Lecture 1

Introduction to Electronics Introduction to Electronics

Rabie A. Ramadanrabieramadan@gmail.com

http://www.rabieramadan.org/classes/2014/electronics/

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Welcome Back

Class Organization

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• Attendance is very important

• Assignments

• Projects

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Class Rules

• I am not here to punish you

• Trust yourself and do your best

I want you to learn and compete with others working on the same field

• I want you to be confident when you speak with others

Textbooks

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Class Format

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• Some presentations by myself

• Q& A in class

• Quick questions in class to be answered

Topics to be Covered next few Lectures

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• That electronic circuits process signals, and thus understanding electrical signals is essential

• The Thevenin and Norton representations of signal sources.

• The representation of a signal as the sum of sine waves.

• The analog and digital representations of a signal.

• The most basic and pervasive signal-processing function: signal amplification, and correspondingly, the signal amplifier.

• How amplifiers are characterized (modeled) as circuit building blocks independent of their internal circuitry.

• How the frequency response of an amplifier is measured, and how it is calculated, especially in the simple but common case of a single-time constant (STC) type response.

Introduction • Microelectronics refers to the integrated-circuit (IC) integrated-circuit (IC)

technology. technology.

• Contains hundreds of millions of components in a small piece of silicon (known as a silicon chip) whose area is on the order of 100 mm2.

Applications

Introduction • One such microelectronic circuit is a complete digital computer, complete digital computer,

which accordingly is known as a microcomputera microcomputer or, more generally, a microprocessor.

• We shall study electronic devices that can be used singly (in the design of discrete circuits) or as components of an integrated-circuit (IC) chip.

• We shall study the design and analysis design and analysis of interconnectionsinterconnections of these devices.

• We shall also learn about available IC chips and their application in the design of electronic systems.

Introduction • Today we will learn about signals and about one of

the most important signal-processing functions electronic circuits are designed to perform, namely, signal amplification.

Signals

• Signals contain information about things and activities around us in the physical world.

• Information about the weather including temperature , humidity, wind speed , etc.

• The voice of radio announcer in the microphone is a signal.

Signals • To extract required information from a set “signals” ,

there are some “processingprocessing” .

• Usually the processingprocessing done by “electronic “electronic systems”.systems”.

• To do so, the signal must be first converted to electrical signals , voltage or currentelectrical signals , voltage or current.

• This conversion is done by “transducerstransducers “

Transducers • A variety of transducers exist .

• Each type of suitable for special type of physical signal.

• Sound wave Sound wave generated by human is converted into electrical signals using microphonemicrophone .

Transducers

• We are not interested are not interested in transducers by themselves.

• We will assume that the signals are already exist in a form of voltage or current.

Thevenin Form

• The signal is represented by Vs(t)

• Source resistance Rs

Norton Form

• The signal is represented by current source is (t)

• Source resistance Rs

Source Resistance

• Rs in Thevenin preferred to be low

• Rs in Notron preferred to be High

Relation between the two forms

Voltage Divider Rule

Example

Example

Problem

Hint

Current Divider Rule

Example

Example

Example

Problem

Hint

Just Smile

Slide 2- 31

Thevenin – V0 Computation at RL

• Rs is the source resistance

• RL is load resistance

• Compute the load voltage V0 ?

Thevenin – V0 Computation at RL

Norton Compute i0

Exerciseshttp://people.clarkson.edu/~jsvoboda/eta/dcWorkout/thevenin.pdf

Slide 2- 36

Signals and Time

• The signal can be represented by Time-Varying quantity as follows:

Frequency Spectrum of Signals• An extremely useful characterization of a Signal, and for that

matter of any arbitrary function of time, IS In terms of its frequency spectrum.

• Such a description of signals is obtained through the mathematical tools of Fourier series and Fourier transform.

• Suffice it to say that they provide the means for representing a voltage signal Vs(t) or a current signal is(t) as the sum of sine-wave signals of different frequencies and amplitudes.

Frequency Spectrum of Signals

• This makes the sine wave a very important signal in the analyses, design, and testing of electronic circuits

Frequency Spectrum of Signals

Analog and Digital Signals

• Analog Signals – Handled by analog Circuits

Analog and Digital Signals

• Digital Signals:– Signals are represented in a form of numbers

– Each number represents a signal magnitude at an instance of time.

From Analog to Digital

• Sampling

From Analog to Digital • The signal is no longer continuous like in its analog form

• It is said Io be quantized discretized or digitized

Important Note

Important Note

Important Note • If we use N binary digits (bits) to represent each

sample of the analog signal. then the digitized sample value can be expressed as

• b0 is the Least Significant Bit (LSB)

• bN-1 is the Most Significant Bit (MSB)

Analog to-digital converter ( A/D or ADC)

• increasing the number of bits reduces the quantization error and increases the resolution of the analog-to-digital conversion.

• however, usually mobtained at the expense of more complex and hence more costly circuit implementations

Exercise