Amateur Extra › E6 Circuit Components › E6A05
E6A05
How does DC input impedance at the gate of a field-effect transistor (FET) compare with that of a bipolar transistor?
Pick an answer to check it.
Answer: C. An FET has higher input impedance
An FET gate is insulated or reverse biased, so it draws almost no DC current and has very high input impedance. A bipolar transistor's base draws current, giving lower input impedance.
Tip: FET gate barely sips current: high impedance.