Graphene-based EMI shielding for vertical noise coupling reduction in 3D mixed-signal system

Vertical noise coupling caused by the near-field coupling between the RF/analog IC and logic IC is a severe problem in 3D mixed-signal systems. To reduce the vertical noise coupling, graphene is an appropriate material due to its inherent characteristics such as very low thickness, high flexibility, high mechanical strength, and EMI absorbing characteristic. Especially, the EMI absorbing characteristic is an important property as the shield to prevent the vertical noise coupling, as it reduces the re-coupling of the reflected EMI by the shield into other ICs. We measure the reduction of the vertical noise coupling by the mono-layer graphene shield in the 3D mixed-signal system composed of a low noise amplifier (LNA), an on-chip switching model DC-DC converter, and the mono-layer graphene in the frequency and time domain. Through the measurement results, we observed that the mono-layer graphene can maximally reduce the vertical noise coupling by -17 dB in the frequency domain. Additionally, the vertically coupled noise is reduced by 25% in the time domain measurement.