I'm fairly new to using op amps, so this may be a simple issue. I am building an inverting amplifier for monitoring a negative voltage on an analog rail. Since the ADC I'm using requires a positive voltage an inverting amplifier seems to be the way to go.
In this configuration the output voltage is higher than expected. With a -2V input and unity gain I would expect the output to be 2V, however it is slightly higher at 2.097V. The voltage at the inverting pin is 48.9mV, which seems to be the cause of the higher than expected output voltage.
Things I've tried
- Changing V- to -5V. This solves the issue, but I'd prefer to not require another voltage rail
- Using an ideal op amp the circuit works as expected, further indicating there is some parameter of non-ideal op amps that I don't understand
Any suggestions are appreciated