CN212183494U

CN212183494U - Small-size high-attenuation crystal filter

Info

Publication number: CN212183494U
Application number: CN202020949400.8U
Authority: CN
Inventors: 徐雨
Original assignee: Liaoyang Hongyu Crystal Co ltd
Current assignee: Liaoyang Hongyu Crystal Co ltd
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2020-12-18
Anticipated expiration: 2030-05-29

Abstract

The utility model relates to a little volume high attenuation crystal filter, including base, shell, PCB board, filtering crystal, chip capacitor and inductance coils, the quantity of filtering crystal is two, and its technical essential is: the two filtering crystals are stacked on the base, opposite surfaces of shells of the two filtering crystals are welded comprehensively, the shell of the filtering crystal below is welded comprehensively with the opposite surface of the base, the PCB is vertically arranged on the upper surface of the base, the wiring end side of the filtering crystal is welded with the PCB in an assembling mode, the inductance coil is an inductance coil wound by a phi 4.0 annular magnetic core, the number of the inductance coil is two, shielding boxes are arranged outside the inductance coil, the two shielding boxes are symmetrically arranged on two sides of the filtering crystal in the horizontal direction and are welded with the shells of the filtering crystal comprehensively by soldering tin, and wiring ends of the inductance coil penetrate through the shielding boxes to be welded with the PCB in an assembling mode. The utility model discloses compact structure, use reliably, solved current wave filter and be difficult to satisfy the problem of miniaturization and the dual requirement of decay index.

Description

Small-size high-attenuation crystal filter

Technical Field

The utility model relates to a piezoelectricity quartz crystal filter technical field, concretely relates to little volume high attenuation crystal filter.

Background

The quartz crystal filter is composed of a filter crystal as a main element, plays a role of filtering, is much superior to a filter composed of an LC resonance circuit in frequency selectivity, frequency stability, transition band steepness, insertion loss and the like, and is widely used for electronic equipment such as communication, navigation, measurement and the like.

At present, although a quartz crystal filter theoretically adopts multi-section cascade connection, the out-of-band attenuation can be effectively improved, and rectangular coefficients can be reduced, for example, the out-of-band attenuation of the filter with the external dimension of 19.4mm multiplied by 14.4 mm multiplied by 7 mm (L multiplied by W multiplied by H) can reach 60 dB. However, due to the limitation of the overall dimension requirement of product miniaturization, only two cascaded monolithic crystal filters can be adopted, and the two cascaded filters generally cause the problem of poor out-of-band attenuation of the finished product, generally the out-of-band attenuation of the two cascaded filters can reach 40dB to 50dB, and meanwhile, under the requirement of small overall dimension indexes, the distance between the input end and the output end of the filter is inevitably closer than the distance between the large-volume input end and the large-volume output end, the generated electromagnetic interference intensity is high, and the index of the out-of-band attenuation is liable to be further deteriorated.

Disclosure of Invention

The utility model aims at providing a compact structure, use reliable small-size high attenuation crystal filter, solve the problem that current wave filter is difficult to satisfy the dual requirement of miniaturization and attenuation index, do not influence the attenuation index when realizing that crystal filter is miniaturized.

The technical scheme of the utility model is that:

the utility model provides a little volume high attenuation crystal filter, includes the base, with base welded shell, locate PCB board, filtering crystal, chip capacitor and the inductance coils in the shell, the quantity of filtering crystal is two, and its technical essential is: the two filtering crystals are overlapped in the middle of the upper surface of the base, the opposite surfaces of the two filtering crystal shells are fully welded by soldering tin, the shell of the filtering crystal below is fully welded with the opposite surface of the base by soldering tin, the PCB is vertically arranged on the upper surface of the base and is electrically connected with the lead of the base, the terminal side of the filter crystal is assembled and welded with the PCB, the inductance coils are wound by phi 4.0 annular magnetic cores, the number of the inductance coils is two, the outer parts of the inductance coils are respectively provided with a shielding box for encapsulating the inductance coils, in the horizontal direction, the two shielding boxes are symmetrically arranged at two sides of the filter crystal and are comprehensively welded with the shell of the filter crystal by using soldering tin, the wiring end of the inductance coil passes through the shielding boxes to be assembled and welded with the PCB, the quantity of chip capacitor is five and arranges in PCB board filtering crystal side dorsad, filtering crystal, chip capacitor and inductance coils constitute filter circuit.

In the small-size high-attenuation crystal filter, the filter crystal is a three-lead filter crystal and has a ground lead, an input lead and an output lead.

