Test tool for band-pass filter

Abstract

The utility model discloses a band-pass filter testing tool, which comprises two radio frequency probes, a radio frequency connector, a door-shaped frame I, a door-shaped frame II and a base, and is characterized in that the base comprises a bottom plate, a middle vertical plate and a right end vertical plate, the middle vertical plate and the right end vertical plate are respectively and fixedly connected to the middle part and the right end of the bottom plate, and the middle vertical plate and the right end vertical plate are of door-shaped structures; the four corners of the first door-shaped frame and the four corners of the second door-shaped frame are movably arranged on the four guide columns in a sleeving mode, the four guide columns on the right side section of the second door-shaped frame are all connected with compression springs in a sleeving mode, and the compression springs can make the first door-shaped frame attached to the second door-shaped frame. The two radio frequency probes are fixedly connected to the tops of the first door-shaped frame and the second door-shaped frame respectively and are electrically connected with the two radio frequency connectors respectively, the two radio frequency connectors are fixedly connected to the bottoms of top cross beams of the first door-shaped frame and the second door-shaped frame respectively, and the two radio frequency probes can be clamped into the input ends and the output ends of arc-shaped U-shaped grooves in the two ends of the band-pass filter. According to the utility model, the pad is prevented from being damaged by secondary welding at a client.

Description

Technical Field

[0001] The utility model relates to a test tooling for a band-pass filter, belonging to the technical field of band-pass filters. Background Art

[0002] As Figure 7-8 The shown band-pass filter includes a housing, a coil encapsulated in the housing, and pins arranged at the bottom of the housing. The pins include left and right radio frequency input and output and a large-area ground at the bottom. The main technical indicators are: insertion loss ≤ 4.5 dB; rectangularity coefficient K60 / K3 ≤ 3.5; 3 dB bandwidth: 20 MHz ± 1.5 MHz.

[0003] The existing band-pass filters are designed with the same size and the same indicators, and have a relatively complex topological structure, great debugging difficulty, low reliability and low efficiency. To address this problem, a band-pass filter prepared by a new preparation method overcomes this problem. However, in the test performance, when the input and output ends of the band-pass filter are connected by welding for testing, the pads are easily damaged. Summary of the Invention

[0004] The technical problem to be solved by the utility model is: a test tooling for a band-pass filter to solve the problems existing in the above-mentioned prior art.

[0005] The technical solution adopted by the utility model is: a test tooling for a band-pass filter, including two radio frequency probes, radio frequency connectors, a first U-shaped frame, a second U-shaped frame and a base. The base is a horizontal F-shaped structure, that is, it includes a bottom plate, a middle vertical plate and a right vertical plate respectively fixedly connected to the middle and the right end of the bottom plate. The middle vertical plate and the right vertical plate are U-shaped structures, and four guiding columns are fixedly connected to the four corners. The four corners of the first U-shaped frame and the second U-shaped frame are movably sleeved on the four guiding columns, and compression springs are sleeved on the four guiding columns on the right side section of the second U-shaped frame. The compression springs can make the first U-shaped frame and the second U-shaped frame fit together. The two radio frequency probes are respectively fixedly connected to the tops of the first U-shaped frame and the second U-shaped frame and are respectively kept in electrical connection with the two radio frequency connectors. The two radio frequency connectors are respectively fixedly connected to the bottoms of the top crossbeams of the first U-shaped frame and the second U-shaped frame. The two radio frequency probes can be clamped into the input end and the output end of the arc-shaped U-shaped grooves at both ends of the band-pass filter.

[0006] Further, the first U-shaped frame and the second U-shaped frame are made of copper material and are grounded in a large area. The two radio frequency connectors are respectively connected with an input cable and an output cable.

[0007] Further, a groove is arranged on the left side of the base.

[0008] Further, the input cable and the output cable are connected to a network analyzer.

[0009] Furthermore, both ends of each of the above-mentioned guide posts are fixedly connected to the middle vertical plate and the right-end vertical plate by two locking screws.

