GATE EC 2014 Set 1 — Question 21

A current buffer, also known as a current follower, is an amplifier circuit designed to have a current gain of approximately unity. Its purpose is to take a current from a source and deliver it to a load, isolating the source from the load.Input Impedance:
To be effective, a current buffer must draw the entire current from the source it is connected to. According to the current divider rule, to maximize the current flowing into the buffer's input, its input impedance ($R_{in}$) must be much smaller than the source impedance. Ideally, the input impedance should be zero ($R_{in} \to 0$).Output Impedance:
The buffer should act as a constant current source to the load, meaning the output current should be independent of the load impedance. A circuit that behaves like a current source has a very high output impedance ($R_{out}$). Ideally, the output impedance should be infinite ($R_{out} \to \infty$).Therefore, a good current buffer has low input impedance and high output impedance.This is in contrast to a voltage buffer (voltage follower), which has high input impedance and low output impedance.Hence, the correct option is (B).