High performance broadband noise filter using inductance cancellation technique and various capacitors

In this paper, the noise attenuation effects of various integrated noise filters by an inductance cancellation technique are compared. The integrated noise filters consist of a capacitor and a coupled magnetic coil. The various integrated filters use 2-terminal capacitor or 3-terminal capacitor as the capacitor. The coupled magnetic coil provides an inductance cancellation effect for the parasitic inductance both of the capacitor and the wires. The attenuation effects of the integrated filters analysed by an electromagnetic field analysis are verified by a measurement of fabricated filters. The shapes of the coupled coils are designed using the electromagnetic field analysis to obtain the highest attenuation effect of the integrated filters up to 1GHz. The attenuation effect of the various integrated noise filters with the coupled coil and that of the two kinds of capacitors without the coupled coil are investigated. The attenuation effect of the integrated filter using the 2-terminal capacitor with the coupled coil is higher than that of the 3-terminal capacitor without the coupled coil, and is compatible with that of the integrated filter using the 3-terminal capacitor with the coupled coil. The integrated filter with a 2-terminal capacitor has advantage in the viewpoint of the inductance cancellation effect compared with a 3-terminal capacitor.