【2017年整理】单级低频小信号放大器.ppt

楚州职教中心 花卉 单级低频小信号放大器 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 复习1:如图，在电路中测出的各三极管的三个电 极的对地电位。判断各三极管处于何种工作状态？ 6V 1.3V 2V 4.8V 4.5V 0.7V 5V 4V 0V 放大区 饱和区 截止区 V V V Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. A B 复习2：放大器的组成和各元器的作用 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 单电源供电 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 无信号输入的状态 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 静态：是把放大器的输入端短路，则放大器 处于无信号输入的工作状态(ui = 0)。 此时，晶体管直流电压UBE、UCE和对应的IB、 IC ，统称为静态工作点Q，分别记作UBEQ、UCEQ、IBQ、 ICQ。 三、放大器的静态工作 1.概念 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 将电容开路。 2.静态工作点的估算 将电容开路。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. （1）估算IBQ（ UBEQ=0.7V) 用估算法分析放大器的静态工作点 （ UBEQ、 IBQ、ICQ、UCEQ） Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. （2）估算ICQ 、UCEQ ICQ UCEQ ICQ= IBQ UCEQ =VCC — ICQRC Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例题：用估算法计算静态工作点。 已知：VCC=12V，RC=2K， Rb=226K ，=60。 请注意电路中IB和IC的单位  解：UBEQ = 0.7V 三极管工作 在放大区 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 课堂练习1：用估算法计算静态工作点。 已知：VCC=12V，RC=4K，Rb=300K ，=37.5。（忽咯UBEQ ） 三极管工作 在放大区 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 课堂练习2： 放大器中已知VCC=15V，RC=2.5kΩ，Rb=150kΩ ，β=60，试估算放大器的静态工作点。（忽咯UBEQ ） 三极管进入了饱和区 Evaluation only. Created with Aspose.Slides for