A voltage follower, also known as a buffer circuit, is a simple electronic circuit designed to provide impedance matching and isolation between two parts of an electronic system. Its primary purpose is to isolate or decouple one circuit from another while maintaining the same voltage level. This is achieved by using an operational amplifier (op-amp) or a transistor configured in an appropriate way.
The main functions and purposes of a voltage follower circuit are:
Impedance Matching: In electronic systems, different circuits or components often have different input and output impedance levels. Impedance mismatch can lead to signal loss, distortion, or loading effects. A voltage follower helps to match the impedance between a source and a load, ensuring that the source is not affected by the load's impedance.
Isolation: Sometimes, a sensitive or high-impedance input circuit needs to be connected to a low-impedance load. Without a buffer, connecting these directly might affect the operation of the input circuit. A voltage follower isolates the input from the load, preventing the load from affecting the input's performance.
Voltage Level Preservation: A voltage follower ensures that the output voltage accurately tracks the input voltage. It provides unity gain, meaning that the output voltage is equal to the input voltage. This can be useful when you want to maintain the same voltage level while driving a load.
Eliminating Loading Effects: When you connect a load to a source, it can draw current from the source. If the load's impedance is significantly lower than the source's impedance, this can result in a significant voltage drop across the source's internal resistance. By using a voltage follower, the load effectively draws current from the buffer instead of the source, minimizing loading effects.
Voltage Isolation: In some cases, you might want to isolate a sensitive input circuit from a potentially noisy or high-voltage source. A voltage follower can provide this isolation by acting as a barrier between the input and the source.
Voltage Buffering: When driving a capacitive or high-impedance load, the output of a signal source might not be able to supply sufficient current to charge or discharge the load quickly. A voltage follower can supply the necessary current to the load without affecting the signal source.
Overall, the voltage follower circuit is a versatile tool in electronics design, enabling efficient signal transfer between components with different impedance characteristics and providing isolation and protection for sensitive circuits. It ensures that signals can be transferred accurately and reliably without degradation or interference.