An n-channel JFET has IDSS=2mA and Vp=-4v. Its transconductance gm (in mA/V) at VGS=-2v equals___________?
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Answer: B. 0.5
Explanation
JFET transconductance equation relates transconductance to gate-source and pinch-off voltages. Substituting minus two volts into the formula yields half the maximum transconductance value. Calculating with IDSS of 2mA and Vp of -4v results in 0.5 mA/V. JFETs are voltage-controlled devices where gate voltage modulates channel width. Transconductance measures how effectively gate voltage controls drain current flow. Pinch-off voltage represents the gate bias required to pinch the conducting channel closed.
Analog circuit designers use JFET transconductance to calculate small-signal voltage gains. Sensor interface circuits often employ JFETs for high input impedance amplification. RF mixer circuits utilize JFET transconductance properties for signal modulation. Zero point twenty-five is a mathematical error resulting from incorrect formula usage. Zero point seventy-five represents an incorrect calculation for the given voltage ratio. One milliamp per volt overestimates the transconductance value for the specified bias.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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