Electronic – Understanding EOS SUBCKT behavior

A .SUBCKT model is generally used to model a circuit by its building blocks of actual devices so that it can be instantiated over and over by a top level wrapper.

A .MACRO model, uses some functional blocks for certain elements (such as substituting a non-linear functional model for an op-amp) in order to speed up simulation time at the possible cost of accuracy loss. *

*See 'SPICE Book', A. Vladimerscu.

**Macro is used in a slightly different manner in HSPICE manuals. In the HSPICE manual, they refer to the macro as the callable higher level object to be instantiated. e.g. INV would be an instantiable macro cell block (providing only block, node names, and parameters), while one (or more) level(s) lower would contain the sub-circuit device modeling.

It's also possible for the macro to be provided by a vendor to provide behavioral modelling without divulging the internal sub-circuit designs.

.SUBCKT is a macro function, meaning that when encountered it gets substituted. .LIB is similar but for long term files.

Node names within a .SUBCKT have local scope (Except GND).

Node names on the same line as .SUBCKT are the external node names.

subckt's are called using X prefix.

Your SPICE deck above for top_inv8 is saying, "This is a standalone cell, made up of 3 inv7's and 1 intrpsr_inv8.

Who ever wrote this gave that cell the name of Top, this is the cell that is at the very top level of the design.