Reconfigurable multi-channel frequency-selecting filtering base and module based on LTCC (Low Temperature Co-Fired Ceramic) technology

Abstract

The invention provides a reconfigurable multi-channel frequency selection filtering base and module based on an LTCC technology. The base comprises a plurality of layers of LTCC substrates, at least M filter installation positions, at least two radio frequency switch installation positions and a plurality of vertical via holes. The plurality of layers of LTCC substrates are sequentially a slotting layer, a microstrip line transmission layer, a strip line transmission layer, a signal transmission layer and an external bonding pad layer, each strip line transmission layer comprises a strip line and a plurality of layers of LTCC substrates, and the radio frequency switch mounting position and the filter mounting position are assembled on the surface of the microstrip line transmission layer. Cascade connection is achieved between the radio frequency switch installation positions and between the filter installation positions and the radio frequency switch installation positions through microstrip lines or vertical via holes, and radio frequency signals, power signals and control signals are transmitted to the radio frequency switch installation positions and the filter installation positions on the surface of the microstrip line transmission layer through the external bonding pad layer via the vertical via holes. According to the invention, the rapid reconstruction of the whole multi-channel frequency-selecting filtering base can be realized only by replacing the filter.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave radio frequency circuits, and in particular to a reconfigurable multi-channel frequency-selective filtering base and module based on LTCC technology. Background Art

[0002] The frequency selection filter module consists of a switching circuit and a multi-channel filter. It switches to the required frequency band through the switching circuit to meet different frequency selection requirements. Nowadays, with the rapid development of information communication, realizing the design of filter operating frequency selectability will be one of the effective ways to improve communication efficiency. The traditional frequency selection filter module is large in size and does not conform to the mainstream trend of miniaturization of current communication systems. It also cannot meet the current domestic and international demand for miniaturization, integration, and mass production of electronic components in the RF field. Low-temperature co-fired ceramic (LTCC) is a recently developed multilayer substrate wiring technology that has become a mainstream technology for passive integration and a key development in the passive component field. It involves stacking and sintering multiple layers of unfired green ceramic material to form an integrated ceramic multilayer. Passive components (such as low-capacitance capacitors, resistors, filters, impedance converters, and couplers) are embedded within the multilayer ceramic substrate and then laminated together. Metals such as silver, copper, and gold can be used for the inner and outer electrodes, improving the quality factor of the circuit system. LTCC technology, by sintering at 900°C, creates high-density circuits that do not interfere with each other in three dimensions. This allows for the fabrication of circuit substrates with a high number of layers and the embedding of multiple passive components, eliminating the cost of packaging components. This allows for the integration of both passive and active components within a high-layer, three-dimensional circuit substrate, increasing circuit assembly density and further reducing size and weight.

[0003] However, the filtering frequency bands of most existing multi-channel frequency-selective filter modules are fixed when they leave the factory. If the user's filtering requirements do not match the module's preset frequency band, the module cannot be used, forcing the user to purchase a new module to meet specific frequency band requirements, which undoubtedly greatly increases the cost of use. Summary of the Invention

[0004] The present invention aims to solve the shortcomings of the prior art and provides a reconfigurable multi-channel frequency-selective filter base and module based on LTCC technology.

[0005] In order to solve the above technical problems, the present invention is solved by the following technical solutions: A reconfigurable multi-channel frequency-selective filter base based on LTCC technology, wherein the multi-channel frequency-selective filter base is an M-channel frequency-selective filter base, comprising several layers of LTCC substrates, at least M filter mounting positions, at least two radio frequency switch mounting positions, and several vertical vias; the several layers of LTCC substrates are stacked in sequence: a slotted layer, a microstrip line transmission layer, a stripline transmission layer, a signal transmission layer, and an external pad layer, wherein the slotted layer comprises at least one layer of LTCC substrate, the microstrip line transmission layer comprises several microstrip lines and at least one layer of LTCC substrate, the number of the stripline transmission layer is one or more layers, each stripline transmission layer comprises several striplines and at least two layers of LTCC substrate, and the number of the signal transmission layer is one or more layers. Each signal transmission layer includes several transmission circuits and at least one LTCC substrate, and the external pad layer includes several external pads and at least one LTCC substrate; the RF switch mounting position and the filter mounting position are used to install corresponding RF switches and filters, and the RF switch mounting position and the filter mounting position are assembled on the surface of the microstrip line transmission layer. The microstrip line transmission layer and the stripline transmission layer, the signal transmission layer and the external pad layer are connected through vertical vias. The RF switch mounting positions and the filter mounting positions and the RF switch mounting positions are cascaded through vertical vias or microstrip lines. The RF signal, the RF switch power signal and the RF switch control signal are all transmitted through the external pads through the vertical vias to the RF switch and filter on the surface of the microstrip line transmission layer.

