lab report and MATLAb programming

Table of Contents

Introduction……………………………………………………………………… 3

Experimental Procedure ……………………………………………………….. 4

Results and Analysis. …………..…………….….…………………………… 6

Conclusion ………………………………………………………………… 8

Introduction

An amplifier is an electronic device that can increase the power of a signal. An amplifier uses electric power from a power supply to increase the amplitude of a signal. Our experiment was performed with these 4 objectives in mind:

1. Determine the gain of an audio amplifier.

2. Identify the voltage range where the gain, or amplification factor was linear.

3. Determining the FRF of the amplifier.

4. Determine the frequency range when the gain behavior is not dependent on the frequency.

These properties allow their user to determine whether or not the amplifier is working. An amplifier is working correctly when the output signal is linearly proportional to the input signal. Amplifiers are present all around the world. Therefore, it is essential to understand the basic working principles behind them.

Theoretical Overview

The properties of an amplifier like the gain of frequency response function help us understand whether an amplifier is working correctly. A properly acting amplifier’s output signal is linearly proportional to the input signal.

The amplifier properties that we will study in our experiment are:

· Gain

The gain of an amplifier is defined as the measure this ability of amplifying a signal. Gain is a ratio of output voltage to input voltage and does not have any unit. The ratio should be a linear proportionality

· Frequency Response function (FRF)

Frequency response function of an amplifier is the Fourier transform of the output over the Fourier transform of the input. Generally, the frequency response analysis of a circuit or system is shown by plotting its gain against a frequency scale over which the circuit or system is expected to operate.

· Bandwidth of amplifier

The bandwidth represents the amount or width of frequencies that the amplifier is most effective in amplifying .The region where the Gain or amplification factor is constant and does not depend on the frequency is known as the bandwidth of the amplifier.

Experimental Procedure

Equipment consists of data acquisition hardware, a power amplifier, and cables to connect the amplifier to DAQ equipment. The input signal will be attached at A1 port and the output signal will be attached at A4 port.

The experiment is divided in the following three procedures:

Procedure A – First LabVIEW code

The first LabVIEW code generated a sine signal. The signal had a defined frequency of 1 kHz and a changing amplitude. The signal continued in a loop so that the output signal could be measured at different amplitudes. Nearly 2000 sample points were calculated during 0.1 seconds.

Procedure B – Second LabVIEW code

A total of 14 iterations were taking in this part. Frequency was changed while the amplitude was kept constant.

Procedure C – Third LabVIEW code

A total of 25000 samples were measured in 0.1 seconds with a noise of amplitude 0.2 and frequency of 1 kHz added to the signal

Results & Discussions

The results of our experiments showed that the ratio of output voltage to input voltage was a linearly proportionality. The output voltage increased with increasing input voltage. This shows that the amplifier was working correctly.

The gain of the amplifier was measured to be around 35.25 volts.

When noise was added to the signal, there was no significant change detected in the gain of the amplifier. So we can assume that noise had little impact on the gain.

· Figure: Graph of gain versus frequency

· Figure: Frequency Response function

Conclusion

The experiment proved to be a great learning experience. We successfully developed an understanding of the amplifier and its related properties. The gain of the amplifier was calculated to be around 35.25 Volts. The gain showed linear behavior. The impact of noise was also found out to be insignificant to the gain. The results and findings of our experiment were within the acceptable range.

Possible sources of error include errors in the measuring instrument, human involvement, errors in calculation etc. Electronic equipment used in the experiment is considered to be ideal but in actual it has some tolerance value. This can also affect our results.