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CN-224205064-U - Broadband impedance matching filtering high-pass circuit based on 75 ohm system

CN224205064UCN 224205064 UCN224205064 UCN 224205064UCN-224205064-U

Abstract

The utility model provides a broadband impedance matching filtering high-pass circuit based on a 75 ohm system, which comprises a PCB and a microstrip line, wherein the microstrip line is a strip-shaped wiring buried in the PCB, a snake-shaped matching inductor and a fan-shaped matching capacitor are combined, the snake-shaped matching inductor provides high-frequency inductance compensation, the fan-shaped matching capacitor realizes capacitance matching and adapts to different connector interfaces, the first snake-shaped resonance inductor, the second snake-shaped resonance inductor and a total parameter capacitor form a mixed parameter resonance branch, the bandwidth is widened, the bandwidth can reach 0-4.5GHZ, the bandwidth is increased by 2GHZ compared with the bandwidth of a filter commonly used in the existing system, the bandwidth is increased by 1 time, the common resonance capacitor and the common resonance inductor are combined to form a lumped parameter resonance branch, out-of-band noise is restrained, the volume is reduced, the return loss is more than 15dB, the requirement is improved by 50% compared with the existing filter, the structure can be applied to radar and television systems, the traditional circuit bandwidth is limited, the matching flexibility is poor, and the broadband matching circuit has high power.

Inventors

  • LI HANBIN
  • GAO BIN

Assignees

  • 苏州艾福电子通讯股份有限公司

Dates

Publication Date
20260505
Application Date
20250425

Claims (7)

  1. 1. The utility model provides a broadband impedance match filtering high-pass circuit based on 75 ohm system, includes PCB board (2) and microstrip line, the microstrip line is buried in the inside banded line of PCB board (2), one end of microstrip line is input (5-2), and the other end is output (5-1), is used for accepting signal input and output, and characterized in that, the input (5-2) department that is close to the microstrip line connects first adjustable impedance matching network, first adjustable impedance matching network comprises first fan-shaped matching capacitor (4-2) and first serpentine matching inductor (6-2) parallelly connected, and output (5-1) department that is close to the microstrip line connects second adjustable impedance matching network, second adjustable impedance matching network comprises second fan-shaped matching capacitor (4-1) and second serpentine matching inductor (6-1) parallelly connected, through first adjustable impedance matching network and second adjustable impedance matching network, and the resonance parameter that realizes between resonance impedance matching circuit and the ordinary resonant frequency of resonance circuit and ordinary resonance parameter (8) are satisfied by adjusting fan-shaped matching capacitor (4-1) and second serpentine matching inductor (6-1) and second serpentine matching inductor (8).
  2. 2. The broadband impedance matching filtering high-pass circuit based on the 75 ohm system as set forth in claim 1, wherein the common resonance capacitor (8) is a debugging capacitor, and the debugging capacitor is a high-precision high-Q capacitor, so that the requirement that the return loss is more than 15dB can be met.
  3. 3. The broadband impedance matching filtering high-pass circuit based on the 75 ohm system according to claim 1, wherein a first snake-shaped resonant inductor (7-2) is connected between the first adjustable impedance matching network and the total parameter resonant circuit, a second snake-shaped resonant inductor (7-1) is connected between the second adjustable impedance matching network and the total parameter resonant circuit, and the first snake-shaped resonant inductor (7-2), the second snake-shaped resonant inductor (7-1) and the total parameter capacitor form a mixed parameter resonant branch.
  4. 4. The broadband impedance matching filtering high-pass circuit based on the 75 ohm system according to claim 1, wherein a coupling capacitor (3) is arranged between the first adjustable impedance matching network, the first serpentine resonant inductor (7-2), the common resonant capacitor (8), the common resonant inductor (9), the second serpentine resonant inductor (7-1) and the second adjustable impedance matching network, and the coupling capacitor (3) is connected with the microstrip line.
  5. 5. The broadband impedance matching filter high-pass circuit based on a 75 ohm system according to claim 4, wherein said coupling capacitor (3) is adjacent to the edge of the microstrip line and forms an angle of 45 degrees with the microstrip line.
  6. 6. The broadband impedance matching filtering high-pass circuit based on the 75 ohm system according to claim 1, wherein the PCB (2) adopts a reverse polarity symmetrical structure, and the PCB (2) adopts a reverse polarity symmetrical structure, wherein the input end (5-2) and the output end (5-1) are in mirror symmetry with a central axis, the second fan-shaped matching capacitor (4-1) is in mirror symmetry with the first fan-shaped matching capacitor (4-2) with the central axis, the second snake-shaped matching inductor (6-1) is in mirror symmetry with the first snake-shaped matching inductor (6-2) with the central axis, the second snake-shaped resonant inductor (7-1) is in mirror symmetry with the first snake-shaped resonant inductor (7-2) with the central axis, and the common resonant capacitor (8) is in mirror symmetry with the common resonant inductor (9) with the central axis.
  7. 7. The broadband impedance matching filtering high-pass circuit based on the 75 ohm system as set forth in claim 1, wherein the PCB (2) is fixed to the metal shielding cavity through a screw (1).

