] In a possible implementation, the multi-layer substrates are bonded together using an adhesive layer, wherein the adhesive layer is made of one material or a combination of multiple materials selected from the group consisting of tungsten, molybdenum, nickel, and platinum.

[0024] In a second aspect, an embodiment of the present invention provides a method for preparing a radio frequency front-end module with an integrated filter, comprising:

[0025] Making interconnection through holes at preset positions on the multilayer substrate, and making a plurality of first grounding holes and second grounding holes in preset areas on the substrate of the filter to be made;

[0026] A grounding metal layer is prepared in a first preset area on a substrate on which a filter is to be fabricated, and an interdigitated cavity filter is fabricated on the grounding metal layer using a thick film photolithography process; wherein the taps of the filter serve as input and output ports for signal transmission, and first grounding holes are annularly arranged on the grounding metal layer outside the input and output ports, and a second grounding hole surrounding the filter is provided on the grounding metal layer outside the filter;

[0027] Placing all substrates in a preset stacking order to form a multi-layer substrate;

[0028] The substrate group is sliced, co-fired, brazed and plated to form a single substrate assembly;

[0029] Pasting a radio frequency chip on the topmost substrate of a single substrate assembly and bonding the radio frequency chip to the interconnection through-holes;

[0030] A package is fixed on the single substrate assembly and sealed with a cover.

[0031] In a third aspect, an embodiment of the present invention provides a wireless communication system, comprising a radio frequency front-end module with an integrated filter according to any one of the first aspects.

[0032] The RF front-end module with integrated filter, preparation method and wireless communication system provided by the present invention integrate the filter and the RF chip in a multi-layer substrate, and connect the filter and the RF chip through signal transmission lines between the multi-layer substrates. Finally, the filter and the RF chip are packaged together through integrated packaging, and no re-packaging is required during the subsequent circuit assembly process. Therefore, the RF front-end module with integrated filter has a compact structure and light weight, which meets the needs of current wireless communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 1 is a schematic structural diagram of a radio frequency front-end module with an integrated filter provided in an embodiment of the present invention;

[0035] Figure 2 The embodiment of the present invention provides Figure 1 Schematic diagram of the filter structure. DETAILED DESCRIPTION

[0036] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below with reference to the accompanying drawings.

[0038] As mentioned in the background, current RF front-end development is moving toward miniaturization, lightweight integration, high-frequency integration, low cost, and high reliability. As a key passive component in RF circuits and systems, low-pass filters also need to be reduced in size while maintaining superior performance.

[0039] Currently, filters are primarily fabricated using microstrip lines, waveguides, and cavities. While these filters can achieve low loss, they are often large. Furthermore, after micro-assembly, circuits must be protected using integrated packaging or metal packaging. These packaging materials significantly increase circuit quality, but also increase process complexity, leading to increased production cycle times and costs.

[0040] In order to solve the problems of the existing technology, an embodiment of the present invention provides a radio frequency front-end module with an integrated filter, a preparation method and a wireless communication system. The following first introduces the radio frequency front-end module with an integrated filter provided by an embodiment of the present invention.

[0041] A radio frequency front-end module with integrated filters comprises a multi-layer substrate and a filter and a radio frequency chip integrated on the multi-layer substrate.

[0042] A signal transmission line is provided within the multilayer substrate, running through the multilayer substrate and used for signal transmission. The signal transmission line can connect the filter and the RF chip, and also connect to an external RF signal port. The filter is located between any two layers of the substrate and includes an input port and an output port for signal transmission. A plurality of first grounding holes filled with metal are symmetrically arranged around the input port and the output port. The plurality of first grounding holes are respectively arranged around the input port and the output port on the side away from the filter body. The signal transmission line connects the input port and the output port respectively.

[0043] The RF chip is assembled on the top substrate. The input end of the RF chip is connected to the output port of the filter through a signal transmission line, and the output end is connected to the RF signal outlet through a signal transmission line.

[0044] The radio frequency chip may include but is not limited to a power amplifier chip and a low noise amplifier chip, which can amplify or reduce the noise of the received / transmitted radio frequency signals.

[0045] Specifically, conventional cavity filters require multiple layers of substrates to form a cavity-type filter, which occupies a large space. In order to reduce the space occupied by the filter, the filter can be prepared between two substrates.

