What are the advantages of FET? FET is a constant current device which is controlled by voltage. By varying the input voltage we can control the output current. There are basically two types of FET1 is MOSFET and second is JFET. FET have following advantages. 1. FET have high input impedance. 2. FET have very high power gain. 3. FET is smaller in size. 4. FET is majority carrier device. 5. FET generate less noise as compared to BJT. These are some advantages of FET, field effect transistor.