7.2.3.2. Operating
Conditions:
This section models the environmental
variations of IC. These are known as Process, Voltage, and temperature
variations. In short it is called PVT.
A set of values of PVT is known as
operating condition. A logic library is characterised for one set of operating
condition. Generally there are different libraries specific to different
operating condition. There are three operating conditions very commonly used in
ASIC synthesis and implementation. Based on the affect on cell delay due to the
variation in PVT these classifications are made.
They are:
Ø worst
(also called ‘max’ or ‘slow’)à
library in which cells are characterised for maximum delay
Ø best(also
called ‘min’ or ‘fast’)àlibrary
in which cells are characterised for minimum delay
Ø nominal(also
called ‘typical’ or ‘normal’)àlibrary
in which cells are characterised for typical delay
Eg.:
/* Operation Conditions */
nom_process :
1.00;
nom_temperature :
125.00;
nom_voltage :
0.95;
voltage_map (VDD,0.95);
voltage_map (VSS,0.00);
define(process_corner, operating_conditions,
string);
operating_conditions (slow) {
process_corner : "SlowSlow";
process :
1.00;
voltage :
0.95;
temperature :
125.00;
tree_type :
balanced_tree;
}
default_operating_conditions : slow;
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