Noise isolation in mixed-signal systems

What is it about?

This paper proposes a novel T-shape electromagnetic bandgap (EBG) structure to suppress simultaneous switching noise (SSN) in mixed-signal systems. Noise is generated due to simultaneous switching multiple drivers in the digital ICs. It is called as SSN. It could propagate between power and ground planes of underlying PCB platform and interfere with the functionality of nearby RF/Analog ICs. So, the RF modules are isolated from the digital module for proper functioning of entire mixed-signal system. A high-impedance surface, called T-shape EBG has been implemented between digital and RF modules. It will exhibit the characteristics of bandgap for a wide frequency range to suppress the propagation of switching noise. A single unit-cell of T-EBG is periodically patterned over one side of the PCB and the other side is kept continuous. In this paper different characteristics of T-EBG have been simulated and verified with the measurement results. A 3 × 3 T-EBG layout provides an isolation of -40 dB from 0.72 to 6.39 GHz. A scaled version of T-EBG is used to shift the bandgap towards higher frequency range from 2.22 to 7.19 GHz. Also, a novel layout methodology has been proposed to broaden the bandgap from 2.02 to 18.84 GHz without reducing the thickness of dielectric substrate.

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