PVT

작성자:

  •  What is PVT?
PVT stands for process, voltage, temperature.


Process
-Speed of nMOS/pMOS is different due to the cause of the process.
-Types of speed -> fast / typical / slow
-FF/FS/TT/SF/SS(nMOS/pMOS)


Voltage
-Speed of pMOS/nMOS changes according to the supply voltage.
-In general, ±10% of the typical is taken as the best/worst case. 

Temperature
-Speed of pMOS/nMOS changes according to temperature
-in reality, temperature inversion arises in 65nm, mostly 28nm and below.

  • Why do we use PVT?
To verify in advance timing according to process or environmental conditions.


  • PVT corners and its effect on delay




Additionally..

Synthesis를 진행할 때의 PVT best/worst 조건은 어떤 기준에 의해서 정해 질까?

Synthesis는 아직 net이 없는 상태 이므로, 이후 real net이 생긴다면 net delay에 의해 holdtime은 개선될 것이다. 그러므로 synthesis를 진행하는 경우의 PVT에서는 setuptime을 우선적으로 고려해 delay의 best/worst조건을 생각해야 한다. 

이처럼 Synthesis에서의 PVT best/worst 조건은 delay(timing)을 기준으로 한다. 구체적으로, 위의 표에서와 같이 delay를 maximum으로 하는 SS/Low voltage/High Temperature를 worst case, delay를 minimum으로 하는 FF/High voltage/low temperature가 best case 임을 알 수 있다.






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