Single Ended to Differential conversion using two OpAmps - oscillations on output

Question

Hello,
I am having issues with a common SE to Differential conversion circuit basing on two Op Amps as shown in simulation. The problem I have is oscillations around 1-2 MHz on output. I added a capacitor in parallel to R1 (180 pF), tried different opamps (AD8513, ADA4898, OP4177, OP4227) - frequency shifts, amplitude differs but oscillations still occur. LTSpice shows a peak of gain near 2 MHz.
Could anyone explain my why this happens? What can I do to remove it?

jeobico · Accepted Answer

Hi bswiadkowski 
 Try to change the resistance values of RB RA R7 and R6 to 1k ohm. The possible issue here is that large resistance can induce stability issues. 
 You can check this article on the Stability section. 
 https://www.analog.com/en/analog-dialogue/studentzone/2019/07/25/14/48/studentzone-june-2017.html 
 Hope this helps. 
 Regards, 
 JE

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Single Ended to Differential conversion using two OpAmps - oscillations on output

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