Transistor amplifier circuit common base amplifier circuit common collector amplifier circuit 3

3. Common base amplifier circuit

The common base amplifier circuit has a small input resistance and a large output resistance, Transistor and has good frequency characteristics. However, the common base amplifier circuit only has voltage amplification capability and does not have current amplification capability. Let's take a look at the AC circuit diagram directly.

Does this circuit look strange? The current flowing from the emitter to the collector is a common base amplification circuit (although the current flow itself feels strange, it is indeed like this). Through the introduction of the common emitter circuit, I believe everyone should be familiar with the four components on the schematic. Let's take a direct look at the formula of this circuit:Transistor

In fact, the magnitude of this voltage amplification factor is the same as when the emitter of the common emitter amplifier circuit is not connected to a resistor, except for a negative sign. The meaning of each letter in the formula is the same as that of the common emitter amplifier circuit, that is, β represents the amplification factor of the transistor, R L 'is equal to R c and R L is added, R b b' is composed of the base lead resistance and the base body resistance, and the calculation method of R b'e is also the same as that of the common emitter amplifier circuit.Transistor