1.Lib文件中的internal power到底是指短路功耗还是短路功耗+开关功耗?
个人理解:工具报出的power包含三部分:internal power,switch power,leakage power。
internal power是指cell本身的功耗,其包含短路功耗和翻转功耗;
switch power是指wire上的翻转功耗。
楼主,这个问题好像是两种都有的,就是有的lib里面的internal只包含短路电流功耗,有的lib里面包含了短路电流功耗和cell的翻转功耗。
ptpx中有这样一个命令 power_table_include_switching_power 默认情况是true就是说包含了cell内部的翻转功耗。详细可见ptpx ug 区别的方法文中如是说:
“The best way of finding out the formula used in the characterization is to consult the library
vendor. A workaround is to inspect the falling power tables. If most of them have negative
numbers, it is likely that formulas 1 and 2 are used in characterization.”
如下图为PTPX报出的log:
2.internal power 在lib中记录的是energy (焦耳) 还是power (瓦特) ?
“Internal power in the Liberty (.lib) format refers to the amount of energy consumed by a cell during a switching event,” 来自SILICONSMART的UG,
The unit for switching power and internal power is a derived unit. It is derived from the following function:
(capacitive_load_unit voltage_unit^2) ⁄ time_unit
来自Library Compiler Modeling Timing, Signal Integrity, and Power in Technology Libraries User Guide
换算到标准量纲是mJ
据说,通常internal_power的单位是pJ,如果是其他的量纲,需要标明。