Question

The most costly coupling is ____________ coupling

(a) Transformer

(b) Impedance

(c) RC

(d) Direct

This question was posed to me in final exam.

This is a very interesting question from Class A Output Stage topic in division Differential and Multistage Amplifiers of Electronic Devices & Circuits

Answer 1

Right option is (a) Transformer

Explanation: In Transformer coupling, audio transformers are used. This requires a larger core and more turns, making a more expensive transformer coupling. Transformer coupling is very widely used at radio frequencies, but it is also practical at audio frequencies, say 30 to 30,000 Hz.