This series of blog posts focuses on analog electronics, and is dedicated to articles on analog electronics that can be understood by junior high school students. If it is helpful to you, please continue to follow me.
This series of mind maps
one. Question
1: First, let’s think about the meaning of “community”?
"Common" means public.
Common emitter circuit: input and output · share the emitter.
2: How to judge whether it is a common emission base amplifier?
That end is grounded, it is a total of xx levels.
two. Comparison of the three major circuits
The principle of the common emitter circuit
is as follows:
时间短可不看，只要记住**两点**即可
1. 条件：交流电路中分析。
2. 接地：那一端接地，就是 共XX。
Principle: In the circuit shown in the figure, the emitter of Q1 is directly grounded, and the emitter of Q2 is grounded through capacitor C3. Because C3 has a large capacity, the capacitive reactance to the AC signal is small and it is a path, so it is the transmission of the AC signal. pole is equivalent to ground, so this is a common emitter amplifier.
It can be seen from the circuit that the base and collector of the triode are not grounded, the input signal is input into the triode from between the base and the ground, and the input signal is output from between the collector of the triode and the ground. collector output.
common collector amplifier
1.间接接地 vs 直接接地
大家看图a1 中间有一个电阻后再接地，不是纯导线，为间接接地。
大家看图a2 导线直接接地，这是我们要找的接地。
- Principle: (Don’t look at it for a short time) The collector is connected to the DC power supply +V, and the +V terminal is equivalently grounded for AC (C1 connects the +V terminal to the AC ground), so the collector of the triode is grounded, which is a common-collector amplifier. The AC signal is input from the base (input between the base and ground), and the signal is output from the emitter (output between the emitter and ground). A bypass capacitor cannot be connected between the emitter and the ground, otherwise the amplifier will be short-circuited and there will be no signal output.
Common base stage amplifier:
Principle: The base is directly grounded through the bypass capacitor C2, so that the base is shared, so this is a common base amplifier. The AC signal is input from the emitter (input between the emitter and ground), and output from the collector (output between the collector and ground).
three. Summary :
1. The end of the triode is grounded, and that end is a total of xx levels.
2. Direct grounding and indirect grounding: Only direct grounding of wires is direct grounding.
3. Attached picture:
