Design and Modelling of Miniaturized Bandgap Structure for Wideband GHz-Noise Suppression Based on LTCC Technology

A novel electromagnetic bandgap (EBG) structure is proposed for broadband suppression of gigahertz simultaneous switching noise. The structure is composed of three-dimensional interdigital capacitors (3D-IDC) and series U-shaped transmission lines periodically. The EBG structure can be miniaturized based on the LTCC fabrication technology. A theoretical circuit model which considers the inductive coupling in the 3D-IDC will be developed to predict the stopband. The accuracy of the proposed model will be verified by comparing with both the full-wave simulation and the measurement results. This modeling method is also employed to study the variation of bandgap dependent on different geometrical parameters for the 3D-IDC and the U-shaped transmission line. A prototype is implemented using the LTCC technology with the dimension 1.2 mm × 3.8 mm × 0.728 mm. Both simulation and measurement show the rejection band is from 2 to 5.5 GHz. Over 45 dB noise reduction in the stop band could be achieved. In addition, the suppressive ability is also verified in the chip-package co-simulation. From the simulation result, significant reduction of power noise could be found both in digital and mixed signal circuits.