Dear all,
Could I use this device for voltage follower?
If this device is usable, where is the reason at data sheet?
Best regards,
Takao,
Most op amps are stable in the unity gain (follower) configuration and if they are not this is typically specified on the front page of the datasheet. But you can confirm this by looking at the Open-Loop Gain graph shown below and to make sure that the phase margin (shown in red) for the Gain=1 (shown in blue) is at least 45 degrees. In case of OPA4348 shown below the phase margin for unloaded output is around 65 degrees so the circuit should be stable.
The rule of thumb is that a small-signal overshoot of less than 25% should assure stability of the circuit. Thus according to the graph below OPA4348 should be stable in G=1 with up to ~700pF loads.
For more detailed discussion of the stability in op amps, please read/watch the TI Precsion Lab material under link below:
