For most systems single transistor amplifier does not provide sufficient gain or output impedance matching. The solution is only to combine multiple stages of amplification. In this amplifier circuit we are going to shows a simple two transistor amplifier. In the single transistor amplifier circuit we have made a very simple amplifier with one transistor, one resistor and on capacitor but amplifier has been designed with tow transistors.
We have design this amplifier by using two transistors includes PNP and NPN transistors and we adopted the overall topology of the Sziklai pair.
The two transistor amplifier provides a reasonably high impedance while providing a low output. It is an ideal amplifier circuit for applications where a higher level of output required than the single transistor stage.
The amplifier that consists of two transistors is also known as two stage amplifier. This type of amplifier circuit has two transistors, connected to a common power supply. Working of RC Coupled Amplifier can be explained by the following diagram.
Advantages of Two stage amplifier
The main advantage of this amplifier is excellent frequency response. Compared to a single transistor amplifier, this combination have the following advantages:
- Higher input-output isolation
- Higher input impedance
- Higher output impedance
- Higher gain or higher bandwidth
- Lower cost
- Easy to understand
The gain remain constant over the audio frequency range that is way it is most importance for speech, music etc.
Disadvantage of two stage amplifier
- It uses low power it effective load resistance.
- Single stage and tow stages amplifier become noisy with age.
- Due to poor impedance matching, power transfer will be low.
- Powerful amplifiers of class are costly and bulky due to the large power supply and heat sink.
Two-stage RC Coupled Amplifier
This circuit diagram of Two-stage RC Coupled Amplifier with full detail of components. In this diagram each and every thing is clear even an inexperienced person can make and understand its working.