A low-insertion-loss low-pass filter for mobile communication frequency bands

Abstract

The present invention belongs to the technical field of filters for radio frequency front-end circuits and specifically discloses a near-insertion-loss-free low-pass filter for mobile communication frequency bands, comprising an LTCC ceramic body, a circuit layer, and an external electrode. The circuit layer is located within the LTCC ceramic body and, from top to bottom, comprises a first circuit layer, a second circuit layer, a third circuit layer, a fourth circuit layer, a fifth circuit layer, a sixth circuit layer, a seventh circuit layer, an eighth circuit layer, a ninth circuit layer, a tenth circuit layer, and an eleventh circuit layer. The external electrode is located at the bottom of the LTCC ceramic body and comprises an input port, an output port, a first ground port, and a second ground port. The external electrode is connected to the circuit layer via a via. The present invention solves the problem that conventional filters are prone to mutual coupling between lumped components, generating unnecessary parasitic parameters, thereby reducing the Q value of the filter circuit and increasing insertion loss, thereby achieving near-insertion-loss-free operation in mobile communication frequency bands.

Description

Technical Field

[0001] The present invention belongs to the technical field of filters of radio frequency front-end circuits, and in particular relates to a low-insertion-loss low-pass filter for mobile communication frequency bands. Background Art

[0002] With the rapid development of modern communication technology, small size, lightweight, and high reliability have become the inevitable trends in the development of modern communication systems. Filters, as the core frequency-selective components in transceiver systems, extract or filter signals of different frequencies. Traditional microstrip lowpass filters, due to their large size, narrow stopband, and insufficient rejection, are not easily integrated with other compact mobile communication terminals, limiting their use in microwave communication systems. Therefore, developing small, low-insertion-loss, wide stopband, and high-rejection bandpass filters has become a current research hotspot and challenge.

[0003] Compared to traditional filter designs, low-temperature co-fired ceramic (LTCC) technology uses low-resistivity materials such as gold, silver, and copper as conductive media. The equivalent circuit is embedded within the ceramic body through metal vias, enabling flexible structural layouts and significantly reducing the size of passive components. This plays a significant role in improving the integration, reliability, and electrical performance of filters. Compared to other traditional filter designs, LTCC technology offers the following advantages: excellent compatibility and high-frequency transmission characteristics, the ability to implement multi-layer wiring and various cavity structures, higher integration and assembly density, reduced size and weight, higher reliability, lower costs, and shorter production cycles. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of traditional microstrip low-pass filters due to their large structural size, narrow stopband and insufficient suppression, and inconvenience in integration with other compact mobile communication terminals. A low insertion loss low-pass filter for mobile communication frequency bands is proposed.

[0005] The technical solution of the present invention is: a low-insertion-loss low-pass filter for mobile communication frequency bands, comprising an LTCC ceramic body, a circuit layer, and an external electrode; the circuit layer is located inside the LTCC ceramic body, and the circuit layer includes, from top to bottom, a first circuit layer, a second circuit layer, a third circuit layer, a fourth circuit layer, a fifth circuit layer, a sixth circuit layer, a seventh circuit layer, an eighth circuit layer, a ninth circuit layer, a tenth circuit layer, and an eleventh circuit layer; the external electrode is located at the bottom of the LTCC ceramic body, and the external electrode includes an input port, an output port, a first ground port, and a second ground port, the input port and the output port are symmetrically arranged, and the first ground port and the second ground port are symmetrically arranged; the external electrode and the circuit layer are connected through a via.

[0006] The beneficial effects of the present invention are:

[0007] The present invention uses low-temperature co-fired ceramic technology to embed the circuit layer into the LTCC ceramic body and connect the external electrode to the circuit layer through vias. This solves the problem that traditional filters easily cause mutual coupling between lumped components, generating unnecessary parasitic parameters, thereby reducing the Q value of the filter circuit and increasing insertion loss, making the mobile communication frequency band almost insertion loss-free.

