CN111029692A

CN111029692A - Novel absorption formula band pass filter based on LTCC

Info

Publication number: CN111029692A
Application number: CN201911169057.3A
Authority: CN
Inventors: 曹小芝; 杨冕; 常钰敏; 方洁; 赵子豪
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2020-04-17

Abstract

The invention relates to a novel absorption band-pass filter based on LTCC (low temperature co-fired ceramic), which realizes three-dimensional integration of the filter by a low-temperature co-fired ceramic process technology, and comprises an input port with characteristic impedance of 50 ohms, a first output port, a second output port and a third output port, as well as a first spiral coupler, a second spiral coupler, a first coupler connecting column, a second coupler connecting column, a first upper connecting column, a second upper connecting column, a first lower connecting column, a second lower connecting column, a first band-pass filter, a second band-pass filter, a first shielding layer, a second shielding layer and a third shielding layer. The invention is formed by connecting two directional couplers and two eight-stage resonant emission filters in series, can effectively absorb out-of-band signals, obviously improves the anti-interference capability of the system, and is suitable for the condition of high precision requirement but no volume.

Description

Novel absorption formula band pass filter based on LTCC

Technical Field

The invention relates to a microwave technology, in particular to a novel absorption type band-pass filter based on LTCC.

Background

With the rapid development of wireless communication technologies such as mobile communication, radar communication and the like and military and national defense electronic systems, miniaturization, high performance and low cost have become the key development direction in the microwave radio frequency field at present, which puts higher requirements on microwave radio frequency devices. The filter is used for effectively filtering a frequency point of a specific frequency in the power line or frequencies except the frequency point to obtain a power signal of the specific frequency or eliminate the power signal of the specific frequency. Since the commonly used reflective band pass filter implements the selection of the frequency by reflecting the out-of-band signal to the input. However, the reflected wave and the existing signal are mixed in a mixed mode to generate a nonlinear intermodulation signal, interference is generated on equipment, and the anti-interference capability of the system is greatly reduced. Therefore, the research on the absorption band-pass filter is of great significance to the rapid development of wireless communication technologies such as mobile communication and radar communication and military and national defense electronic systems.

Disclosure of Invention

The invention aims to provide a novel absorption type band-pass filter based on LTCC.

The technical scheme for realizing the purpose of the invention is as follows: the utility model provides a novel absorption formula band pass filter based on LTCC, it is three-dimensional integrated through the three-dimensional of low temperature cofiring ceramic technology realization filter, be 50 ohm input port including characteristic impedance, first output port, second output port and third output port, and first spiral coupler, second spiral coupler, first coupler spliced pole, second coupler spliced pole, first upper spliced pole, second upper spliced pole, first lower floor's spliced pole, second lower floor's spliced pole, first band pass filter, second band pass filter, first shielding layer, the second shielding layer, the third shielding layer, wherein: the first shielding layer is arranged above the first band-pass filter, the second shielding layer is arranged between the first band-pass filter and the second band-pass filter, and the third shielding layer (sd3) is arranged below the second band-pass filter and is symmetrical with the first shielding layer about the second shielding layer; the first band-pass filter and the second band-pass filter are axisymmetric; the first spiral coupler and the second spiral coupler are axisymmetrical; the first band-pass filter and the second band-pass filter are composed of eight stages of resonance units and impedance matching, and each resonance unit is of a three-layer coupling strip line structure;

one end of an upper coupling line of the first coupler is connected with the input port through a first input lead; the other end of the first spiral coupler is connected with a first upper connecting column, the first upper connecting column is connected with a first band-pass filter through a fourth input lead, the first band-pass filter is connected with a second upper connecting column through a third output lead, the second upper connecting column is connected with an upper coupling line of the second spiral coupler, and the upper coupling line of the second spiral coupler is connected with a first output port through a second output lead; one end of a lower coupling line of the first spiral coupler is connected with a first lower connecting column, and the first lower connecting column is connected with a second band-pass filter through a second input lead; the other end of the lower coupling line of the first spiral coupler is connected with a third output port through a third input lead, the second band-pass filter is connected with the lower end of a second lower connecting column through a first output lead, the upper end of the second lower connecting column is connected with the lower coupling line of the second spiral coupler, and the lower coupling line of the second spiral coupler is connected with a second output port through a fourth output lead.