[0010] Furthermore, metal sleeves are provided at the places where the screws pass through the middle vertical plate and the right-end vertical plate.

[0011] The beneficial effects of the present utility model: Compared with the prior art, the present utility model adopts this test tooling. During the debugging and testing process of the band-pass filter, there is no need to weld the product pins, avoiding secondary welding at the client side. The door-shaped frame structure facilitates wiring and avoids interference with each other. The U-shaped groove directly snaps onto the probe. Under the action of the spring, the clamping is stable and reliable, easy to install and disassemble, and the test data is stable and accurate. Description of the Drawings

[0012] Figure 1 is a schematic top-layer layout diagram of the PCB circuit board;

[0013] Figure 2 is a schematic bottom-layer layout diagram of the PCB circuit board;

[0014] Figure 3 is a schematic layout diagram of the surface-mounted components on the PCB circuit board;

[0015] Figure 4 is a schematic layout diagram of the inductors on the PCB circuit board;

[0016] Figure 5 is a schematic structural diagram of the test tooling for the band-pass filter;

[0017] Figure 6 is a schematic left-view structural diagram of the test tooling;

[0018] Figure 7 is a schematic three-dimensional structural diagram of the band-pass filter;

[0019] Figure 8 is a schematic bottom-view structural diagram of the band-pass filter;

[0020] Figure 9 is a schematic circuit diagram of the band-pass filter. Detailed Embodiments

[0021] The present utility model will be further introduced below in conjunction with the drawings and specific embodiments.

[0022] Embodiment 1: As Figure 5-6As shown in the figure, a test fixture for a band-pass filter includes two RF probes 201, RF connectors 202, a first portal frame 203, a second portal frame 204, and a base 205. The base 205 is a horizontal F-shaped structure, that is, it includes a bottom plate and a middle vertical plate 206 and a right-end vertical plate 207 fixedly connected to the middle and the right end of the bottom plate respectively. The middle vertical plate 206 and the right-end vertical plate 207 are in a portal shape, and four guide posts 208 are fixedly connected to the four corners. The first portal frame 203 and the second portal frame 204 are movably sleeved on the four guide posts 208 at the four corners, and compression springs 209 are sleeved on the four guide posts 208 on the right-side section of the second portal frame 204. The compression springs 209 can make the first portal frame 203 and the second portal frame 204 fit together. The two RF probes 201 are respectively fixedly connected to the tops of the first portal frame 203 and the second portal frame 204 and are respectively kept in electrical connection with the two RF connectors 202. The two RF connectors 202 are respectively fixedly connected to the bottoms of the top crossbeams of the first portal frame 203 and the second portal frame 204 by screws. The input end and the output end of the arc-shaped U-shaped grooves at both ends of the band-pass filter can be clamped onto the two RF probes 201. The first portal frame 203 and the second portal frame 204 are made of copper material and are grounded over a large area. The two RF connectors are respectively connected with an input cable 210 and an output cable 211. The two left-right arranged RF probes can firmly clamp the band-pass filter through the elastic force of the compression springs. The grounded part at the bottom of the band-pass filter is closely attached to the grounded first portal frame 203 and the second portal frame 204. The input RF pins and the output RF pins of the band-pass filter are connected to a network analyzer through the RF probes, the input cable, and the output cable for index testing. A groove 214 is provided on the left side of the base 205 to facilitate placing the detection device.

[0023] Using this test fixture, there is no need to weld the product pins during the debugging and testing process of the band-pass filter, avoiding secondary welding at the client side.

[0024] Both ends of each guide post 208 are fixedly connected to the middle vertical plate 206 and the right-end vertical plate 207 by two locking screws 212, and the connection is stable and reliable. Metal sleeves 213 are provided at the places where the screws pass through the middle vertical plate 206 and the right-end vertical plate 207, which can improve the support stability.

[0025] Principle of using the test fixture:

[0026] 1. Connect two RF cables to the two RF connectors, and the RF connectors are respectively connected to the "RFin" and "RFout" of the two first portal frames 203 and the second portal frame.

