CN214625336U - Dielectric band-pass filter assembly for inhibiting frequency multiplication harmonic - Google Patents

Abstract

The utility model provides a restrain doubling of frequency harmonic medium band-pass filter subassembly, this filter subassembly includes dielectric filter body, shielding shell and PCB board, its characterized in that, the PCB board has at least one LTCC low pass filter weld zone; the LTCC low-pass filter welding area is provided with at least one LTCC low-pass filter, one port of the LTCC low-pass filter is connected with a port on the PCB, and the other port of the LTCC low-pass filter is connected with one port of the dielectric filter body; and the LTCC low-pass filter is designed to be capable of inhibiting multiple frequency harmonics of the band-pass filter, so that the frequency-doubling harmonic defect of the band-pass filter is overcome by overlapping the suppression sections of the LTCC low-pass filter.

Description

Dielectric band-pass filter assembly for inhibiting frequency multiplication harmonic

Technical Field

The utility model relates to a band pass filter, concretely relates to medium band pass filter subassembly of suppression doubling of frequency harmonic.

Background

A band-pass filter is a filter that passes frequency components in a certain frequency range, but attenuates frequency components in other ranges to an extremely low level, as opposed to the concept of a band-stop filter; an example of an analog bandpass filter is a resistor-inductor-capacitor circuit (RLC circuit). These filters may also be generated using a low pass filter in combination with a high pass filter.

The conventional dielectric band-pass filter is limited in structure and difficult to realize multiple frequency suppression, a traditional design can be used for adding a winding inductor-patch capacitor circuit in a planar structure to build a low-pass circuit to suppress frequency multiplication, the design occupies a large area, and multiple frequency suppression can be realized in a volume which is not limited to requirements.

The dielectric band-pass filter body is a ceramic body consisting of a plurality of high-Q dielectric resonant cavities, and the ceramic body is provided with an input/output electrode surface, an end surface with a metal pattern and the other 4 surfaces of the ceramic body are attached with a grounding metal layer. The design of the end face of the metal pattern is primarily distributed by a simulated resonance equivalent circuit, and capacitors, inductors and cross-order coupling in the equivalent resonance circuit are correspondingly designed to form an equivalent band-pass filter which has the advantages of low loss, high near-end inhibition and the like, but the dielectric filter is limited by the structure and can generate resonance warping for 2-frequency multiplication and multiple-frequency multiplication inhibition, so that the defects of 2-frequency multiplication and multiple-frequency multiplication harmonic cannot be inhibited.

SUMMERY OF THE UTILITY MODEL

In order to solve the above technical problem, the present invention provides a dielectric band pass filter assembly for suppressing frequency doubling harmonics, the filter assembly comprising a dielectric filter body, a shielding case and a PCB board, wherein the PCB board has at least one LTCC low pass filter welding area;

the LTCC low-pass filter welding area is provided with at least one LTCC low-pass filter, one port of the LTCC low-pass filter is connected with a port on the PCB, and the other port of the LTCC low-pass filter is connected with one port of the dielectric filter body; and the LTCC low-pass filter is designed to be capable of inhibiting multiple frequency harmonics of the band-pass filter, so that the frequency-doubling harmonic defect of the band-pass filter is overcome by overlapping the suppression sections of the LTCC low-pass filter.

The input/output circuit of the PCB provided by the prior art is connected with the input/output circuit of the dielectric filter body, and the invention disconnects the input or output path of the original PCB and the dielectric filter body, specifically, one input port of the LTCC low-pass filter is connected with the input port on the PCB, and the other output port is connected with one input port of the dielectric filter body; or; one input port of the LTCC low-pass filter is connected with an output port on the PCB, and the other output port of the LTCC low-pass filter is connected with one output port of the dielectric filter body; and further, pins for the patch LTCC low-pass filter are designed on the PCB, and the LTCC low-pass filter can inhibit multiple frequencies of the band-pass filter.

In some embodiments, the impedance of the PCB line is matched with the input and output impedance of the dielectric band-pass filter, and the input and output impedance of the LTCC low-pass filter is matched with the designed impedance of the communication system.

