A lowpass filter with an embedded capacitor for wideband noise suppression in Multi-GHz PCBs

This paper presents a novel lowpass filter with an embedded capacitor which can substitute conventional filter network and suppress switching noise with a large bandwidth in Multi-GHz PCBs. A new design methodology of the low pass filter network is proposed. A new SPICE model of embedded capacitor based on transmission line theory is built and a comparison between H-spice and GTLE is used to illuminate its validity. With the model and finite elements method, the feature of the embedded capacitor, in which different frequency modes were excited by special exciting positions, was studied and the design procedure of an ECF was developed. As an application example, a typical power supply filter network and its replacement, an embedded capacitor with a 100 uF SMD capacitor, were studied.