[0046] The filter is an interdigital filter with a filter cavity etched into the grounded metal layer. Taps and coupling lines are located within the filter cavity. Multiple coupling lines are arranged in an interdigitated pattern within the filter cavity, with one end of each coupling line connected to the grounded metal layer. The taps serve as input and output ports. A first grounding via extends vertically through the grounded metal layer, forming a quasi-coaxial vertical interconnection with the signal transmission line.

[0047] In addition, outside the grounding metal layer, in addition to the first grounding hole, a second grounding hole is also provided. Both the first grounding hole and the second grounding hole pass through the upper and lower surfaces of the substrate and are filled with metal. Among them, the first grounding hole and the transmission through-hole used as the signal transmission line form a quasi-coaxial interconnection structure. The second grounding hole surrounds the filter cavity. The second grounding hole is mainly used to connect to the ground plane. The function of the first grounding hole surrounding the input port and the output port is to form a vertical transmission structure with the signal transmission through-hole located on the substrate, that is, a quasi-coaxial interconnection structure for transmitting microwave signals. A signal transmission line is provided in the transmission through-hole on the substrate.

[0048] Signal transmission through holes are provided on the multi-layer substrate, and the signal transmission through holes are three-dimensional vertical interconnected through holes. Signal transmission lines are provided in all signal transmission through holes for connecting filters and RF chips.

[0049] In some embodiments, the multi-layer substrate is composed of a first substrate and a second substrate from bottom to top, and the filter is arranged in a first preset area on the upper surface of the first substrate. That is, the ground metal layer is located on the upper surface of the first preset area of ​​the first substrate, and the filter is located between the first substrate and the second substrate. The RF chip is arranged in the second preset area of ​​the topmost substrate. The first preset area and the second preset area do not overlap in the direction perpendicular to the multi-layer substrate. It should be noted here that the multi-layer substrate includes at least three layers of substrates, the filter is between the first substrate and the second substrate, and the RF chip is located on the upper surface of the third substrate.

[0050] Multiple RF chips can be provided, and the RF chips and the signal transmission lines are connected by bonding wires. The bonding is done by gold wire bonding, and the length of the gold wire must be less than 100 times the gold wire diameter.

[0051] The radio frequency chip is fixed on the upper substrate by a sintering process, and the reserved position for the radio frequency chip is at least 0.05 mm larger than the chip.

[0052] In addition, a sealed packaging shell is arranged around the substrate of the radio frequency chip, and the packaging shell includes a packaging tube and a cover plate for packaging the radio frequency chip.

[0053] In some embodiments, the multi-layer substrates are bonded by an adhesive layer, wherein the adhesive layer is one material or a combination of multiple materials selected from tungsten, molybdenum, nickel, and platinum.

[0054] Figure 1 And Figure 2 An integrated filter radio frequency front-end module is also shown, which includes three substrates, a filter 20, two radio frequency chips 41, and a packaging shell.

[0055] The three substrates are sequentially arranged from bottom to top as a first substrate 11, a second substrate 12, and a third substrate 13, and three-dimensional vertical interconnection through holes are arranged on the three substrates, and signal transmission lines 31 are arranged in the through holes. The filter 20 is located between the first substrate 11 and the second substrate 12. The substrates can be made of AlN.

[0056] A ground metal layer 21 is arranged in a first preset area on the first substrate 11, and a filter cavity 22 is etched on the ground metal layer 21. A plurality of coupling lines 23 and two taps 24 are arranged in the filter cavity 22. The plurality of coupling lines are in a interdigitated shape in the filter cavity 22, and one end of each coupling line 23 is connected to the ground metal layer 21. An input port 27 and an output port 28 for transmitting signals are arranged on the two taps, respectively. A first ground hole 25 and a second ground hole 26 are also arranged on the ground metal layer 21, wherein a plurality of first ground holes 25 are arranged around the input port 27 and the output port 28 away from the body of the filter 20, and the second ground hole 26 is arranged around the filter cavity 22. The first ground hole 25 and the second ground hole 26 both penetrate the first substrate 11 from top to bottom, and the inside is filled with metal.