In some embodiments, the cut-off frequency point of the LTCC low pass filter is greater than the highest frequency point of the pass band of the band pass filter assembly and less than 2 times of the center frequency of the dielectric filter body, and the falling edge of the pass band of the LTCC low pass filter does not fall within the pass band range of the band pass filter as the pass band type selection range.

Preferably, the dielectric filter body has more than 2 resonant cavities.

Preferably, the metal shielding case is sleeved outside the dielectric filter body.

Preferably, the PCB comprises a top layer and a bottom layer which are connected up and down, two corner areas of the top layer and the bottom layer of the PCB are respectively provided with an input and output electrode port, and the top layer and the bottom layer of the PCB are connected through the input and output electrode ports; the left side and the right side of the top layer of the PCB are respectively provided with a dielectric ceramic body input bonding pad and a dielectric ceramic body output bonding pad;

the LTCC low-pass filter welding area is arranged between an input bonding pad of a dielectric ceramic body of the PCB and an input electrode port of the top layer of the PCB; or between the output pad of the dielectric ceramic body of the PCB and the output electrode port on the top layer of the PCB.

Preferably, the LTCC low pass filter pad area includes an LTCC low pass filter input/output port pin and an LTCC low pass filter ground pin.

Preferably, the PCB is provided with a metal hole penetrating through the PCB in a region except the input/output pad of the dielectric ceramic body and the grounding pin of the LTCC low-pass filter.

Preferably, one input port of the LTCC low-pass filter is connected with an input port on the PCB, and the other output port of the LTCC low-pass filter is connected with one input port of the dielectric filter body; or one input port of the LTCC low-pass filter is connected with the output port on the PCB, and the other output port of the LTCC low-pass filter is connected with one output port of the dielectric filter body

The grounding of the whole integrated assembly is ensured to be good, and the non-pad area of the circuit board is covered by green oil.

The shielding cover is made of hardware, generally made of zinc white copper or stainless steel silver plating, and is characterized in that one side of the shielding cover is provided with a shielding shell integrally at the top end of the dielectric band-pass filter, the other side of the shielding cover is provided with a shielding surface on the surface with a metal end surface pattern, the interval between the shielding shell and the dielectric body is generally within the range of 0.8-1.3 mm, and the advantage that the dielectric band-pass filter can realize high inhibition electrical performance and can isolate the mutual communication interference of surrounding devices by serially connecting the dielectric body is achieved;

in this embodiment, the LTCC low pass filter is an integrated component with small size, low loss, good suppression of frequency multiplication harmonic, low cost, and can be mounted on a chip, and the LTCC low pass filter specification is selected as an appropriate LTCC low pass filter specification, and the highest frequency point of the pass band of the band pass filter is selected as being 2 times smaller than the center frequency of the dielectric band pass filter, and the LTCC low pass filter should have a fluctuation value in the pass band of the band pass filter of less than or equal to 0.5dB, and the suppression section conforms to the frequency multiplication range value of the band pass filter, and is used as the type selection range. The defect of multiple frequency suppression of the dielectric band-pass filter is made up through a dielectric band-pass filter and LTCC series superposition mode.

In some embodiments, the band pass filter has more than 2 resonator band pass filters.

Description of the drawings:

FIG. 1 is an input-output electrode pattern;

FIG. 2 is another input-output electrode pattern;

FIG. 3 is a 6-cavity dielectric band-pass filter end face metal pattern with capacitive coupling as the equivalent input and output electrodes

FIG. 4 is another 6-cavity dielectric band-pass filter end face metal pattern with capacitive coupling at the equivalent input end and inductive coupling at the output end

FIG. 5 is an equivalent circuit diagram of a 6-cavity bandpass filter of FIG. 3

FIG. 6 is an equivalent circuit diagram of a 6-cavity bandpass filter of FIG. 4

FIGS. 7 and 8 are PCB layout diagrams of a dielectric bandpass filter assembly for suppressing double frequency harmonics

FIG. 9 is a 6-cavity dielectric bandpass filter shield design;

fig. 10 and 11 are graphs comparing the assembly of series LTCC low pass filters with dielectric bulk filters without low pass.

Detailed Description

Examples

Examples of implementations in accordance with this patent are described in detail below with reference to the figures.

