Small crystal filter

Abstract

The utility model discloses a miniature crystal filter, and relates to the technical field of wireless communication. The filter comprises a filter base and a filter core group, the filter base comprises a metal substrate and a metal lead column, and the metal lead column penetrates through the metal substrate; the filter core group comprises a printed circuit board, a chip capacitor, a crystal resonator and a magnetic ring; and the printed circuit board is welded with the metal lead columns. The filter core group is vertically mounted, and the chip capacitors are assembled at positions reserved between the left and right ends of the upper-layer plate and the two columns of crystal resonators, so that the capacitors and the crystal resonators are in the same plane, and the height space consumption of the filter is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to wireless communication technical field more particularly, it is a kind of small crystal filter. BACKGROUND

[0002] In recent years, with the continuous development of communication technology, the performance requirement of filter is higher and higher.Small crystal filter needs to have excellent characteristics such as high selectivity, low loss, high stability while keeping small size and light weight;At the same time, with the miniaturization and integration trend of equipment in the field of wireless communication, radar, radio, etc., the demand for small crystal filter is increasing.

[0003] The volume of crystal filter is limited by insufficient component technology level and existing design structure space waste, the volume of most crystal filters on the market is too large, which cannot meet market requirements.

[0004] Therefore, it is necessary to develop a small crystal filter. UTILITY MODEL CONTENT

[0005] The utility model aims at overcoming the insufficient of the prior art, and provides a small crystal filter.

[0006] In order to achieve the above object, the technical scheme of the utility model is as follows: a small crystal filter, characterized by comprising a filter base and a filter core group, the filter base comprises a metal substrate and four metal lead columns, the metal lead columns pass through the metal substrate;

[0007] The filter core group comprises a printed circuit board, a patch capacitor and a crystal resonator located on the top of the printed circuit board, and a magnetic ring located on the bottom of the printed circuit board.

[0008] The printed circuit board is welded with the metal lead column.

[0009] The magnetic ring is sleeved with a magnetic ring shell.

[0010] In the above technical scheme, the printed circuit board is a double-layer board, the patch capacitor and the crystal resonator are fixed on the upper layer board by soldering, and the magnetic ring is attached to the lower layer board.

[0011] In the above technical scheme, the patch capacitor is a chip multilayer ceramic capacitor, and the crystal resonator is a patch crystal resonator.

[0012] In the above technical scheme, the magnetic ring shell is a double-sided opening metal shell, and the long-side opening surface is attached to the lower layer board of the printed circuit board.

[0013] In the above technical solution, the crystal resonator has two rows, and the plurality of patch capacitors are located between the two rows of crystal resonators and at the left and right ends of the upper layer of the printed circuit board.

[0014] In the above technical solution, further comprising a shell, the metal substrate is provided with a step around, the shell bottom matches with the step, and the filter core group is located in the shell.

[0015] In the above technical solution, the crystal resonator has a size of 3.2mm*2.5mm*0.70mm.

[0016] In the above technical solution, the magnetic ring is a 3*2.5*0.5mm nickel powder core magnetic ring.

[0017] In the above technical solution, the shell and the filter core group top reserve 0.2mm space, and the crystal filter has a volume of 26mm*12mm*5.3mm.

[0018] Compared with the prior art, the utility model has the following advantages:

[0019] 1) In order to make good use of the space in the filter, the filter core group of the utility model is vertically installed, that is, the printed circuit board is installed vertically above the filter base; the printed circuit board has double-layer wiring, the upper layer is provided with patch capacitors and crystal resonators, the crystal resonators are distributed in two rows on the upper layer of the printed circuit board, and patch capacitors are arranged at the left and right ends of the upper layer and between the two rows of crystal resonators, so that the capacitors and the crystal resonators are in the same plane, and the height space consumption of the filter is reduced.

[0020] 2) The utility model is provided with a magnetic ring on the lower layer of the printed circuit board, the magnetic ring is closely attached to the lower layer of the printed circuit board, and a double-opening magnetic ring shell is provided on the magnetic ring, so that the magnetic ring is prevented from swinging on the core and signal crosstalk between the magnetic rings is reduced.