[0027] 2. Separate the door frame 1 (203) and the door frame 2, align the RF input and output terminals of the band-pass filter under test with the two RF probes of the test fixture, clamp the band-pass filter with the test fixture, and make the grounding terminal at the bottom of the band-pass filter closely fit with the grounded door frame 1 (203) and the door frame 2 (204).

[0028] 3. Connect the "RFin" RF cable to the output port of the network analyzer, and connect the "RFout" RF cable to the input port of the network analyzer for measurement to test the center insertion loss, 3dB bandwidth, rectangularity factor, and voltage standing wave ratio of the band-pass filter.

[0029] Embodiment 2: As Figure 1-9 shown, a circuit structure of a band-pass filter with a center frequency of 275 MHz and a low rectangularity factor includes a capacitor C1, a capacitor C2, an inductor L1, an inductor L2, an inductor L3, an inductor L4, an inductor L5, and an inductor L6. The capacitor C1, the inductor L1, the inductor L2, the inductor L4, the inductor L5, and the capacitor C2 are connected in series in sequence. The other ends of the capacitor C1 and the capacitor C2 are grounded. One end of the inductor L3 is connected to the series connection end between the inductor L1 and the inductor L2, and the other end of the inductor L3 is connected to the input end. One end of the inductor L6 is connected to the series connection end between the inductor L4 and the inductor L5, and the other end of the inductor L6 is connected to the output end. One series connection end of the inductor L2 and the inductor L4 is grounded. The layout of the filter in the PCB circuit board adopts left-right symmetry. The inductor L3 and the inductor L6 are wound by stacking 3 magnetic rings.

[0030] The circuit structure is arranged on a PCB circuit board 1. A metal shell 2 is covered on the PCB circuit board 1. Four inserts 3 are arranged at the bottom of the metal shell. The lower ends of the inserts 3 pass through the rectangular holes 4 on the PCB circuit board 1 and then are bent to fit on the bottom of the PCB circuit board 1, and the metal shell is only locked on the PCB circuit board 1. The whole product is welded to the circuit board through the metal shell, with a simple and compact appearance, having a certain anti-interference ability, and the metal shell is convenient for marking and printing. The middle parts of both ends of the PCB circuit board 1 are respectively set as the input end 5 and the output end 6, and the input end 5 and the output end 6 are of U-shaped slot structure.

[0031] Embodiment 3: As Figure 1-9 shown, a preparation method of a band-pass filter with a center frequency of 275 MHz and a low rectangularity factor, the method includes the following steps:

[0032] Step 1. PCB circuit board layout: The PCB circuit board has two layers. The bottom layer of the PCB circuit board is grounded with a large area (as Figure 1 ), and on the top layer, the space outside the component pads and traces is all covered with ground (as Figure 2) By means of a large number of grounding vias, the grounding effect is enhanced. In the PCB circuit board, the filter is laid out symmetrically left and right, so that the parasitic capacitance and inductance generated by the left and right pads are equal, which is convenient for the later production of the product; the RF input and output pins of the product are made symmetrical and consistent to ensure the correct transmission and reception of RF signals.

[0033] Step 2. The manufacturing method includes the following steps:

[0034] 2.1) After preparing the chip capacitors, perform chip mounting according to the circuit diagram of the band-pass filter ( Figure 3 ) using lead-free solder paste S-SnAg 3.0 Cu 0.5 to obtain a semi-finished chip-mounted product through SMT machine chip mounting and reflow soldering;

[0035] 2.2) Prepare the corresponding inductors according to the parameter table in Table 1;

[0036]

[0037] 2.3) Use lead-free solder paste S-SnAg 3.0 Cu 0.5 and solder the inductors to the corresponding positions on the PCB circuit board according to the pad diagram with a 0.5 mm pitch;

[0038] 2.4) Assemble the semi-finished assembled product onto the test fixture, debug the filter inductor to achieve the optimal performance, and then fix it with Nanda 704 silicone;

[0039] 2.5) Use a metal shell and lead-free solder paste S-SnAg 3.0 Cu 0.5 with a 0.5 mm pitch to cover it; 2.6) After covering, conduct tests and electrical performance index tests to form a data report, and then clean, externally inspect, and package the product to form a finished product.