FIG. 1 shows an example of an input/output electrode system (U-shaped electrodes); fig. 2 shows another example of an input/output electrode system (L-shaped electrode), in which the shaded area is a non-metal layer area, and the blank area is a metal layer area, which may be a metal conductor material such as a silver layer, a copper layer, or a tin layer.

FIG. 3 is a six-cavity dielectric bandpass filter end face metal pattern, in which 6 resonator walls are attached with metal layers to form an integral dielectric block; 301. 302 is a U-shaped electrode mode extension region that forms input-output electrode capacitive coupling with the resonators 305, 310; the resonant cavities 305 and 306 form inductive coupling at intervals 313, the resonant cavities 306 and 307 form capacitive coupling at intervals, the resonant cavities 307 and 308 form inductive coupling at intervals 311, the resonant cavities 308 and 309 form capacitive coupling at intervals, the resonant cavities 309 and 310 form inductive coupling at intervals 314 and metal layers, the resonant cavities 306, 307, 308 and 309 are respectively provided with a section of 312 metal layer inductive coupling at the extension surface of the U-shaped electrode to form 2 step-crossing transmission zero point couplings, and the metal layers 303 and 304 are respectively provided with reserved areas for welding shielding shells;

fig. 4 is a six-cavity dielectric band-pass filter end face metal pattern, in total, 6 dielectric blocks are formed by attaching metal layers on the walls of the resonant cavities, the 401 metal layer is an L-shaped electrode type extension region, one metal layer is connected with the resonant cavity 405 to form inductive coupling connection, the resonant cavities 405, 406 and 407 are spaced to form capacitive coupling, the spacing between the resonant cavities 407 and 408 forms inductive coupling to the 411 metal layer, the spacing between the resonant cavities 408 and 409 forms capacitive coupling, the spacing between the resonant cavities 409 and 410 forms inductive coupling to the disconnected metal layers 412 and 414, and the 402 metal layer is an L-shaped electrode type extension region and forms output capacitive coupling with the resonant cavity 414; the resonant cavities 406, 407, 408 and 409 are respectively provided with a section 413 of metal layer inductive coupling on the L-shaped electrode extension surface to form 2 step transmission zero point couplings, and the metal layers 403 and 404 are respectively provided with welding shielding shell reserved areas;

fig. 5 and 6 illustrate equivalent circuit diagrams of the embodiments of fig. 3 and 4.

Based on the dielectric band pass filter with six cavities provided above, the embodiment of the utility model provides a dielectric band pass filter component for inhibiting frequency doubling harmonics, which comprises a dielectric filter body (as described in the previous figures 1-4), a PCB (printed circuit board), an LTCC (low temperature co-fired ceramic) low-pass filter and a shielding shell;

the technical scheme of the invention is as follows: the PCB board has at least one LTCC low pass filter land;

the LTCC low-pass filter welding area is provided with at least one LTCC low-pass filter, one port of the LTCC low-pass filter is connected with a port on the PCB, and the other port of the LTCC low-pass filter is connected with one port of the dielectric filter body; and the LTCC low pass filter is designed to be able to suppress multiple frequency harmonics of the band pass filter.

The LTCC low-pass filter is arranged on the PCB assembly, wherein one port of the LTCC low-pass filter is connected with one port of the dielectric filter in series, and the other port of the LTCC low-pass filter is connected with one port of the PCB;

specifically, the PCB has a dielectric ceramic body input and output welding area and an LTCC low-pass filter welding area; the input and output welding area of the dielectric ceramic body of the PCB is provided with a pad surface welding connection of the dielectric ceramic body, the welding area of the LTCC low-pass filter is provided with a pad surface welding connection of the LTCC low-pass filter, one port of the LTCC low-pass filter is connected with one port of the dielectric filter in series, the other port of the LTCC low-pass filter is connected with one port of the PCB, the LTCC low-pass filter is designed to be capable of inhibiting multiple frequency harmonics of the band-pass filter, and therefore the multiple frequency harmonic defect of the dielectric band-pass filter is overcome by overlapping the inhibition section of the LTCC low-pass filter.

