Control nature of a JFET — current-controlled or voltage-controlled? Evaluate the statement: “A JFET can be either a current-controlled device or a voltage-controlled device.” Choose whether this characterization matches standard JFET operation.

Introduction / Context:Device control type—current-controlled vs. voltage-controlled—guides how we build amplifiers and bias networks. BJTs are typically modeled as current-controlled (collector current set by base current), while JFETs and MOSFETs are modeled as voltage-controlled (drain current set by gate-source voltage).

Given Data / Assumptions:

• JFET has a reverse-biased gate-channel p-n junction under normal operation.
• Gate current is extremely small; input impedance is very high.
• Small-signal drain current depends on gate-source voltage (Id ≈ f(V_GS)).

Concept / Approach:In a JFET, the electric field from the reverse-biased gate modulates the channel width. Thus, the drain current is primarily a function of V_GS, not gate current. Modeling uses transconductance gm = dId/dVGS, underscoring voltage control. Only if the gate is (undesirably) forward-biased would appreciable current flow into the gate, but this is outside proper linear operation and risks damage or distortion.

Step-by-Step Solution:

Verification / Alternative check:Datasheets specify transconductance (gm) and gate leakage currents in nanoamps or microamps, emphasizing voltage control and negligible input current.

Why Other Options Are Wrong:

Common Pitfalls:Projecting BJT intuition onto JFETs; confusing rare, abnormal forward-gate conditions with intended device use.

Final Answer:Incorrect