Suppression of radiated emission from an 8-bit micro-controller using gate-oxide filtering capacitors

The voltage fluctuations of the power/ground lines on ICs, packages, and modules have become the major source of the radiated emission. Combined suppression techniques including shielding, cabling and filtering at the package level and the module level are not enough for the complete suppression of radiated emission. Moreover, the power/ground line fluctuations and the resulted radiated emissions caused by the IC surge current must be controlled and considered at the IC design procedure. We have demonstrated more than 10-dB suppression of the radiated emission from a commercial 8-bit micro-controller using on-chip gate oxide filtering capacitors. The filtering capacitors are placed under the power/ground buses and the signal buses without ever increasing the die size.