Wideband Compartment Shielding Technique for Miniaturized Packages Based on Electrically Small Single-Negative Meta-Diaphragm

This article focuses on realizing wideband compartment shielding in the shielding can packages of miniaturized high-speed chip modules and circuits. Because the conventional diaphragms with a low profile are difficult to cope with the high-order mode interference and evanescent wave interference, a new “meta-diaphragm,” which is based on the single-negative (SNG) metamaterial, is proposed to address these inherent problems. It is demonstrated that benefitting from the large propagation attenuation introduced by the proposed meta-diaphragm, a good shielding performance can be achieved at the first higher order resonance mode. Moreover, by elaborately embedding resistors in the meta-diaphragm, the additional interferences at other resonance frequencies can be significantly suppressed. Furthermore, the structure of the meta-diaphragm is optimized with two approaches: evolving from the single-band SNG structure to the double-band one and integrating with the parasitic patches. The two approaches enable its independent controlling ability at different frequency ranges and enhancement of low-frequency shielding performance. Based on the proposed technique, an experiment is implemented to suppress the resonance-dominated interference between the passive traces in a shielding can. The result agrees well with those from theoretical prediction. The final experimental shielding can’s profile and width are 5 and 20 mm, respectively; the meta-diaphragm’s profile is only 1.5 mm, i.e., < 1/3 of shielding can’s profile, and its electrically length is only 3 mm, i.e., $0.1\lambda _{0}$ at 10 GHz, and the measured (simulated) meta-diaphragm can significantly suppress radio frequency interference (RFI) within 10.2–17 GHz (10–16.9 GHz) and realize $< -33.5$ dB ( $< -40$ dB) coupling within 100 kHz–18 GHz (dc-to-20 GHz). The miniaturized dimension and wideband results indicate that our proposed technique could meet the compartment shielding requirement of a series of miniaturized packages in the practical radio frequency (RF) chip modules and circuits.