What is a voltage follower and what advantages does it offer in signal conditioning?

What is a voltage follower and what advantages does it offer in signal conditioning?

• A. A fixed gain amplifier that amplifies by a preset factor.
• B. A buffer that converts a voltage to current.
• C. A unity-gain buffer that presents high input impedance and low output impedance, preventing loading of previous stages and isolating stages for better drive capability.
• D. A differentiator stage.

Answer: (C)

A voltage follower is a unity-gain buffer built with an op-amp wired so the output feeds back to the inverting input while the input signal is applied to the non-inverting input. Because the gain is about one, it doesn’t amplify the voltage, it simply copies it. The big advantage is impedance management. It presents a very high input impedance, so it draws almost no current from the source, preventing the source from being loaded down. At the same time it provides a low output impedance, which means it can drive the next stage or a longer cable without the signal sagging. In short, it isolates stages: the source and the load don’t affect each other as much, and the buffer can supply the current the next stage needs for proper drive. In signal conditioning, this is useful when you have a high-impedance sensor or signal source and you want to preserve the signal level while feeding a subsequent stage that might require more current or a definite low-impedance drive, such as an ADC input or a long interconnect. Note that other options describe devices that change the signal magnitude, convert voltage to current, or alter the signal shape, which is why they don’t capture the buffering and drive-provision role of a voltage follower.

A voltage follower is a unity-gain buffer built with an op-amp wired so the output feeds back to the inverting input while the input signal is applied to the non-inverting input. Because the gain is about one, it doesn’t amplify the voltage, it simply copies it.

The big advantage is impedance management. It presents a very high input impedance, so it draws almost no current from the source, preventing the source from being loaded down. At the same time it provides a low output impedance, which means it can drive the next stage or a longer cable without the signal sagging. In short, it isolates stages: the source and the load don’t affect each other as much, and the buffer can supply the current the next stage needs for proper drive.

In signal conditioning, this is useful when you have a high-impedance sensor or signal source and you want to preserve the signal level while feeding a subsequent stage that might require more current or a definite low-impedance drive, such as an ADC input or a long interconnect. Note that other options describe devices that change the signal magnitude, convert voltage to current, or alter the signal shape, which is why they don’t capture the buffering and drive-provision role of a voltage follower.