模电基本—基本放大电路.ppt

Q点估算 直流通路 I1 I2 IB RB1 +EC RC RB2 RE 估算法 戴维南等效 ； ; Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 性能分析 rbe RC RL RB 交流等效电路 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. CE的作用：交流通路中， CE将RE短路，RE对交流不起作用，放大倍数不受影响。 问题：如果去掉CE，放大倍数怎样？ I1 I2 IB RB1 +EC RC C1 C2 RB2 CE RE RL ui uo Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 去掉 CE 后的微变等效电路 rbe RC RL RE RB 将RE折算到基极 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. § 2.5 三种基本接法 共射放大电路：iB控制iC,电压电流均放大 共集放大电路：iB控制iE,电流放大 共基放大电路：iE控制iC,电压放大 实现功率放大的目标 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 2.5.1 基本共集放大电路（射极输出器） RB +EC C1 C2 RE RL ui uo RB +EC RE 直流通道 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 一、静态分析 IB IE 折算 RB +EC RE 直流通道 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 二、交流负载线 ic 其中： uce RB RC RL ui uo 交流通路 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. iC 和 uCE是全量，与交流量ic和uce有如下关系 所以： 即：交流信号的变化沿着斜率为： 的直线。 这条直线通过Q点，称为交流负载线。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 交流负载线的作法 IC UCE EC Q IB 过Q点作一条直线，斜率为： 交流负载线 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 2.3.3 图解法 一、静态工作点的分析： 输入回路： IB UBE Q IBQ UBEQ Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 输出回路： 先估算 IB ，然后在输出特性曲线上作出直流负载线，与 IB 对应的输出特性曲线与直流负载线的交点就是Q点。 IC UCE Q EC Evaluation only. Created with Aspose.Slide