Transistor Sizing

Several methods of choosing appropriate sizes for transistors in a VLSI schematic to meet a specified delay criteria are considered. Simulated annealing and heuristic techniques are investigated. MOST is a Prolog program which makes use of information provided by the PTA timing analyzer to implement these various approaches. Both MOST and PTA are written entirely in interpreted Prolog nonetheless, performance gains of over 50 as compared to an unsized circuit can be realized in a few minutes of CPU time. Using a simple RC timing model, heuristics are found to be more efficient than simulated annealing.