[0008] Preferably, the first circuit layer includes a first electrode plate;

[0009] The second circuit layer includes a second electrode plate;

[0010] The third circuit layer includes a third electrode plate;

[0011] The fourth circuit layer includes a fourth electrode plate;

[0012] The fifth circuit layer includes a fifth electrode plate;

[0013] The sixth circuit layer includes a sixth electrode plate;

[0014] The seventh circuit layer includes a seventh electrode plate;

[0015] The eighth circuit layer includes an eighth electrode plate;

[0016] The ninth circuit board includes a ninth electrode plate and a tenth electrode plate;

[0017] The tenth circuit layer includes an eleventh electrode plate;

[0018] The eleventh circuit layer includes a twelfth electrode plate;

[0019] The first electrode plate, the second electrode plate and the third electrode plate are connected through a first via hole and a second via hole;

[0020] The fourth electrode plate, the fifth electrode plate and the sixth electrode plate are connected through the second via hole and the third via hole;

[0021] The seventh electrode plate is connected to the fourth electrode plate, the fifth electrode plate and the sixth electrode plate through the third via hole;

[0022] The eighth electrode plate is connected to the ninth electrode plate through the fourth via hole;

[0023] The ninth electrode plate is connected to the input port through the fifth via hole;

[0024] The tenth electrode plate is connected to the output port through the sixth via hole, the tenth electrode plate is connected to the first ground port through the seventh via hole, and the tenth electrode plate is connected to the second ground port through the eighth via hole;

[0025] The twelfth electrode plate is connected to the first ground port through the seventh via hole, and the twelfth electrode plate is connected to the second ground port through the eighth via hole.

[0026] The beneficial effects of the above preferred solution are:

[0027] This preferred solution adopts a multi-layer layout structure, achieving the smallest volume in the industry within the same frequency band, and has the characteristics of miniaturization, low insertion loss, wide stopband, and high suppression.

[0028] Preferably, one end of the first electrode plate, one end of the second electrode plate, and one end of the third electrode plate are connected via a first via hole, and the other end of the first electrode plate, the other end of the second electrode plate, and the other end of the third electrode plate are connected via a second via hole to form a first equivalent inductor L1;

[0029] The ninth electrode plate and the eleventh electrode plate form a first equivalent capacitor C1 through interlayer coupling;

[0030] One end of the fourth electrode plate, one end of the fifth electrode plate, and one end of the sixth electrode plate are connected via a second via hole, and the other end of the fourth electrode plate, the other end of the fifth electrode plate, and the other end of the sixth electrode plate are connected via a third via hole to form a first equivalent inductor L2;

[0031] The tenth electrode plate and the eleventh electrode plate form a second equivalent capacitor C2 through interlayer coupling;

[0032] The ninth electrode plate, the seventh electrode plate and the tenth electrode plate form a third equivalent capacitor C3 through interlayer coupling;

[0033] The eleventh electrode plate and the twelfth electrode plate form a fourth equivalent capacitor C4 through interlayer coupling.

[0034] The beneficial effects of the above preferred solution are:

[0035] By reasonably selecting the equivalent component values ​​of the filter and optimizing the coupling relationship of its equivalent components in the vertical space, two equivalent inductors and four equivalent capacitors are formed to form the low-pass filter. It is possible to layout multiple inductor and capacitor components in an extremely small volume while achieving low loss and high suppression effects.

[0036] Preferably, one end of the first equivalent inductor L1, one end of the first equivalent capacitor C1, and one end of the third equivalent capacitor C3 are connected to the input port; the other end of the first equivalent inductor L1 and the other end of the first equivalent capacitor C1 are connected to one end of the second equivalent inductor L2, one end of the second equivalent capacitor C2, and one end of the fourth equivalent capacitor C4; the other end of the fourth equivalent capacitor C4 is connected to the first ground port and the second ground port; the other end of the second equivalent inductor L2, the other end of the second equivalent capacitor C2, and the other end of the third equivalent capacitor C3 are connected to the output port.

