最近在分析波形的时候,发现某个PAD模型的行为与想象的不一致,就进入stdcell里面看了下,主要是pmos和nmos相关的东西,暂列如下:
开关级基元14种
是实际的MOS关的抽象表示,分电阻型(前缀r表示)和非电阻型;
(1)MOS开关
·nmos开关:控制信号高,开关导通,否则关闭;
·pmos开关:控制信号低,开关导通,否则关闭;
·cmos开关:模拟了nmos和pmos开关的组合,一般ncontrol和pcontrol是互补信号:coms 实例名(out,data,ncontrol,pcontrol);
(2)双向开关:MOS开关只提供了单向驱动能力,双向开关的每个脚都声明为inout类型,可做输入驱动或输出被驱动,即可以互相驱动且随时保持一致。
无条件双向开关tran和有条件双向开关tranif0(只有当conrol为0时两端互相驱动)、tranfi1(当control为1时两端互相驱动):
tranifx 实例名(inout1,inout2,control);
bufif1, bufif0, notif1, notif0 gates
The instantiation of these tri-state gates (Example 3) can contain zero, one, two, or three delays. The strength declaration should contain two specified strengths - strength1 and strength0 (see Strengths for more explanations).
These gates have three ports: the first is an output port, the second is a data port, and the third is a control port. The control port is used to set gates in high-impedance state.
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