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2.6.3 静态分析

2.6.3 静态分析. + E C. R C. R B. I B. U BE. 直流通道. ( 1 )根据直流通道估算 I B. 一、估算法. R B 称为 偏置电阻 , I B 称为 偏置电流 。. R C. R B. 直流通道. ( 2 )根据直流通道估算 U CE 、 I B. I C. U CE. 例: 用估算法计算静态工作点。. 已知: E C =12V , R C =4k  , R B =300k ,  =37.5 。. 解:. 请注意电路中 I B 和 I C 的数量级。. 二、图解法. 图解步骤:

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2.6.3 静态分析

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  1. 2.6.3 静态分析 +EC RC RB IB UBE 直流通道 (1)根据直流通道估算IB 一、估算法 RB称为偏置电阻,IB称为偏置电流。

  2. RC RB 直流通道 (2)根据直流通道估算UCE、IB IC UCE

  3. 例:用估算法计算静态工作点。 已知:EC=12V,RC=4k,RB=300k,=37.5。 解: 请注意电路中IB 和IC 的数量级。

  4. 二、图解法 图解步骤: (1)用估算法求出基极电流IB(如40μA)。 (2)根据IB在输出特性曲线中找到对应的曲线。 (3)作直流负载线。根据集电极电流IC与集、射间电压UCE的关系式UCE= EC-ICRC可画出一条直线,该直线在纵轴上的截距为EC/RC,在横轴上的截距为EC,其斜率为-1/ RC,只与集电极负载电阻RC有关,称为直流负载线。 (4)求静态工作点Q,并确定UCE、IC的值。晶体管的IC和UCE既要满足IB=40μA的输出特性曲线,又要满足直流负载线,因而晶体管必然工作在它们的交点Q,该点就是静态工作点。由静态工作点Q便可在坐标上查得静态值IC和UCE。

  5. 由UCE=EC-ICRC所决定的直流负载线 两者的交点Q就是静态工作点 IB=40μA的输出特性曲线 过Q点作水平线,在纵轴上的截距即为ICQ 过Q点作垂线,在横轴上的截距即为UCEQ

  6. 本节结束

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