Original question:
Hi people,
hope you can help me with this. When running the simulation I do not get the expected values. Amp working here with Gain :~45 and applying an offset of 300mV and unipolar supply of +Vdc. I´m overseeing something but do not get what. Attached the simulation file.
Thanks out there!!
BR
Hey Hugo,
I've added some math in the post-processing to show what the theoretical value is that should be output from the amplifier. I increased your offset to be mid-supply and reduced the amount of input current, as your transfer function will be ((I*Rshunt)*(10k/220))+V(offset). (similar results can be achieved by reducing the value of your shunt resistor if the input current must be 30A)
This theoretical value is plotted in the output of the simulation.
If the real value no longer matches up with the theoretical value, it's likely one of the op amp parameters is being violated, the input common-mode is in a valid range, but the expected output in the previous configuration violates the output swing of the device. You can see this below where the theoretical output (red curve) swings below 0V. The amplifier is only able to output close to the negative rail, but cannot go below it.
Best,
Jerry