In some embodiments, an integrated assembly of an LTCC miniaturized low pass filter, a shielding case and a series connection is attached to a PCB, wherein the line impedance of the PCB is required to be close to the input/output impedance of the dielectric band pass filter and the input/output impedance of the LTCC low pass filter to the designed impedance of the communication system; the pin positions of the input and output ports of the LTCC low pass filter are required to respectively correspond to the input and output positions of the dielectric body filter and the PCB (wherein one port of the LTCC is connected in series with one port of the PCB, and the other port of the LTCC is connected with one port of the dielectric filter), and the assembly realizes the effect of 2-fold frequency and multiple-fold frequency suppression superposition by serially connecting the dielectric band pass filter with the LTCC low pass filter; specifically, in order to suppress multiple frequency harmonics, the LTCC low pass filter attached to the PCB needs to match the pass band of the band pass filter and the multiple frequency harmonic frequency band, in some embodiments, the pass band of the band pass filter is 3300-3600 MHz, and it needs to suppress 2 frequency multiplication and 3 frequency multiplication of 20dB, then the frequency band range of the 2 frequency multiplication harmonic is 6600-7200 MHz, the frequency band range of the 3 frequency multiplication harmonic is 9900-10800 MHz, the pass band bandwidth of the LTCC low pass filter attached to the PCB selects the highest frequency point of the pass band of the band pass filter, which is less than 2 times the central frequency of the dielectric band pass filter, and the fluctuation value of the LTCC low pass filter in the pass band of the band pass filter is less than or equal to 0.5dB, and the suppression section conforms to the frequency multiplication range value of the band pass filter, which is used as the model selection range. And the LTCC patch is designed between the input and output ends of the PCB and the input and output ends of the dielectric body filter, and if the LTCC low-pass filter out of the range, no effect or weak effect can be achieved.

FIGS. 7 and 8 illustrate a PCB formed of a material having a low dielectric constant, a high temperature resistance and a thermal expansion coefficient close to those of the ceramic body, the PCB having a dielectric ceramic body bonding area, an LTCC low pass filter bonding area and a metal shield bonding area; the PCB comprises a top layer 701 and a bottom layer 715 which are connected up and down, wherein non-pad areas of the circuit board are covered by solder resist with green oil, meanwhile, a plurality of metal through holes with different sizes are used for connecting the top layer 701 and the bottom layer 715 in non-welding areas of the circuit board, and a mode of filling resin materials in the holes is used for ensuring the grounding effect and avoiding the tin leakage effect; the input and output electrode ports 708 and 709 at the top layer of the PCB are connected with the input and output electrode ports 716 and 717 at the bottom layer in a metal via hole mode, metal holes penetrating through the PCB are arranged on a welding area of a non-welded medium body of the PCB and a grounding welding area of the LTCC low-pass filter, and the top layer of the PCB is electrically connected with the bottom layer through the input and output electrode port via holes;

the PCB top layer has input and output pads 702, 703 of a dielectric filter body, LTCC low- pass filter pins 704, 705, 706, 707, 710, 711, wherein 705, 707 are input and output port pins of the LTCC low-pass filter, 704, 706, 710, 711 are LTCC low-pass filter ground pins.

The input and output pads 702 and 703 of the dielectric filter body are respectively arranged at the left side and the right side of the top layer of the PCB, and the welding areas 704, 705, 706, 707, 710 and 711 of the LTCC low-pass filter are arranged between the input pad 702 of the dielectric ceramic body of the PCB and the input electrode port 708 of the top layer of the PCB; or between the output pad 703 of the dielectric ceramic body of the PCB and the output electrode port 709 at the top layer of the PCB.

The PCB board provided in this embodiment further includes a shielding metal region 713, which is provided with 2 through holes 712 and 714, for ensuring the stability of the gap between the dielectric ceramic body and the metal shielding case during the mounting process.

