# Lab Report on the Operational Amplifier

### Paper's Detail

Category | Engineering |

Paper Type | Report Writing |

Reference Type | APA |

Words | 1650 |

**The operational amplifier**

**Introduction of The operational amplifier**

In
this report, there is complete information about the operational amplifier.
This report will discuss the operational amplifier in detail. In the first part
of the report, there is complete information about the design calculation used
for the operational amplifier. The next thing is that there is complete
information about the circuit design used for this report. In the first part,
the design calculation will be presented of the low pass filter and also for
the wien bridge oscillator * (Classes.engineering., 2019)*.

Moreover,
the software simulations are presented about these amplifier with their
simulated waveforms. Then after this the results are tested by changing the
values of resistance and capacitors. Then there is some difference between the
multisim and practical results of the amplifiers. In the last, there is
complete information about the frequency response graphs *(Nptel. Aac.in/courses)*.

**Design calculations of The operational
amplifier**

First
of all there is complete design calculations for the low pass filter that is
applied on the operational amplifier. For that case we just have to assume it
is an ideal operational amplifier so according to that the current conversion
will become

The
voltage gain will become

Now
rearrange the equation and also applied integration from 0 to t

From
the above equation it can be noted that the output voltage is the integral of
the input. On the other hand is the voltage constant.

Now
for the frequency domain analysis, it will be done through expressing the
impedance of the feedback components. Due to this the transfer function can be
written as

According
to the information the above equation is showing that there is 90 degree phase
difference that is present between the input and output signal. This shift is
present at all frequencies. Due to this the gain of this amplifier will become

The
feedback path is consisted of the capacitor. Through this it will become easy
to calculate the equivalent impedance path

According
to this the transfer function that is also the main gain of the amplifier will
become

For
getting the values applied the AC and DC analysis on the operational amplifier.
For the DC analysis of the operational amplifier cut off the capacitors. And
apply KVL on the circuit * (Brisebois, 2009)*.

**Detail comments related to circuit design**
**of The operational amplifier**

For
designing the circuit there is need to evaluate the value of capacitor and
resistance. Through these values it will be simple to design this circuit. For
designing the circuit there is need to apply the AC and DC analysis on the
operational amplifier. According to the information the first operational amplifier
is the High gain amplifier. In that particular amplifier the gain of the
amplifier is extremely high. Due to this factor, we will use non inverting
amplifier and its gain will be

According
to the information for designing the high gain amplifier is simple. The main
reason is that the value of the resistance will be adjusted at such a way so
that its gain will become extremely high. According to the given scenario there
is need of voltage gain of 10x.

In
the next circuit, there is complete design of the low pass filter. For that
case, there is need of 1 kHz frequency. But the voltage gain will be remained
the same. The main thing is that the value of capacitor and resistor is
adjusted in such way so that there will be no voltage loss in the circuit and
required voltage gain is achieved, then after this checked the gain on the
oscilloscope

And
analyze the voltage gain of the system.

In
the last, there is implementation of the Wien Bridge Oscillator. For that
oscillator there is need of positive feedback at the output. For this the
circuit is implemented in such a way that there will be positive feedback at
the output of the circuit. The design of this oscillator is not too much
simple. The main reason is that there is parallel and series combination of the
resistor and capacitor are applied in such way for obtaining the positive
feedback at the output.

**Multisim simulations**

** **

This
is the circuit for the high gain amplifier. For that circuit, we have use the
R1 of 1k and the R2 of 100 ohms. Through this value we are able to achieve the
value of 10x gain at the required output. On the other hand the duty cycle that
is applied on the input side is 50 and the required amplitude of the wave is
applied at the input is 100. The input frequency of the circuit is about 7.764
Hz. The operating voltages of the operational amplifier is set at 15 volts.

This
is the required waveform that is giving information about the gain of the
operational amplifier. This waveform is obtain by double clicking on the
oscilloscope. Through this, such waveform will be obtain easily without any
difficulty. From this waveform it can be seen that there is 90 degree phase
shift is present between these waves. This showing that the green wave is the
input wave and on the other hand the red wave is denoting the output waveform
of the amplifier.

This
is the multisim simulation of the low pass operational amplifier. For that
case, the value of capacitor is set at 10 micro farad and the value of resistor
R1 is adjusted at 1k ohm and the R2 is set at the 100 ohm. The voltage gain of this
amplifier is the same as the previous one, as it can be seen from this image.

**Production** **of The operational amplifier**

For
the production of wave, the input voltages are set at 15 volts for both the
circuits. The next thing is that the operating voltages of the operational
amplifier is set at 15.6 volts.

**Difference between practical and Multisim
results **

There
is a lot of difference between the practical and software results. It can be
seen that in the software simulation the results are completely absolute and
perfect. This means that through the help of software results will can easily
obtain the real values of the amplifier. But the next thing is when the
practical is performed there is some difference in the output values.

This
can be seen on the oscilloscope. There is also difference in the output voltage
gain that is obtained by this amplifier. There are a lot of reason that will
give complete information why there are differences are present between the
voltage gain and the oscilloscope results of the amplifier. The first reason is
that the value of the resistors and capacitors are not absolute. There is some
difference present between these values. Due to these differences the value of
the output voltages has been changed completely. This is the reason why there
is somehow difference is present in the practical values.

**Comments on frequency response graphs **

The
frequency response graphs are implemented on the log table and also on the
software through the help of bode plot function.

It
can be noted that from the graph the horizontal frequency is adjusted at the 10
MHz and the vertical one is arranged at 50 db. By turning on the magnitude mode
the frequency response is displayed on the window. This shows that the cutoff
frequency is set at 20 dB and after this value the magnitude of the frequency
started to going down towards the main value.

Now the work for
the phase diagram of the frequency response