TINA / Spice: OPA847 PSpice Simulation

Hi Wilfrid,

                Based on the information provided, I see that you're trying to build an inverting attenuator circuit. The RC filter makes this circuit AC coupled. So at DC it's just an open circuit. At AC you should expect a gain of 20log(5/10) = -6dB. Did you get this? If you can share your bode plot and a link to the article above, I should be able to further assist you. 

Best Regards,

Bala Ravi

Hi Wilfrid,

                     Kai is right. OPA847 is only stable for gains >= 12. You can find this information on the datasheet. So your bode plot is wrong. If you're just trying to simulate, you can try using TLV9002 or TLV9062 TINA models. Based on your setup a correct bode plot would look like this:

Also a correction to what I said earlier, at AC the capacitor would be short, making the gain = 20log(5/20) = -12dB. 

Best Regards,

Bala Ravi

Hi Wilfrid,
I did not completely read the article. But, from a quick view the sensing circuit senses the noise and the op-amp circuit generates the cancellation voltage to cancel the noise. Another advantage of using an op-amp is having a high input impedance and a low output impedance . I hope this helps!

Best Regards,
Bala Ravi