LTCC-based switch type band-pass filter

Abstract

The invention relates to an LTCC (Low Temperature Co-Fired Ceramic)-based switch type band-pass filter. The filter comprises a multi-layer LTCC substrate, a resonator, a switching circuit and a control circuit are packaged into a whole through a three-dimensional integration technology, and the multi-layer LTCC substrate is formed by vertically stacking and sintering a plurality of layers of ceramic green sheets; the number of the resonators is at least two, the adjacent resonators realize electromagnetic coupling through a rectangular coupling window, and the tail ends of the resonators are connected to a bottom layer grounding plane through metalized through holes; the switching circuit comprises a plurality of PIN diodes, the diodes are embedded between the fourth layer and the fifth layer of the LTCC by flip-chip bonding, the anodes are connected with the control line through through holes, and the cathodes are directly grounded; the control circuit comprises a coplanar waveguide and a high-frequency choking coil, and the coplanar waveguide is connected with the high-frequency choking coil in series. The switch and the filter are integrally packaged, and the size is smaller than 5 mm * 3 mm * 1 mm; the switching state insertion loss is less than or equal to 2dB, and the turn-off isolation is greater than or equal to 30dB; lTCC packaging is resistant to high temperature and vibration, and is suitable for severe environments.

Description

Technical Field

[0001] This invention relates to the field of microwave communication technology, and more particularly to an LTCC-based switchable bandpass filter. Background Technology

[0002] Extensive research has been conducted on bandpass filters both domestically and internationally. However, the low-frequency band requires too much space and has low integration density, which is far from meeting the requirements for miniaturization. Furthermore, most current filters lack sufficient attenuation in the stopband to suppress clutter frequencies near the passband. Therefore, how to realize a miniature bandpass filter with good filtering characteristics has become one of the urgent problems to be solved in the industry. Summary of the Invention

[0003] The purpose of this invention is to provide a small-sized, low-insertion-loss, frequency-band-switching LTCC-based switchable bandpass filter to solve the problems in the prior art.

[0004] The technical solution of this invention is: an LTCC-based switching bandpass filter, wherein the filter comprises a multilayer LTCC substrate, and the resonator, switching circuit, and control circuit are integrated into one unit using three-dimensional integration technology. The multilayer LTCC substrate is formed by vertically stacking and sintering multiple layers of ceramic green sheets; The resonator has at least two components, and adjacent resonators are electromagnetically coupled through a rectangular coupling window. The ends of the resonators are connected to the bottom ground plane through metallized vias. The switching circuit includes multiple PIN diodes, which are flip-chip embedded between the 4th and 5th layers of LTCC. The anode is connected to the control line through a through-hole, and the cathode is directly grounded. The control circuit includes a coplanar waveguide and a high-frequency choke, wherein the coplanar waveguide is connected in series with the high-frequency choke.

[0005] Preferably, the dielectric constant εr of the ceramic green sheet is 5.5~7.5, and the thickness of a single sheet is 0.1mm / layer.

[0006] Preferably, the resonator is a stepped impedance resonator, the edge of the rectangular coupling window is 0.15mm from the end of the resonator, the linewidth of the high impedance segment of the stepped impedance resonator is 0.08~0.12mm, the linewidth of the low impedance segment is 0.25~0.35mm, and the length ratio of the high impedance segment to the low impedance segment is 1:1.5~2.5.

[0007] Preferably, the switching circuit is embedded between LTCC layers and connected in series with the resonator branch path to change the effective electrical length of the resonator.

[0008] The beneficial effects of this invention are: integrated design: the switch and filter are packaged in one piece, with a size of less than 5mm×3mm×1mm; low insertion loss: insertion loss in the switching state ≤2dB, and isolation during shutdown ≥30dB; high reliability: the LTCC package is resistant to high temperature and vibration, and is suitable for harsh environments. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of the present invention.

[0010] In the diagram, 1 is the LTCC substrate, 2 is the resonator, 3 is the switching circuit, 4 is the control circuit, and 5 is the PIN diode. Detailed Implementation

[0011] Based on an LTCC switching bandpass filter, the filter includes a multilayer LTCC substrate 1, and a resonator 2, a switching circuit 3, and a control circuit 4 are integrated into a single unit using three-dimensional integration technology. The multilayer LTCC substrate 1 is formed by vertically stacking and sintering multiple layers of ceramic green sheets; The resonator 2 has at least two components, and adjacent resonators 2 are electromagnetically coupled through a rectangular coupling window. The ends of the resonators 2 are connected to the bottom ground plane through metallized through-holes. The switching circuit 3 includes multiple PIN diodes 5, which are flip-chip embedded between the 4th and 5th layers of the LTCC. The anode is connected to the control line through a through-hole, and the cathode is directly grounded. The control circuit 4 includes a coplanar waveguide and a high-frequency choke, wherein the coplanar waveguide is connected in series with the high-frequency choke.

[0012] The dielectric constant εr of the ceramic green sheet is 5.5~7.5, and the thickness of a single sheet is 0.1mm / layer.

[0013] The resonator 2 is a stepped impedance resonator. The edge of the rectangular coupling window is 0.15 mm from the end of the resonator. The linewidth of the high impedance section of the stepped impedance resonator is 0.08~0.12 mm, the linewidth of the low impedance section is 0.25~0.35 mm, and the length ratio of the high impedance section to the low impedance section is 1:1.5~2.5.

[0014] The switching circuit 3 is embedded between the LTCC layers and connected in series with the branch path of the resonator 2 to change the effective electrical length of the resonator 2.

[0015] In the description of this invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0016] In this invention, unless otherwise explicitly specified and limited, for example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements or an interaction between two elements. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0017] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings.

[0018] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A LTCC-based switched bandpass filter, characterized in that: The filter comprises a multilayer LTCC substrate (1), and a resonator (2), a switching circuit (3), and a control circuit (4) are integrated into one unit using three-dimensional integration technology. The multilayer LTCC substrate (1) is formed by vertically stacking and sintering multiple layers of ceramic green sheets; The resonator (2) has at least two components. The adjacent resonators (2) are electromagnetically coupled through a rectangular coupling window. The ends of the resonators (2) are connected to the bottom ground plane through metallized through-holes. The switching circuit (3) includes multiple PIN diodes (5). The diodes (5) are embedded between the 4th and 5th layers of the LTCC using flip-chip bonding. The anode is connected to the control line through a through-hole, and the cathode is directly grounded. The control circuit (4) includes a coplanar waveguide and a high-frequency choke, wherein the coplanar waveguide is connected in series with the high-frequency choke.

2. The LTCC-based switched bandpass filter according to claim 1, characterized in that: The dielectric constant εr of the ceramic green sheet is 5.5~7.5, and the thickness of a single sheet is 0.1mm / layer.

3. The LTCC-based switched bandpass filter according to claim 1, characterized in that: The resonator (2) is a stepped impedance resonator. The edge of the rectangular coupling window is 0.15 mm from the end of the resonator. The line width of the high impedance section of the stepped impedance resonator is 0.08~0.12 mm, the line width of the low impedance section is 0.25~0.35 mm, and the length ratio of the high impedance section to the low impedance section is 1:1.5~2.

5.

4. The LTCC-based switched bandpass filter according to claim 1, characterized in that: The switching circuit (3) is embedded in the interlayer of the LTCC substrate (1) and connected in series with the branch path of the resonator (2) to change the effective electrical length of the resonator (2).

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