Common-base amplifier phase property: In a small-signal common-base (CB) BJT amplifier, is the output signal inverted 180 degrees relative to the input?

Introduction / Context:
BJT small-signal stages come in three canonical forms: common-emitter (CE), common-collector (CC, emitter follower), and common-base (CB). Each has distinct input/output phase relationships that matter for multistage amplifier design and feedback networks.

Given Data / Assumptions:

• Operating region: forward-active, small-signal.
• Biasing ensures linear operation around a quiescent point.
• Source drives the emitter for CB; output is taken at the collector.

Concept / Approach:
The CE stage inverts (≈180°) due to how collector current variations translate into collector voltage across the load. In contrast, the CB stage exhibits a noninverting voltage transfer because the input signal is applied to the emitter; an increase in emitter current leads to an increase in collector current and a corresponding output voltage change that is in phase (considering sign conventions and load orientation). Hence, the CB stage is effectively noninverting for voltage signals, though its input impedance is low and current gain is near unity.

Step-by-Step Solution:

Verification / Alternative check:
Small-signal hybrid-pi analysis yields a positive voltage transfer for CB with appropriate polarity references and confirms near-unity current gain but significant voltage gain.

Why Other Options Are Wrong:

Common Pitfalls:
Misremembering which stage inverts; overlooking the emitter-driven nature of CB.

Final Answer:
Incorrect — CB stage is noninverting (0° phase shift)