[0057] The three substrates are bonded together by an adhesive layer 14, which is one material or a combination of multiple materials selected from tungsten, molybdenum, nickel, and platinum.

[0058] The first ground hole 25, the input port 27 and the output port 28 arranged on the two taps, and the signal transmission lines 31 in the interconnection through holes connected thereto form a coaxial vertical interconnection structure. The second ground hole 26 is mainly used for connecting the ground plane.

[0059] Ground holes are arranged on the three substrates and penetrate the substrates, and the ground holes are connected to the ground metal on each substrate. This is not shown in the figure.

[0060] The first grounding hole 25, the second grounding hole 26 and the three-dimensional vertical interconnection through hole are all made on the substrate group by using the HTCC AlN process.

[0061] The radio frequency chip 41 is assembled on the third substrate 13, the input end of the radio frequency chip 41 is connected with the output port 28 of the filter 20 through the signal transmission line 31, and the output end is connected with the radio frequency signal outlet 33 through the signal transmission line 31. The input port 27 of the filter 20 is connected with the radio frequency signal inlet 32 through the signal transmission line 31. The radio frequency signal inlet 32 and the radio frequency signal outlet 33 are arranged on the ceramic substrate.

[0062] The plurality of radio frequency chips 41 and the signal transmission line 31 are connected through the bonding wire 36. The bonding is gold wire bonding, and the length of the gold wire satisfies less than 100 times the diameter of the gold wire. The plurality of radio frequency chips 41 are fixed on the third substrate by using the sintering process.

[0063] In addition, a sealed packaging shell is arranged on the periphery of the third substrate 13, and the packaging shell includes a packaging tube shell 34 and a cover plate 35, which are used for packaging the radio frequency chip. The cover can be laser capped or parallel capped.

[0064] The integrated filter radio frequency front-end module provided by the application integrates the filter and the radio frequency chip in the multilayer substrate, realizes the connection of the filter and the radio frequency chip through the signal transmission line between the multilayer substrates, and finally integrates and packages the filter and the radio frequency chip together, so that the integrated filter radio frequency front-end module does not need to be packaged again in the subsequent circuit assembly process, is compact in structure, light in weight, and meets the needs of the current wireless communication system.

[0065] In the second aspect, the application provides a preparation method of an integrated filter radio frequency front-end module, including:

[0066] First, interconnection through holes are made at predetermined positions of the multilayer substrate, and a plurality of first grounding holes and second grounding holes are made in a predetermined area of the substrate to be made into a filter. The substrate can be made of AlN. The interconnection through holes, the first grounding holes and the second grounding holes are filled with metal. The first grounding holes, the second grounding holes and the three-dimensional vertical interconnection through holes are all made on the substrate group by using the HTCC AlN process.

[0067] Then, a grounding metal layer is prepared in the first predetermined area of the substrate to be made into a filter, and an interdigital cavity filter is made on the grounding metal layer by using a thick film photoetching process. The filter is provided with an input port and an output port for signal transmission, and the input port and the output port are both annularly arranged with the first grounding holes on the outer side of the grounding metal layer. The second grounding hole is arranged on the outer side of the grounding metal layer and surrounds the filter.

[0068] Then, all the substrates are placed according to the preset stacking order, and a dense substrate group structure is formed under certain temperature and pressure, and the communication of the vertical metallization pattern is ensured, and the multi-layer substrate is formed by stacking. After slicing, co-firing, soldering and plating of the multi-layer substrate group, a single substrate assembly is formed.

[0069] Finally, the radio frequency chip is pasted on the uppermost substrate of the single substrate assembly, and the radio frequency chip is bonded with the interconnection via. The packaging tube is fixed on the single substrate assembly, and the packaging tube is sealed with a cover plate.

[0070] Wherein, the fixing of the radio frequency chip adopts sintering process, and the side length of the reserved position of the chip should be at least 0.05mm larger than the side length of the chip. The fixed packaging tube adopts laser cap sealing or parallel cover sealing. The multiple radio frequency chips and the signal transmission lines are connected through the bonding lead. The bonding adopts gold wire bonding, and the length of the gold wire satisfies less than 100 times the diameter of the gold wire.

