Difficulty: Easy
Correct Answer: A-3, B-1, C-2
Explanation:
Introduction / Context:The hybrid (h-parameter) model is a popular small-signal representation of bipolar junction transistors. Correct units reinforce physical meaning: impedance in ohms, admittance in siemens, and current gain as dimensionless.
Given Data / Assumptions:
Concept / Approach:By definition: h_ie is an input impedance (V/I) → ohms; h_oe is an output admittance (I/V) → siemens; h_fe is a ratio of currents (ΔI_c/ΔI_b) → dimensionless. Recognize that “e” subscript denotes the common-emitter configuration and the “i/o, e/f” letters indicate input/output and impedance/admittance or current/voltage relationships.
Step-by-Step Solution:
Match A (h_ie) → 3 (ohms).Match B (h_oe) → 1 (siemens).Match C (h_fe) → 2 (no units).Verification / Alternative check:Dimensional analysis of the hybrid equations v1 = h11 i1 + h12 v2 and i2 = h21 i1 + h22 v2 confirms the unit assignments for the corresponding elements.
Why Other Options Are Wrong:
Common Pitfalls:Memorizing symbols without understanding that “ie” and “oe” encode which port and which type of quantity is being referenced.
Final Answer:A-3, B-1, C-2
Discussion & Comments