Has AD8041S a Unitiy Gain stability

Hi ASchirmer810 

We will look into this matter and if possible, can you provide a screenshot of the circuit or a more detailed description of the configuration such as input voltage, resistance or capacitance values, etc.?

The information for G=1 and G=5 would be much appreciated.

Regards,

JE

Hi JE,

yes, I can provide a schematic with more details.

The input voltage at positive input is 0V ... 0.5V

The first picture shows the circuit which we have acutally implemented in hardware. We don't want the Gain of 5. But this was the only way to run the OP-AMP stable (without low pass filter, without C1 and C4) 

The second picture shows the circuit which runs in simulation. There is implemented Gain 1 and the corner frequency of the low pass 2nd order is higher (R1 and R2 reduced to 1k instead of 10k).

But we are still wondering about stability of the OP-AMP. Can you give some information how to check the stability.

Thanks, Best regards Alessandro

Hi JE,

yes, I can provide a schematic with more details.

The input voltage at positive input is 0V ... 0.5V

The first picture shows the circuit which we have acutally implemented in hardware. We don't want the Gain of 5. But this was the only way to run the OP-AMP stable (without low pass filter, without C1 and C4) 

The second picture shows the circuit which runs in simulation. There is implemented Gain 1 and the corner frequency of the low pass 2nd order is higher (R1 and R2 reduced to 1k instead of 10k).

But we are still wondering about stability of the OP-AMP. Can you give some information how to check the stability.

Thanks, Best regards Alessandro

Hi ASchirmer810 

Using the Ltspice software, we can check the stability of the op-amp. See the link below for the tutorial video.

LTspice: Stability of Op Amp Circuits

However, I am still checking for some stability issues of your circuit. Stability issues of op amp are usually due to capacitive loads, for some are very large feedback resistors and other factors. Is the oscillation present on your hardware? Is it correct to assume that the test node that you've checked is on "R_PVSUB"? I am suspecting that there are parasitic capacitances on your PCB or hardware but it was not yet concluded.

Also, the following link can be of help for compensating stability issues for op amps.

Ask The Application Engineer—32: Practical Techniques to Avoid Instability Due to Capacitive Loading

Hope this helps. 

Regards,

JE