[0037] The beneficial effects of the above preferred solution are:

[0038] The present invention embeds the above-mentioned inductor and capacitor components into eleven circuit layers in a ceramic body, respectively, and has microwave characteristics of miniature size, high Q value, and wide stopband.

[0039] Preferably, the outer electrodes are packaged in a planar grid array.

[0040] The beneficial effects of the above preferred solution are:

[0041] The external electrode is placed on the bottom of the LTCC ceramic body using a planar grid array package and is connected to the circuit layer line inside the LTCC ceramic body through a via hole.

[0042] Preferably, the low-pass filter further comprises a mark, and the mark and the external electrode are located on the opposite side of the LTCC ceramic body.

[0043] The beneficial effects of the above preferred solution are:

[0044] Identification symbols are set on the top of the low-pass filter to identify the position of each port.

[0045] Preferably, the circuit layer is built into the LTCC ceramic body through a low temperature co-fired ceramic process.

[0046] The beneficial effects of the above preferred solution are:

[0047] The present invention incorporates a multilayer circuit of a low-pass filter into a ceramic body based on a low-temperature co-fired ceramic process, enabling integration of various equivalent components on a three-dimensional circuit substrate, thereby achieving miniaturization and high density of the circuit.

[0048] Preferably, the circuit layer is made of embedded metal material, and the embedded metal material includes copper or palladium silver.

[0049] The beneficial effects of the above preferred solution are:

[0050] The use of the above-mentioned high-conductivity metal materials is beneficial to improving the quality factor of the circuit system. For example, the use of palladium silver as the embedded metal material will not oxidize during the sintering process and does not require electroplating protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The figure shows a schematic structural diagram of a low-insertion-loss low-pass filter used in mobile communication frequency bands.

[0052] Figure 2 Shown is a schematic diagram of the internal structure of a low-pass filter.

[0053] Figure 3 Shown is the first circuit layer schematic of the low-pass filter.

[0054] Figure 4 Shown is the second circuit layer schematic of the low-pass filter.

[0055] Figure 5 Shown is the third circuit layer schematic of the low-pass filter.

[0056] Figure 6 Shown is the fourth circuit layer schematic of the low-pass filter.

[0057] Figure 7 Shown is the fifth circuit layer schematic of the low-pass filter.

[0058] Figure 8 Shown is the sixth circuit layer schematic of the low-pass filter.

[0059] Figure 9 Shown is the seventh circuit layer schematic of the low-pass filter.

[0060] Figure 10 Shown is the eighth circuit layer schematic of the low-pass filter.

[0061] Figure 11 Shown is the ninth circuit layer schematic of the low-pass filter.

[0062] Figure 12 Shown is the tenth circuit layer schematic diagram of the low-pass filter.

[0063] Figure 13 Shown is the schematic diagram of the eleventh circuit layer of the low-pass filter.

[0064] Figure 14 Shown is the equivalent schematic diagram of a low-pass filter.

[0065] Figure 15 Shown is the electrical performance curve of the low-pass filter.

[0066] Explanation of the accompanying drawings: 1. Input port; 2. Output port; 3. First ground port; 4. Second ground port; 5. Identification; P1. First electrode plate; P2. Second electrode plate; P3. Third electrode plate; P4. Fourth electrode plate; P5. Fifth electrode plate; P6. Sixth electrode plate; P7. Seventh electrode plate; P8. Eighth electrode plate; P9. Ninth electrode plate; P10. Tenth electrode plate; P11. Eleventh electrode plate; P12. Twelfth electrode plate; H1. First via hole; H2. Second via hole; H3. Third via hole; H4. Fourth via hole; H5. Fifth via hole; H6. Sixth via hole; H7. Seventh via hole; H8. Eighth via hole. DETAILED DESCRIPTION

[0067] The exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the accompanying drawings are merely exemplary and are intended to illustrate the principles and spirit of the present invention, rather than to limit the scope of the present invention.