Compared with the prior art, the invention has the remarkable advantages that: 1) the directional coupler is formed by connecting two directional couplers and two eight-stage resonant radio filters in series, so that the directional coupler has high stop band rejection, can effectively absorb out-of-band signals, and obviously improves the anti-interference performance of a system; 2) the method realizes three-dimensional integration by using a low temperature co-fired ceramic (LTCC) process technology, and has the advantages of good port isolation, low insertion loss, good return loss, small volume, good electrical property, high integration, high yield, low expansion coefficient and the like.

Drawings

Fig. 1 is a schematic structural diagram of a novel LTCC-based absorption band pass filter of the present invention, wherein (a) is a top view, (b) is a front view, (c) is a front view of an internal structure, and (d) is a right view of the internal structure.

Fig. 2 is a simulation curve of the novel LTCC-based absorption band pass filter of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings and specific embodiments.

With reference to fig. 1(a), (b), (c) (d), a novel LTCC-based absorption band pass filter realizes three-dimensional integration of the filter by a low-temperature co-fired ceramic process technology, including an INPUT port INPUT, a first OUTPUT port OUTPUT1, a second OUTPUT port OUTPUT2, and a third OUTPUT port OUTPUT3, each having a characteristic impedance of 50 ohms, and a first helical COUPLER1, a second helical COUPLER2, a first COUPLER connection column H1, a second COUPLER connection column H2, a first upper connection column H3, a second upper connection column H4, a first lower connection column H5, a second lower connection column H6, a first band pass filter BPF1, a second band pass filter BPF2, a first shielding layer sd1, a second shielding layer sd2, and a third shielding layer sd3, wherein: the first shielding layer sd1 is above the first band-pass filter BPF1, the second shielding layer sd2 is in the middle of the first and second band-pass filters BPF1 and BPF2, the third shielding layer (sd3) is below the second band-pass filter BPF2, and is symmetrical to the first shielding layer sd1 about the second shielding layer sd 2; the first band-pass filter BPF1 is axisymmetric to the second band-pass filter BPF 2; the first spiral COUPLER1 is axisymmetrical with the second spiral COUPLER 2; the first band-pass filter BPF1 and the second band-pass filter BPF2 are composed of eight-stage resonance units and impedance matching, and each resonance unit is of a three-layer coupling strip line structure;

one end of an upper coupling line of the first COUPLER1 is connected with the INPUT port INPUT through a first INPUT lead Lin 1; the other end of the first spiral COUPLER COUPLER is connected with the lower end of a first upper layer connecting column H3, the upper end of the first upper layer connecting column H3 is connected with a first band pass filter BPF1 through a fourth input lead Lin4, the first band pass filter BPF1 is connected with the upper end of a second upper layer connecting column H4 through a third OUTPUT lead Lout3, the lower end of the second upper layer connecting column H4 is connected with an upper layer coupling line of the second spiral COUPLER COUPLER2, and the upper layer coupling line of the second spiral COUPLER COUPLER2 is connected with a first OUTPUT port OUTPUT1 through a second OUTPUT lead Lout 2; one end of a lower coupling line of the first spiral COUPLER COUPLER1 is connected with a first lower connecting column H5, and the first lower connecting column H5 is connected with a second band-pass filter BPF2 through a second input lead Lin 2; the other end of the lower coupling line of the first spiral COUPLER1 is connected with a third OUTPUT port OUTPUT3 of Lin3 through a third input lead, the second band-pass filter BPF2 is connected with a second lower connecting column H6 through a first OUTPUT lead Lout1, the second lower connecting column H6 is connected with the lower coupling line of the second spiral COUPLER2, and the lower coupling line of the second spiral COUPLER2 is connected with the second OUTPUT port OUTPUT2 through a fourth OUTPUT lead Lout 4.

As a more specific implementation, the first band pass filter BPF1 is composed of a first band pass filter first resonance unit D11, a first band pass filter second resonance unit D12, a first band pass filter third resonance unit D13, a first band pass filter fourth resonance unit D14, a first band pass filter fifth resonance unit D15, a first band pass filter sixth resonance unit D16, a first band pass filter seventh resonance unit D17, a first band pass filter eighth resonance unit D18, and a first impedance matching IM1, where: the first band pass filter first resonance unit D11 is bilaterally symmetrical to the first band pass filter eighth resonance unit D18, the first band pass filter second resonance unit D12 is bilaterally symmetrical to the first band pass filter seventh resonance unit D17, the first band pass filter third resonance unit D13 is bilaterally symmetrical to the first band pass filter sixth resonance unit D16, and the first band pass filter fourth resonance unit D14 is bilaterally symmetrical to the first band pass filter fifth resonance unit D15;

