Why NPN Transistors are mostly used than PNP Transistors?

You may notice NPN transistors are mostly used than PNP transistors in electronic circuits but why? There are so many important and useful advantages of NPN transistor, for which, they are widely used in electronic circuits. The advantages are explained below.

Electron Mobility

Electron mobility is a property which tells how quickly an electron can move through a semiconductor when it pulled by an electric field.

We know that in PNP transistor the majority charge carrier is Holes but in NPN transistor the majority carrier is electrons. As the electrons have higher or faster mobility than holes, the conductivity also more. For this reason, NPN transistors are more preferable than PNP transistors because the NPN transistor provides more conductivity.

Negative Ground

We know that in electronic circuits all the negative(-ve) or common terminals are grounded. In the case of PNP transistor, the +ve lines become a common point for both input and output which cannot be grounded. 

But in the case of NPN transistor, -ve lines become a common point for both input and output which can be grounded. So, the using of NPN transistor instead of PNP transistor helps to ground the negative terminal.

Switching 

When the transistors are used in electronic circuits for switching purpose, then the NPN transistor is more preferable than the PNP transistor because the switching speed of the NPN transistor is greater than the PNP transistor. Also, we need to connect input supply in reverse bias and output circuit in forward bias. So, there is no need to reverse the output circuit.

Manufacturing Facility

The manufacturing of NPN transistors is more economical than PNP transistors because the PNP requires almost three times more silicon chip surface area than NPN. So, the production of NPN transistor is cost effective and economical.

Amplification

For small amplifier circuits using BJT, NPN transistor is more suitable because the response time and switching speed of NPN transistor are very fast due to electron mobility. NPN transistor has a better frequency response than the PNP transistor.

Common Emitter Configuration

The widely used configuration for amplification is a common emitter configuration. For the common emitter configuration, the NPN transistor is best because, in common emitter configuration, the -ve line becomes a common point for both input and output signal. But if we use PNP transistor in common emitter configuration, the +ve line becomes a common point for both input and output signals which cannot be grounded.

Reliability

NPN transistor provides more reliability than the PNP transistor along with it's higher speed, smaller size, low cost, etc. Also, it is easy to provide proper polarization for the connection.

Read Also:

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• Why all Electronic Devices Works on DC not AC?
• Why Diode used in Solar Panel, Relay and Soldering Iron?
• Can a step-up transformer be used as an amplifier?

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