Amplifier circuits are usually composed of one or more electronic components such as transistors, integrated circuits, and so on. These components can be arranged and combined according to different circuit structures to achieve different amplification effects.
There are three main types of basic amplification circuits:
1. Direct amplification circuits, whose gain is fixed.
2. Amplifier circuits controlled by voltage gain, where the gain can be varied by voltage adjustment.
3. An amplifier circuit controlled by current gain, where the gain can be varied by current adjustment.
Amplifier circuits are commonly used in electronic equipment, such as communication systems, audio equipment, medical equipment, measuring instruments and so on. Amplifier circuits increase the voltage and current of a signal, thereby improving the noise ratio and linearity of the signal and enabling the signal to be transmitted far from the source.
Amplifiers can also be classified according to the way they work, and there are three main types:
1. Single-ended amplifiers, which operate on a single-ended voltage for both input and output.
2. Differential amplifiers, whose inputs and outputs operate on differential voltages.
3. Operational amplifiers, which perform arithmetic and logical operations.
The gain of an amplifier circuit can be achieved by adjusting circuit parameters, commonly used parameters are current gain, voltage gain and power gain. Gain is usually measured in multiples or decibels (dB).
In addition, the amplifier circuit has many other key performance indicators, such as: linearity, noise ratio, bandwidth, etc., in the design and use of amplifier circuits need to consider these factors.