11 June 2019

Difference between voltage amplifier and power amplifier

The function of the voltage amplifier is to raise the voltage level of the signal. In order to achieve high voltage amplification, the transistor should have a thin base input resistance should have a thin base, input resistance should be low as compared to the collector resistance and the transistor should be able to take or permit higher collector load. In the power amplifier, the main function is to deliver a large amount of power and handle a large current. In order to achieve this high power amplification the transistor used are of a large size so as to dissipate the heat produced, It is based should be thick so as to carry a large current of the order of 100mA,  This post gives information about the difference between the voltage amplifier and the power amplifier to better understand this topic.

The main key difference between a voltage amplifier and the power amplifier are listed below.

Difference :

  • Voltage amplifier is the amplitude of the input AC signal is small, the Power Amplifier is the amplitude of the input AC signal is large.
  • The voltage amplifier is the collector current is low about 1mA, while in power amplifier the collector current is very high above greater than 100 mA.
  • Voltage amplifier is transistor used can dissipate less heat produced during its operation, while in power amplifier used can dissipate more heat produced as compared to voltage amplifier during its operation.
  • RC coupling is used in a voltage amplifier, In power amplifier invariably transformer coupling is used.
  • In voltage amplifier transistor used has a thin base to handle low current, power amplifier used has a thick base to handle the large current.
  • In the voltage amplifier the AC power output is low, In power amplifier the AC power output is high.
  • The physical size of transistor used is usually small and is known as low or medium power transistor while in power amplifier size of transistor used is usually large and is known as a power transistor.
  • In a voltage amplifier, the collector load has high resistance typically 4 kilo-ohms to 10-kilo-ohms while in power amplifier the collector load has low resistance typically 5 ohms to 20 ohms.
  • Voltage amplifier has a high voltage gain, while the power amplifier has a high power gain.
  • In most voltage amplifier current gain is very low while the power amplifier has significant current gain which results in the power gain.
  • Voltage amplifier dissipated relatively less heat than power amplifier, therefore, the voltage amplifier has higher power efficiency than a power amplifier. Also, power amplifier requires additional; cooling mechanism due to this fact.
  • A voltage amplifier is designed to achieve maximum voltage amplification however it is not important to raise the power level, On the other hand, while in a power amplifier is designed to obtain maximum output power.
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