A voltage follower, also known as a buffer circuit, is a simple electronic circuit that has an input and an output, where the output voltage precisely follows the input voltage. In other words, it has a gain of 1, which means it doesn't amplify or attenuate the input signal; it only replicates the input voltage without changing its amplitude. The main purpose of a voltage follower circuit is to isolate the input from the output and provide a high input impedance and low output impedance.
The basic configuration of a voltage follower circuit consists of an operational amplifier (op-amp) with a unity gain configuration. An operational amplifier is a versatile integrated circuit that can be used to perform various signal processing tasks. When used as a voltage follower, the op-amp's inverting (-) input is connected to the output and the non-inverting (+) input is connected to the input signal. The op-amp's output is connected directly back to its inverting input, forming a feedback loop.
Key characteristics and uses of a voltage follower circuit:
Unity Gain: As mentioned earlier, the voltage follower has a gain of 1, so the output voltage is the same as the input voltage. This can be helpful in cases where you need to isolate the input signal from the load or downstream circuitry without affecting its amplitude.
High Input Impedance: The input impedance of a voltage follower is typically very high. This means that it draws very little current from the source supplying the input voltage, preventing loading effects that could distort the original signal.
Low Output Impedance: The output impedance of a voltage follower is usually quite low. This low impedance allows the voltage follower to deliver the replicated signal to the load with minimal signal loss or distortion.
Buffering: The primary use of a voltage follower is to act as a buffer between a source and a load. It prevents the load from affecting the original signal source and ensures that the load receives the signal with minimal distortion.
Impedance Matching: Voltage followers are sometimes used for impedance matching. If a signal source has a high output impedance and needs to be connected to a load with a lower input impedance, a voltage follower can bridge the impedance gap.
Signal Isolation: In some cases, voltage followers can provide isolation between two circuits. The input and output sides of the voltage follower can be electrically isolated, which can be useful in scenarios where signal integrity or safety is a concern.
Overall, a voltage follower (buffer) circuit is a simple yet important component in electronics, especially in signal processing and interfacing applications where maintaining signal integrity, isolation, and impedance matching are crucial.