A voltage follower, also known as a buffer circuit, is an electronic circuit configuration used to isolate and amplify signals. Its primary purpose is to maintain the voltage level of an input signal while providing a high input impedance and a low output impedance. In simpler terms, a voltage follower circuit ensures that the output voltage follows the input voltage closely without introducing significant changes in voltage or current.
The voltage follower is constructed using an operational amplifier (op-amp) or a similar amplifying device. The basic setup involves connecting the inverting input terminal of the op-amp to the output terminal and connecting the non-inverting input terminal to the input signal source. A feedback loop is used to stabilize the circuit and ensure that the op-amp adjusts its output to match the input voltage.
The key purposes and benefits of using a voltage follower circuit are as follows:
Impedance Matching: Voltage followers are commonly used to match the impedance between a signal source and a load. When a signal source has a high output impedance (internal resistance), it may struggle to drive a load with lower input impedance. By using a voltage follower in between, the high input impedance of the follower prevents signal degradation due to mismatched impedances.
Isolation: A voltage follower provides electrical isolation between the input and output circuits. This isolation can be important in cases where the input and output circuits have different ground references or when you want to prevent interactions between the two circuits.
Signal Amplification: While the primary goal of a voltage follower is not amplification, it can still provide a small degree of amplification due to the open-loop gain of the op-amp. However, this amplification is usually close to unity (gain of 1), meaning that the output voltage closely tracks the input voltage.
Voltage Stabilization: The voltage follower circuit helps stabilize the output voltage against changes in load impedance. Since the op-amp adjusts its output to match the input voltage, variations in the load won't significantly affect the output voltage.
Voltage Isolation in Feedback Networks: Voltage followers are often used in feedback networks of more complex electronic systems. They can isolate the effects of one stage from another, preventing unwanted interactions and maintaining the integrity of the overall system.
In summary, the voltage follower circuit serves as a valuable tool in electronics for maintaining signal integrity, impedance matching, and isolating different parts of a circuit. Its ability to provide a faithful replica of the input voltage, while effectively isolating input and output circuits, makes it a versatile building block in various electronic applications.