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 show a simple two-transistor amplifier. In the single-transistor amplifier circuit, we have made a very simple amplifier with one transistor, one resistor, and one capacitor but the amplifier has been designed with two transistors.

We have designed this amplifier by using two transistors including 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 is required than the single transistor stage.

Two Transistor Amplifier

An amplifier that consists of two transistors is also known as a two-stage amplifier. This type of amplifier circuit has two transistors, connected to a common power supply. The working of RC Coupled Amplifier can be explained by the following diagram.

Two Transistor Amplifier

Advantages of the Two-stage amplifier

The main advantage of this amplifier is its excellent frequency response. Compared to a single transistor amplifier, this combination has 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 remains constant over the audio frequency range which is the way it is most important for speech, music, etc.

The disadvantage of two stage amplifier

  • It uses low power it effective load resistance.
  • Single-stage and tow stages amplifiers 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

Two-stage RC Coupled Amplifier

This circuit diagram of a Two-stage RC Coupled Amplifier with full detail of components. In this diagram, and everything is clear even an inexperienced person can make and understand its working.