Exemplarily, fig. 9 provides a 6-cavity dielectric band-pass filter shielding shell design diagram, a material generally adopts zinc-white copper or stainless steel silver plating, a height of a shielding shell 813 is designed according to a dielectric body, a length depth of 803 is generally slightly smaller than that of the dielectric body, depths of 801 and 802 are correspondingly designed according to a metal position of a reserved patch of a metal end face pattern of the dielectric body, 6 through windows 804, 805, 806, 807, 808 and 809 are reserved on right-angle surfaces of 803 and 813 to facilitate measurement of the dielectric body after assembly, 811 and 812 are metal shielding shell positioning pins for ensuring stable clearance between a ceramic body and a metal shielding shell during patch, and 810 is a metal shielding shell and PCB welding surface for integrating the metal shielding shell and the dielectric body after welding to prevent internal signal leakage and avoid external signal interference.

Fig. 10 and 11 are graphs comparing the dielectric body filter without the low pass filter with the assembly of the series LTCC low pass filter, and it can be clearly seen that the dielectric body of the filter connected in series with the LTCC low pass filter has better suppression in the frequency band of 2 times and multiple times of the harmonic than the dielectric body of the filter without the low pass filter.

Claims (10)

1. A dielectric band-pass filter assembly for suppressing double frequency harmonics, the filter assembly comprising a dielectric filter body, a shield case and a PCB, wherein the PCB has at least one LTCC low pass filter land;

the LTCC low-pass filter welding area is provided with at least one LTCC low-pass filter, one port of the LTCC low-pass filter is connected with a port on the PCB, and the other port of the LTCC low-pass filter is connected with one port of the dielectric filter body; and the LTCC low pass filter is designed to be able to suppress multiple frequency harmonics of the band pass filter.

2. The frequency doubling harmonic suppression dielectric bandpass filter assembly of claim 1 wherein the PCB board line impedance matches the dielectric bandpass filter input output impedance and the LTCC low pass filter input output impedance matches the communication system design impedance.

3. The dielectric band-pass filter assembly for suppressing frequency multiplication harmonic according to claim 1, wherein a cut-off frequency point of the LTCC low-pass filter is greater than a highest frequency point of a pass band of the band-pass filter assembly and is less than 2 times of a center frequency of a dielectric filter body, a fluctuation value of the LTCC low-pass filter in the pass band of the band-pass filter is less than or equal to 0.5dB, and a suppression section conforms to a frequency multiplication range value of the band-pass filter and is used as a model selection range.

4. The frequency-doubling harmonic suppression dielectric bandpass filter assembly of claim 1 wherein the dielectric filter body has more than 2 resonant cavities.

5. The frequency doubling harmonic suppression dielectric bandpass filter assembly of claim 1 wherein the dielectric filter body input/output port is designed as an end output or a side output.

6. The dielectric bandpass filter assembly according to claim 1, wherein the dielectric filter has a metal line led out from the input or output port and connected to the metal block of the input first cavity or the output first cavity.

7. The dielectric band-pass filter assembly for suppressing frequency multiplication harmonics according to claim 1, wherein the PCB comprises a top layer and a bottom layer which are connected up and down, two corner regions of the top layer and the bottom layer of the PCB are respectively provided with an input and output electrode port, and the top layer and the bottom layer of the PCB are connected through the input and output electrode ports; the left side and the right side of the top layer of the PCB are respectively provided with a dielectric ceramic body input bonding pad and a dielectric ceramic body output bonding pad;

the LTCC low-pass filter welding area is arranged between an input bonding pad of a dielectric ceramic body of the PCB and an input electrode port of the top layer of the PCB; or between the output pad of the dielectric ceramic body of the PCB and the output electrode port on the top layer of the PCB.

8. The frequency-doubled harmonic suppressed dielectric bandpass filter assembly of claim 7 wherein the LTCC low pass filter bond pad region comprises an LTCC low pass filter input/output port pin and an LTCC low pass filter ground pin.

9. The frequency doubling harmonic suppression dielectric band pass filter assembly according to claim 7, wherein the PCB is provided with metal holes penetrating through the PCB in regions other than the input/output pads of the dielectric ceramic body and the grounding pins of the LTCC low pass filter.

10. The frequency doubling harmonic suppression dielectric bandpass filter assembly of claim 7 wherein one input port of the LTCC low pass filter is connected to an input port on the PCB and the other output port is connected to one input port of the dielectric filter body; or one input port of the LTCC low-pass filter is connected with the output port on the PCB, and the other output port of the LTCC low-pass filter is connected with one output port of the dielectric filter body.

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