Operation condition And timing analysis

Operation condition 主要指芯片运行的环境的不同,在这里加上Interconnect net 模型.

 

Operating condition	Description
Process derating factor	This value is related to the scaling of device parameters resulting from variations in the fabrication process. A process number less than the nominal value usually results in smaller delays.
Ambient temperature	The chip temperature affects device delays. The temperature of the chip depends on several factors, including ambient air temperature, power consumption, package type, and cooling method.
Supply voltage	A higher supply voltage usually results in smaller delays.
Interconnect model type	This value defines an RC tree topology that PrimeTime uses to estimate net capacitance and resistance during prelayout analysis.

 

当Operation condition设置好只好,PT/DC/ICC/Encounter等可以根据R/C去计算pin-pin之间的延迟.

如何check Setup或者hold就是analysis mode 的问题了.

主要包括以下三种:(源自User manual)

• Single operating condition mode – Uses a single set of delay parameters for the entire design, based on one set of process, temperature, and voltage conditions.

• On-chip variation (OCV) mode – Performs a conservative analysis that allows both minimum and maximum delays to apply to different paths at the same time. For a setup check, it uses maximum delays for the launch clock path and data path, and minimum delays for the capture clock path. For a hold check, it uses minimum delays for the launch clock path and data path, and maximum delays for the capture clock path.

• Advanced on-chip variation (AOCV) mode – Determines derating factors based on metrics of path logic depth and the physical distance traversed by a particular path.

   可以看到在OCV中,capture clock path使用best case, data path 使用worst case(对于Setup检查). 当某一段path既是clock path又是data path的时候.这段path具有双重的属性.这样更加的pessimistic.  For a more accurate analysis, this pessimism can be corrected. For more
information, see Clock Reconvergence Pessimism Removal.