[0006] Optionally, the vertical vias include a first vertical via, a second vertical via, a third vertical via, and a fourth vertical via; The RF switch installation positions and the filter installation position and the RF switch installation position are connected to the stripline conductor strip on the stripline transmission layer through the first vertical via to realize RF cascade; The radio frequency switch installation positions are connected to the transmission circuit on the signal transmission layer through the second vertical via to realize DC cascade; Connecting the plurality of layers of LTCC substrates through the third vertical via to achieve a common ground; The fourth vertical via is connected to the external pad, and the radio frequency signal, the radio frequency switch power supply signal and the radio frequency switch control signal are respectively transmitted through the corresponding external pad and the corresponding fourth vertical via to the radio frequency switch and filter on the surface of the microstrip line transmission layer; Among them, the first vertical via hole, the second vertical via hole and the fourth vertical via hole are located in the peripheral area of the filter installation position or the RF switch installation position, and the third vertical via hole is located in the vertical projection area of the filter installation position or the RF switch installation position.

[0007] Optionally, the RF switch installation positions or the RF switch installation position and the filter installation position are cascaded through a microstrip line on a microstrip line transmission layer.

[0008] Optionally, the radio frequency switch installation position is composed of a cascade of a sub-b radio frequency switch installation positions, wherein: ; The one-point B RF switch installation position includes a first-level input RF switch installation position, a plurality of second-level input RF switch installation positions, a first-level output RF switch installation position and a plurality of second-level output RF switch installation positions; The output ports of the first-level input RF switch installation position are cascaded with the input ports of the second-level input RF switch installation position, the output ports of the second-level input RF switch installation position are cascaded with the input ports of the filter installation position, the output ports of the filter installation position are cascaded with the output ports of the second-level output RF switch installation position, and the input ports of the second-level output RF switch installation position are cascaded with the output ports of the first-level output RF switch installation position.

[0009] Optionally, the slotted layer is formed by slotting the LTCC substrate to expose the microstrip line transmission layer. The number of LTCC substrate layers in the slotted layer is obtained by the height of the corresponding RF switch, the height of the corresponding filter, the gold wire bonding height, and the thickness of a single-layer LTCC substrate, as shown below:

[0010] Among them, max() represents the maximum value function, B represents the number of LTCC substrate layers in the slotted layer, and H SW Represents the height of a single corresponding RF switch, H F Represents the height of a single corresponding filter, H BW Indicates the gold wire bonding height, D LTCC Indicates the thickness of a single-layer LTCC substrate, Indicates rounding up.

[0011] Optionally, the microstrip line transmission layer includes a plurality of microstrip lines, at least one LTCC substrate located between the microstrip line conductor strip and the microstrip line ground plate, wherein the microstrip line conductor strip is located on a surface of the LTCC substrate facing the slotted layer; The stripline transmission layer is composed of several striplines, at least one LTCC substrate located between the stripline conductor strips and the grounding plate on the stripline, and at least one LTCC substrate located between the stripline conductor strips and the grounding plate below the stripline.

[0012] Optionally, the microstrip line ground plate is a microstrip line RF ground, and the stripline lower ground plate and the stripline lower ground plate are both stripline RF grounds. When the microstrip line RF ground is adjacent to the stripline RF ground or different stripline RF grounds, the microstrip line RF ground and the stripline RF ground or different stripline RF grounds share the same ground plate.

[0013] Optionally, by adjusting the width of the stripline conductor strip and the number of layers of the LTCC substrate in the stripline transmission layer, the characteristic impedance of the stripline in the stripline transmission layer is achieved to be 50Ω.

[0014] The present application also provides a reconfigurable multi-channel frequency-selective filter module based on LTCC technology, which includes a filter, a radio frequency switch, and any of the above-mentioned reconfigurable multi-channel frequency-selective filter bases based on LTCC technology. The filter is electrically connected to the filter mounting position, and the radio frequency switch is electrically connected to the radio frequency switch mounting position.

[0015] Optionally, the radio frequency switch is an MMIC radio frequency switch, and the filter is an FBAR filter.

[0016] The present invention has significant technical effects due to the adoption of the above technical solutions: the present invention proposes an innovative reconfigurable multi-channel frequency-selective filter base based on LTCC technology, which is an M-channel frequency-selective filter base that integrates a multi-layer LTCC substrate, multiple filter mounting positions, multiple RF switch mounting positions, and precisely laid out vertical vias. The multi-layer LTCC substrate of the base is sequentially composed of at least one slotted layer, a microstrip line transmission layer, at least one stripline transmission layer, at least one signal transmission layer, and an external solder pad layer. The RF switch mounting position and the filter mounting position are both cleverly assembled on the surface of the microstrip line transmission layer, which not only fully utilizes the multi-layer wiring advantages of LTCC technology, but also realizes efficient connection between the microstrip line transmission layer and other layers through carefully designed vertical vias. In the present invention, the stripline is set in the stripline transmission layer in the middle layer, and the RF switch and filter are connected through vertical vias and striplines, allowing users to easily replace or combine filters according to the frequency band required for filtering. Crucially, only the filter itself needs to be replaced during this process, with no adjustments to other key components, such as the slotted layer, microstrip transmission layer, stripline transmission layer, and circuit transmission layer. This greatly simplifies the process, enabling the rapid reconfiguration of the entire multi-channel frequency-selective filter module simply by replacing the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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.

[0018] Figure 1 is a schematic cross-sectional view of an embodiment of the present invention; Figure 2 is a schematic top view of an embodiment of the present invention; Figure 3 2 is a bottom view schematically showing an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to the embodiments. The following embodiments are for explanation of the present invention and the present invention is not limited to the following embodiments. In the absence of conflict, the features in the following embodiments may be combined with each other.