the first band pass filter first resonant cell D11 is composed of a strip line D11a, a strip line D11m, a strip line D11b, D11a and D11b are symmetric with respect to D11m, the first band pass filter second resonant cell D12 is composed of a strip line D12a, a strip line D12m, a strip line D12b, and D12a and D12b are symmetric with respect to D12m, the first band pass filter third resonant cell D13 is composed of a strip line D13a, and D13a are symmetric with respect to D13a, the first band pass filter fourth resonant cell D a is composed of a strip line D14a, and D14a are symmetric with respect to D14 a. The first band pass filter fifth resonance unit D15 is composed of a strip line D15a, a strip line D15m, a strip line D15b, and D15a and D15b are symmetrical with respect to D15m, the first band pass filter sixth resonance unit D16 is composed of a strip line D16a, a strip line D16m, a strip line D16b, and D16a and D16b are symmetrical with respect to D16m, the first band pass filter seventh resonance unit D17 is composed of a strip line D17a, and D17a are symmetrical with respect to D17a, the first band pass filter eighth resonance unit D a is composed of a strip line D18a, and D18a are symmetrical with respect to D18 a. The first zigzag cross-coupled line Z1 is composed of a strip line Z11, a strip line Z12 and a strip line Z13, and the second zigzag cross-coupled line Z2 is composed of a strip line Z21, a strip line Z22 and a strip line Z23; the strip line D11m in the first band pass filter first resonance unit D11 is connected to the first upper layer connecting post H3 through the fourth input lead Lin4, the strip line D14m in the first band pass filter fourth resonance unit D14 is connected to one end of the first matching impedance IM1, the other end of the first matching impedance IM1 is connected to the strip line D15m in the first band pass filter fifth resonance unit D15, the strip line D18m in the first band pass filter eighth resonance unit D18 is connected to the second upper layer connecting post H4 through the third output lead Lout3, and the strip lines D11a, D11 strip 11b, D12a, D12b, D13a, D13b, D14b, D15b, D16 strip b, D17, D72, D18D 72, D14D b, the front side connecting terminals b, and the back side connecting posts H b, and the strip lines b, b are connected to the GND filter b, b.

As a more specific implementation, the second band-pass filter BPF2 is composed of a second band-pass filter first resonance unit D21, a second band-pass filter second resonance unit D22, a second band-pass filter third resonance unit D23, a second band-pass filter fourth resonance unit D24, a second band-pass filter fifth resonance unit D25, a second band-pass filter sixth resonance unit D26, a second band-pass filter seventh resonance unit D27, a second band-pass filter eighth resonance unit D28, and a second impedance matching IM1, where: the first resonance unit D21 of the second band-pass filter is bilaterally symmetrical to the eighth resonance unit D28 of the second band-pass filter, the second resonance unit D22 of the second band-pass filter is bilaterally symmetrical to the seventh resonance unit D27 of the second band-pass filter, the third resonance unit D23 of the second band-pass filter is bilaterally symmetrical to the sixth resonance unit D26 of the second band-pass filter, and the fourth resonance unit D24 of the second band-pass filter is bilaterally symmetrical to the fifth resonance unit D25 of the second band-pass filter;

the second band pass filter first resonance unit D21 is composed of a strip line D21a, a strip line D21m, a strip line D21b, and D21a and D21b are symmetrical with respect to D21m, the second band pass filter second resonance unit D22 is composed of a strip line D22a, a strip line D22m, a strip line D22b, and D22a and D22b are symmetrical with respect to D22m, the second band pass filter third resonance unit D23 is composed of a strip line D23a, a strip line D23m, a strip line D23b, and D23a and D23b are symmetrical with respect to D23m, the second band pass filter fourth resonance unit D24 is composed of a strip line D24a, a strip line D24m, a strip line D24b, and D24a and D24b are symmetrical with respect to D24 m. The second band pass filter fifth resonance unit D25 is composed of a strip line D25a, a strip line D25m, a strip line D25b, and D25a and D25b are symmetrical with respect to D25m, the second band pass filter sixth resonance unit D26 is composed of a strip line D26a, a strip line D26m, a strip line D26b, and D26a and D26b are symmetrical with respect to D26m, the second band pass filter seventh resonance unit D27 is composed of a strip line D27a, a strip line D27m, a strip line D27b, and D27a and D27b are symmetrical with respect to D27m, the second band pass filter eighth resonance unit D28 is composed of a strip line D28a, a strip line D28m, a strip line D28b, and D28a and D28b are symmetrical with respect to D28 m. The third zigzag cross-coupled line Z3 is composed of stripline Z31, stripline Z32, stripline Z33, and the fourth zigzag cross-coupled line Z4 is composed of stripline Z41, stripline Z42, stripline Z43. The strip line D21m in the second band-pass filter first resonance unit D21 is connected to the first lower layer connecting post H5 through the second input lead Lin2, the strip line D24m in the second band-pass filter fourth resonance unit D24 is connected to one end of the second matching impedance IM2, the other end of the second matching impedance IM2 is connected to the strip line D15m in the second band-pass filter fifth resonance unit D25, the strip line D28m in the second band-pass filter eighth resonance unit D28 is connected to the second lower layer connecting post H6 through the first output lead Lout1, and the strip lines D21a, D21b, D22a, D22b, D23a, D23b, D24b, D25b, D26b, D27, D b, the front ground side and the back ground terminals 3614, GND b, and the second band-input lead Lin 3614.

