Frequency domain analysis of switching noise on power supply network

In this paper, we propose an approach for the analysis of power supply noise in the frequency domain for power/ground (P/G) networks of tree topologies. We model the P/G network as a linear time invariant (LTI) pseudo-distributed RLC network and the gates (or cells) as time-varying current sources. Voltage fluctuation caused by the switching events is calculated based on the effective impedances seen by the corresponding current sources and the spatial correlation between the nodes of the power network. Superposition is applied to the LTI system to obtain the overall noise spectrum at any node of the power supply network. Inverse Fast Fourier Transformation (IFFT) is then performed on the frequency domain noise spectrum to obtain the time domain noise waveform. The proposed algorithm has a complexity of O(n/sup 2/). Experimental results show that our approach can produce accurate noise waveforms.