Meter-wave low-cost switch filter bank integration method

Abstract

The invention discloses an integration method of a meter-wave low-cost switch filter bank, which is characterized in that a single board integrates an eight-way surface acoustic wave filter bank, two groups of one-to-eight radio frequency switch networks, a radio frequency coaxial connector and a low-frequency pin header on two sides to realize meter-wave eight-way switch gating and frequency division filtering functions. Based on the six-layer FR4 through hole printed board, the standard packaging surface acoustic wave filter, the general SMP connector and the 2.54 pin header, the low cost advantage is remarkable. A double-sided high-density layout wiring technology is adopted, and the plane size of the eight-way switch filter bank is only 35 * 38mm, which is reduced by about 40% compared with that of a conventional single-sided layout scheme. And meanwhile, other components can still be mounted in an area between the mother board and the module, so that the integration level of the mother board is improved. And the shielding cover is used for shielding and protecting the radio frequency circuits on the two sides, so that the overall anti-interference capability of the switch filter bank module is improved.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency circuits, and in particular to a method for integrating a meter-wave low-cost switch filter group. Background Art

[0002] The filter is a general frequency-selective device that has the function of filtering out interference spectra outside the passband. It is widely used in the receiver front end of radar, communication, electronic warfare and other equipment, and usually appears in the RF front-end circuit in the form of a multi-way switch filter group. With the rapid development of RF front-ends, there is an urgent need for RF switch filter groups to resist strong interference, be miniaturized, and be universal. However, in the meter-wave frequency band, the current common method for implementing switch filter groups is still to use discrete SAW filter devices and RF switch devices, which has a series of problems such as large planar layout area and poor versatility. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a low-cost eight-way switch filter group integration method for meter waves.

[0004] The purpose of the present invention is achieved through the following technical solutions.

[0005] A low-cost meter-wave switch filter group integration method is disclosed. An eight-way SAW filter group, two groups of eight-way RF switch networks, RF coaxial connectors and low-frequency pin headers are integrated on both sides of a single board to realize the meter-wave eight-way switch gating and frequency division filtering functions.

[0006] The printed circuit board adopts a 6-layer stacking design, the board uses 3 layers of FR4 CORE, combined with the through-hole process, and the printed circuit board is pressed in one time.

[0007] Only surface mount components and pin components are used, and they are produced through standard reflow soldering process.

[0008] The low-cost Meter-wave switch filter group uses 4-channel standard SMD9171A package SAW filters and 4-channel standard SMD0505B package SAW filters.

[0009] The low-cost switch filter group of meter wave uses 6 miniaturized QFN packaged four-switch to build a 2-way eight-switch network, with a total of 6 bits of control.

[0010] The front and back RF circuit areas of the low-cost meter-wave switch filter group are shielded with a 3mm high metal shielding cover.

[0011] Compared with the prior art, the advantages of the present invention are:

[0012] 1. The present invention is based on a 6-layer FR4 through-hole printed circuit board, a standard package SAW filter, a universal SMP connector and a 2.54 pin header, and has a significant low-cost advantage.

[0013] 2. The present invention adopts double-sided high-density layout and wiring technology, and the plane size of the eight-way switch filter group is only 35×38mm, which is about 40% smaller than the conventional single-sided layout solution. At the same time, other components can still be mounted in the area between the motherboard and the module, which improves the integration of the motherboard.

[0014] 3. The present invention uses a shielding cover to shield and protect the radio frequency circuits on both sides, thereby improving the overall anti-interference capability of the switch filter group module. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a principle block diagram of an eight-way switch filter group of the present invention.

[0016] Figure 2 This is a laminated structure diagram of the printed circuit board of the present invention.

[0017] Figure 3 This is an assembly diagram of the eight-way switch filter group module of the present invention.

[0018] Figure 4 This is a diagram showing the application of the eight-channel switch filter group module of the present invention on an upper-level motherboard.

[0019] Figure 5 This is the printed circuit board layout of the eight-channel switch filter group module of the present invention. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] A low-cost meter-wave switch filter group integration method is disclosed. An eight-way SAW filter group, two groups of eight-way RF switch networks, RF coaxial connectors and low-frequency pin headers are integrated on both sides of a single board to realize the meter-wave eight-way switch gating and frequency division filtering functions.

[0022] The printed circuit board adopts a 6-layer stacking design, and the board only uses 3 layers of FR4 CORE. Combined with the through-hole process, the printed circuit board processing only requires one pressing, which can significantly reduce costs.

[0023] Only surface mount components and pin components are used, which can be quickly mass-produced through standard reflow soldering process, with significant cost advantages.

[0024] Use 4-way standard SMD9171A package SAW filters and 4-way standard SMD0505B package SAW filters.

