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What is Called Feedthrough Capacitor Filter ?
Date: 2023-05-15    View: 368

With the rapid increase of the working frequency of electronic equipment, the frequency of electromagnetic interference is getting higher and higher. The interference frequency usually reaches hundreds of MHz, or even more than GHz. The higher the frequency of voltage or current, the more likely it is to produce radiation. Therefore, it is these very high frequency interference signals that cause the problem of radiation interference to become increasingly serious. Therefore, a basic requirement for the filter used to solve radiation interference is to be able to attenuate these high-frequency interference signals. This filter is the radio frequency interference filter, also known as EMI/EMC filter. We also call it the feethrough capacitor filter for short according to its physical structure characteristics.

The effective filtering frequency range of the common RF interference filter is several kHz tens of MHz, while the effective filtering frequency range of the RF interference filter is from several kHz to more than GHz. Filters constructed in the traditional way cannot be used as RF filters. This is due to two reasons: the first reason is that the parasitic inductance of the traditional capacitor is large (resulting in series resonance, increasing the bypass impedance), resulting in a capacitor at a higher frequency does not have a lower impedance, can not play the role of the bypass. The second reason is that the stray capacitance between the input and output of the filter leads to the coupling of high-frequency interference signals, making the filter lose its effect on high-frequency interference. The way to solve this problem is to use the feethrough capacitor as the bypass capacitor.

The feethrough capacitor is a three-terminal capacitor, with a very small parasitic inductance, the bypass impedance is very small, and because the feethrough capacitor can be directly installed on the metal panel, so its ground inductance is smaller, almost no lead inductance influence, so the self-resonant frequency is very high. At the same time, because of the through-core design and the input and output ends are isolated by metal plates, the high-frequency signal is effectively prevented from directly coupling from the input end to the output end. This combination of low pass and high resistance, in the 1GHz frequency range, provides excellent inhibition. These two characteristics determine that the feethrough capacitor has the filtering effect close to the ideal capacitor, that is, the feethrough capacitor/RF interference filter is the ideal device for interference/anti-interference filtering.

After years of research and development and improvement of the production process, Kete Microwave Electronics company's R&D personnel further improve the density and air tightness of the product, further improve the voltage resistance and reliability of the product, so that the product has a wider range of applications, from the initial application in the TV high frequency head, gradually expanded to mobile phone repeater station, instrument, satellite antenna, medical equipment. Recently, due to the rise of the Internet of Things and intelligent AI industry, our products have expanded to automotive electronics, aerospace, military products and other fields.


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