===== Inverting Amplifier with OpAmp =====

==== Background Information ====
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Operational amplifiers are widely used in audio equipment. For example, audio mixers allow individual audio channels to be amplified or attenuated in order to adjust the overall sound. One common operational-amplifier configuration used for signal processing is the inverting amplifier. By selecting appropriate resistor values, the amplification factor can be adjusted to achieve the desired signal level. In an inverting amplifier, the gain is determined by the ratio of the feedback resistor to the input resistor.
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{{drawio>mexlefirst_intern:inverting_amplifier_lab_6-1.svg}}
  * The input voltage Ue is at the inverting input of the operational amplifier.
  * The feedback is done by a voltage divider of R1 and R2.
  * The voltage gain is **\(A_{\mathrm{V}} = -\frac{R_2}{R_1}\)**

==== Experimental Tasks ====
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To analyze the behaviour of the inverting amplifier, the following circuit is used:\\ \\ 
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Supply voltages (from power supply unit):\\  
UCC = + 3V, UEE = - 3V\\ 
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Values of the components used:\\ 
R1 = 20kΩ, R2 = 10 kΩ\\ 
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  - Calculate the voltage gain of the inverting amplifier.\\ \\ 
  - Build the circuit on the MEXLE board.\\ Please note: the level shifting circuit is required, since bipolar signals are needed for the experimental tasks.\\ Once inserted into the board, the operational amplifier is automatically connected to the power supply! Using the jumper on the OpAmp module, either a bipolar voltage supply of \(+3\,\mathrm{V} / -3\,\mathrm{V}\) or an unipolar voltage supply of \(+3\,\mathrm{V} / 0\,\mathrm{V}\) can be selected. For this experiment, please set the jumper to the left to provide a bipolar voltage. \\ \\ 
  - Configure the function generator of the handheld oscilloscope to provide a sawtooth wave signal. Use the following settings:
      *Amplitude: 3 V 
      *Frequency: 2 000 Hz 
      *Duty Cycle: 50% \\ \\ 
  - Connect the alligator clips of the signal generator to the level shifting circuit and supply the MEXLE board with power via the Micro-USB connector. Then, connect Channel 1 to the input voltage of the inverting amplifier cirucuit and Channel 2 to the output voltage of the inverting amplifier circuit. Sketch the waveforms of the input and output voltage displayed on the oscilloscope.\\ \\ <wrap left>{{drawio>mexlefirst_intern:oscilloscope_screen.svg}}</wrap>\\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ 
  - Move the lower jumper on the OpAmp module to the right to select a unipolar supply voltage. Describe and explain the output voltage waveform displayed on the oscilloscope screen.\\ \\ 
  - Calculate the new voltage gain, in case R1 and R2 are swapped.\\ \\ 
  - Swap the resistors on the MEXLE-board. Describe and explain the output voltage waveform displayed on the oscilloscope screen.\\ \\