Discrete and continuous substrate noise spectrum dependence on digital circuit characteristics

This work presents an experimental investigation about the relation between specific characteristics of a digital circuit (clock frequency and architecture) and the substrate noise spectrum that it generates. Both the discrete impulse train term and the continuous term of the substrate noise spectrum are investigated. The results indicate that the continuous term sets an upper bound to the substrate noise reduction that may be obtained by changing the digital frequency or by staggering the simultaneous activity of the circuit, two techniques that have been proposed in the literature to reduce substrate noise.