Small-signal h-parameters (common-emitter, typical orders of magnitude): Match each parameter symbol to its representative magnitude or unit category. List I List II A. h_ie (input resistance) 1. 49 (current gain h_fe) B. h_re (reverse voltage) 2. 25 × 10^-6 siemens (output conductance h_oe) C. h_fe (forward current gain)3. 2.4 × 10^-4 (dimensionless) D. h_oe (output conductance) 4. 1000 ohms (kΩ range)
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AA-1, B-2, C-3, D-4
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BA-4, B-3, C-2, D-1
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CA-3, B-4, C-1, D-2
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DA-4, B-3, C-1, D-2
Answer
Correct Answer: A-4, B-3, C-1, D-2
Explanation
Introduction / Context:h-parameters summarize a BJT’s small-signal behavior. Remembering their typical magnitudes helps you sanity-check datasheets and exam problems quickly.
Given Data / Assumptions:
- Common-emitter configuration assumed.
- Representative (order-of-magnitude) values are used.
- Exact values vary with bias and device type; the goal is correct pairing.
Concept / Approach:
Recall: h_ie is an input resistance (kΩ range), h_re is a very small reverse transfer (10^-4), h_fe is the familiar current gain (tens to hundreds), and h_oe is an output conductance (tens of μS).
Step-by-Step Solution:
h_ie → ≈ 1 kΩ ⇒ A-4.h_re → ≈ 2.4 × 10^-4 (dimensionless) ⇒ B-3.h_fe → ≈ 49 (unitless current gain) ⇒ C-1.h_oe → ≈ 25 × 10^-6 S (μS) ⇒ D-2.Verification / Alternative check:
Typical transistor small-signal models list h_ie in the kilo-ohm range, h_fe near 50–200, h_re in the 10^-4–10^-3 range, and h_oe in tens of μS, confirming the mapping.
Why Other Options Are Wrong:
- Swapping h_ie with a conductance value mixes resistance with siemens.
- Assigning large numeric gain to h_re contradicts its back-transfer meaning.
Common Pitfalls:
Confusing h_fe (current gain) with β in DC; while related, the small-signal and DC operating points may differ.
Final Answer:
A-4, B-3, C-1, D-2