backend-cell

介绍后端工艺库的特点。

Vth阈值电压

CMOS集成电路的Vth阈值电压相关的基本概念。通常将传输特性曲线中输出电压随输入电压改变而急剧变化转折区的中点对应的输入电压称为阈值电压。

HVT = High V threshold. Can be used in the path where timing is not critical. So by using HVT cells we can save power.

LVT - Low V threshold. One should use these cells in timing critical paths. These cells are fast but , comsumes more power due to its leakage. So it will consume more power. So use only when timing is critical.

SVT(RVT) - Standard V threshold. Best of both world. Medium delay and medium power requirment. So if timing is not met by small magin with HVT, you should try with SVT. And at last LVT.

阈值电压越低，因为饱和电流变小，所以速度性能越高；但是因为漏电流会变大，因此功耗会变差。

速度性能由高到低：SLVT -> LVT -> SVT -> HVT

功耗由小到大：HVT -> SVT -> LVT -> SLVT