[0020] Example 1: A reconfigurable multi-channel frequency-selective filter base based on LTCC technology, the multi-channel frequency-selective filter base is an M-channel frequency-selective filter base, including N layers of LTCC substrate, at least two RF switch mounting positions, M filter mounting positions and a plurality of vertical vias. The N layers of LTCC substrate are sequentially composed of a slotted layer (including a B layer of LTCC substrate), a microstrip line transmission layer, a C layer of stripline transmission layer, a D layer of signal transmission layer and an external pad layer, wherein the microstrip line transmission layer includes at least one layer of LTCC substrate and a plurality of microstrip lines, and each stripline transmission layer includes a plurality of striplines and c i layers of LTCC substrates, each signal transmission layer includes a plurality of transmission circuits and at least one layer of LTCC substrate, and the external pad layer includes a plurality of external pads and at least one layer of LTCC substrate, wherein, are all integers greater than or equal to 1, c i is an integer greater than or equal to 2, and The RF switch mounting position is used to install the corresponding RF switch, and the filter mounting position is used to install the corresponding filter. The RF switch mounting position and the filter mounting position are assembled on the surface of the microstrip line transmission layer. The microstrip line transmission layer and the stripline transmission layer, the signal transmission layer and the external pad layer are connected through vertical vias. The RF switch mounting positions and the filter mounting positions and the RF switch mounting positions are cascaded through vertical vias or microstrip lines. The RF signal, RF switch power supply signal and RF switch control signal are all transmitted through the external pad through the vertical vias to the corresponding RF switch and filter on the surface of the microstrip line transmission layer.

[0021] In this application, the surface of the LTCC substrate facing the slotted layer is referred to as the first surface, and the other surface of the LTCC substrate opposite to the first surface is referred to as the second surface. For ease of description, in this application, the direction from the slotted layer in the base to the external pad layer is defined as the direction from top to bottom. The N-layer LTCC substrate is sequentially referred to as L 1,..., L N .

[0022] In this embodiment, L1~L BThe layers (a total of B layers of LTCC substrates) are all slotted layers. The slotted layers include stacked B layers of LTCC substrates. The LTCC substrates in the slotted layers are slotted to expose the microstrip line transmission layer, and then the RF switch and filter are installed on the microstrip line transmission layer. The number of slotted layers is obtained by the height of the corresponding RF switch, the height of the corresponding filter, the height of the gold wire bonding and the thickness of the LTCC single-layer substrate, so that L B+1 The devices on the first surface of the layer substrate are at a certain distance from the L1 layer substrate, so that the module based on the base can be welded with a ceramic cover on the L1 layer substrate to achieve the hermetic packaging of the multi-channel frequency selective filter module. The number of slotted LTCC substrate layers B is expressed as follows:

[0023] Among them, max() represents the maximum value function, B represents the number of slotted LTCC substrate layers, and H SW Represents the height of the corresponding single RF switch, H F Denotes the height of the corresponding single filter, H BW Indicates the gold wire bonding height, D LTCC Indicates the thickness of a single-layer LTCC substrate, Indicates rounding up.

[0024] In this embodiment, L B+1 The first LTCC substrate serves as the microstrip transmission layer, comprising several microstrip lines, at least one LTCC substrate layer positioned between the several microstrip conductor strips, and a microstrip ground plane (lower ground plane). The first surface of the microstrip transmission layer is equipped with two RF M-switch mounting points and M filter mounting points. The RF switch mounting points are used to install RF switches, while the filter mounting points are used to install filters of different frequency ranges. This allows filters of corresponding frequency ranges to be selected based on actual needs, thereby reconstructing an M-channel frequency-selective filter module that can handle different frequency range combinations. The filter mounting point is located between the two RF switch mounting points and is cascaded with each RF switch mounting point, thereby achieving cascade connection between the filter and RF switch, forming M paths for the RF switch.

[0025] In this embodiment, the RF one-point M switch installation position can also be replaced by a RF switch installation position composed of a cascade of one-point B RF switch installation positions, where a is a positive integer greater than or equal to 2, and b is a positive integer. The quantitative relationship must satisfy All one-point-B RF switch mounting positions are divided into a first-level input RF switch mounting position, several second-level input RF switch mounting positions, a first-level output RF switch mounting position, and several second-level output RF switch mounting positions. The first-level input RF switch mounting position is cascaded with the second-level input RF switch mounting position, the first-level output RF switch mounting position is cascaded with the second-level output RF switch mounting position, the second-level input RF switch mounting position is cascaded with the filter mounting position, and the second-level output RF switch mounting position is cascaded with the filter mounting position. The cascading between the RF switch mounting positions facilitates the cascading of RF switches in modules based on this base. The microstrip ground plane serves as the RF ground of the microstrip line. The shape and size of the microstrip ground plane are consistent with the LTCC substrate. It is flat and covers the entire layer of LTCC substrate. It is located below the microstrip line and serves as the reference potential of the signal to ensure stable signal transmission and reduce interference.

