How cell delays varies with PVT conditions...:

How cell delay will be evaluted.

 
    cell delay is function of input transition and output load.But cell delay also varies with PVT conditions.

PVT conditions::

• Process Variation :: Variations in the process parameters can be impurity concentration densities, oxide thicknesses and diffusion depths.

As process increases delay increases.

• Voltage variation:: The delay of a cell is dependent on the saturation current. In this way, the power supply inflects the propagation delay of a cell. Throughout a chip, the power supply is not constant and hence the propagation delay varies in a chip. 

As voltage increases cell drives faster i.e. delay decreases.

• Temperature variation::As we know mobility of electrons depends on temperature ,which effects the delay.

As temperature increases mobility of charge carriers decreases, hence delay increases.