Difference Between BJT vs MOSFET

Difference Between BJT vs MOSFET

If you are a physics student, you should be able to spot the difference between BJT and MOSFET systems. You see, those electronic materials help give experts the output signal for infinitesimal variations in small input performance. Interestingly enough, you may be struggling to distinguish between them because the terms are much too technical for you to deal with.

Well, one assurance you will get from us is that this guide will simplify them for you. In the end, you will not grapple with the words any longer. So, we will start with the definitions and then focus on the dissimilarities.

Definition of BJT

BJT is a type of semiconductor used in place of vacuum tubes in the past. With this gadget, the overall output of a circuit can be controlled easily. In such circuits, the output of the base terminal is often dependent on the current through the terminal or emitter. In other words, the current flowing through the base terminal determines how a user can apply the transistor.

Coming to its architecture, this is made of silicon pieces. It is also important to note that it has 3 regions and 2 junctions. While the 2-junction structure is known as the P-junction, the 3-region structure is called the N-junction.

In clear terms, there are PNP and NPN types of such electrical equipment. Based on the simple terminology, P stands for positive, and the main electricity carriers are the holes. N means negative, and the most significant electricity carriers are the electrons.

It is usually ideal for carrying low-power applications such as those seen in switching purposes. With the voltage, the charge through the terminal into the collector end is regulated. It was invented by physicists John Bardeen and Walter Brattain with the guidance of William Shockley in 1947–1948. Before we discuss the difference between MOSFET and BJT, let’s explain the former a little.

Definition of MOSFET

MOSFET means metal oxide semiconductor field-effect transistor. Looking at it closely, this is a device designed to execute the principle of controlled oxidation in circuits. It was a brainchild of physicists Mohammed Atalla and Dawon Kahng at Bells Labs in 1959. Indeed, it is typically made of silicon.

With the voltage of the gate fully working, it is very easy to determine the electrical conductivity of the entire system. It is capable of changing conductivity, which, on the other hand, influences its signal amplifying or switching capacities. The benefit of using this device is that it does not require any current to control its load. When current is applied to the gate terminal, it ramps up conductivity.

In a similar vein, when voltage is applied to this same electrical gadget at the same terminal, conductivity is reduced significantly. It exists in P-type and N-type channels. The N-type has either an enhancement or depletion mode. Looking at the architectural design, the N-type is the product of the source and drain terminals.

Main Differences Between BJT vs MOSFET

To understand MOSFET vs BJT, study the table closely.

Basis of ComparisonBJTMOSFET  
TypesThis has PNP and NPNIt has N and P channels
PrincipleThis is a current-controlled circuitThis is a voltage-controlled circuit
Temperature coefficientNegativePositive
InventorsJohn Bardeen and Walter Brattain with the guidance of William ShockleyMohammed Atalla and Dawon Kahng
Year of Invention1947–19481959
Electrostatic dischargeThis is not a problemElectrostatic discharge can cause a major problem
ResistanceIt is low hereIn this case, it is high
Input impedanceLowHigh
Switching frequencyIt is very lowIt is extremely high
Full meaningsBipolar junction transistorMetal oxide semiconductor field-effect transistor

Difference Between BJT and MOSFET: Conclusion

Without a doubt, this piece has been informative thus far. To summarize this guide on BJT vs MOSFET, it is important to point out the key dissimilarities between them.

It is easy to deduce that while the former is low on impedance, switching frequency, and input impedance, the reverse is the case with the latter as they are all high. Looking at their principles, BJT focuses on controlling current, whereas MOSFET emphasizes controlling voltage. Finally, those are the most crucial dissimilarities between them.