Negative unate / Positive unate logic & Low skew cells

[amara]

Can anyone explain what are the Negative unate logic cells, Positive unate logic cells, Special cells and Low skew cells?

 

[deh_fuhrer]

Re: Negative unate / Positive unate logic & Low skew cel

Can anyone explain what are the Negative unate logic cells, Positive unate logic cells, Special cells and Low skew cells?

Negative unate means cell output logic is inverted version of input logic.
le.g., in inverter having input A and output Y, Y is negative unate with respect to A.

Positive unate means cell output logic is same as that of input..
e.g., buffer

These positive unate and negative unate are constructs defined in liberty file and they are defined for output pin with respect to some input pin...