A method and apparatus for improved formal equivalence checking to verify
the operation of components in a VLSI integrated circuit. The present
invention enhances previous techniques for dynamic circuits by generating
a multi-level transistor abstraction for dynamic circuits. Two-levels of
abstracted code are generated. First, an abstracted legal Verilog.RTM. is
generated for the evaluate phase of a dynamic circuit. Second,
"comment-logic" in Verilog.RTM. syntax is generated for the pre-charge
phase of the dynamic circuit. Using the method and apparatus of the
present invention, it is possible to obtain a multi-level transistor
abstraction for both the "clk=0" and the "clk=1" conditions. The binary
decision diagram property of the circuit being analyzed is used to
generate multi-level representations for both the pre-charge (clk=0) and
the evaluate phases (clk=1). The multi-level abstracted model of the
present invention has several advantages over the prior art. The legal
Verilog.RTM. can be used for traditional simulation and equivalency
verification, ATPG. The "comment logic" can be used with a property
checking tool to verify that the clock connectivity is correct. In
addition, the present invention has the advantage of being able to
generate legal Verilog.RTM. with pre-charge for verification against RTL
with detailed pre-charge information.