[0021] 3) The magnetic ring shell of the utility model is designed as a double opening, compared with the traditional single opening design, the magnetic ring shell is closely attached to the upper surface of the printed circuit board, the lower layer of the printed circuit board serves as one surface of the magnetic ring shell, the height corresponding to the thickness of the magnetic ring shell can be saved, and the length, width and height of the magnetic ring shell are reduced in the case of accommodating the magnetic ring. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is an assembly drawing of the utility model.

[0023] Figure 2 It is a structural schematic view of the filter base and the filter core group.

[0024] Figure 3 It is a top view of the filter core group.

[0025] 100 - filter base, 110 - metal base plate, 111 - step, 120 - metal lead post, 200 - filter core set, 210 - printed circuit board, 211 - metalized via, 220 - patch capacitor, 230 - crystal resonator, 240 - magnetic ring, 241 - magnetic ring housing, 300 - housing. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in detail below with reference to the drawings, but they do not constitute limitations to the present application, and are only examples. Meanwhile, the advantages of the present application will become more apparent and easier to understand through the description.

[0027] Referring to the drawings, a small crystal filter is characterized in that it comprises a filter base 100 and a filter core set 200, the filter base 100 comprises a metal base plate 110 and four metal lead posts 120, and the metal lead posts 120 pass through the metal base plate 110.

[0028] The filter core set 200 comprises a printed circuit board 210, a patch capacitor 220 and a crystal resonator 230 on the top of the printed circuit board 210, and a magnetic ring 240 on the bottom of the printed circuit board 210.

[0029] The printed circuit board 210 is welded with the metal lead posts 120.

[0030] The magnetic ring 240 is sleeved with a magnetic ring housing 241.

[0031] The printed circuit board 210 is a double-layer board, the patch capacitor 220 and the crystal resonator 230 are fixed on the upper layer board by soldering, and the magnetic ring 240 is attached to the lower layer board.

[0032] The patch capacitor 220 is a patch multilayer ceramic capacitor, and the crystal resonator 230 is a patch crystal resonator.

[0033] The magnetic ring housing 241 is a double-face opening metal housing, and the long-side opening face is attached to the lower layer board of the printed circuit board 210. Compared with the traditional single opening design, the magnetic ring housing 241 is removed from the upper face of the printed circuit board 210 in the present application, the lower layer board of the printed circuit board 210 serves as the top face of the magnetic ring housing 241, the height (about 0.1-0.2mm) equivalent to the thickness of the magnetic ring housing 241 can be saved, and the length, width and height of the magnetic ring housing 241 are reduced in size under the condition of accommodating the magnetic ring 240.

[0034] As Figure 3As shown, the crystal resonator 230 has two rows, and the plurality of patch capacitors 220 are located between the two rows of crystal resonators 230 and at the left and right ends of the upper layer of the printed circuit board 210; the crystal resonators 230 are distributed in pairs in two rows on the upper layer of the printed circuit board 210, and positions are left at the left and right ends of the upper layer and between the two rows of crystal resonators for assembling capacitors, so that the patch capacitors 220 and the crystal resonators 230 are in the same plane, and the height space consumption of the crystal filter is reduced.

[0035] Further comprising a shell 300, the metal substrate 110 is provided with a step 111 around, the bottom of the shell 300 matches with the step 111, and the filter core group 200 is located in the shell 300.

[0036] The size of the crystal resonator 230 in length, width and height is 3.2mm*2.5mm*0.70mm. The crystal resonator 230 selects a patch type 3225 crystal resonator, and the size in length, width and height is 3.2mm*2.5mm*0.70mm. Compared with a traditional UM-5 plug-in type crystal resonator (7mm*3.2mm*6mm), the volume is reduced by 23 times. At the same time, the electrical performance still retains 90% of the level of the plug-in type crystal resonator.

