Classification and characteristics of through-core capacitor filters
The feedthrough capacitor filter is a three-terminal capacitor, but compared with the ordinary three-terminal capacitor, because it is directly mounted on the metal panel, its grounding inductance is smaller and there is almost no effect of the lead inductance. The input and output are separated by a metal plate, which eliminates high-frequency coupling. These two characteristics determine that the feedthrough capacitor has a filtering effect close to the ideal capacitor.
The internal circuit form of the filter is divided into many types. The combination of ferrite beads and capacitors according to different circuit structures can form filter circuits such as C, LC, Pi, and T. These circuits provide different filtering characteristics. The more filters there are, the shorter the transition band between the passband and the stopband, and the greater the insertion loss. Let us understand the characteristics and applications of these types.
Type C filter, single capacitor structure. It is a low self-inductive device that avoids high frequency ground noise interference. It is suitable for signal line filtering and DC power line filtering. It is suitable for high impedance sources and high loads.
LC filter, this is an EMI filter with inductive and capacitive elements. Different installation methods (directions) can be used in situations where the source impedance is high and the load impedance is low, or the source impedance is low and the load impedance is high.
The Pi-type filter is composed of two capacitive elements and an inductive element between the two capacitive elements. Compared to C-type, LC-type structure provides better high-frequency filtering performance. It is suitable for occasions with high source impedance and load impedance, and high requirements on interference suppression performance (insertion loss).
The T-type filter consists of two inductive elements and one capacitive element. It is similar to the Pi-type filter structure, but it is not widely used without the Pi-type filter. It is suitable for occasions with low source impedance and load impedance and high interference suppression performance (insertion loss).
Enjoy my work?
Don't forget to support and like, so I can know your companionship.