Assignment on Inverting Amplifier Circuit

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Introduction
To increase the frequency response which an op-amp can be connected using negative feedback
to stabilize the gain. A small noise voltage can causes the extremely high open loop gain in an
unstable situation. Unwanted oscillation can also occur. In open loop gain parameter can vary
from one device to the next device. To creating an effective reduction gain, negative feedback is
back out of phase with the input. This closed loop gain is usually less than the open loop gain.
Op amp amplifier is basically divided into two types.
They are 1. Inverting OP-AMP Amplifier
2. Non-Inverting OP-AMP Amplifier
Non-inverting Operational Amplifier
An operational amplifier or OP-AMP is a DC-coupled voltage amplifier with a very high voltage
gain. It is basically a multistage amplifier. A number of amplifier stages are interconnected to
each other in a very complicated manner.1 Its internal circuit consists of many transistors, FETs
and resistors. All this occupies a very little space.
It is the second basic configuration of an operational amplifier circuit. In this amplifier, the input
voltage signal, (VIN) is applied directly to the non-inverting (+) input terminal. It means that the
output gain of the amplifier becomes “Positive” Abdelhak Benkrid, Operational amplifier
applications. This is in contrast with the Inverting Amplifier circuit. Its output gain is negative in
value. The result of this is that the output signal is “in-phase” with the input signal "High
Performance Voltage Differencing Inverting Buffer Amplifier (VDIBA)". It is the second basic
configuration of an operational amplifier circuit. In this amplifier we are going to give input
1 "High Performance Voltage Differencing Inverting Buffer Amplifier (VDIBA)", International
Journal for Research in Applied Science and Engineering Technology V.X (2017): 1095-1099.

voltage as Vin.2 Then the output voltage of the amplifier will be positive Abdelhak Benkrid,
Operational amplifier applications. This is totally reverse of the inverting amplifier. The output
for the inverting amplifier is Negative whereas the output for the Non inverting amplifier is
positive.
The feedback for the Non-Inverting amplifier is given as Rf and R2. There will be a voltage
divider between them and resistance will become Rf–R2. This will produce the negative
feedback.
Part 1: Phase margin and crossover frequency measurements
Open Loop Frequency Response
From the name itself we can understand that it will be open loop and there will no feedback or
attachment between the input and output signal. The gain which we are getting at this loop is
called open loop gain. It is represented as G0.3 Here we are going to calculate the phase margin
and cross over frequency.4
2 Abdelhak Benkrid, Operational amplifier applications (Saarbrücken, Germany: LAP Lambert
Academic Publishing, 2013).
3 Ivan Sønderby and Morten H. Hansen, "Open-loop frequency response analysis of a wind
turbine using a high-order linear aeroelastic model", Wind Energy 17.8 (2013): 1147-1167.
4 Steven T Karris, Electronic Devices and Amplifier Circuits (Fremont, California, USA:
Orchard Publications, 2012).

Phase margin
The difference the phase and 180 degree is called Phase margin. This formula is applicable only
when the gain is Zero.
Phase Crossover frequency
When the phase shift is equals to -180 degree, we have to calculate the frequency. That
frequency is called as Phase cross over frequency. It is denoted by ωpc.
Here we are going to calculate the phase margin and cross over frequency. We have to assume
that β=1.
Part 2: Closed Loop Analysis.
Closed loop frequency response