[0026] Layer (total The number of stripline transmission layers is one or more. For the i-th stripline transmission layer, it includes several striplines and c i Layer LTCC substrate, where c i The LTCC substrate includes a k-type substrate located between the stripline conductor strip and the stripline ground plane. i,1 LTCC substrate, k-type substrate located between the stripline conductor strip and the ground plane under the stripline i,2 Layer LTCC substrate, where k i,1 and k i,2 are all positive integers, and k i,1 +k i,2 =c i . By setting the width of the stripline conductor strip and the number of layers of the LTCC substrate in the stripline transmission layer, the characteristic impedance of the stripline is made to be 50 ohms to reduce the transmission loss. When the number of channels M is large, and the microstrip line transmission layer and one layer of stripline transmission layer alone cannot meet the wiring requirements of the transmission lines required for the cascade between RF switches and between RF switches and filters, the number of stripline transmission layers can be increased. The upper ground plane and the lower ground plane of the stripline both serve as the RF ground of the stripline. The shape and size of the stripline ground plane are consistent with the LTCC substrate. They are flattened and cover the entire layer of LTCC substrate and are located on the first surface and the second surface of the stripline transmission layer respectively. If the microstrip line RF ground and the stripline RF ground are located on the first surface / second surface of the same layer of substrate (that is, the RF grounds are adjacent and there is no LTCC substrate between the RF grounds), then the microstrip line and the stripline can share the RF ground, that is, the RF ground is the same ground plane. Similarly, multiple stripline RF grounds can also share the same ground plane as the stripline RF ground.

[0027] The signal transmission layer can be one or more layers. Each layer includes several transmission circuits and at least one LTCC substrate. The transmission circuits can be located on either the second or first surface of the signal transmission layer. The signal transmission layer is positioned below the stripline transmission layer to avoid compromising the integrity of the stripline transmission layer. The number of signal transmission layer layers (D) should be determined based on the number of power and control signals and the actual wiring requirements.

[0028] L N The LTCC substrate is the external pad layer, L N The second surface of the layer is an external pad, wherein the middle of the second surface is a large-area ground pad, and the surrounding areas include a small pad for power signal transmission, several small pads for control signal transmission, and several small pads for RF signal transmission.

[0029] In this embodiment, the vertical vias include a plurality of first vertical vias, a plurality of second vertical vias, a plurality of third vertical vias, and a plurality of fourth vertical vias. Because the entire multi-channel frequency-selective filter base is very small, has a large number of channels, and has many RF signal connection lines between components, simply using microstrip lines is far from sufficient. Vertical vias are required to transition to a stripline transmission layer to achieve more connections.

[0030] The first vertical via V is passed between the RF switches and between the filter and the RF switch. RF The stripline conductor strip connected to the first surface of the stripline transmission layer realizes the radio frequency cascade. For example, the output signal of the radio frequency switch is transmitted through the first vertical via hole V RF Transmitted to the stripline on the first surface of the stripline transmission layer, and then through other first vertical vias V RF The first vertical via V RF The number and position of are determined according to the number of channels, device positions and specific wiring conditions.

[0031] Since the entire multi-channel frequency selection filter base is very small, has a large number of channels, and has a large number of DC signal connection lines for the RF switch, it is far from enough to use only microstrip lines. It is necessary to transition to the stripline transmission layer through vertical vias to achieve more connections. The RF switches are connected to the transmission circuit on the signal transmission layer through the second vertical via to achieve DC cascade. The specific power signal and control signal of the RF switch are transmitted through the second vertical via V CD The signal is transmitted to the transmission circuit of the signal transmission layer, and then passes through other second vertical vias V CD Transmitted to the next cascaded RF switch. Vertical via V CD The number and position of the pins must be determined based on the number of power / control signals, device location, and specific wiring conditions.

[0032] Through the third vertical via V GND The common ground is achieved between different layers of LTCC substrates, ensuring the stability and reliability of the multi-channel frequency selection filter base circuit and improving the integration and performance of the multi-channel frequency selection filter base. GND The number should be as large as possible and the location can be determined according to actual conditions.

[0033] The fourth vertical via is connected to the external pad, and the RF signal, RF switch power signal and RF switch control signal are transmitted through the corresponding external pad and the corresponding fourth vertical via to the RF switch and filter on the surface of the microstrip line transmission layer. Specifically: the external voltage is input from the power signal transmission pad, and the RF signal is transmitted through the fourth vertical via V PAD Transmitted to the microstrip line transmission layer where the device is located (i.e. L B+1 The control signal is input from the control signal transmission pad and passes through the fourth vertical via V PAD The RF signal is transmitted to the microstrip line transmission layer to control the opening of a certain channel of the RF switch. The RF signal is input from the RF signal transmission pad and passes through the fourth vertical via V PAD Transmitted to the microstrip line transmission layer.

[0034] The first vertical via, the second vertical via and the fourth vertical via are located in the peripheral area of the filter mounting position or the RF switch mounting position. The first vertical via, the second vertical via and the fourth vertical via are all used to transmit signals. They are distributed near the corresponding filter or RF switch, which can shorten the length of the gold wire bonding as much as possible, thereby ensuring the quality of signal transmission.

[0035] The third vertical via is located in the vertical projection (directly below) of the filter mounting position or the RF switch mounting position. The third vertical via is a grounding hole. The third vertical via is set directly below the corresponding RF switch and filter to ensure good grounding of the filter and the RF switch.

