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Theory Of Op-Amps And Voltage/Signal Amplification

EEE 310 - OPERATIONAL AMPLIFIERS AND ACTIVE NETWORKS
LECTURE NOTES

TABLE OF CONTENT
1. INTRODUCTION 2
1.1 Signals 2
1.2 Classification of Signals 4
1.2.1 Digital vs. Analogue 4
1.2.2 Continuous-time vs. Discrete-time 5
1.2.3 Hazy Part of the Classification 5
1.3 System Response 6
1.4 Linearity vs Non-linearity 6
2. AMPLIFIERS 7
2.1 Types of Amplifiers 8
2.1.1 Signal Amplifier 8
2.1.2 Power Amplifier 8
2.2 Amplifier Circuit Symbol 8
2.3 Amplifier Gain 9
2.3.1 Voltage Gain 9
2.3.2 Current Gain 10
2.3.3 Power Gain 10
2.3.4 Decibel values of Voltage, Current and Power Gains 10
2.3.5 DC Supply to An Amplifier 11
2.3.6 Amplifier Saturation 12

1.INTRODUCTION
1.1Signals
A signal can be defined as detectable transmitted energy that can be used to carry information. Put in another way, a signal is a time-dependent variation of a characteristic of a physical phenomenon, used to convey information. For example, a signal could be the current flowing through a light dependent resistor (LDR), giving information about the amount of illumination in the LDR's environment. Another signal could be the colour of a methyl orange solution indicating the pH of the solution. Signals discussed in this course will be restricted simply to voltage signals and current signals. Hence, in this course, a signal will be either a voltage or a current.
There are two common ways in which signals are represented:
i.Time-domain representation; and
ii.Frequency-domain representation.
The time-domain representation is the representation which you are more likely than not most familiar with. Here, the signal is represented as a function of time. The plot of the signal is a plot of its magnitude against time. Figure 1.1 shows a time-domain representation of a signal. The signal in figure 1.1 is

Figure 1.1: Time-domain representation of a signal
Mathematically, the signal is represented as to show that it is a time-domain signal. We may represent this same signal in the...