Experiment 7 :Operational Amplifier as a Integrator Circuit

Aim:


To design and simulate an Integrator circuit and observe output with different input waveforms. 

Theory:


The circuit in fig 1 is an integrator, which is also a low-pass filter with a time constant=R1C. When a voltage, Vin is firstly applied to the input of an integrating amplifier, the uncharged capacitor C has very little resistance and acts a bit like a short circuit (voltage follower circuit) giving an overall gain of less than 1, thus resulting in zero output. As the feedback capacitor C begins to charge up, its reactance Xc decreases and the ratio of Zf/R1 increases producing an output voltage that continues to increase until the capacitor is fully charged. At this point the ratio of feedback capacitor to input resistor (Zf/R1) is infinite resulting in infinite gain and the output of the amplifier goes into saturation. (Saturation is when the output voltage of the amplifier swings heavily to one voltage supply rail or the other with no control in between). The circuit design generate triangular wave providing square wave as input to the integrator. Hence, the integrator circuit generates integral output with respect to the input waveform. 


The integrator Circuit

Procedure:

 

1.     Connect the circuit as shown in the circuit diagram.

2.     Give the input signal as specified.

3.     Switch on the power supply.

4.     Note down the outputs from the CRO

5.     Draw the necessary waveforms on the graph sheet.

 

Observations:

 

1.     Observe the output waveform from CRO. A square wave will generate a triangular wave and sine wave will generate a cosine wave.

2.     Measure the frequency and the voltage of the output waveform in the CRO.

3.     Calculate 

4.     Compare the calculated output voltage with the experimentally observed voltage from the output waveform.

5.     Observe outputs of the integrator circuit using different input waveforms.
 

Result:


The integrator circuit design output waveforms have been studied. 

Precautions:

1.     Connections should be verified before checking the output