這幾個都是CMOS集成電路的**Vth閾值電壓**相關的基本概念。通常將傳輸特性曲線中輸出電壓隨輸入電壓改變而急劇變化轉折區的中點對應的輸入電壓稱為**閾值電壓**。 * **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**- 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. * **RVT**-?Regular?V threshold. ?Another name for SVT. 閾值電壓越低，因為飽和電流變小，所以速度性能越高；但是因為漏電流會變大，因此功耗會變差。 速度大小按快到慢依次排列為SLVT, LVT, RVT, HVT。 功耗大小卻正好相反。即HVT的cell其閾值電壓最大其摻雜濃度越高，其泄露功耗最小； 對于NPN的晶體管是n型半導體，其導電是電子，P襯底多子是空穴，摻雜越高電子越少，越難以導電，閾值電壓上升，泄露功耗變少。 對于PNP晶體管是P型半導體，其導電是空穴，N型襯底是電子，摻雜越高空穴越少，越難以導電。