[0040] The prepared band-pass filter has the following advantages:

[0041] 1) Adopting a new topological circuit structure, the number of capacitors and inductors is reduced, which is convenient for debugging, reduces costs at the same time, and the product size is small, being 20×10×5 (±0.2) mm. By optimizing the circuit parameters, the number of inductors is reduced, making it smaller than the conventional 25×15×5 (±0.2) mm;

[0042] 2) There are only 6 inductors, greatly reducing the debugging and layout difficulties;

[0043] 3) Inductors L3 and L6 are wound by stacking 3 magnetic rings, increasing the inductance under the same number of turns;

[0044] 4) The layout of the filter in the PCB circuit board is symmetric left and right, making the parasitic capacitance and inductance generated by the left and right pads equal, which is convenient for the later production of the product; the RF input and output pins of the product are made symmetric and consistent to ensure the correct transmission and reception of RF signals.

[0045] 5) The circuit structure adopts a symmetric left-right design, which can make the input-output matching better and is convenient for debugging.

[0046] Table 2 Circuit performance parameters

[0047] Theoretical frequency Measured frequency Center insertion loss 3dB bandwidth Rectangular coefficient Voltage Standing Wave Ratio (VSWR) (MHz) (MHz) ≤4.5dB 20.5±1MHz K60 / 3≤3 @275MHz±8MHz≤1.5 275 275.10 4.32 20.63 2.89 1.37

[0048] When a conventional band-pass filter cannot meet the requirements that the insertion loss is less than or equal to 4.5 dB and the rectangularity coefficient K60 / K3 ≤ 3.5 under the same size, a new topology structure is adopted for the realization of the filter to reduce the number of capacitors and inductors, which is convenient for debugging and reduces costs at the same time.

[0049] A preparation method of a band-pass filter with a center frequency of 275 MHz and a low rectangularity coefficient is provided. The main inductance coil is wound with 3.5 turn diameter and 0.5 mm enameled wire. During assembly, the middle position of the main coil is grounded, making the coil speed smaller than that of the conventional one, and the volume is also greatly reduced. The Q value is higher than that of the conventional inductor, which has great advantages in small package band-pass filters, can reduce the loss of the band-pass filter, and at the same time greatly reduce the influence of the cover on the performance indicators of the band-pass filter.

[0050] Among them, for the test of this band-pass filter, as Figure 5-6The shown test tooling includes two RF probes 201, RF connectors 202, a first U-shaped frame 203, a second U-shaped frame 204 and a base 205. The base 205 is a horizontal F-shaped structure, that is, it includes a bottom plate and a middle vertical plate 206 and a right-end vertical plate 207 fixedly connected to the middle and the right end of the bottom plate respectively. The middle vertical plate 206 and the right-end vertical plate 207 are U-shaped structures, and four guide posts 208 are fixedly connected at the four corners. The four corners of the first U-shaped frame 203 and the second U-shaped frame 204 are movably sleeved on the four guide posts 208, and compression springs 209 are sleeved on the four guide posts 208 on the right-side section of the second U-shaped frame 204. The compression springs 209 can make the first U-shaped frame 203 and the second U-shaped frame 204 fit together. The two RF probes 201 are respectively fixedly connected to the tops of the first U-shaped frame 203 and the second U-shaped frame 204 and are respectively kept in electrical connection with the two RF connectors 202. The two RF connectors 202 are respectively fixedly connected to the bottoms of the top crossbeams of the first U-shaped frame 203 and the second U-shaped frame 204 through screws. The input end and the output end of the arc-shaped U-shaped grooves at both ends of the band-pass filter can be clamped on the two RF probes 201. The first U-shaped frame 203 and the second U-shaped frame 204 are made of copper material and are grounded over a large area. The two RF connectors are respectively connected with an input cable 210 and an output cable 211. The two left-right arranged RF probes can firmly clamp the band-pass filter through the elastic force of the compression springs. The grounded part at the bottom of the band-pass filter is closely attached to the grounded first U-shaped frame 203 and the second U-shaped frame 204. The input RF pins and the output RF pins of the band-pass filter are connected to a network analyzer through the RF probes and the input cable and the output cable for index testing. A groove 214 is arranged on the left side of the base 205 to facilitate placing the detection device.

