Modeling and Analysis of a New Packaging Structure for Noise Isolation in Mixed-Signal Systems

摘要

The integration of heterogeneous components/sub-systems (e.g., RF, high-speed digital, MEMS…) on the samernchip, package or board requires the use of efficient noise isolation/suppression structures or techniques tornminimize electromagnetic interference (EMI). So far, electromagnetic band gap (EBG) structures have beenrnconsidered to be the most effective means to suppress noise coupling and prevent EMI over a wide range ofrnfrequencies. However, EBGs reduce the integration density because they consist of many periodically arrangedrnpatches, vias, and at times, surface mount components (capacitors and/or inductors) which consume much of thernboard space. EBGs also cause return-path discontinuity (RPD) problems for signal lines routed above/belowrnone of their patterned layers, thus resulting in signal integrity (SI) issues. Therefore, in this paper, we propose arnnew packaging structure for noise isolation – the interconnected patch ring (IPR) structure. It is just as effectivernas EBGs in noise suppression/isolation, but overcomes most of the limitations of EBGs and other conventionalrnnoise isolation structures. To illustrate some of its advantages, we modeled and simulated the IPR structure tornsuppress the propagation of noise from 700 MHz to 2.5 GHz – the frequency range used by many wirelessrncommunication standards (e.g., GSM 900/1800, Bluetooth, UMTS and 2.4 GHz WLAN). Test samples of the IPRrnwere designed, fabricated and measured. The measurement results showed good isolation throughout thernrequired frequency range (Proof of Concept). Furthermore, a very good correlation was obtained betweenrnmeasurement and simulation, thus experimentally validating the simulation results.