低功耗設計——internal power理解

1.Lib文件中的internal power究竟是指短路功耗仍是短路功耗+開關功耗?html

我的理解:工具報出的power包含三部分:internal power,switch power,leakage power。
internal power是指cell自己的功耗,其包含短路功耗和翻轉功耗;
switch power是指wire上的翻轉功耗。ide

樓主,這個問題好像是兩種都有的,就是有的lib裏面的internal只包含短路電流功耗,有的lib裏面包含了短路電流功耗和cell的翻轉功耗。
ptpx中有這樣一個命令 power_table_include_switching_power 默認狀況是true就是說包含了cell內部的翻轉功耗。詳細可見ptpx ug 區別的方法文中如是說:
「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.」工具

以下圖爲PTPX報出的log:
在這裏插入圖片描述ui

2.internal power 在lib中記錄的是energy (焦耳) 仍是power (瓦特) ?設計

「Internal power in the Liberty (.lib) format refers to the amount of energy consumed by a cell during a switching event,」 來自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
來自Library Compiler Modeling Timing, Signal Integrity, and Power in Technology Libraries User Guide
換算到標準量綱是mJorm

聽說,一般internal_power的單位是pJ,若是是其餘的量綱,須要標明。htm

參考:
低功耗設計基礎:深刻理解Internal Power
lib中internal power的具體定義blog

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