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电压放大倍数是低频电压放大器的一个主要指标。不管是设计还是实际装调,都需要知道它。图1为一典型的电压放大器电路。常见的求电压放大倍数的公式为: K=U_出/U_入=β(R′_z/r_(bε))式中:R′_z=(R_cR_z)/(R_c+R_z),是等效负载电阻;r_(bε)是晶体管的输入电阻。实际使用这个公式时,有两个问题: (1)手册上给出的β值与实际工作点的β值可能出入很大。如手册上给定3AX31的β值为30～200,
Voltage magnification is a major indicator of low-frequency voltage amplifiers. Whether it is the design or the actual installation, you need to know it. Figure 1 shows a typical voltage amplifier circuit. The common formula for voltage magnification is: K = U_out / U_in = β (R’_z / r_ (bε)) where: R’_z = (R_cR_z) / (R_c + R_z) Effective load resistance; r_ (bε) is the transistor’s input resistance. There are two problems when actually using this formula: (1) The β value given in the manual may deviate from the β value at the actual working point. As the manual given 3AX31 β value of 30 to 200,