Day 10 Inverting Voltage Amplifier

Today is our first introduction to operational amplifiers, or op amps for short. Our first lab is centered on an inverting op amp, or an op amp that performs multiplication by a negative constant. Below is our circuit diagram that includes the OP 27 and its representation in the circuit. We have designed the circuit so that the Vout = -2 * Vin. The blue numbers around the Op Amp represent the pin terminals on the actual op amp. We have a supply rail from -5 to +5 that is powering the op amp.

Below are the actual measured value of the feedback resistor and the input resistor, respectively. Our ratio, therefore, is not exactly Vo = -2Vi, but very close.

Below is our successfully designed circuit. We have all of the resistors, input voltages, and supply rail voltages connected at the right pins. We had to connect the op amp across the bridge of the breadboard because otherwise the pins would be connected to each other which would make the op amp inoperable for what we needed.

The last step was to measure and plot our measurements for Vin vs. Vout, using Matlab. The graph of the data below demonstrates the properties of the Op Amp very well because we see that the amp saturates when approaching the supply rail voltages, and is inverted from the input voltage.

Op Amps have been some of the most interesting circuit elements to work with so far. They operate the same internally, but depending on how you design the circuit around it is what changes the operation of the op amp. Looking forward to learning more about the Op Amp.