[0051] With this test tooling, there is no need to weld the product pins during the debugging and testing of the band-pass filter, avoiding secondary soldering at the client side.

[0052] Both ends of each guide post 208 are fixedly connected to the middle vertical plate 206 and the right-end vertical plate 207 through two locking screws 212, and the connection is stable and reliable. Metal sleeves 213 are arranged at the places where the screws pass through the middle vertical plate 206 and the right-end vertical plate 207, which can improve the support stability.

[0053] Principle of using the test tooling:

[0054] 1. Connect two RF cables to the two RF connectors, and the RF connectors are respectively connected to the "RFin" and "RFout" of the two first U-shaped frames 203 and the second U-shaped frames;

[0055] 2. Separate the first U-shaped frame 203 and the second U-shaped frame, align the RF input end and the RF output end of the measured band-pass filter with the two RF probes of the test tooling, clamp the band-pass filter with the test tooling and make the grounded end at the bottom of the band-pass filter closely attached to the grounded first U-shaped frame 203 and the second U-shaped frame 204;

[0056] 3. Connect the "RFin" RF cable to the output port of the network analyzer, and connect the "RFout" RF cable to the input port of the network analyzer for measurement to test the center insertion loss, 3dB bandwidth, rectangularity factor, and voltage standing wave ratio of the band-pass filter.

[0057] As described above, it is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily think of changes or substitutions, which should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope of the claims.

Claims

1. A test tooling for a band-pass filter, characterized in that: It includes two RF probes, RF connectors, a first U-shaped frame, a second U-shaped frame and a base. The base is a horizontal F-shaped structure, that is, it includes a bottom plate, a middle vertical plate and a right-end vertical plate which are respectively fixedly connected to the middle and the right end of the bottom plate. The middle vertical plate and the right-end vertical plate are U-shaped structures, and four guide posts are fixedly connected to the four corners. The first U-shaped frame and the second U-shaped frame are movably sleeved on the four guide posts at the four corners, and compression springs are sleeved on the four guide posts on the right-side section of the second U-shaped frame. The compression springs can make the first U-shaped frame and the second U-shaped frame fit together. The two RF probes are respectively fixedly connected to the tops of the first U-shaped frame and the second U-shaped frame and are respectively kept electrically connected to the two RF connectors. The two RF connectors are respectively fixedly connected to the bottoms of the top cross beams of the first U-shaped frame and the second U-shaped frame. The two RF probes can be inserted into the input end and the output end of the arc-shaped U-shaped grooves at both ends of the band-pass filter.

2. The test tooling for a band-pass filter according to claim 1, characterized in that: The first U-shaped frame and the second U-shaped frame are made of copper material and are grounded over a large area. The two RF connectors are respectively connected with an input cable and an output cable.

3. The test tooling for a band-pass filter according to claim 1, characterized in that: A groove is provided on the left side of the base.

4. The test tooling for a band-pass filter according to claim 2, characterized in that: The input cable and the output cable are connected to a network analyzer.

5. The test tooling for a band-pass filter according to claim 1, characterized in that: Both ends of each guide post are fixedly connected to the middle vertical plate and the right-end vertical plate through two locking screws.

6. The test tooling for a band-pass filter according to claim 5, characterized in that: Metal sleeves are provided at the places where the middle vertical plate and the right-end vertical plate are penetrated by screws.

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