Near-insertion-loss low-pass filter for mobile communication frequency band

Abstract

The invention belongs to the technical field of filters of radio frequency front-end circuits, and particularly discloses an almost insertion-loss-free low-pass filter for a mobile communication frequency band, which comprises an LTCC (Low Temperature Co-Fired Ceramic) body, a circuit layer and an outer electrode, the circuit layer is located in the LTCC body, and the circuit layer sequentially 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 from top to bottom; the outer electrode is located at the bottom of the LTCC body and comprises an input port, an output port, a first grounding port and a second grounding port; and the outer electrode is connected with the circuit layer through a via hole. According to the invention, the problems that the Q value of a filter circuit is reduced and the insertion loss is increased due to the fact that a traditional filter easily causes mutual coupling between lumped components and unnecessary parasitic parameters are generated are solved, and an action communication frequency band almost has no insertion loss.

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 nearly lossless low-pass filter used in a mobile communication frequency band. Background Art

[0002] With the rapid development of modern communication technology, small size, light weight and high reliability have become the inevitable trend of the development of modern communication systems. As the core frequency selection device in the transceiver system, the filter is used to extract or filter out signals of different frequencies in the communication system. The traditional microstrip low-pass filter has a large structure size, a narrow stopband and insufficient suppression, and is not easy to integrate with other compact mobile communication terminals, which limits its use in microwave communication systems. Therefore, the development of small-volume, low-insertion-loss, wide stopband and high-suppression bandpass filters has become a current research hotspot and difficulty.

[0003] Compared with traditional forms of filters, low temperature co-fired ceramic technology (LTCC) uses gold, silver, copper and other materials with low resistivity as conductive media, and buries the equivalent circuit inside the ceramic body through metal vias, which enables flexible selection of structural layout, greatly reduces the volume of passive components, and plays an important role in improving the integration, reliability and electrical performance of filters. Compared with other traditional filter forms, LTCC technology has the following advantages: good compatibility and high-frequency transmission characteristics, multi-layer wiring and various cavity structures, high integration and assembly density, small volume and weight, high reliability, low cost and short production cycle. Summary of the invention

[0004] The purpose of the present invention is to solve the problems that traditional microstrip low-pass filters have large structural dimensions, narrow stopband and insufficient suppression, and are not easy to integrate with other compact mobile communication terminals. A nearly lossless low-pass filter for mobile communication frequency bands is proposed.

[0005] The technical solution of the present invention is: a nearly zero-insertion-loss low-pass filter for a mobile communication frequency band, 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 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 from top to bottom; 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 is connected to the circuit layer 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 connects the external electrode to the circuit layer through vias, thereby solving the problem that traditional filters easily cause mutual coupling between lumped components, generate unnecessary parasitic parameters, and thus cause the Q value of the filter circuit to decrease and the insertion loss to increase, 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 a fourth via hole;

[0023] The ninth electrode plate is connected to the input port through a 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 at 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 inductance 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 inductance 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 are coupled with each other to form a third equivalent capacitor C3;

[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, 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 outer electrode is placed at 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 embeds a multilayer circuit of a low-pass filter into a ceramic body based on a low-temperature co-fired ceramic process, can realize the integration of various equivalent components on a three-dimensional circuit substrate, and realizes miniaturization and high density of the circuit.

[0048] Preferably, the circuit layer adopts an 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 material is beneficial to improving the quality factor of the circuit system. For example, palladium silver is used as the embedded metal material, which 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 diagram of the structure of a nearly lossless low-pass filter used in the mobile communication frequency band.

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

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

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

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

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

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

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

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

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

[0065] Fig.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] Now, exemplary embodiments of the present invention will 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 only exemplary and are intended to explain 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 nearly zero-insertion-loss low-pass filter for mobile communication frequency bands 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.

[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 Fig. 9 As shown, the seventh circuit layer includes a seventh electrode plate P7;

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

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

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

[0080] like Fig.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 hole 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 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 inductance 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 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 to form a first equivalent inductance 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 Fig.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 comprises 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 adopts an 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] Fig.15Schematic electrical performance curve diagram of a low-pass filter with almost zero insertion loss for mobile communication frequency band in an embodiment of the present invention. Fig.15 As shown in the figure, the insertion loss of the channel filter S21 in the working frequency band of 699-2690MHz is only 0.10dB, and the out-of-band suppression of 5150-5960MHz reaches more than 28dB. Fig.15 As shown, the return loss of the channel is above 20 dB. The above indicators reflect 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] The present invention provides a nearly lossless low-pass filter for mobile communication frequency band based on multi-layer interconnection technology. It has excellent performances such as high Q value, small size, extremely low insertion loss, and high attenuation. At the same time, under the premise of ensuring that its electrical performance is not affected, the tolerance of the processing technology is maximized, high process stability and consistency are achieved, and it is easy to integrate with other circuit modules, and has broad application prospects in the field of new generation wireless communications.

[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 should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A nearly lossless low-pass filter for mobile communication frequency band, characterized in that: The invention comprises a 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 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 from top to bottom; 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 grounding port (3) and a second grounding port (4); the input port (1) and the output port (2) are symmetrically arranged, and the first grounding port (3) and the second grounding port (4) are symmetrically arranged; the external electrode is connected to the circuit layer through a via hole.

2. The nearly lossless low-pass filter for mobile communication frequency band according to claim 1, characterized in that: 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 board comprises 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); The first electrode plate (P1), the second electrode plate (P2) and the third electrode plate (P3) are connected through 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) through a fourth via hole (H4); The ninth electrode plate (P9) is connected to the input port (1) through a fifth via hole (H5); The tenth electrode plate (P10) is connected to the output port (2) through the sixth via hole (H6), the tenth electrode plate (P10) is connected to the first ground port (3) through the seventh via hole (H7), and the tenth electrode plate (P10) is connected to the second ground port (4) through 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 nearly lossless low-pass filter for mobile communication frequency band according to claim 2, characterized in that: 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 inductance 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) to form a first 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) forms a third equivalent capacitor C3 with the seventh electrode plate (P7) and the tenth electrode plate (P10) through interlayer coupling; The eleventh electrode plate (P11) and the twelfth electrode plate (P12) form a fourth equivalent capacitor C4 through interlayer coupling.

4. The nearly lossless low-pass filter for mobile communication frequency band according to claim 3, characterized in that: 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).

5. The nearly lossless 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.

6. The nearly lossless 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.

7. The nearly lossless 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.

8. The nearly lossless low-pass filter for mobile communication frequency band according to claim 1, characterized in that: The circuit layer adopts an embedded metal material, and the embedded metal material includes copper or palladium silver.

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