Tool/software:
For the first application, I was planning to use it as a non-inverting amplifier with a gain of 15. I have a part requirement to have an RC filter of 200Ohms and 47nF on my device’s output (Amplifier input). My main goal is to amplify the signal with as little offset as possible. Can you double check if what I have is good or if you have any concerns? The input current being used is pretty low (20uA)
Hi Sam,
I ran an analysis of your circuit, and it looks like the op amp output is saturated. The 20uA input current is being forced in and out of the high input impedance op amp. This can be seen on the measurement IP below. The voltage differential, VOS, would normally be at 0.4uV. However, in the measurement below you can see the inputs are getting ripped apart at a delta of 131.35mV. This in turn is causing the output to rail out. This is not seen when analyzing the circuit with a voltage input.
One possible solution would be to convert the input current with a TIA. The TIA will convert your current to a voltage. Can you clarify more on your design goals with the current circuit? Below is the simulation showing the large input differential, and the output saturation.
Best regards,
Carrie
Hi Sam,
If your input is a voltage, then there should be no issues with your design. Below is the same simulation as before, but with a voltage generator instead of a current generator. VOS is small, indicating the inputs are no longer getting ripped apart. Note that IP is very low (70pA), and the output voltage is 1.65V, matching the expected gain. Please let me know if you have further questions.
Best,
Carrie
