Shielding Methods for Gigahertz-Frequency Wideband Analog-Integrated Circuits

Coupling between closely spaced wideband analog radio frequency integrated circuits can cause degradation in device performance. Methods for reducing the coupling between packages were tested, with a strong focus on maintaining manufacturability and minimizing any increase in coupling between structures within the package. Methods include the application of magnetic absorbing material or resistive sheets to the package surface and the inclusion of conductive vias in the package walls. Package modifications were tested from 5–40 GHz through both full-wave simulation and physical measurement. The best tradeoff in performance and manufacturability below 20 GHz was found using 250-Ω/sq. resistive sheets connected to the return plane with vias in the package corners, while above 20 GHz, the best tradeoff was found by covering the package with magnetic absorbing materials. The magnetic absorbing material can be embedded directly in the package polymer itself, allowing easy manufacture.