As a specific implementation, the first spiral COUPLER1 and the second spiral COUPLER2 are both broadside-coupled stripline structures.

As a more specific implementation, the first spiral COUPLER1 is composed of a first upper layer coupling spiral L1a and a first lower layer coupling spiral L1b, and the second spiral COUPLER2 is composed of a second upper layer coupling spiral L2a and a second lower layer coupling spiral L2 b.

Examples

In order to verify the effectiveness of the solution of the present invention, the present embodiment designs a novel LTCC-based absorption filter with the size of only 12.8mm × 5mm × 2.5mm, the operating frequency of 2.7GHz to 3.3GHz, and the simulation curve of the filter is shown in fig. 2, where S11 represents absorption performance, S21 represents isolation port, S31 represents near-end interference, and S41 represents insertion loss. It can be seen that the absorption performance of the absorption filter is better than 23.9dB in the range of 2.2 GHZ-4.4 GHZ, better than 10dB in the range of 1.65 GHZ-4.55 GHZ, the insertion loss is better than 1dB, the in-band fluctuation is better than 0.2dB, the stop band rejection is better than 40dB at the 2GHZ and low frequency end, and the 4GHZ and high frequency end, and the isolation port has almost no signal output. All indexes of the invention meet the requirements and leave allowance for the processing and production errors.

In summary, the absorption bandwidth of the absorption band-pass filter is substantially determined by the bandwidth of the coupler, and the stop-band rejection of the absorption filter is determined by the band-pass filter.

Claims

1. The utility model provides a novel absorption formula band pass filter based on LTCC, characterized by, realize the three-dimensional integration of filter through low temperature cofired ceramic technology, including characteristic impedance 50 ohm INPUT port (INPUT), first OUTPUT port (OUTPUT1), second OUTPUT port (OUTPUT2) and third OUTPUT port (OUTPUT3), and first spiral COUPLER (COUPLER1), second spiral COUPLER (COUPLER2), first COUPLER connecting column (H1), second COUPLER connecting column (H2), first upper connecting column (H3), second upper connecting column (H4), first lower floor connecting column (H5), second lower floor connecting column (H6), first band pass filter (BPF1), second band pass filter (BPF2), first shielding layer (sd1), second shielding layer (sd2), third shielding layer (sd3), wherein: the first shielding layer (sd1) is above the first band-pass filter (BPF1), the second shielding layer (sd2) is in the middle of the first band-pass filter (BPF1) and the second band-pass filter (BPF2), the third shielding layer (sd3) is below the second band-pass filter (BPF2), and is symmetrical to the first shielding layer (sd1) about the second shielding layer (sd 2); the first band-pass filter (BPF1) is axisymmetric to the second band-pass filter (BPF 2); the first spiral COUPLER (COUPLER1) is axisymmetric to the second spiral COUPLER (COUPLER 2); the first band-pass filter (BPF1) and the second band-pass filter (BPF2) are both composed of eight-stage resonance units and impedance matching, and each resonance unit is of a three-layer coupling strip line structure;

