TL074: TL074I Output Oscillation Question

Hi GaryC, 

GaryC said:

Please help to check the schematic and provide your suggestions for solving the problem

What is pin 10 driving in actual application? Can you send me the schematic? TL074I will need some compensation in order get rid of the high frequency oscillation. 

Best,

Raymond

Hi Raymond,

Please refer to the below schematic. They use different channels of CD4066 for switching different Gain. They found when they turn-on switch D, then it cause the high frequency oscillation. 

May I know how to compensate the loop? Could you help to use TINA to simulation the problem?

BR,

Gary

Hi Gary,

GaryC said:

They found when they turn-on switch D, then it cause the high frequency oscillation. 

Can you clarify which measured node that is seen oscillation at p76B's pin7, T90 or T71. I want to know the closest oscillation node after p76B's output pin7 terminal.  

Based on your schematic, the TL074's op amp configuration for D channel looks like the following. Could you confirm that my understanding is correct per your description?

I need to understand the switch's on resistance and associated parasitic capacitance. Not all the information is specified in the CD4066's datasheet. I assumed that the switch is turned on in 20nsec - 40nsec range. Is it the Switch D turned on in the middle of operation while the system is live (real-time gain changing events). 

Can you describe the switch turn-on sequences? There are other Switches in the circuit - do you observe oscillation at the op amp's other settings at output? Is this an exiting product? When was the oscillation issues surfaced? The TL074I product has issued PCN recently, see the PCN. It will be good to describe the history of the product. 

https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/5046/PCN20221219006.1.pdf

This is public forum. If you want to discuss in private, please send me the information via TI's internal email. 

Best,

Raymond