In the small-volume high-attenuation crystal filter, the filter circuit is composed of a filter crystal MCF1, a filter crystal MCF2, a chip capacitor C1, a chip capacitor C2, a chip capacitor C3, a chip capacitor C4, a chip capacitor C5, an inductor T1 and an inductor T2, one end of the chip capacitor C1 is connected to the signal input terminal, the other end is connected to one terminal of the inductor T1, the other terminal of the inductor T1 is connected to the input lead of the filter crystal MCF1, the inductor T1 is connected to the common terminal of the filter crystal MCF1 to the ground terminal of the chip capacitor C3, the output lead of the filter crystal MCF1 is connected to the input lead of the filter crystal MCF2, the common terminal of the filter crystal MCF1 and the filter crystal MCF2 to the ground terminal of the chip capacitor C5, the output terminal of the filter crystal MCF2 is connected to one terminal of the inductor T2, and the other terminal of the chip capacitor T2 is connected to one terminal of the inductor C2, the other end of the chip capacitor C2 is connected with a signal output end, and the filter crystal MCF2 and the common end of the inductance coil T2 are connected with the chip capacitor C4 in a terminal-to-ground mode. Chip capacitor C1 and chip capacitor C2 are separate value electric capacity, break down inductance coil and filtering crystal when avoiding the heavy current to pass through.

In the small-size high-attenuation crystal filter, the base is provided with an input lead connected with one chip capacitor, an output lead connected with the other chip capacitor and two grounding leads.

In the small-size high-attenuation crystal filter, the length of the shell is 15mm, the width of the shell is 12mm, and the distance from the bottom surface of the base to the top surface of the shell is 7.5 mm.

The utility model has the advantages that:

1. through adopting the inductance coils and the above-mentioned components and parts overall arrangement of minor diameter hydroxyl ring type magnetic core, reduce the filter volume, the wave filter overall dimension can reach 15mm x 12mm x 7.5mm (L x W x H), and filtering crystal passes through base upper surface ground connection on the one hand, and on the other hand passes through the whole board ground connection of PCB board, improves the ground connection area greatly, and the out-of-band attenuation can reach more than 75dB, has realized the technological effect of little volume high attenuation.

2. Because of the restriction of volume, the magnetic core winding inductance coil of phi 5.0 that prior art adopted has been abandoned, select the annular magnetic core winding inductance coil of phi 4.0 that the diameter is littleer, advantage one: the short circuit condition caused by scalding the polyamide layer of the enameled wire in the welding process due to the small volume can be avoided; the advantages are two: the gap between the inner wall of the shielding box and the annular magnetic core is increased, and the annular magnetic core can be more effectively encapsulated by glue filling, so that the long-term stability and reliability of the inductor are ensured; the advantages are three: when the annular magnetic core is selected, the Q value of the inductor can be ensured under the condition of reducing the internal volume of the filter, and other technical indexes of the product are not influenced.

Drawings

Fig. 1 is a schematic structural diagram of the present invention;

FIG. 2 is a schematic structural diagram of the components on the PCB board of the present invention;

FIG. 3 is a top view of FIG. 2;

fig. 4 is a schematic circuit diagram of the present invention;

in the figure: 1. the PCB comprises a shell, 2 parts of a PCB board, 3 parts of a base, 4 parts of a filter crystal, 5 parts of an inductance coil, 6 parts of a lead, 7 parts of a terminal and 8 parts of a chip capacitor.

Detailed Description

As shown in fig. 1-4, the small-volume high-attenuation crystal filter includes a base 3, a housing 1 welded to the base 3, a PCB board 2 disposed in the housing 1, a filter crystal 4, a chip capacitor 8, and an inductor 5.

The number of the filter crystals 4 is two, the two filter crystals 4 are stacked in the middle of the upper surface of the base 3, opposite surfaces of the shells of the two filter crystals 4 are welded completely through soldering tin, and the shell of the filter crystal 4 below is welded completely through soldering tin with the opposite surface of the base 3. PCB board 2 sets up and locates the base 3 upper surface and is electrically connected with the lead wire 6 of base 3, the terminal side and the PCB board 2 assembly welding of filtering crystal 4. The inductance coils 5 are inductance coils wound by phi 4.0 hydroxyl ring-shaped magnetic cores, the number of the inductance coils is two, the shielding boxes for encapsulating the inductance coils are respectively arranged outside the inductance coils, in the horizontal direction, the two shielding boxes are symmetrically arranged on two sides of the filter crystal and are comprehensively welded with the shell of the filter crystal 4 by soldering tin, and the wiring ends of the inductance coils 5 penetrate through the shielding boxes to be assembled and welded with the corresponding wiring ends 7 on the PCB 2. The quantity of chip capacitor 8 is five and arranges in PCB board 2 filtering crystal side dorsad, filtering crystal 4, chip capacitor 8 and inductance coils 5 constitute filter circuit.

