what is the function and benefit of 2 amplifiers composited

Thread Starter

Robert0214

Joined Jan 31, 2018
3
Hi All,
About below circuit in the figure,Could someone help to explain the benefit of 2 amplifer compsited?
Below CLC425 is Voltage FeeBback ampflier,CLC430 is Current FeedBack amplifer.
But i also find some circuit use 2 voltage feeback amplifers together.
I do not understand the benefit of 2 amplifers composited.
Thanks a lot
upload_2018-2-2_9-36-57.png
 

AnalogKid

Joined Aug 1, 2013
10,986
There can be many different reasons for combining two opamps in series. For example, an opamp with extremely low noise followed by one that can drive a relatively low impedance load, such as a microphone preamp and a 600 ohm line driver.

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MisterBill2

Joined Jan 23, 2018
18,167
Hi All,
About below circuit in the figure,Could someone help to explain the benefit of 2 amplifer compsited?
Below CLC425 is Voltage FeeBback ampflier,CLC430 is Current FeedBack amplifer.
But i also find some circuit use 2 voltage feeback amplifers together.
I do not understand the benefit of 2 amplifers composited.
Thanks a lot
View attachment 144959
The reason to use two amplifiers was explained to me as being caused by a term called "Gain-bandwidth Product", which is exactly what it says. The reason that this is a limiting factor is fairly complex, but usually the op-amp gain drops as the frequency to a given amplifier rises. But it is a device function, not a system function. So the result is that two op- amplifiers each with a gain of 10 will give better response than just one of the same kind set for a gain of 100. And often it is cheaper than using one much higher performance op-amp.
But a caution is that you need to pay close attention to the input voltages of the amplifiers in the chain so as to avoid overloads.
 
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