An investigation on parasitic couplings and feedback loops in the CMOS circuits

Two major problems in network partitioning are investigated: the parasitic coupling capacitances between the partitioned subcircuits, and the feedback loops. The coupling capacitance effect is shown to be negligible if state transitions in the neighboring subcircuits do not occur simultaneously. A decoupling criterion is developed to decide whether the coupling between the subcircuits is negligible. A loop-merging algorithm is developed to handle feedback in loops such a manner that the network topology is described by a unidirectional signal path graph, which makes it possible for a single-sweep Gauss-Seidel relaxation. Moreover, an event-driven algorithm is proposed to take advantage of the hierarchical loop structure resulting from the merge algorithm