[0071] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0072] In addition, the present application also provides a wireless communication system comprising the above-mentioned integrated filter radio frequency front-end module, which not only realizes the integrated packaging of the filter and the radio frequency chip, but also does not need to be integrated or metal packaged again after the filter and the radio frequency chip are assembled, so that the integration degree of the wireless communication system is high, and the weight of the whole system is greatly reduced.

[0073] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A radio frequency front-end module with integrated filter, characterized in that: include: A multi-layer substrate and a filter and a radio frequency chip integrated on the multi-layer substrate; wherein, A signal transmission line is provided in the multi-layer substrate and penetrates the multi-layer substrate for signal transmission; The filter is located between any two layers of substrates and includes a signal input port and an output port. A plurality of first grounding holes filled with metal are symmetrically arranged around the input port and the output port, and the plurality of first grounding holes are respectively arranged around the input port and the output port on a side away from the filter body. The signal transmission lines are respectively connected to the input port and the output port. The RF chip is mounted on the upper substrate, the input end of the RF chip is connected to the output port of the filter through the signal transmission line, and the output end of the RF chip is connected to the RF signal outlet through the signal transmission line; Wherein, the filter comprises: a grounding metal layer, on which a filter cavity is etched; a plurality of coupling lines, interdigitatedly arranged in the filter cavity, with one end of each coupling line connected to the ground metal layer; and taps serving as the input port and the output port, respectively; The first grounding hole vertically penetrates the grounding metal layer and forms a quasi-coaxial vertical interconnection structure with the signal transmission line.

2. The RF front-end module according to claim 1, wherein: The multi-layer substrate comprises a first substrate and a second substrate from bottom to top, and the filter is arranged in a first preset area on the upper surface of the first substrate; The radio frequency chip is arranged in the second preset area of ​​the uppermost substrate; The first preset area and the second preset area do not overlap in a direction perpendicular to the multi-layer substrate.

3. The RF front-end module according to claim 2, wherein: The multi-layer substrate is a three-layer substrate, the filter is located between the first substrate and the second substrate, a third substrate is provided on the upper surface of the second substrate, and the RF chip is provided on the upper surface of the third substrate; The first substrate, the second substrate and the third substrate are all provided with interconnected signal transmission lines for connecting the filter and the radio frequency chip.

4. The RF front-end module according to claim 2, wherein: The grounding metal layer is further provided with a second grounding hole penetrating the first substrate, and the second grounding hole surrounds the outside of the filter cavity.

5. The RF front-end module according to claim 1, wherein: A plurality of RF chips are provided, and the RF chips are connected to each other, and the RF chips and the signal transmission lines are connected via bonding wires.

6. The radio frequency front-end module according to claim 1, wherein: A sealed packaging shell is further provided on the periphery of the substrate of the radio frequency chip. The packaging shell comprises a packaging tube shell and a cover plate, and is used to package the radio frequency chip.

7. The radio frequency front-end module according to claim 1, wherein: The multi-layer substrates are bonded together by an adhesive layer, wherein the adhesive layer is made of one material or a combination of multiple materials selected from tungsten, molybdenum, nickel or platinum.

8. A method for preparing a radio frequency front-end module with an integrated filter, characterized in that: include: Making interconnection through holes at preset positions on the multilayer substrate, and making a plurality of first grounding holes and second grounding holes in preset areas on the substrate of the filter to be made; A grounding metal layer is prepared in a first preset area on a substrate on which a filter is to be fabricated, and an interdigitated cavity filter is fabricated on the grounding metal layer using a thick film photolithography process; wherein the taps of the filter serve as input and output ports for signal transmission, and the grounding metal layer outside the input and output ports is provided with first grounding holes arranged in an annular pattern, and the grounding metal layer outside the filter is provided with second grounding holes surrounding the filter; Placing all substrates in a preset stacking order to form a multi-layer substrate; The substrate group is sliced, co-fired, brazed and plated to form a single substrate assembly; Pasting a radio frequency chip on the uppermost substrate of the single substrate assembly, and bonding the radio frequency chip to the interconnection through-hole; A package is fixed on the single substrate assembly, and the package is sealed with a cover.

9. A wireless communication system, characterized in that: A radio frequency front-end module comprising the integrated filter according to any one of claims 1 to 7.

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