JFET terminology check: Are the “breakdown voltage” and the “pinch-off voltage” simply two names for the same JFET voltage? Choose the best evaluation.

Difficulty: Easy

Correct Answer: Incorrect

Explanation:


Introduction / Context:
JFET operation involves two important voltages: pinch-off and breakdown. Knowing the difference prevents biasing a device into destructive regions or misreading transfer curves.



Given Data / Assumptions:

  • Pinch-off voltage (V_P): channel just pinched and current becomes relatively constant with V_DS increase.
  • Breakdown voltage (V_BR): avalanche or junction breakdown occurs at excessive reverse bias.
  • We consider standard JFET operation with reverse-biased gate-channel junction.


Concept / Approach:
V_P defines the transition to the constant-current region (for a given V_GS), whereas V_BR is a high-voltage limit where the gate-channel junction avalanches. They are separated by a large margin on the output characteristic. Confusing them risks device failure.



Step-by-Step Solution:

Locate V_P on output curves: point where I_D saturates with rising V_DS.Locate V_BR: far to the right; current spikes due to breakdown.Different physics and vastly different magnitudes → not the same.Therefore the statement is incorrect.


Verification / Alternative check:
Review any JFET datasheet: V_P (or V_GS(off)) appears near a few volts; breakdown ratings are much higher (tens of volts), clearly distinct.



Why Other Options Are Wrong:
Correct / Ambiguous / Equivalent only for p-channel: None align with standard JFET curves where these voltages are categorically different.



Common Pitfalls:
Equating current saturation with breakdown, or misreading V_GS(off) as a breakdown limit. Each has separate specifications and design implications.



Final Answer:
Incorrect

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