[0068] Example:

[0069] like Figure 1 and Figure 2 As shown, a low-insertion-loss low-pass filter for mobile communication frequency bands includes an LTCC ceramic body, a circuit layer, and an external electrode; the circuit layer is located inside the LTCC ceramic body, and the circuit layer includes, from top to bottom, a first circuit layer, a second circuit layer, a third circuit layer, a fourth circuit layer, a fifth circuit layer, a sixth circuit layer, a seventh circuit layer, an eighth circuit layer, a ninth circuit layer, a tenth circuit layer, and an eleventh circuit layer; the external electrode is located at the bottom of the LTCC ceramic body, and the external electrode includes an input port 1, an output port 2, a first ground port 3, and a second ground port 4, wherein the input port 1 and the output port 2 are symmetrically arranged, and the first ground port 3 and the second ground port 4 are symmetrically arranged; the external electrode and the circuit layer are connected through vias.

[0070] In this embodiment, if Figure 3 As shown, the first circuit layer includes a first electrode plate P1;

[0071] like Figure 4 As shown, the second circuit layer includes a second electrode plate P2;

[0072] like Figure 5 As shown, the third circuit layer includes a third electrode plate P3;

[0073] like Figure 6 As shown, the fourth circuit layer includes a fourth electrode plate P4;

[0074] like Figure 7 As shown, the fifth circuit layer includes a fifth electrode plate P5;

[0075] like Figure 8 As shown, the sixth circuit layer includes a sixth electrode plate P6;

[0076] like Figure 9 As shown, the seventh circuit layer includes a seventh electrode plate P7;

[0077] like Figure 10 As shown, the eighth circuit layer includes an eighth electrode plate P8;

[0078] like Figure 11 As shown, the ninth circuit board includes a ninth electrode plate P9 and a tenth electrode plate P10;

[0079] like Figure 12 As shown, the tenth circuit layer includes an eleventh electrode plate P11;

[0080] like Figure 13 As shown, the eleventh circuit layer includes a twelfth electrode plate P12;

[0081] The first electrode plate P1, the second electrode plate P2 and the third electrode plate P3 are connected through the first via hole H1 and the second via hole H2;

[0082] The fourth electrode plate P4, the fifth electrode plate P5 and the sixth electrode plate P6 are connected through the second via hole H2 and the third via hole H3;

[0083] The seventh electrode plate P7 is connected to the fourth electrode plate P4, the fifth electrode plate P5 and the sixth electrode plate P6 through the third via H3;

[0084] The eighth electrode plate P8 is connected to the ninth electrode plate P9 through the fourth via H4;

[0085] The ninth electrode plate P9 is connected to the input port 1 through the fifth via H5;

[0086] The tenth electrode plate P10 is connected to the output port 2 through the sixth via H6, the tenth electrode plate P10 is connected to the first ground port 3 through the seventh via H7, and the tenth electrode plate P10 is connected to the second ground port 4 through the eighth via H8;

[0087] The twelfth electrode plate P12 is connected to the first ground port 3 through the seventh via hole H7 , and the twelfth electrode plate P12 is connected to the second ground port 4 through the eighth via hole H8 .

[0088] In this embodiment, one end of the first electrode plate P1, one end of the second electrode plate P2, and one end of the third electrode plate P3 are connected via a first via H1, and the other end of the first electrode plate P1, the other end of the second electrode plate P2, and the other end of the third electrode plate P3 are connected via a second via H2 to form a first equivalent inductor L1;

[0089] The ninth electrode plate P9 and the eleventh electrode plate P11 form a first equivalent capacitor C1 through interlayer coupling;

[0090] One end of the fourth electrode plate P4, one end of the fifth electrode plate P5, and one end of the sixth electrode plate P6 are connected via a second via H2, and the other end of the fourth electrode plate P4, the other end of the fifth electrode plate P5, and the other end of the sixth electrode plate P6 are connected via a third via H3 to form a first equivalent inductor L2;

[0091] The tenth electrode plate P10 and the eleventh electrode plate P11 form a second equivalent capacitor C2 through interlayer coupling;

[0092] The ninth electrode plate P9, the seventh electrode plate P7 and the tenth electrode plate P10 form a third equivalent capacitor C3 through interlayer coupling;

[0093] The eleventh electrode plate P11 and the twelfth electrode plate P12 form a fourth equivalent capacitor C4 through interlayer coupling.

