请教 Thomas H.Lee的CMOS射频集成电路设计 里的两个问题

bensonne

1.LNA中，“对允许输入信号幅值的两个基本限制，噪声系数确定了下界，失真决定了上界”，如何根据一个LNA的噪声系数决定输入信号的最小幅值？
2.书的第2版中，"it may be said that the level-3 model is essentially the last with parameters that are at least somewhat traceable to the underlying physica and whose equation set is sufficiently small to make calculations by hand or by spreadsheet a praction option.For this reason many engineers use level-3 models in the early stages of a design ,both for hand calculations and for initial simulations."
实际工作真的用level-3模型来手算？现在中国这样的人多吗？
多谢！

yora

<P>好象下限是-174DBM.然后你加上噪声,就是输入信号的最小幅值</P>

ddsylvie

可以按照如下的公式来计算：
Pin,min(dBm)=-174dBm/Hz+Noise Figure+10logB+SNRmin
这个的B是信号带宽，SNRmin是要求达到的最小的信噪比