An imaging model for analog macrocell layout generation

The unique construction properties for the layout of commonly used analog circuit topologies or macrocells are defined. An object-oriented imaging model is introduced for automatically generating the physical layout of analog macrocells for an annotated net list. Each macrocell is represented as a generic layout template which adapts its two-dimensional shape to specific applications. Macrocell composition is directed by a set of commands that satisfy layout constraints such as area, matching, and element ratioing. The model can construct complex geometric shapes such as common-centroids and serpentines and may be queried after cell composition for information required in parasitic element extraction. A library of some 20 commonly used CMOS analog macrocells has been described using this model