日志
CTS问答
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Meet DRC(maximum transition/capctiance/fanout/buffer levels).
Meet the clock tree targets(max skew and min inserction delay).
other:Constraints are upper bound goals.If constraints are not met,violations will be reported.
Targets are "nice to have"goals.If targets are not met,no violations will be reported.
2.How is a float pin different from a stop pin?
A float pin allows the user to define when the clock edge is supposed to arrive at the pin.This can be used to give IP blocks or RAMs extra margin/setup time if needed.
3.What is the difference between stop and exclude pins?
List some examples of implicit stop/exclude pins.
Implicit stop pins:clock pins of FFs,latches and macro cells.
Implicit exclude pins:non-clock input pins of sequential cells(data,set,reset,etc);
clock output ports;clock pins of sequential cells where the output is floating;
incorrectly defined clock pins.
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