A Design Method for Interference Suppression of Passive Intermodulation Circuit

Abstract

The invention discloses a passive intermodulation circuit interference suppression design method, which belongs to the technical field of circuit design. In this method, the N-type RF coaxial connector is firstly used as the nonlinear source of passive intermodulation to establish a nonlinear equivalent circuit model; The third-order and fifth-order harmonic power values ​​under the power; then the active compensation signals of different frequencies and different powers are transmitted to the equivalent nonlinear circuit together with the useful signal, and the spectrum distribution in the reflected signal and the transmitted signal is simulated. Obtain the system intermodulation interference suppression results based on active compensation signals; in addition, design a passive nonlinear structure and intermodulation feedback network, and observe the changes of forward and reverse intermodulation signals without introducing additional power; finally , choose the scheme with the best suppression effect. The invention is simple and easy to implement, and a scheme with higher economic benefits can be selected to realize a low intermodulation system.

Description

technical field [0001] The invention belongs to the technical field of circuit design, in particular to a passive intermodulation circuit interference suppression design method. Background technique [0002] In high-power transceivers, passive intermodulation (PIM) distortion is generally considered a negative interference effect, especially in multiplexed transceiver applications. Although the intermodulation product (IM) power is much lower than the power of the transmitted signal, it is equivalent to the power of the received signal, which will affect the sensitivity of the receiver. Especially in the case of poor contact, improper use of magnetic materials, poor quality of metal coating, etc., the passive intermodulation phenomenon is very serious and strongly interferes with communication signals. In addition, many connectors are used in the wild, with alternating changes in temperature and humidity, the influence of wind, rain, lightning, and vibration, and the intera...

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Problems solved by technology

These low-PIM designed components reduce PIM interference, but it requires higher material and labor costs

At present, the research work on the nonlinear effect of RF coaxial connectors mainly stays in qualitative analysis, and basically concludes that avoiding the use of magnetic materials, appropriately increasing contact pressure, maintaining a clean contact interface, and protecting the use of connectors, etc. Conclusion, but theoretical research on the principles and methods of designing low intermodulation connectors is still relatively rare, and there is also a lack of support from targeted experimental measurement data

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