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| 二、稳定工作点的放大电路 |
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（一）温度对静态工作点的影响 |
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温度升高之后晶体管参数β，ICBO，UBE的变化都使ICQ增大，静态工作点向饱和区移动。如果温度降低，则将使ICQ减小，静态工作点向截止区移动。另外，更换晶体管，相当于改变了特性曲线也会使静态工作点发生变化。 |
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怎样稳定静态工作点 |
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1. 将放大器置于恒温装置中；
2. 在直流偏置电路中引入负反馈来稳定静态工作点；
3. 在偏置电路中采取温度补偿措施。
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（二）分压式电流负反馈偏置电路 |
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1.工作原理 |
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这种电路在设计时，应适当选择电阻Rb1和Rb2的适当阻值范围，使之满足下面两个条件。 |
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晶体管基极直流电位 |
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可以近似看作恒定不变 |
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工作点稳定过程： |
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所以 |
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也可以近似看作恒定不变 |
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