Automatic determination of signal flow through MOS transistor networks

Abstract We describe a method for automatically determining the signal flow through hierarchically specified MOS transistor nets. Direction is determined from the circuit schematic only; no knowledge of signal values or input/output relations is assumed, and particular design rules are not relied on. Unlike previous methods used for MOS transistor nets, our method does not require some transistors to be determined manually, and the method can deal with bidirectional transistors. Circuits are represented using Horn clauses as a hierarchical specification language, and the method is implemented in Prolog. We point out some interesting connections with the statistical thermodynamics of spin systems.