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The mixed-mode simulator is currently one of the most efficit
tools for timing verification of analog-digital CMOS
VLSI circuits. We have developed a mixed-mode simulator by
combining the conventional circuit level simulation
techniques, sampled- data level circuit techniques for
analog circuit simulation and the gate level techniques for
digital circuit simulation based on the event-driven concept.
A new scheme at the macrocell level is proposed for memory
storage savings and less execution time required while
preserving reasonable accuracy. It decomposes a circuit
into a number of subcircuits called macrocells. The
scheme can exploit a general multirate behavior that refers to
macrocell simulation at different rates over a given interval
of time so that different algorithms can be employed in
the simulator. Furthermore, a new partitioning scheme called
block tearing approach is proposed, in which timing partition
is used in addition to the partition of macrocells. It can
further be implemented in multi-processor machines to speed
up since these partitioned blocks are built upon the pipeline
structure. Benchmark tests of several example circuits show
good performance in terms of speed and accuracy. The simulator
is well suited for hierarchical VLSI circuits which are cell-
based such as current circuit design.
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