one end of an upper coupling line of the first COUPLER (COUPLER1) is connected with the INPUT port (INPUT) through a first INPUT lead (Lin 1); the other end of the first spiral COUPLER (COUPLER1) is connected with a first upper connecting column (H3), the first upper connecting column (H3) is connected with a first band-pass filter through a fourth input lead (Lin4), the first band-pass filter (BPF1) is connected with a second upper connecting column (H4) through a third OUTPUT lead (Lout3), the second upper connecting column (H4) is connected with an upper coupling line of the second spiral COUPLER (COUPLER2), and an upper coupling line of the second spiral COUPLER (COUPLER2) is connected with a first OUTPUT port (OUTPUT1) through a second OUTPUT lead (Lout 2); one end of a lower coupling line of the first spiral COUPLER (COUPLER1) is connected with a first lower connecting column (H5), and the first lower connecting column (H5) is connected with the second band-pass filter through a second input lead (Lin 2); the other end of the lower coupling line of the first spiral COUPLER (COUPLER1) is connected with a third OUTPUT port (OUTPUT3) through a third input lead (Lin3), the second band-pass filter (BPF2) is connected with the lower end of a second lower connecting column (H6) through a first OUTPUT lead (Lout1), the upper end of the second lower connecting column (H6) is connected with the lower coupling line of the second spiral COUPLER (COUPLER2), and the lower coupling line of the second spiral COUPLER (COUPLER2) is connected with the second OUTPUT port (OUTPUT2) through a fourth OUTPUT lead (Lout 4).

2. The LTCC-based novel absorptive bandpass filter according to claim 1, wherein the first bandpass filter (BPF1) is composed of a first bandpass filter first resonance unit (D11), a first bandpass filter second resonance unit (D12), a first bandpass filter third resonance unit (D13), a first bandpass filter fourth resonance unit (D14), a first bandpass filter fifth resonance unit (D15), a first bandpass filter sixth resonance unit (D16), a first bandpass filter seventh resonance unit (D17), a first bandpass filter eighth resonance unit (D18), a first matching impedance (IM1), wherein: the first band-pass filter first resonance unit (D11) is bilaterally symmetrical to the first band-pass filter eighth resonance unit (D18), the first band-pass filter second resonance unit (D12) is bilaterally symmetrical to the first band-pass filter seventh resonance unit (D17), the first band-pass filter third resonance unit (D13) is bilaterally symmetrical to the first band-pass filter sixth resonance unit (D16), and the first band-pass filter fourth resonance unit (D14) is bilaterally symmetrical to the first band-pass filter fifth resonance unit (D15);

the first band pass filter first resonance cell (D11) is composed of a strip line D11a, a strip line D11m, a strip line D11b, and D11a and D11b are symmetric with respect to D11m, the first band pass filter second resonance cell (D12) is composed of a strip line D12a, a strip line D12m, a strip line D12b, and D12a and D12b are symmetric with respect to D12m, the first band pass filter third resonance cell (D13) is composed of a strip line D13a, a strip line D13m, a strip line D13b, and D13a and D13b are symmetric with respect to D13m, the first band pass filter fourth resonance cell (D14) is composed of a strip line D14a, a strip line D14m, a strip line D14b, and D14a and D14b are symmetric with respect to D14 m; the first band pass filter fifth resonance cell (D15) is composed of a strip line D15a, a strip line D15m, a strip line D15b, and D15a and D15b are symmetric with respect to D15m, the first band pass filter sixth resonance cell (D16) is composed of a strip line D16a, a strip line D16m, a strip line D16b, and D16a and D16b are symmetric with respect to D16m, the first band pass filter seventh resonance cell (D17) is composed of a strip line D17a, a strip line D17m, a strip line D17b, and D17a and D17b are symmetric with respect to D17m, the first band pass filter eighth resonance cell (D18) is composed of a strip line D18a, a strip line D18m, a strip line D18b, and D18a and D18b are symmetric with respect to D18 m; the first zigzag cross-coupled line (Z1) is composed of stripline Z11, stripline Z12 and stripline Z13, and the second zigzag cross-coupled line (Z2) is composed of stripline Z21, stripline Z22 and stripline Z23; a strip line D11m in a first band pass filter first resonance unit (D11) is connected to the upper end of a first upper connection post (H3) through a fourth input lead (Lin4), a strip line D14m in a first band pass filter fourth resonance unit (D14) is connected to one end of a first matched impedance (IM1), a strip line D15 1 in a first band pass filter fifth resonance unit (D1) is connected to the other end of the first matched impedance (IM1), a strip line D18 1 in a first band pass filter eighth resonance unit (D1) is connected to the upper end of a second upper connection post (H1) through a third output lead (Lout1), strip lines D11 1, D12 1, D13 1, D14, D72, D1, D3615, D1, D72, D16D 72, D72D 1, D1, 1D 1, the strip lines D11m, D12m, D13m, D14m, D15m, D16m, D17m, and D18m in the first bandpass filter are connected to the rear-side ground terminal (GND 2).