Description

Broadband impedance matching filtering high-pass circuit based on 75 ohm system Technical Field The utility model relates to the technical field of electricity, in particular to a broadband impedance matching filtering high-pass circuit based on a 75 ohm system. Background The existing 75 ohm system filter is mainly divided into two types, namely an LTCC filter integrated type and a PCB microstrip filter type, wherein the LTCC filter is used for realizing filtering through a laminated circuit, input and output are directly matched with 75 ohms, but the problems are that the bandwidth is narrow, the return loss is only 500MHz, the return loss is less than 8dB, the out-of-band rejection capability is weak, the consistency is poor, the frequency band of the PCB microstrip filter is slightly wider than 0-2.5GHz, the size is large, the impedance matching is fixed, the suitability is poor, and the PCB microstrip filter cannot be compatible with various radio frequency connectors such as F type and N type. The prior patent number is CN108832907A, the broadband impedance matching network of the data transmission station and the design method thereof are disclosed, wherein the matching network comprises a first resonant circuit, the first resonant circuit comprises a first inductor and a first capacitor, the first inductor and the first capacitor are connected in parallel or connected between a device to be matched and a terminal after being connected in parallel, the method comprises the steps of obtaining a first impedance track of a first reflection coefficient of the device to be matched on a Smith chart, and designing the broadband impedance matching network of the data transmission station, which can enable the first impedance track to curl or twist, according to the position relation between the first impedance track and a preset return loss circle, wherein the matching network comprises a first resonant circuit formed by the first inductor and the first capacitor, and when impedance matching of the device to be matched is carried out, the first inductor and the first capacitor are connected between the device to be matched and the terminal after being connected in parallel, so that the impedance matching bandwidth of the device to be matched can be enlarged only through the matching network and the design method thereof. The broadband requirement is still not met, as there is insufficient suppression of spurious signals, such as television system spurious signals. Disclosure of utility model Therefore, the utility model provides a 75 ohm impedance matching high-pass filter circuit which meets the requirements of broadband 0-4.5GHz and has high return loss, realizes miniaturization and high integration, is suitable for various radio frequency connectors such as F type and N type, and improves out-of-band rejection capability such as rejection of more than or equal to 50dB at 340 MHz. A broadband impedance matching filtering high-pass circuit based on a 75 ohm system comprises a PCB 2 and a microstrip line, wherein the microstrip line is a strip-shaped wiring buried in the PCB 2, one end of the microstrip line is an input end 5-2, the other end is an output end 5-1 and is used for receiving signal input and output, the circuit is characterized in that a first adjustable impedance matching network is connected at the position close to the input end 5-2 of the microstrip line and is composed of a first fan-shaped matching capacitor 4-2 and a first snake-shaped matching inductor 6-2 in parallel, a second adjustable impedance matching network is connected at the position close to the output end 5-1 of the microstrip line and is composed of a second fan-shaped matching capacitor 4-1 and a second snake-shaped matching inductor 6-1 in parallel, through the first adjustable impedance matching network and the second adjustable impedance matching network, capacitive reactance and inductive reactance compensation can be realized by adjusting the capacitive inductance values of the second fan-shaped matching capacitor 4-1 and the second serpentine matching inductor 6-1, matching of various radio frequency connector interfaces can be met, a lumped parameter resonant circuit is connected between the first adjustable impedance matching network and the second adjustable impedance matching network and consists of a common resonant capacitor 8 and a common resonant inductor 9, out-of-band suppression is effectively increased, effective suppression reaches 50Db at 340MHZ, better effects on television system spurs are achieved, various television systems can be widely used, and the first disadvantage is effectively solved. Furthermore, the common resonance capacitor 8 adopts a debugging capacitor, the debugging capacitor is a high-precision high-Q value capacitor, the requirement that the return loss is more than 15dB can be met, and the return index of the current broadband filter is improved. Further, a first snake-shaped reson