Signal Integrity Assessment of Interconnects Routed Within Bandgap Metallic Cavities

Abstract

The use of metallic pins covering the lid of a metallic cavity has been shown to effectively suppress the coupling mechanisms based on the cavity resonances. However, no clear evidence is available on the effectiveness of this solution for the signal transmission over microstrip interconnects routed on substrates inside the cavity. A comprehensive analysis is carried out to fill this gap by analyzing the signal propagation on single-ended and differential microstrip, thus demonstrating that the pins help to minimize the detrimental impact of the resonating cavity within the bandgap limits. The effectiveness of the pinned cavity to suppress the coupling among microstrips routed on the same substrate is demonstrated. Experimental data based on a pinned cavity with different pin lengths are provided to confirm that the intended bandgap is properly achieved and that the quality of the transmitting signal is ensured within the bandgap.