In this embodiment, the filter crystal 4 is a three-lead filter crystal, and has a ground lead, an input lead, and an output lead. The base 3 is provided with an input lead connected with one chip capacitor, an output lead connected with the other chip capacitor, and two grounding leads.

The filter circuit is composed of a filter crystal MCF1, a filter crystal MCF2, a chip capacitor C1, a chip capacitor C2, a chip capacitor C3, a chip capacitor C4, a chip capacitor C5, an inductance coil T1 and an inductance coil T2, wherein one end of the chip capacitor C1 is connected with a signal input end, the other end of the chip capacitor C1 is connected with one terminal of the inductance coil T1, the other terminal of the inductance coil T1 is connected with an input lead of the filter crystal MCF1, the inductance coil T1 is connected with the chip capacitor C3 in a way of being opposite to the common end of the filter crystal MCF1, an output lead of the filter crystal MCF1 is connected with an input lead of the filter crystal MCF2, the common end of the filter crystal MCF1 and the filter crystal MCF2 is connected with the chip capacitor C5 in a way of being opposite to earth, an output end of the filter crystal MCF2 is connected with one terminal of the inductance coil T2, and the other terminal of, the other end of the chip capacitor C2 is connected with a signal output end, and the filter crystal MCF2 and the common end of the inductance coil T2 are connected with the chip capacitor C4 in a terminal-to-ground mode. Chip capacitor C1 and chip capacitor C2 are separate value electric capacity, break down inductance coil and filtering crystal when avoiding the heavy current to pass through. The chip capacitor is welded in the interstage circuit of the circuit board and plays a role in coupling. The housing and the base are encapsulated by resistance welding.

In this embodiment, the length of the housing 1 of the filter is 15mm, the width is 12mm, the distance from the bottom surface of the base 3 to the top surface of the housing 1 is 7.5mm, and the size of the filter is greatly reduced.

The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention should be covered by the present patent.

Claims

1. The utility model provides a little volume high attenuation crystal filter, includes the base, with base welded shell, locate PCB board, filtering crystal, chip capacitor and the inductance coils in the shell, the quantity of filtering crystal is two, its characterized in that: the two filtering crystals are overlapped in the middle of the upper surface of the base, the opposite surfaces of the two filtering crystal shells are fully welded by soldering tin, the shell of the filtering crystal below is fully welded with the opposite surface of the base by soldering tin, the PCB is vertically arranged on the upper surface of the base and is electrically connected with the lead of the base, the terminal side of the filter crystal is assembled and welded with the PCB, the inductance coils are wound by phi 4.0 annular magnetic cores, the number of the inductance coils is two, the outer parts of the inductance coils are respectively provided with a shielding box for encapsulating the inductance coils, in the horizontal direction, the two shielding boxes are symmetrically arranged at two sides of the filter crystal and are comprehensively welded with the shell of the filter crystal by using soldering tin, the wiring end of the inductance coil passes through the shielding boxes to be assembled and welded with the PCB, the quantity of chip capacitor is five and arranges in PCB board filtering crystal side dorsad, filtering crystal, chip capacitor and inductance coils constitute filter circuit.

2. The small-volume high-attenuation crystal filter according to claim 1, characterized in that: the filter crystal is a three-lead filter crystal and is provided with a grounding lead, an input lead and an output lead.

3. The small-volume high-attenuation crystal filter according to claim 1, characterized in that: the filter circuit is composed of a filter crystal MCF1, a filter crystal MCF2, a chip capacitor C1, a chip capacitor C2, a chip capacitor C3, a chip capacitor C4, a chip capacitor C5, an inductance coil T1 and an inductance coil T2, wherein one end of the chip capacitor C1 is connected with a signal input end, the other end of the chip capacitor C1 is connected with one terminal of the inductance coil T1, the other terminal of the inductance coil T1 is connected with an input lead of the filter crystal MCF1, the inductance coil T1 is connected with the chip capacitor C3 in a way of being opposite to the common end of the filter crystal MCF1, an output lead of the filter crystal MCF1 is connected with an input lead of the filter crystal MCF2, the common end of the filter crystal MCF1 and the filter crystal MCF2 is connected with the chip capacitor C5 in a way of being opposite to earth, an output end of the filter crystal MCF2 is connected with one terminal of the inductance coil T2, and the other terminal of, the other end of the chip capacitor C2 is connected with a signal output end, and the filter crystal MCF2 and the common end of the inductance coil T2 are connected with the chip capacitor C4 in a terminal-to-ground mode.

4. The small-volume high-attenuation crystal filter according to claim 1, characterized in that: the base is provided with an input lead connected with one chip capacitor, an output lead connected with the other chip capacitor and two grounding leads.

5. The small-volume high-attenuation crystal filter according to claim 1, characterized in that: the shell is 15mm long, and wide 12mm, base bottom surface to shell top surface distance is 7.5 mm.