3. The novel LTCC-based absorption band pass filter according to claim 1, wherein the second band pass filter (BPF2) is composed of a second band pass filter first resonance unit (D21), a second band pass filter second resonance unit (D22), a second band pass filter third resonance unit (D23), a second band pass filter fourth resonance unit (D24), a second band pass filter fifth resonance unit (D25), a second band pass filter sixth resonance unit (D26), a second band pass filter seventh resonance unit (D27), a second band pass filter eighth resonance unit (D28), a second matching impedance (IM2), wherein: the first resonance unit (D21) of the second band-pass filter is bilaterally symmetrical to the eighth resonance unit (D28) of the second band-pass filter, the second resonance unit (D22) of the second band-pass filter is bilaterally symmetrical to the seventh resonance unit (D27) of the second band-pass filter, the third resonance unit (D23) of the second band-pass filter is bilaterally symmetrical to the sixth resonance unit (D26) of the second band-pass filter, and the fourth resonance unit (D24) of the second band-pass filter is bilaterally symmetrical to the fifth resonance unit (D25) of the second band-pass filter;

the second band pass filter first resonance cell (D21) is composed of a strip line D21a, a strip line D21m, a strip line D21b, and D21a and D21b are symmetric with respect to D21m, the second band pass filter second resonance cell (D22) is composed of a strip line D22a, a strip line D22m, a strip line D22b, and D22a and D22b are symmetric with respect to D22m, the second band pass filter third resonance cell (D23) is composed of a strip line D23a, a strip line D23m, a strip line D23b, and D23a and D23b are symmetric with respect to D23m, the second band pass filter fourth resonance cell (D24) is composed of a strip line D24a, a strip line D24m, a strip line D24b, and D24a and D24b are symmetric with respect to D24 m; the second band pass filter fifth resonance cell (D25) is composed of a strip line D25a, a strip line D25m, a strip line D25b, and D25a and D25b are symmetric with respect to D25m, the second band pass filter sixth resonance cell (D26) is composed of a strip line D26a, a strip line D26m, a strip line D26b, and D26a and D26b are symmetric with respect to D26m, the second band pass filter seventh resonance cell (D27) is composed of a strip line D27a, a strip line D27m, a strip line D27b, and D27a and D27b are symmetric with respect to D27m, the second band pass filter eighth resonance cell (D28) is composed of a strip line D28a, a strip line D28m, a strip line D28b, and D28a and D28b are symmetric with respect to D28 m; the third zigzag cross-coupled line (Z3) is composed of stripline Z31, stripline Z32 and stripline Z33, and the fourth zigzag cross-coupled line (Z4) is composed of stripline Z41, stripline Z42 and stripline Z43; a strip line D21m in a first resonance unit (D21) of the second band-pass filter is connected with the lower end of a first lower-layer connecting post (H5) through a second input lead (Lin2), a strip line D24m in a fourth resonance unit (D24) of the second band-pass filter is connected with one end of a second matched impedance (IM2), a strip line D15 2 in a fifth resonance unit (D2) of the second band-pass filter is connected with the other end of the second matched impedance (IM2), a strip line D28 2 in an eighth resonance unit (D2) of the second band-pass filter is connected with the lower end of the second lower-layer connecting post (H2) through a first output lead (Lout2), strip lines D21 2, D22 2, D23 2, D24, D2, D25, D26, D72, D2, D, the strip lines D11m, D12m, D13m, D14m, D15a, D16m, D17m, and D18m in the second band-pass filter are connected to the front-side ground (GND 1).

4. The LTCC-based novel absorptive bandpass filter according to claim 1, wherein the first spiral COUPLER (COUPLER1) and the second spiral COUPLER (COUPLER2) are both broadside-coupled stripline structures.

5. The novel LTCC-based absorbing bandpass filter according to claim 4, characterized in that the first helical COUPLER (COUPLER1) consists of a first upper layer coupling helix (L1a) and a first lower layer coupling helix (L1b), and the second helical COUPLER (COUPLER2) consists of a second upper layer coupling helix (L2a) and a second lower layer coupling helix (L2 b).

First upper coupling helix (L1a) one end is passed through third input lead (Lin3) and is connected third OUTPUT port (OUTPUT3), first upper connecting post (H3) upper end is connected to first lower coupling helix (L1a) other end, first OUTPUT port (OUTPUT1) is connected through third OUTPUT lead (Lout3) to second upper coupling helix (L2a) one end, second lower connecting post (H6) upper end is connected to second lower coupling helix (L2b) other end.