Learning of basic amplification circuit

One 、 Basic composition of amplification circuit

1. The concept of amplification

（1） features ： Power amplification

（2） The essence ： Control and conversion of energy

（3） Necessary condition ： Active components

（4） Prerequisite ： No distortion

（5） test signal ： Sine wave

2. How to build a basic amplification circuit

（1） The goal is ： Turn low-power signals into high-power signals

（2） Conditions ：a. Components b. Power Supply

（3） technology roadmap ：a. The triode works under amplification

b. Small signal can control ib

c. There is a reasonable output

（4） Basic common emission amplifier circuit

 3. Amplification circuit

（1） Direct coupled common emission amplifier circuit

  Input is AC , The output has AC and DC

（2） Resistance capacitance coupled common emission amplifier circuit

Input is AC , The output is also pure AC . The capacitance in the figure has positive and negative poles , The capacity is generally large , Electrolytic capacitor .

Two 、 Performance and index of amplification circuit

（1） Magnification （Auu,Aui,Aii,Aiu）

（2） Input resistance Ri

（3） Output resistance R0

（4） Passband

（5） Nonlinear distortion

（6） Maximum undistorted output voltage

（7） Maximum output power and efficiency

3、 ... and 、 Analysis method

1. DC path and AC path

（1） DC path ：Ui=0, Capacitance is open circuit , Inductance is open circuit

The DC path of the basic common emitter amplifier ：

The direct current path of the direct coupling common emission amplifier circuit ：

DC path of resistance capacitance coupled common emission amplifier circuit ：

2. Communication channels ： Set DC source to zero , Capacitor short circuit , Inductive open circuit

The AC path of resistance capacitance coupled common emission amplifier circuit ：

The AC path of a direct coupled common emission amplifier circuit ：

The AC path of the basic common emitter amplifier ：