[0037] The patch capacitor 220 selects a smaller 0402 type. Compared with 0805 and 0603 types, the volume is small, and the 0402 type capacitor is easier to solder by hand than a 0201 type capacitor.

[0038] The magnetic ring 240 is a nickel powder core magnetic ring with a size of 3*2.5*0.5mm, and the volume is as small as possible while the high and low temperature performance and Q value are maintained.

[0039] The shell 300 leaves a space of 0.2mm at the top of the filter core group 200, and the volume of the crystal filter is 26mm*12mm*5.3mm.

[0040] In actual use, in order to ensure that the crystal filter has excellent attenuation and rectangular coefficient, the circuit of the utility model adopts a Chebyshev difference bridge type design; according to the Chebyshev difference bridge type circuit, electrical connection is performed on components, so that the combined crystal filter has a small volume and good rectangular coefficient and attenuation index.

[0041] During assembly, four metalized through holes 211 are reserved at four corners of the printed circuit board 210, and correspond to the four metal lead columns 120; the assembled filter core group 200 is first passed through the four metal lead columns 120, then the metal lead columns 120 are fixed by soldering with the printed circuit board 210, and finally the bottom surface of the shell 300 is tightly attached to the step 111 of the metal substrate 110.

[0042] The shell 300 and the filter core set 200 reserve 0.2mm space; the shell 300 and the metal substrate 110 are both 4J29 materials (the thickness of the metal substrate 110 is less than or equal to 1mm: the thickness of the shell 300 is less than or equal to 0.4mm), which can shield the interference of external signals and have good strength.

[0043] The final volume of the utility model is 26mm*12mm*5.3mm, the volume of a same five-section crystal filter in the market is 36.5mm*22mm*11mm, compared with the volume is greatly reduced, and the utility model also has good rectangular coefficient and stopband attenuation.

[0044] Other unexplained parts belong to the prior art.

Claims

1. A miniature crystal filter, characterized in that: It includes a filter base (100) and a filter core (200). The filter base (100) includes a metal substrate (110) and four metal lead posts (120), which pass through the metal substrate (110). The filter core assembly (200) includes a printed circuit board (210), a surface mount capacitor (220) and a crystal resonator (230) located on the top of the printed circuit board (210), and a magnetic ring (240) located at the bottom of the printed circuit board (210). The printed circuit board (210) is soldered to the metal lead post (120); The magnetic ring (240) is fitted with a magnetic ring shell (241).

2. A miniature crystal filter according to claim 1, characterized in that: The printed circuit board (210) is a double-layer board. The surface mount capacitor (220) and the crystal resonator (230) are fixed to the upper layer board by soldering, and the magnetic ring (240) is attached to the lower layer board.

3. A miniature crystal filter according to claim 1, characterized in that: The chip capacitor (220) is a chip multilayer ceramic capacitor, and the crystal resonator (230) is a chip crystal resonator.

4. A miniature crystal filter according to claim 2, characterized in that: The magnetic ring housing (241) is a double-sided open metal housing, with the long side opening surface attached to the lower layer of the printed circuit board (210).

5. A miniature crystal filter according to claim 2, characterized in that: The crystal resonators (230) have two columns, and a plurality of the chip capacitors (220) are located between the two columns of crystal resonators (230) and at the left and right ends of the upper layer of the printed circuit board (210).

6. A miniature crystal filter according to claim 1, characterized in that: It also includes a housing (300), the metal substrate (110) is provided with steps (111) around its perimeter, the bottom of the housing (300) matches the steps (111), and the filter core (200) is located inside the housing (300).

7. A miniature crystal filter according to claim 3, characterized in that: The dimensions of the crystal resonator (230) are 3.2mm × 2.5mm × 0.70mm (length × width × height).

8. A miniature crystal filter according to claim 4, characterized in that: The magnetic ring (240) is a 3×2.5×0.5mm nickel powder core magnetic ring.

9. A miniature crystal filter according to claim 6, characterized in that: The outer casing (300) and the top of the filter core (200) have a reserved space of 0.2mm, and the crystal filter has a volume of 26mm×12mm×5.3mm.

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