[0036] Therefore, the RF cascade between RF switches is achieved by: (1) directly connecting through the microstrip conductor strip on the first surface of the microstrip transmission layer; (2) the output RF signal of the RF switch passes through the first vertical via V RF Transmitted to the stripline conductor strip on the first surface of the stripline transmission layer, and then passed through another first vertical via V RF Transmitted to the next cascaded RF switch.

[0037] The DC cascade between RF switches is achieved by: (1) directly connecting through the microstrip conductor strip on the first surface of the microstrip transmission layer; (2) the output DC signal of the RF switch is connected through the second vertical via V CDThe signal is transmitted to the transmission circuit on the second surface of the signal transmission layer, and then passes through another second vertical via hole V CD Transmitted to the next cascaded RF switch.

[0038] The RF level connection between the RF switch and the filter can be achieved by: (1) directly connecting through the microstrip conductor strip on the first surface of the microstrip transmission layer; (2) the output RF signal of the RF switch is connected through the first vertical via hole V RF Transmitted to the stripline conductor strip on the first surface of the stripline transmission layer, and then passed through another first vertical via V RF Transmitted to the filter to achieve cascade connection between the RF switch and the filter.

[0039] It is important to note that the three device connection methods—RF-level interconnection between RF switches, DC-level interconnection between RF switches, and RF-level interconnection between RF switches and filters—are all preferentially connected through microstrip conductor strips. In practical applications, microstrip conductor strips alone cannot complete all device connections and must be connected through vertical vias. Therefore, there is a question of which device microstrip conductor strips should be used for priority connection. Generally, the principle of proximity is adopted, and microstrip conductor strips and vertical vias are flexibly used according to actual conditions to achieve all device connections, making wiring as simple and direct as possible.

[0040] It should be noted that the base in this embodiment does not include an RF switch or filter, but only has mounting locations for the RF switch and the filter. However, for ease of description, especially when referring to signal transmission, the RF switch and the filter are referred to rather than the corresponding mounting locations. Those skilled in the art will understand that, for the base, signals from the RF switch and the filter are transmitted to the corresponding mounting locations and then to the device.

[0041] The base in this application provides a filter installation position, allowing users to easily replace or combine filters according to the frequency of the required filtering. It has high flexibility and configurability, and does not require any adjustments to other key components such as the slotted layer, microstrip line transmission layer, stripline transmission layer, and circuit transmission layer. This feature greatly simplifies the operating process, making it possible to quickly reconstruct the entire multi-channel frequency-selective filter module only by replacing the filter. In addition, the LTCC multi-layer structure process makes it possible to transform two-dimensional planar wiring into three-dimensional wiring, but this is only the starting point for volume reduction. The key is that each layer and each component in the base are carefully designed and laid out to ensure that they can work together in the best way. Through the synergy of the overall structure, not only the volume of the base is significantly reduced, but also excellent performance is maintained.

[0042] Example 2: A reconfigurable multi-channel frequency-selective filter module based on LTCC technology includes a filter, a radio frequency switch, and a reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to any one of the above embodiments. The filter is electrically connected to a filter mounting position, and the radio frequency switch is electrically connected to a radio frequency switch mounting position.

[0043] The first surface of the microstrip transmission layer is equipped with two RF M switches and M filters. The RF switches are MMIC RF switches, and the filters are single-channel FBAR filters. Each filter processes signals within a different frequency range, forming an M-channel frequency-selective filter base. The filters are located between the two RF switches and are cascaded with each RF switch to form M channels of the RF switch.

[0044] In this embodiment, the RF one-to-M switch can be replaced by an RF switch composed of a cascade of one-to-B RF switches. All the one-to-B RF switches are divided into one first-level input RF switch, several second-level input RF switches, one first-level output RF switch and several second-level output RF switches. The b output ports of the first-level input RF switch are respectively cascaded with the input ports of the second-level input RF switch, the b output ports of the first-level output RF switch are respectively cascaded with the input ports of the second-level output RF switch, the b output ports of the second-level input RF switch are respectively cascaded with the input ports of the filter, and the b output ports of the second-level output RF switch are respectively cascaded with the output ports of the filter.

[0045] The process of implementing frequency band selection in a reconfigurable multi-channel frequency selection filter module based on LTCC technology is as follows: (1) The power signal of the RF switch and the channel control signal of the RF switch enter the multi-channel frequency selection filter module through the power signal transmission pad and the control signal transmission pad on the external pad layer respectively, and pass through the fourth vertical via V PAD Transmitted to the microstrip line transmission layer L B+1 After receiving the power signal and the control signal, the RF switch controls the RF switch to form a target RF channel.

[0046] (2) The RF signal enters the multi-channel frequency selection filter module through the RF signal transmission pad on the external pad layer, and passes through the fourth vertical via V PAD Transmitted to the microstrip transmission layer. (3) The RF signal is transmitted to the target filter through the target RF channel.

[0047] (4) The target filter that receives the RF signal filters the RF signal, allowing only the RF signals within the target frequency band to pass through, thereby suppressing the RF signals in other frequency bands.

[0048] (5) The filtered RF signal passes through the output RF switch and then through the fourth vertical via V PADAnd the output pads of the external pad layer are finally output to the external circuit.

