Advanced Qualification · A-002 Advanced components and circuits · A-002-004-005
How does the input impedance of a field-effect transistor (FET) compare with that of a bipolar transistor?
- AOne cannot compare input impedance without knowing supply voltage
- BAn FET has low input impedance; bipolar transistor has high input impedance
- CThe input impedance of FETs and bipolar transistors is the same
- DAn FET has high input impedance; bipolar transistor has low input impedance
Correct answer: D — An FET has high input impedance; bipolar transistor has low input impedance. From the official ISED question bank, verified word for word.
Why
A field-effect transistor controls current using an electric field, so almost no current flows into its input, creating very high input impedance. The full explanation — and one for every question — is in Pro.
Practise this section
Advanced components and circuits is section A-002 of the Advanced exam: Advanced components and circuits: semiconductors, amplifier classes, oscillators, mixers, filters and digital logic.
Drill A-002 — free, no account