BJT Amplifier Configurations vs. Key Characteristics Match each bipolar transistor configuration to its most typical small-signal characteristics.

Introduction / Context:
BJT amplifiers are commonly implemented in three configurations: common emitter (CE), common collector (CC, emitter follower), and common base (CB). Each has distinctive voltage and current gain properties important for stage selection in analog design.

Given Data / Assumptions:

• CE: general-purpose gain stage.
• CC: buffer with high input and low output impedance.
• CB: wide bandwidth, low input impedance stage.

Concept / Approach:

Rules of thumb: CE provides both significant voltage and current gain; CC has voltage gain slightly less than 1 but high current gain; CB exhibits current gain less than 1 but high voltage gain. These patterns guide the matching directly.

Step-by-Step Solution:

Verification / Alternative check:

Small-signal hybrid-pi models or gm*r_o approximations reproduce these qualitative results, confirming the mapping.

Why Other Options Are Wrong:

Swapped pairings contradict core behavior: CC cannot provide voltage gain > 1; CB cannot provide current gain > 1 under typical bias conditions.

Common Pitfalls:

Confusing CC with CE because both can show strong current gain; overlooking that CC is primarily a buffer.

Final Answer:

A-1, B-2, C-3