BJT fundamentals (naming the three configurations): In bipolar junction transistor amplifier theory, the three standard circuit configurations are known as common-base (CB), common-emitter (CE), and common-collector (CC, also called the emitter follower). Is this statement accurate?

Introduction / Context:
Bipolar junction transistors (BJTs) are used in three canonical amplifier topologies: common-base (CB), common-emitter (CE), and common-collector (CC). The CC configuration is popularly called the emitter follower because its output (emitter) “follows” the input voltage at the base with approximately unity gain but lower impedance. Recognizing this standard taxonomy is foundational for understanding gain, input/output impedance, and phase inversion across BJT stages.

Given Data / Assumptions:

• The statement lists common-base, common-emitter, and emitter-follower as the three configurations.
• “Emitter follower” is synonymous with “common collector.”
• Small-signal, linear operation around a bias point is assumed.

Concept / Approach:
The “common-” label indicates which terminal is shared by both input and output circuits. In CE, the emitter is common and the stage provides significant voltage and current gain with 180° phase inversion. In CB, the base is common; the stage provides low input impedance and high voltage gain with no inversion. In CC (emitter follower), the collector is common; the stage provides high input impedance, low output impedance, and near-unity voltage gain with no inversion. Together, these three cover the standard BJT amplifier families used in cascades and buffers.

Step-by-Step Solution:

Verification / Alternative check:
Any introductory electronics text defines the three standard BJT configurations precisely in this way, often summarizing their gain and impedance properties in a comparison table.

Why Other Options Are Wrong:
Limiting to NPN ignores that topology names are independent of polarity. Frequency limits and beta values do not alter the naming of configurations.

Common Pitfalls:
Confusing “emitter follower” with CE; forgetting that “follower” means voltage gain near one but strong buffering (low Rout, high Rin).

Final Answer:
Correct