Concept:-
FET:- FET stands for Field Effect Transistor and is a three-terminal active device that uses an electric field to control the current flow. The three terminals are Gate, Source and, Drain.
FET as Amplifier:- FET can be used as an amplifier when one or more FETs are used. The most common type of FET amplifier is the MOSFET amplifier.
Loading effect –It can be defined as the effect on the source by the load impedance. Usually loading effect reduces the voltage level of a voltage source
We will analyze this problem by going through options.
Option 1:-
High input impedance.
One of the most important factors that is kept in mind while designing FET as an amplifier is, it should have high input impedance. It minimizes the effect of loading on input and a thus significant amount of input voltage signal is maintained for amplification. Hence it is the best option to pick.
Other options-
Small size, temperature dependence and, unipolar nature are also important features of FETs when comparing with BJTs.But when we are talking about FET as an amplifier its high input impedance and low output impedance matter.
Small size: Smaller the size of FET better it is for modern uses.
Temperature dependence: BJT leakage current or reverse saturation current is highly sensitive to temperature. It doubles for every 10o celcius.There is no leakage current in FET which makes it thermally stable as compared to BJT.
Unipolar nature: Unlike BJTs FETs are unipolar in nature. As there is only one type of charge carrier.