[0049] Example 3: like Figures 1 to 3 As shown, Figure 1-Figure 3 They are respectively a cross-sectional schematic diagram, a top schematic diagram and a bottom schematic diagram of an embodiment of the present invention, wherein Figure 1 for Figure 2 Cross-sectional view along line AA. In this embodiment, a reconfigurable 16-channel frequency-selective filter module based on LTCC technology is provided, comprising a 16-channel frequency-selective filter base, 10 one-to-four MMIC RF switches SW1-SW10, and 16 FBAR filters UF1-UF16. The 16 filters are mounted in corresponding filter mounting positions in the base, and the 10 RF switches are mounted in corresponding RF switch mounting positions in the base. The 16-channel frequency-selective filter module comprises 17 layers of LTCC substrates. The raw ceramic material of the LTCC substrates is Dupont 951, each layer is 96 μm thick, and the conductive band material is Au, with a thickness after firing of 6-12 μm. The 17 layers of LTCC substrates are sequentially designated L1, ..., L17 from top to bottom.

[0050] The L1 to L5 LTCC substrates are slotted layers. All five layers of the LTCC substrates are slotted so that the devices on the first surface of the L6 substrate are at a certain distance from the L1 substrate. This facilitates the assembly of microstrip lines, RF switches, filter mounting locations, and corresponding devices on the L6 layer. Furthermore, a ceramic cover can be welded to the L1 substrate to achieve hermetic packaging.

[0051] The L6 substrate is a microstrip transmission layer. Several microstrip conductor strips M1 are located on the first surface of the L6 substrate. The microstrip ground plane is located on the second surface of the L6 substrate as the radio frequency ground of the microstrip line. Figure 2 As shown, 10 one-to-four MMIC RF switches SW1~SW10 and 16 FBAR filters UF1~UF16 are assembled on the first surface of the microstrip line transmission layer. The microstrip line conductor strip is used to provide connection points with the FBAR filter and the MMIC RF switch to transmit microwave RF signals.

[0052] The 10 1 / 4 MMIC RF switches SW1~SW10 are all positive-current controlled, integrated with TTL, and have a full-off function. The MMIC RF switch has low insertion loss, high isolation, a switching speed of 30ns, and a size of The MMIC RF switches are assembled on the first surface of the L6 substrate through a micro-assembly bonding process. SW1 to SW5 are input switches, and SW6 to SW10 are output switches. SW1 is a primary input RF switch, SW2 to SW5 are secondary input RF switches, SW10 is a primary output RF switch, and SW6 to SW9 are secondary output RF switches.

[0053] 16 FBAR filters UF1~UF16, different operating frequency ranges are selected as needed. The total operating frequency range of the 16-channel frequency selection filter module in this embodiment is 967~1215MHz (a total of 248MHz). This 248MHz operating frequency bandwidth is allocated to 16 FBAR filters. The size of the FBAR filter is , with the characteristics of extremely small size, low insertion loss, high close-frequency suppression, etc., the FBAR filter is assembled on the first surface of the L6 layer substrate through a micro-assembly bonding process.

[0054] The four output ports of MMIC RF switch SW1 are cascaded with the input ports of SW2 to SW5, respectively. The four output ports of MMIC RF switch SW10 are cascaded with the input ports of SW6 to SW9, respectively. The four output ports of MMIC RF switch SW2 are cascaded with the input ports of FBAR filters UF1, UF5, UF9, and UF13, respectively. Similarly, the four output ports of MMIC RF switch SW5 are cascaded with the input ports of FBAR filters UF4, UF8, UF12, and UF16, respectively. The four output ports of MMIC RF switch SW6 are cascaded with the output ports of FBAR filters UF1, UF5, UF9, and UF13, respectively. Similarly, the four output ports of MMIC RF switch SW9 are cascaded with the output ports of FBAR filters UF4, UF8, UF12, and UF16, respectively.

[0055] The L7-L14 substrates serve as the stripline transmission layer. In this embodiment, there are two stripline transmission layers: a first stripline transmission layer and a second stripline transmission layer. The L7-L10 substrates serve as the first stripline transmission layer, while the L11-L14 substrates serve as the second stripline transmission layer. For the first stripline transmission layer, the second surface of the L8 substrate has a stripline conductor strip. Two layers of LTCC substrate are located between the stripline conductor strip and the stripline ground plane, and two layers of LTCC substrate are located between the stripline conductor strip and the stripline ground plane. To minimize transmission loss, the stripline characteristic impedance must be 50 ohms. The second stripline transmission layer is similar to the first stripline transmission layer and will not be described in detail here. The second surfaces of the L6, L10, and L14 substrates serve as the stripline RF ground plane. The second surface of the L6 layer substrate is a radio frequency ground shared by the microstrip line and the stripline, and the second surface of the L10 layer substrate is a radio frequency ground shared by the two striplines.

[0056] The L15-L16 substrate layers are signal transmission layers. In this embodiment, there are two signal transmission layers: a first signal transmission layer and a second signal transmission layer. Layer L15 is the first signal transmission layer, and layer L16 is the second signal transmission layer. Both layers have several transmission circuits on their second surfaces.

