怎样计算三极管的静态工作点?

2025-03-13 18:36:26
推荐回答(3个)
回答1:

因为发射极电流是基极电流的(1+β)倍,发射极电压=发射极电阻*发射极电流。发射极电压也就是发射极电阻上的电压。所以,发射极电压=URe=Ie*Re=(1+β)Ib*Re。在基极回路里,基极到接地点的总电压为:Ube+Ure。Ube为基极和发射极之间的电压=Rbe*Ib。基极流过的电流只有Ib,而基极到地的电压是Ube+URe,除以ib就是从基极看进去的等效电阻Rb。即Rb=(Ube+URe)/Ib=[Ib*Rbe+Ib*(1+β)*Re]/Ib = Rbe+(1+β)Re。输入端b的等效电阻相当于增大了(1+β)Re。 这就是为什么发射极输出器增大了输入阻抗的原因。 严格说,你提供的表达式是不对的。只是一种忽略Ube的近似值。 Ib=(Ube+Ure)/[Rbe+(1+β)Re]才是正确的。 Rbe是发射结等效直流电阻。这是直流量的表示式。如果分析交流量,就把所有大写的量改成小写的。公式的形式是完全一样的。

回答2:

先知道三极管的放大倍数β,有个公式 lb=lc/β 原式β=lc/lb 这个基极电流求出来然后是VCC―UBE/lb=Rb

回答3:

首先看看三极管在电路里作什么接法,是共基极,共发射极还是共集电极,然后再代入相应的公式去计算。具体的公式可以去网上搜一下哦。

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