The input impedance of a JFET is _____________ compared to standard bipolar transistors?
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Answer: C. more than
Explanation
Junction Field Effect Transistors utilize a reverse-biased gate-channel p-n junction during normal operation. Reverse biasing a semiconductor junction restricts gate leakage current to extremely small nanoampere levels. High input impedance prevents the transistor gate circuit from loading down preceding signal stages. Input impedance measures the opposition to signal currents presented by the control terminals of a device. Bipolar junction transistors are current-controlled devices requiring continuous base current during operation. Field effect transistors are voltage-controlled devices governed by electric field effects across the channel.
High input impedance makes JFETs ideal for sensitive measuring instruments and analog sensor interfaces. Audio preamplifiers utilize JFET input stages to prevent signal distortion from source loading effects. Electronic circuit designers choose transistors based on input impedance requirements for signal fidelity. Option A is incorrect because JFET input impedance is significantly higher than bipolar transistors. Option B incorrectly implies that JFET input impedance is lower than standard transistor types. Option D is incorrect because the difference in input impedance characteristics is well documented.
- Subject
- Engineering
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- Electrical Engineering
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- —
- Difficulty
- medium
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