GeminiII: a second generation layout validation program

Gemini is a program that is widely used to compare circuit layout against a specification. Extensions to Gemini that make it faster, enable it to isolate errors better, and extend its domain of application, are described. These improvements have been achieved by changes to the labeling algorithm, extensions to the local matching algorithm, better handling of symmetrical circuits, and the accommodation of series-connected transistors. GeminiII´s algorithm is separated into global labeling and local matching phases. GeminiII dynamically switches between the two, depending on the amount of local structure contained in the circuit, taking advantage of the speed of the local matching algorithm when possible and relying on the power of the more general algorithm when the simple algorithm fails.<>