[0094] In this embodiment, if Figure 14 As shown, one end of the first equivalent inductor L1, one end of the first equivalent capacitor C1, and one end of the third equivalent capacitor C3 are connected to the input port 1; the other end of the first equivalent inductor L1 and the other end of the first equivalent capacitor C1 are connected to one end of the second equivalent inductor L2, one end of the second equivalent capacitor C2, and one end of the fourth equivalent capacitor C4; the other end of the fourth equivalent capacitor C4 is connected to the first ground port 3 and the second ground port 4; the other end of the second equivalent inductor L2, the other end of the second equivalent capacitor C2, and the other end of the third equivalent capacitor C3 are connected to the output port 2.

[0095] In this embodiment, the external electrodes are packaged in a land grid array (LGA).

[0096] The low-pass filter further includes a mark 5 , and the mark 5 and the external electrode are located on the opposite side of the LTCC ceramic body.

[0097] The circuit layer is built into the LTCC ceramic body through a low temperature co-fired ceramic process.

[0098] The circuit layer is made of embedded metal material, and the embedded metal material includes copper or palladium silver.

[0099] In one embodiment of the present invention, the multilayer circuit of the filter is built into a ceramic body of 1.6 mm×0.8 mm×0.6 mm and sintered at a temperature of 890° C.±20° C.

[0100] Figure 15Schematic electrical performance curve diagram of a low insertion loss low pass filter for mobile communication frequency band in an embodiment of the present invention. Figure 15 As shown in Figure 1, the insertion loss of its channel filter S21 is only 0.10dB in the operating frequency band of 699-2690MHz, and the out-of-band suppression of 5150-5960MHz reaches more than 28dB. Figure 15 As shown, the return loss of the channel is above 20dB. The above indicators demonstrate that the low-pass filter provided by the present invention has good transmission characteristics of almost no insertion loss and high attenuation and a wide bandwidth channel.

[0101] This invention provides a low-insertion-loss low-pass filter for mobile communication frequency bands based on multilayer interconnect technology. It exhibits excellent properties, including high Q, compact size, extremely low insertion loss, and high attenuation. Furthermore, while ensuring uncompromising electrical performance, it maximizes processing tolerance, achieving high process stability and consistency. Furthermore, it is easily integrated with other circuit modules, and has broad application prospects in the next-generation wireless communications field.

