Inverting Voltage Amplifier (Week 7 - Day 13)

      This experiment is the first of many that uses operational amplifiers. These neat little package allows us to manipulate our output voltage by performing mathematical operations for us. Our goal in this lab was to achieve a gain of 2V with our inverting amplifier circuit (shown below).

The circuit below samples three resistors. This was in an attempt to achieve a ratio of 2 between the feeder and input resistance.
R₁ = 3.3kΩ + 0.1kΩ = 3.4kΩ
R₂ = 6.8kΩ
And there measured values were:
R₁ = 3.26kΩ + 0.0996kΩ = 3.36kΩ
R₂ = 6.75kΩ

A schematic of this circuit was constructed on EveryCircuit before attempting.

This circuit shows an inverting voltage amplifier with a gain of 2V

After doing calculations, we constructed the actual circuit

Plugging in some numbers into the appropriate equation:

v_out = -(^R₂⁄_R1)v_in

...

From the data and graph, it is clear that we were successful. We achieved an inverted voltage gain of about 2V. Where the blue and yellow lines diverge, we can see where saturation begins to occur (typically below -3.5V and above 3.5V). I believe these precise measurements were due in great part to how close the ratio of the feeder an input resistances were. The ratio between R₁ and R₂ was 2.009 which was only off by a thousandth of an ohm. Hardly anything at all!