Depletion-mode MOSFET (D-MOSFET) biasing: Evaluate the statement “A D-MOSFET cannot be biased using zero-bias (V_GS = 0).” Choose the most accurate assessment.

Introduction / Context:Biasing methods differ for depletion-mode and enhancement-mode MOSFETs. Understanding whether a device conducts at zero gate-source voltage is key for low-power analog stages and simple current sources.

Given Data / Assumptions:

• Device type: D-MOSFET (depletion-mode).
• Claim: zero-bias operation (V_GS = 0) is not possible.
• Standard MOSFET physics and datasheet conventions apply.

Concept / Approach:A D-MOSFET has a physically present channel at V_GS = 0, so it naturally conducts without gate bias. Applying appropriate V_GS of the correct polarity reduces channel carriers (depletes) to reduce I_D; reversing polarity can enhance conduction. Therefore, zero-bias is not only possible but common in simple D-MOSFET applications.

Step-by-Step Solution:

Verification / Alternative check:Datasheets specify I_DSS (drain current at V_GS = 0), confirming valid zero-bias operation for D-MOSFETs.

Why Other Options Are Wrong:Correct: Conflicts with the presence of an I_DSS spec.

Only true for n-channel / only true at very low temperatures: Device polarity and temperature change magnitudes, not the fundamental ability to conduct at V_GS = 0.

Common Pitfalls:Mixing up D-MOSFET and E-MOSFET behavior. Assuming V_GS = 0 always turns a MOSFET off, which is only true for enhancement-mode types.

Final Answer:Incorrect