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voltage follower unknown OA

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meereck

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Hello all,
i would like to build a voltage follower. I found the scheme (see the attachment). Unfortunately, I am not able to get neither LM102 nor LM107. It seems they are obsolete.
What other ICs shall I use. I need to track, as accurately as possible, 2 differential signals, 60kHz, +-100mV.
Shall I employ bipolar of JFET operational amplifiers?

Thank you guys in advance,
regards Meereck
 

If you need an instrumentation amp as shown in your circuit diagram you can, in principle, use any unity gain compensated opamp.
As the input opamps are unity gain followers, it´s off less importance if they are equipped with BJT or FET input stages. However, of great importance are exact resistor values of the output stage.
Because of good accuracy at a frequency of 60 kHz the GBW should at least be (3..5) MHz. But don´t forget the slew rate.
 

LvW said:
If you need an instrumentation amp as shown in your circuit diagram you can, in principle, use any unity gain compensated opamp.
As the input opamps are unity gain followers, it´s off less importance if they are equipped with BJT or FET input stages. However, of great importance are exact resistor values of the output stage.
Because of good accuracy at a frequency of 60 kHz the GBW should at least be (3..5) MHz. But don´t forget the slew rate.
Click to expand...
Hi, thank you for a fast and useful reply.

Any examples of OA which is unity gain compensated?

Have a nice day. Meereck
 

Another comment:
Don´care about the 1 kOhm resistor for offset trimmming. It can be removed.
If you select an opamp with sufficient small offset voltage (say 0.1 mV) such a balance circuitry is not necessary because of the resistor tolerances of the output stage.
 

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