[0057] The L17 layer is an external solder pad layer. Several external solder pads are distributed on the second surface of the L17 substrate, such as Figure 3 As shown, the center is a large ground pad P0, surrounded by pin pads P1 to P20. P3 and P13 are external RF signal transmission pads, P6 is an external power signal transmission pad, P7 to P10 are external control signal transmission pads, and the remaining pin pads are ground pads. External power is transmitted through pad P6 via a vertical via to the first surface of substrate L6, serving as the supply voltage for the MMIC RF switch. TTL switch channel control signals are transmitted through pads P7 to P10 via vertical vias to the first surface of substrate L6, controlling the switching of the target channel of the MMIC RF switch. Microwave RF signals are transmitted through pads P3 and P13 via vertical vias to the first surface of substrate L6. After passing through the FBAR filter of the target channel, they filter the signal in the specified frequency band. By changing the TTL signal, the desired switch channel and FBAR filter can be switched, achieving frequency band selection.

[0058] The vertical via hole includes a first vertical via hole V RF (V RF1 and V RF2 ), the second vertical via V CD (V CD1 and V CD2 ), the third vertical via V GND and the fourth vertical via hole V PAD .

[0059] There are several ways to connect the RF switches SW1 to SW10: (1) directly connect via the microstrip conductor M1 on the first surface of the microstrip transmission layer L6; (2) connect via the first vertical via V RF1 Transmitted to the stripline conductor M2 on the first surface of the substrate L9; (3) through the first vertical via V RF2 Transmitted to the stripline conductor strip M3 on the first surface of the substrate L13.

[0060] There are several ways to connect the MMIC RF switches SW1 to SW10 in a DC cascade: (1) directly connected via the microstrip conductor M1 on the first surface of the microstrip transmission layer L6; (2) connected via the second vertical via V CD1 Transmitted to the transmission circuit M4 of the substrate L16; (3) through the second vertical via V CD2 Transmitted to the transmission circuit M5 of the substrate L17.

[0061] There are several ways to connect the MMIC RF switches SW1~SW10 and the FBAR filters UF1~UF16 in cascade: (1) directly connected through the microstrip conductor M1 on the first surface of the microstrip transmission layer L6; (2) connected through the first vertical via VRF1 Transmitted to the stripline conductor M2 on the first surface of the substrate L9; (3) through the first vertical via V RF2 The transmission is to the stripline conductor M3 on the first surface of the substrate L13. The cascade mode between the devices can be flexibly selected from the above connection modes according to the actual situation.

[0062] There are several ways to connect the MMIC RF switches SW1 to SW10 and the cascade between the MMIC RF switches and the FBAR filter: (1) directly connect through the microstrip conductor M1 on the first surface of the microstrip transmission layer L6; (2) connect through the first vertical via V RF1 Transmitted to the stripline conductor M2 on the first surface of the substrate L9; (3) through the first vertical via V RF2 The cascade connection between the MMIC RF switches SW1 to SW10 also has the following paths: (1) through the second vertical via V CD1 Transmitted to the transmission circuit M4 of the substrate L16; (2) through the second vertical via V CD2 The transmission circuit M5 of the substrate L17 is transmitted. The cascade connection between the devices can be flexibly selected from the above connection methods according to the actual situation.

[0063] The size of the reconfigurable 16-channel frequency-selective filter module based on LTCC technology in this embodiment is only Its operating frequency band is 967-1215MHz, with in-band loss ≤3.4dB, standing wave less than ≤1.5, and out-of-band rejection (fo ± 30MHz) ≥50dBc. This 16-channel frequency-selective filter module not only achieves the miniaturization of multi-channel frequency-selective filter modules but also offers excellent performance. Furthermore, the module can be assembled through micro-assembly adhesive and gold wire bonding processes, which have low assembly requirements and offer advantages such as reconfigurability, ease of assembly, and mass production.

[0064] Various changes and modifications can be made without departing from the spirit and scope of the present invention, and all equivalent technical solutions also fall within the scope of the present invention.

[0065] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0066] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, apparatus, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0067] The present invention is described with reference to the flowcharts and / or block diagrams of the method, terminal device (system), and computer program product according to the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the process in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0068] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0069] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0070] It should be noted that: References in this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment" or "an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment.

[0071] Furthermore, it should be noted that the specific embodiments described in this specification may vary in the shapes and names of their components. Any equivalent or simple variations based on the structure, features, and principles described in the patented concept of this invention are included within the scope of protection of this patent. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments, and these modifications, as long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, shall fall within the scope of protection of this invention.

