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放大电路处于静态时,常用直流量IB、UBE、IC和UCE来描述晶体管的静态工作情况。对应在晶体管的输入特性和输出特性曲线上各确定一点,该点称为静态工作点。 |
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步骤: |
1. 画出直流通路; 2. 利用输入特性曲线来确定IBQ和UBEQ; 3. 利用输出特性曲线确定UCEQ及ICQ。
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(一)画出直流通路 |
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静态时,输入信号电压ui=0,即将信号源短路,就得到放大电路的直流通路。 |
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(二)利用输入特性曲线来确定IBQ和UBEQ |
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1. 晶体管的输入特性曲线 |
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2. 电路中的输入回路 |
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列方程 |
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该线称直流负载线,它与输入特性的交点Q( UBEQ, IBQ)就是静态工作点。 |
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