field-effect transistor,field effect transistor notes


In ordinary transistor both electrons and holes play part
process. For this reason, it is sometimes bipolar junction
The ordinary or bipo!ar transistor have mainly two disadvantaooo
1) It has low input impedance because of forward biased emitter
2) It has considerable noise level
Low input impedance problem improved by careful design and
more one transistor, so is difficult t0 achieve input impedane
than a few mega ohms. The Field Effect Transistor (FET) has large
impedance, which may be more than 100 mega ohms due to its constructia
biasing. FET is génerally much less noisy than the ordinary of bipolar transs
A BJT is a current controlle , which means output characteristics
device controlled by base current and not by base voltage. However,
the output characteristics controlled by input voltage and not uy
current. This is probably the biggest difference between BJT and Ful
There are two basic types of FET
a) Junction Field Effect Transistor (JFET)
b) Metal Oxide Field Effect Transistor (MOSFET)


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