Claims

1. A reconfigurable multi-channel frequency selective filter base based on LTCC technology, wherein the multi-channel frequency selective filter base is an M-channel frequency selective filter base, characterized in that: It includes several layers of LTCC substrates, at least M filter mounting positions, at least two RF switch mounting positions and several vertical vias; The plurality of layers of LTCC substrates are stacked in sequence: a slotted layer, a microstrip line transmission layer, a stripline transmission layer, a signal transmission layer, and an external pad layer, wherein the slotted layer includes at least one layer of LTCC substrate, the microstrip line transmission layer includes a plurality of microstrip lines and at least one layer of LTCC substrate, the number of the stripline transmission layer is one or more, each stripline transmission layer includes a plurality of striplines and at least two layers of LTCC substrate, the number of the signal transmission layer is one or more, each signal transmission layer includes a plurality of transmission circuits and at least one layer of LTCC substrate, and the external pad layer includes a plurality of external pads and at least one layer of LTCC substrate; The RF switch mounting position and the filter mounting position are used to install the corresponding RF switches and filters. The RF switch mounting position and the filter mounting position are assembled on the surface of the microstrip line transmission layer. The microstrip line transmission layer and the stripline transmission layer, the signal transmission layer and the external pad layer are connected through vertical vias. The RF switch mounting positions and the filter mounting position and the RF switch mounting position are cascaded through vertical vias or microstrip lines. The RF signal, RF switch power supply signal and RF switch control signal are all transmitted through the external pad through the vertical vias to the RF switch and filter on the surface of the microstrip line transmission layer.

2. The reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to claim 1, characterized in that: The vertical vias include a first vertical via, a second vertical via, a third vertical via, and a fourth vertical via; The RF switch installation positions and the filter installation position and the RF switch installation position are connected to the stripline conductor strip on the stripline transmission layer through the first vertical via to realize RF cascade; The RF switch installation positions are connected to the transmission circuit on the signal transmission layer through the second vertical vias to realize DC cascading; Connecting the plurality of layers of LTCC substrates through the third vertical via to achieve a common ground; The fourth vertical via is connected to the external pad, and the radio frequency signal, the radio frequency switch power supply signal and the radio frequency switch control signal are respectively transmitted through the corresponding external pad and the corresponding fourth vertical via to the radio frequency switch and filter on the surface of the microstrip line transmission layer; Among them, the first vertical via hole, the second vertical via hole and the fourth vertical via hole are located in the peripheral area of the filter installation position or the RF switch installation position, and the third vertical via hole is located in the vertical projection area of the filter installation position or the RF switch installation position.

3. The reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to claim 1, characterized in that: The RF switch installation positions or the RF switch installation position and the filter installation position are cascaded through a microstrip line on a microstrip line transmission layer.

4. The reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to claim 1, characterized in that: The radio frequency switch installation position is composed of a cascade of a one-point b radio frequency switch installation positions, wherein, ; The one-point B RF switch installation position includes a first-level input RF switch installation position, a plurality of second-level input RF switch installation positions, a first-level output RF switch installation position and a plurality of second-level output RF switch installation positions; The output ports of the first-level input RF switch installation position are cascaded with the input ports of the second-level input RF switch installation position, the output ports of the second-level input RF switch installation position are cascaded with the input ports of the filter installation position, the output ports of the filter installation position are cascaded with the output ports of the second-level output RF switch installation position, and the input ports of the second-level output RF switch installation position are cascaded with the output ports of the first-level output RF switch installation position.

5. The reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to claim 1, characterized in that: The slotted layer is formed by slotting the LTCC substrate to expose the microstrip line transmission layer. The number of LTCC substrate layers in the slotted layer is obtained by the height of the corresponding RF switch, the height of the corresponding filter, the height of the gold wire bonding, and the thickness of the single-layer LTCC substrate, as shown below: Among them, max() represents the maximum value function, B represents the number of LTCC substrate layers in the slotted layer, and H SW Represents the height of a single corresponding RF switch, H F Represents the height of a single corresponding filter, H BW Indicates the gold wire bonding height, D LTCC Indicates the thickness of a single-layer LTCC substrate, Indicates rounding up.

6. The reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to claim 1, characterized in that: The microstrip line transmission layer includes a plurality of microstrip lines, at least one LTCC substrate located between the microstrip line conductor strip and the microstrip line ground plate, wherein the microstrip line conductor strip is located on the surface of the LTCC substrate facing the slotted layer; The stripline transmission layer is composed of several striplines, at least one LTCC substrate located between the stripline conductor strips and the grounding plate on the stripline, and at least one LTCC substrate located between the stripline conductor strips and the grounding plate below the stripline.

7. The reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to claim 6, characterized in that: The microstrip line ground plate is a microstrip line RF ground, and the stripline lower ground plate and the stripline lower ground plate are both stripline RF grounds. When the microstrip line RF ground is adjacent to the stripline RF ground or different stripline RF grounds, the microstrip line RF ground and the stripline RF ground or different stripline RF grounds share the same ground plate.

8. The reconfigurable multi-channel frequency-selective filter base based on LTCC technology according to claim 1, characterized in that: By adjusting the width of the stripline conductor strip and the number of layers of the LTCC substrate in the stripline transmission layer, the characteristic impedance of the stripline in the stripline transmission layer is achieved to be 50Ω.

9. A reconfigurable multi-channel frequency-selective filter module based on LTCC technology, characterized in that: The multi-channel frequency-selective filter module includes a filter, a radio frequency switch, and a reconfigurable multi-channel frequency-selective filter base based on LTCC technology as described in any one of claims 1-8, the filter is electrically connected to the filter mounting position, and the radio frequency switch is electrically connected to the radio frequency switch mounting position. 10 . The reconfigurable multi-channel frequency-selective filter module based on LTCC technology according to claim 9 , wherein the radio frequency switch is an MMIC radio frequency switch, and the filter is an FBAR filter.

Images