I've got what is probably a simple question from an experiment I did. I hooked up a battery to a potentiometer, fed the signal through a voltage follower, and then through an inverting op amp with a gain of about 5.5. Schematic below (R4 & R5 as simulating the 1k pot I used):
I tested a range of input voltages from -1.5 to 1.5V. I had to flip the battery's terminals around to achieve the negative input voltages. I plotted a graph of my measurements (Vout vs Vin):
Everything was pretty much as I expected except for the voltages at which the actual gain curve levels off. I knew they would be appreciably lower than the rail voltages, but what surprised me was that they weren't equal in magnitude. This prompted me to simulate the circuit in Spice. Why is there a difference in the levelling off voltages between the Spice model and the actual measurements? Or maybe the better question is, why are the magnitudes of the levelling-off voltages different?
Thanks!
I tested a range of input voltages from -1.5 to 1.5V. I had to flip the battery's terminals around to achieve the negative input voltages. I plotted a graph of my measurements (Vout vs Vin):
Everything was pretty much as I expected except for the voltages at which the actual gain curve levels off. I knew they would be appreciably lower than the rail voltages, but what surprised me was that they weren't equal in magnitude. This prompted me to simulate the circuit in Spice. Why is there a difference in the levelling off voltages between the Spice model and the actual measurements? Or maybe the better question is, why are the magnitudes of the levelling-off voltages different?
Thanks!