Passive intermodulation circuit interference suppression design method

Abstract

The invention discloses a passive intermodulation circuit interference suppression design method, and belongs to the technical field of circuit design. The method comprises the following steps: firstly, taking an N-type radio frequency coaxial connector as a non-linear source for generating passive intermodulation, and establishing a non-linear equivalent circuit model; performing harmonic balancesimulation on the circuit system, so that third-order and fifth-order harmonic power values of the connector under required frequency bands and required power can be obtained; transmitting active compensation signals with different frequencies and different powers and useful signals to an equivalent nonlinear circuit together, simulating spectrum distribution in the reflection signals and the transmission signals, and obtaining a system intermodulation interference suppression result based on the active compensation signals; besides, designing a passive nonlinear structure and an intermodulation feedback network, and observing changes of forward and reverse intermodulation signals under the condition that extra power is not introduced; and finally, selecting a scheme with an optimal inhibition effect. The method is simple and easy to implement, and a scheme with higher economic benefit 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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