Which statement correctly describes an ideal voltage follower (buffer)?

• A. Low input impedance and high output impedance.
• B. Infinite input impedance and zero output impedance.
• C. Infinite input impedance and infinite output impedance.
• D. Low input impedance and low output impedance.

Answer: (B)

An ideal voltage follower acts as a buffer by presenting a very high input impedance to the source and a very low output impedance to the load, so it doesn’t draw significant current from the source and can drive the load effectively. In this ideal model, the input impedance is infinite and the output impedance is zero, which lets the output voltage track the input voltage exactly. The other descriptions fail because a low input impedance would load the source, and a high or infinite output impedance would prevent proper driving of the load, so buffering wouldn’t occur.