Extra exam question E6A05
Subelement E6, CIRCUIT COMPONENTS· Group E6A
How does DC input impedance at the gate of a field-effect transistor (FET) compare with that of a bipolar transistor?
- A.They are both low impedance
- B.An FET has lower input impedance
- C.An FET has higher input impedance (correct answer)
- D.They are both high impedance
WhyThe DC input impedance at the gate of a field-effect transistor is higher than that of a bipolar transistor. A field-effect transistor's gate is essentially insulated from, or forms a reverse-biased junction with, the channel, giving it a very high DC input impedance compared to a bipolar transistor's base, which draws a real base current through a forward-biased junction, answer C. Both aren't low impedance, and an FET doesn't have lower input impedance than a bipolar transistor, it's the opposite relationship.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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