There are other families of transistors besides the BJT Can

There are other families of transistors besides the BJT. Can you name some applications that only use BJTs?

Solution

There are many other families of Transistors besides BJTs like Metal oxide semiconductor field effect transistor (MOSFET), Fin Field Effect Transistors (FINFETs), Junction field effect transistors (JFETs).

BJTs are faster devices than any other transistor because their transconductance is usually higher than other transistors. So we use them in applications where we require faster switching and higher speeds. However, they come with a disadvantage, which is their increased power dissipation as compared to other counterparts. This is primarly because of higher switching speeds and the large temperature dependant leakage currents.

Some applications that use BJTs only are:

1) Audio and High frequency power amplifiers because of thier low stray capacitance than MOSFETs.

2) TTL and ECL logic. Transistor transistor logic and emitter coupled logic is a very fast logic as it employs BJTs only.

3)Darlington pairs. Darlington pair is a pair BJTs connected such that emitter current of once becomes base current of another. This increases the net current drive of the structure. BJTs are used as they have high transconductance. It uses either two PNP or two NPN BJTs. NPN are preffered.

4) Sziklai pairs.This circuit is complementary to Darlington pair. In contrast to the Darlington arrangement, the Sziklai pair has one NPN and one PNP transistor, and so it is sometimes also called the \"complementary Darlington\"

5) Almost all linear analog integrated circuits including555 timers, Oscillators, Multivibrators, etc all use BJTs because of high current gain and good slew rate.

MOSFETs are used in Digital integrated design and in VLSI applications like memories as they occupy less area than BJTs.