Amplifier coupling methods – Match each coupling with its characteristic advantage List I (Coupling type) A. RC coupling B. Inductive (choke/LC) coupling C. Transformer coupling D. Direct coupling List II (Feature) High voltage gain with impedance matching capability Ability to amplify down to dc and very low frequencies Minimum non-linear distortion (good fidelity in midband) Low collector supply voltage can be used Choose the correct mapping.

Introduction / Context:
Choosing a coupling method affects gain, bandwidth, distortion, and power-supply constraints. This mapping highlights the classic strengths of each technique in small-signal amplifiers.

Given Data / Assumptions:

• RC coupling: broad midband response with good linearity.
• Inductive coupling: allows operation with relatively low supply through high AC load impedance using a choke.
• Transformer coupling: offers step-up/step-down for impedance matching and high voltage gain.
• Direct coupling: passes dc, enabling amplification at very low frequency and bias inter-stage transfer.

Concept / Approach:

Map each coupling to its widely cited advantage: RC → low distortion in midband; inductive → workable with lower Vcc; transformer → gain and matching; direct → dc to low-frequency amplification.

Step-by-Step Solution:

Verification / Alternative check:

Classic analog design references agree with these qualitative comparisons across coupling methods.

Why Other Options Are Wrong:

Assigning impedance matching to RC or direct coupling is incorrect; claiming dc amplification for transformer/RC coupling ignores blocking by reactive components.

Common Pitfalls:

Confusing “low supply voltage” benefit of inductive loads with “high gain” of transformers; overlooking that RC coupling rolls off at low frequencies.

Final Answer:

A-3, B-4, C-1, D-2.