CMOS Testing

CMOS testing is of two types.
1) Functionality tests
2) Manufacturing tests
 Functionality Tests:
                             These are the tests which the designer designs first. Does the counter count? Does the adder add? The functionality tests should prove that the circuit is functionally equivalent to some specification. The specification can be a text, a high level language like C, Fortran etc..or even a table of inputs and outputs.
There is no good theory that explains the functionality tests. The only way is to simulate the circuit as close as possible to the real world.
These tests are tedious. They have long simulation times and long verification sequences.
Manufacturing Tests:
                               The tests check whether the gate functions as expected. The normal that are checked are
1) Layer to layer faults
2)Discontinuous wires
3)Thin oxide wire shorts to well or substrate
These may in turn cause
1)Nodes shorted to Vdd or Vss
2) Nodes shorted to other nodes
These tests are not specifically confined to gate tests but also do work for
1) I/O tests
2)Speed test
3)Idd test