[0025] Use 6 miniaturized QFN packaged 4-for-1 switches to build a 2-way 8-for-1 switch network, with a total of 6 control bits.

[0026] The RF circuit areas on both sides are shielded with 3mm high metal shielding covers, and the module has good anti-interference capabilities.

[0027] The circuit principle block diagram of the present invention is as follows: Figure 1 As shown. In the lower frequency band of meter waves, RF narrowband filters usually use larger SMD9171A and SMD0505B marked package SAW filters. The switch filter group designed by the present invention selects 4-way SMD9171A and 4-way SMD0505B filters, which have strong versatility. When designing the pre-layout, consider placing a group of 4-way switch filter groups on the front and back sides respectively, and the two sizes of filters are staggered. Filter AD is an SMD9171A package filter, and filter EH is an SMD0505B filter. The RF switch uniformly adopts a miniaturized all-four RF switch, the QFN package size is only 3x3mm, and a 2-bit parallel control method is used to achieve switch switching. In order to save control resources, the 2-bit control bits of all four switches are connected together to form a 1-bit controlled all-two switch, which is the RF switch A and RF switch F in the figure. At the same time, the 2-bit control bits of RF switch B and RF switch C are reused, and the 2-bit control bits of RF switch D and RF switch E are reused. The entire eight-way switch filter group only needs 6-bit control bits to complete the control switching. The RF coaxial connector uses the 4mm high optical hole SMP connector SMP-JTD23-S, and the board spacing after the module is installed on the motherboard is designed to be 8mm. The low-frequency straight-plug pin header uses a standard 2.54mm pitch 2×5 pin header socket, which is 6.5mm long on the board after installation. It can be used with the motherboard plug to complete low-frequency interconnection at an 8mm board spacing, realizing 5V power supply, switch control transmission and ground interconnection.

[0028] The present invention aims at a low-cost route, and the printed circuit board adopts a 6-layer stacking design, such as Figure 2 As shown in the figure. The board only uses 3 layers of FR4CORE, combined with the through-hole process, the printed board processing only needs one pressing, which can significantly reduce the cost. The assembly diagram of the eight-way switch filter group is shown in the figure. Figure 3 As shown in the figure, the module only contains surface-mount components and pin components. When the whole board is assembled in batches, it can support the mature reflow soldering process for assembly, which can significantly reduce the manufacturing cost.

[0029] The present invention adopts high-density printed circuit board layout and wiring technology. A large number of RF lines are completed in the Top layer and the Bottom layer using a coplanar waveguide structure, and a small number of short-distance RF lines are completed in the S1 and S2 layers using a stripline structure. At the same time, S1 and S2 complete the routing of the 5V power supply and control line. The printed circuit board layout is as follows: Figure 5 As shown, the plane size is only 35x38mm.

[0030] The eight-channel switch filter group module is applied to the upper motherboard as shown below: Figure 4As shown in the figure, after the module is installed, the board spacing with the motherboard is 8mm. Use SMP-KK28 to interconnect the module RF coaxial connector with the same type of coaxial connector on the motherboard to transmit RF signals, and use 8mm high aluminum alloy support columns and M2 screws and nuts to lock the module and the motherboard. The RF circuit areas on both sides of the module are electromagnetically shielded by shielding covers, so that the integrated switch filter group has good anti-interference ability. At the same time, other components with a height of less than 5mm can still be installed in the area between the module and the motherboard, which improves the integration of the motherboard.

Claims

1. A low-cost metric-wave switching filter bank integration method, characterized in that: The single board integrates an eight-way SAW filter group, two sets of eight-way RF switch networks, RF coaxial connectors and low-frequency pin headers on both sides to achieve the meter-wave eight-way switch selection and frequency division filtering functions.

2. A low-cost metric-wave switching filter bank integration method according to claim 1, characterized in that: The printed circuit board adopts a 6-layer stacking design, the board uses 3 layers of FR4 CORE, combined with the through-hole process, and the printed circuit board is pressed in one time.

3. A low-cost metric-wave switching filter bank integration method according to claim 1, characterized in that: Only surface mount components and pin components are used, and they are produced through standard reflow soldering process.

4. The method for integrating a low-cost metric-wave switching filter bank according to claim 1, characterized in that: The low-cost Meter-wave switch filter group uses 4-channel standard SMD9171A package SAW filters and 4-channel standard SMD0505B package SAW filters.

5. The method for integrating a low-cost metric-wave switching filter bank according to claim 1, characterized in that: The low-cost switch filter group of meter wave uses 6 miniaturized QFN packaged four-switch to build a 2-way eight-switch network, with a total of 6 bits of control.

6. A low-cost metric-wave switching filter bank integration method according to claim 1, characterized in that: The front and back RF circuit areas of the low-cost meter-wave switch filter group are shielded with a 3mm high metal shielding cover.

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