How does a voltage follower circuit function?
1 Answer
A voltage follower circuit, also known as a buffer amplifier, is a basic electronic circuit that is used to isolate or separate two parts of a circuit while maintaining the same voltage level. It consists of an operational amplifier (op-amp) with a high input impedance and a low output impedance.
Here's how a voltage follower circuit functions:
Operational Amplifier (Op-Amp):
The heart of the voltage follower circuit is the operational amplifier. An op-amp is a differential amplifier with high gain, meaning it amplifies the voltage difference between its two input terminals. In an ideal op-amp, the following characteristics are assumed:
Infinite open-loop gain (A → ∞)
Infinite input impedance (Rin → ∞)
Zero output impedance (Rout → 0)
Infinite bandwidth
Zero offset voltage (Voff → 0)
Feedback Configuration:
In a voltage follower circuit, the feedback is configured in a unity gain (gain of 1) configuration. This means that the output voltage of the op-amp is fed back to its inverting (-) input terminal, creating a negative feedback loop. As a result, the op-amp adjusts its output voltage until the voltage at its non-inverting (+) input terminal (which is the input voltage) matches the voltage at its inverting input.
Input and Output Connection:
The input signal is connected to the non-inverting (+) input terminal of the op-amp. The output of the voltage follower is taken from the op-amp's output terminal. Since the feedback is configured for unity gain, the output voltage will be the same as the input voltage.
Operation:
When an input voltage is applied to the non-inverting terminal, the op-amp tries to maintain the same voltage at its inverting terminal by adjusting its output voltage. Due to the high input impedance of the op-amp, very little current flows into the op-amp's input terminals, virtually isolating the input from the output circuit. At the same time, the low output impedance of the op-amp ensures that it can supply a significant amount of current to the load without any significant voltage drop, allowing it to act as a buffer.
In summary, a voltage follower circuit takes an input voltage and produces an output voltage that precisely follows the input voltage, while providing isolation between the input and output stages of the circuit. It is commonly used to match impedances between different parts of a circuit and to prevent loading effects on the signal source.
Here's how a voltage follower circuit functions:
Operational Amplifier (Op-Amp):
The heart of the voltage follower circuit is the operational amplifier. An op-amp is a differential amplifier with high gain, meaning it amplifies the voltage difference between its two input terminals. In an ideal op-amp, the following characteristics are assumed:
Infinite open-loop gain (A → ∞)
Infinite input impedance (Rin → ∞)
Zero output impedance (Rout → 0)
Infinite bandwidth
Zero offset voltage (Voff → 0)
Feedback Configuration:
In a voltage follower circuit, the feedback is configured in a unity gain (gain of 1) configuration. This means that the output voltage of the op-amp is fed back to its inverting (-) input terminal, creating a negative feedback loop. As a result, the op-amp adjusts its output voltage until the voltage at its non-inverting (+) input terminal (which is the input voltage) matches the voltage at its inverting input.
Input and Output Connection:
The input signal is connected to the non-inverting (+) input terminal of the op-amp. The output of the voltage follower is taken from the op-amp's output terminal. Since the feedback is configured for unity gain, the output voltage will be the same as the input voltage.
Operation:
When an input voltage is applied to the non-inverting terminal, the op-amp tries to maintain the same voltage at its inverting terminal by adjusting its output voltage. Due to the high input impedance of the op-amp, very little current flows into the op-amp's input terminals, virtually isolating the input from the output circuit. At the same time, the low output impedance of the op-amp ensures that it can supply a significant amount of current to the load without any significant voltage drop, allowing it to act as a buffer.
In summary, a voltage follower circuit takes an input voltage and produces an output voltage that precisely follows the input voltage, while providing isolation between the input and output stages of the circuit. It is commonly used to match impedances between different parts of a circuit and to prevent loading effects on the signal source.