Electromagnetic Interference Suppression Technology for Miniaturized Microwave Cavities Based on Noise Suppression Sheet(NSS)

The three-dimensional (3-D) integration of high-density radio frequency (RF) front-end components inevitably introduce serious electromagnetic interference (EMI) between device-device, antenna-antenna, and antenna-device. In this paper, the noise suppression sheet (NSS) is quantitatively studied as an effective method to suppress EMI between RF devices in miniaturized packaging cavities. Taking the case when the NSS is loaded in a parallel-plate waveguide (PPW) as a benchmark of the NSS applied in the packages, the dispersion curve of the NSS-loaded structure is analyzed, from which it is demonstrated that the imaginary part of the NSS’s permeability determines the attenuation and reflection amplitude of the EMI. Then, two typical NSS application examples are proposed, i.e., the EMI suppression in the heatsink package above the chip, and the EMI suppression in the flexible circuit. The measured and simulated results indicate that the electrically small NSS with < 0.1λ transverse length can reduce the EMI with a significant magnitude, i.e., > 10 dB. This work provides an important reference for a wide range of industrial applications, such as EMI suppression in packages of chip modules, multi-channel RF systems, flexible electronics, and antenna arrays.