What's the advantage of using a voltage buffer amplifier?

In summary, a voltage follower acts as a buffer to isolate the input circuit from the output circuit, preventing changes in impedance and maximizing power transfer. It is beneficial for cases where a high impedance source cannot be loaded, and allows for changing the impedance between the source and load. This can be demonstrated through the example of using a buffer amplifier between an oscillator and an amplifier stage, to maintain stability and prevent changes in frequency or power output.
  • #1
RonzRknob
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i want to understand what's the advantage of using a voltage follower
 
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  • #2
A voltage follower is used to buffer the signal. It is helpful for changing impedance, too.

For example if you have a high impedance source that you cannot load, maybe a crystal oscillator, you can use the voltage follower to then distribute the signal to multiple loads, or maybe an amplifier that has a lower input impedance like a BJT.
 
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  • #3
RonzRknob said:
i want to understand what's the advantage of using a voltage follower

Voltux said:
A voltage follower is used to buffer the signal. It is helpful for changing impedance, too.

For example if you have a high impedance source that you cannot load, maybe a crystal oscillator, you can use the voltage follower to then distribute the signal to multiple loads, or maybe an amplifier that has a lower input impedance like a BJT.
great answer, Voltux :smile:

@RonzRknob, a buffer, usually (but not always) has a gain of 1 ( unity gain) and is a great way to stop one circuit from affecting another

Using an op-amp in this configuration is a very popular practice eg …..
buffer.gif
upload_2018-8-26_12-36-9.png
jackormanopampbuffer-gif.gif
upload_2018-8-26_12-39-31.png

The sole purpose of a buffer circuit is to isolate the input circuit from the output circuit


Dave
 

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  • #4
@davenn , can you further explain me why isolating the input circuit from the output circuit is beneficial?
 
  • #5
Imagine a source which has a series resistance of Rs and a load with resistance Rl. Try calculating how the power dissipated in the load changes as Rl changes. If Rl = 0 then there would be no voltage across it so the Power I*V would be zero. If RL was infinite there would be no current so again the power dissipated in the load would be zero. It so happens that the power is a maximum when Rl = Rs.

But what if they are fixed and RL <> Rs?

Inserting a buffer amplifier between the two allows you to change the impedance driving the load and maximise power transfer. This is what others mean by changing the impedance.
 
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  • #6
RonzRknob said:
@davenn , can you further explain me why isolating the input circuit from the output circuit is beneficial?

I did answer that in post #3 as did @Voltux in post #2

His example of an oscillator circuit being affected ( loaded down) by the circuit placed on the output of the oscillator is an idea solution.
The circuit following the oscillator may be an amplifier stage, but just directly connection that amplifier to the output of the oscillator without any buffering isolation can cause the oscillator or function incorrectly, commonly by causing it to change it output frequency and or power output.
By putting a unity gain buffer stage in there between the oscillator and the amplifier, stops the amplifier stage from affecting the oscillators output. Thus the oscillator remains stable and its output doesn't frequency/power wobble all over the place.
 
  • #7
CWatters said:
Imagine a source which has a series resistance of Rs and a load with resistance Rl. Try calculating how the power dissipated in the load changes as Rl changes. If Rl = 0 then there would be no voltage across it so the Power I*V would be zero. If RL was infinite there would be no current so again the power dissipated in the load would be zero. It so happens that the power is a maximum when Rl = Rs.

But what if they are fixed and RL <> Rs?

Inserting a buffer amplifier between the two allows you to change the impedance driving the load and maximise power transfer. This is what others mean by changing the impedance.
Thank you , that was helpful
 
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  • #8
davenn said:
I did answer that in post #3 as did @Voltux in post #2

His example of an oscillator circuit being affected ( loaded down) by the circuit placed on the output of the oscillator is an idea solution.
The circuit following the oscillator may be an amplifier stage, but just directly connection that amplifier to the output of the oscillator without any buffering isolation can cause the oscillator or function incorrectly, commonly by causing it to change it output frequency and or power output.
By putting a unity gain buffer stage in there between the oscillator and the amplifier, stops the amplifier stage from affecting the oscillators output. Thus the oscillator remains stable and its output doesn't frequency/power wobble all over the place.
Thanks Dave , I can now see it through
 
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1. What is a voltage buffer amplifier?

A voltage buffer amplifier is an electronic circuit that is used to isolate or separate one part of a circuit from another, while maintaining the same voltage level. It is also known as a unity-gain amplifier since it has a gain of 1, meaning the output voltage is the same as the input voltage.

2. How does a voltage buffer amplifier work?

A voltage buffer amplifier works by using a high input impedance and a low output impedance to prevent the input signal from being affected by the load connected to the output. It also has a high gain, which helps to overcome any losses in the circuit and maintain the same voltage level at the output.

3. What are the advantages of using a voltage buffer amplifier?

The main advantage of using a voltage buffer amplifier is that it isolates the input and output signals, preventing any interference or loading effects. It also helps to maintain the same voltage level at the output, making it useful for impedance matching and signal buffering in electronic circuits.

4. In what situations is a voltage buffer amplifier useful?

A voltage buffer amplifier is useful in situations where the input signal needs to be isolated from the output, or when there is a need to maintain the same voltage level at the output. It is commonly used in audio amplifiers, voltage regulators, and signal conversion circuits.

5. Are there any drawbacks to using a voltage buffer amplifier?

One potential drawback of using a voltage buffer amplifier is that it can introduce noise into the circuit due to its high gain. It also requires a power supply to function, which can add to the complexity and cost of a circuit. Additionally, if the input signal is too large, it can cause the amplifier to saturate, resulting in distortion at the output.

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