[0102] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A low-insertion-loss low-pass filter for mobile communication frequency band, characterized in that: The invention comprises an LTCC ceramic body, a circuit layer and an external electrode; the circuit layer is located inside the LTCC ceramic body, and the circuit layer comprises, from top to bottom, a first circuit layer, a second circuit layer, a third circuit layer, a fourth circuit layer, a fifth circuit layer, a sixth circuit layer, a seventh circuit layer, an eighth circuit layer, a ninth circuit layer, a tenth circuit layer and an eleventh circuit layer; the external electrode is located at the bottom of the LTCC ceramic body, and the external electrode comprises an input port (1), an output port (2), a first ground port (3) and a second ground port (4); the input port (1) and the output port (2) are symmetrically arranged, and the first ground port (3) and the second ground port (4) are symmetrically arranged; the external electrode is connected to the circuit layer through a via hole; The first circuit layer includes a first electrode plate (P1); The second circuit layer includes a second electrode plate (P2); The third circuit layer includes a third electrode plate (P3); The fourth circuit layer includes a fourth electrode plate (P4); The fifth circuit layer includes a fifth electrode plate (P5); The sixth circuit layer includes a sixth electrode plate (P6); The seventh circuit layer includes a seventh electrode plate (P7); The eighth circuit layer includes an eighth electrode plate (P8); The ninth circuit layer includes a ninth electrode plate (P9) and a tenth electrode plate (P10); The tenth circuit layer includes an eleventh electrode plate (P11); The eleventh circuit layer includes a twelfth electrode plate (P12); One end of the first electrode plate (P1), one end of the second electrode plate (P2), and one end of the third electrode plate (P3) are connected via a first via hole (H1), and the other end of the first electrode plate (P1), the other end of the second electrode plate (P2), and the other end of the third electrode plate (P3) are connected via a second via hole (H2) to form a first equivalent inductor L1; The ninth electrode plate (P9) and the eleventh electrode plate (P11) form a first equivalent capacitor C1 through interlayer coupling; One end of the fourth electrode plate (P4), one end of the fifth electrode plate (P5), and one end of the sixth electrode plate (P6) are connected via a second via hole (H2), and the other end of the fourth electrode plate (P4), the other end of the fifth electrode plate (P5), and the other end of the sixth electrode plate (P6) are connected via a third via hole (H3), forming a second equivalent inductance L2; The tenth electrode plate (P10) and the eleventh electrode plate (P11) form a second equivalent capacitor C2 through interlayer coupling; The ninth electrode plate (P9), the seventh electrode plate (P7) and the tenth electrode plate (P10) form a third equivalent capacitor C3 through interlayer coupling; The eleventh electrode plate (P11) and the twelfth electrode plate (P12) form a fourth equivalent capacitor C4 through interlayer coupling; One end of the first equivalent inductor L1, one end of the first equivalent capacitor C1, and one end of the third equivalent capacitor C3 are connected to the input port (1); the other end of the first equivalent inductor L1 and the other end of the first equivalent capacitor C1 are connected to one end of the second equivalent inductor L2, one end of the second equivalent capacitor C2, and one end of the fourth equivalent capacitor C4; the other end of the fourth equivalent capacitor C4 is connected to the first ground port (3) and the second ground port (4); the other end of the second equivalent inductor L2, the other end of the second equivalent capacitor C2, and the other end of the third equivalent capacitor C3 are connected to the output port (2).

2. The low-insertion-loss low-pass filter for mobile communication frequency band according to claim 1, characterized in that: The first electrode plate (P1), the second electrode plate (P2), and the third electrode plate (P3) are connected via a first via hole (H1) and a second via hole (H2); The fourth electrode plate (P4), the fifth electrode plate (P5), and the sixth electrode plate (P6) are connected via the second via hole (H2) and the third via hole (H3); The seventh electrode plate (P7) is connected to the fourth electrode plate (P4), the fifth electrode plate (P5) and the sixth electrode plate (P6) through the third via hole (H3); The eighth electrode plate (P8) is connected to the ninth electrode plate (P9) via a fourth via hole (H4); The ninth electrode plate (P9) is connected to the input port (1) via a fifth via hole (H5); The tenth electrode plate (P10) is connected to the output port (2) via the sixth via hole (H6), the tenth electrode plate (P10) is connected to the first ground port (3) via the seventh via hole (H7), and the tenth electrode plate (P10) is connected to the second ground port (4) via the eighth via hole (H8); The twelfth electrode plate (P12) is connected to the first ground port (3) through the seventh via hole (H7), and the twelfth electrode plate (P12) is connected to the second ground port (4) through the eighth via hole (H8).

3. The low-insertion-loss low-pass filter for mobile communication frequency band according to claim 1, characterized in that: The outer electrodes are packaged in a planar grid array.

4. The low-insertion-loss low-pass filter for mobile communication frequency band according to claim 1, characterized in that: The low-pass filter further comprises a mark (5), wherein the mark (5) and the external electrode are located on the opposite side of the LTCC ceramic body.

5. The low-insertion-loss low-pass filter for mobile communication frequency band according to claim 1, characterized in that: The circuit layer is built into the LTCC ceramic body through a low temperature co-fired ceramic process.

6. The low-insertion-loss low-pass filter for mobile communication frequency band according to claim 1, characterized in that: The circuit layer is made of embedded metal material, and the embedded metal material includes copper or palladium silver.

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