A voltage follower, also known as a buffer circuit, is an electronic circuit that is designed to replicate the input voltage at its output while providing a high input impedance and a low output impedance. In other words, it follows the input voltage without amplifying or attenuating it, and it presents a minimal load to the source while being capable of driving a low-impedance load.
The basic configuration of a voltage follower circuit consists of an operational amplifier (op-amp) with a non-inverting input connected directly to the input voltage source and its output connected to the inverting input. The op-amp's high open-loop gain and feedback mechanism ensure that the output voltage closely matches the input voltage.
Here's a simplified explanation of its operation:
The input voltage is applied to the non-inverting input of the op-amp.
The op-amp tries to maintain a virtual short between its inverting and non-inverting inputs due to its high gain.
The op-amp adjusts its output to bring the inverting input to the same voltage as the non-inverting input, resulting in the output voltage being nearly identical to the input voltage.
Uses of a voltage follower (buffer) circuit:
Impedance Matching: Voltage followers are often used to match the impedance between a signal source and a load. When the source has a high output impedance and the load has a low input impedance, using a voltage follower in between ensures that the signal source is not significantly affected by the load impedance, and the load receives a strong signal.
Isolation: Voltage followers can provide electrical isolation between the input and output circuits. If there's a need to isolate the input and output while maintaining the same voltage level, a voltage follower can achieve this without allowing the input and output circuits to directly interact electrically.
Signal Conditioning: In some cases, a circuit might require a signal to be buffered before further processing. Voltage followers can ensure that the signal's integrity is maintained as it's passed to subsequent stages of the circuit.
Driving Low-Impedance Loads: Some signal sources have relatively high output impedance and cannot drive low-impedance loads effectively. A voltage follower can serve as a buffer to provide the necessary current and voltage capabilities to drive such loads without significant signal degradation.
Voltage Isolation: Voltage followers can be used to isolate voltage levels between different parts of a circuit, preventing voltage differences from affecting sensitive components.
Overall, a voltage follower (buffer) circuit is a simple yet crucial component in electronic systems, enabling efficient transfer of signals while maintaining signal quality and preventing unwanted interactions between different parts of a circuit.