Suppression of noise from digital-to-analog coupling in shielding cavity

Abstract

The metallic shielding cavity provides coupling path for digital lines to analog traces at resonance in the cavity. It induces coupling noise in analog components and thus deteriorate RF performance and result in radiated emission. A novel design to avoid such coupling noise is proposed. With the shorting pins connecting between cavity and ground plane, the resonance can be shifted to the nodal frequency points of the pseudo-random binary sequence (PRBS). This reduces frequency component of energy at the resonance and thus minimizes the coupling noise.