Lecture One

ANALOG ELECTRONICS

ETU 07101

Lecturer: Francis.F.S.Mihayo

Office: Radio Amateur’s, office building

Tel: +255 732 200294

+255 655 257835

Email: [email protected]

mailto:[email protected]

Analogue Electronic circuit design is fun.

You can earn a good living from it and

impress many people to whom electronics

seems the magic.

Analog Electronics

INTEGRATED METHODS OF ASSESSMENT

CA 40%. FE 60%

1 Introduction

2 Operational Amplifiers

3 Diodes and Diode Circuits

4 Bipolar Junction Transistors

5 Differential and Multistage IC Amplifiers

6 Frequency Response

7 Feedback

8 Output Stages and Power Suppliers

TOPIC TO BE COVERED

REFERENCES

Robert Boylestad and Locis Nashelshy, (1991) “Electronic Devices and Circuit Theories” Prentice –Hall

M. Hassul and D.E. Zimmerman, (1996) “Introductory Electronic Devices and Circuits” Prentice Hall

Theodore F. Bogart, Jr, (1993) “Electronics and Circuits” Maxwell Macmillan, 3rd Edition.

Thomas. L. Floyd, (1992) “Electronic Devices, Prentice Hall, 3rd Edition

Analog Electronics

Electronic systems are everywhere in our daily life.

radio, television, refrigerator, MP3&MP4,GPS (global positioning

system), air traffic-control system, electronic instrumentation (signal

generator, oscilloscope, millimeter) computerized monitors for

patients

Electronic systems are composed of subsystems or functional

blocks.

amplifiers, filters, signal sources, wave-shaping circuits, digital logic

functions, digital memories, power suppliers and converters.

Introduction – Electronics Systems

Many electronic systems falls into one or more of these categories:

digital-signal processing systems, communication systems,

medical electronics, instrumentation, control systems, computer systems.

The primary concern of many electronic systems:

to extract, store, transport, or process the information in a signal

Some are concerned mainly with the power content of signals.

Electronic systems

Amplifier — increase the power level of weak signals

Filers — separate desired signals from the undesired and noise

Signal source generators — generate waveforms

Wave-shaping circuits — change one waveform into another

Power supplies — provide necessary DC power to others

Converters — change between analog and digital

Electronic systems

Analog versus Digital

Information-bearing signals can be either analog or digital.

Analog signal takes on a continuous range of amplitude values.

Whereas digital signal takes on a finite set of discrete values (often binary) and frequently changes values only at uniformly spaced points in time

Analog circuits: circuits that connect to, create and

manipulate arbitrary electrical signals

circuits that interface to the continuous-time “real” word

Analog and digital signal can be converted to each other

Relative advantage:

digital circuits are more immune to noise digital circuits tend to be easier to

implement with IC (integrated circuit) technique

digital systems are more adaptable to a variety of use

So why do we still study analog?

The real world is analog Many of the inputs and outputs of

electronic systems are analog signal Many electronic systems, particularly those

dealing with low signal amplitudes or very high frequency required analog approach

The dominance of digital circuits actually increased the amount of analog electronics in existence

Analog versus digital signals

Information-bearing signals can be either analog or digital.

Electronic systems

Figure 1.0: Analog signals take a continuum of amplitude values.

Digital signals take a few discrete amplitudes.

ADC

DAC

Electronic systems

Relative advantages of analog and digital systems

Noise is any undesired disturbance added to the desired signal.

One of the most significant advantages that digital systems have, compared with analog systems, is in the way that noise affects the signals.

Figure 1.2

After noise is added,

the original amplitudes

of a digital signal can

be determined.

This is not true for an

analog signal.

Operational Amplifiers (Op Amps)

Operational Amplifiers

What is an Op amp?

A multistage high-gain amplifier integrated in analysis as a separate block.

A typical op-amp is powered by two dc voltages and has

an inverting(-) and a non inverting input (+) and an output.

The input of an op amp is a differential amplifier therefore has 2 inputs.

The output is singled ended.

Typically configured for a dual power supply rails (+/_V)

Note that for simplicity the power terminals are not shown but understood to exist.

Operational Amplifiers

Operational Amplifiers Properties

open-loop gain: ideally infinite: practical values 20k-200k high open-loop gain virtual short between + and - inputs

input impedance: ideally infinite: CMOS opamps are close to ideal

output impedance: ideally zero: practical values 20-100

zero output offset: ideally zero: practical value <1mV

gain-bandwidth product (GB): practical values ~MHz frequency where open-loop gain drops to 1 V/V

Commercial opamps provide many different properties low noise

low input current

low power

high bandwidth

low/high supply voltage

special purpose: comparator, instrumentation amplifier

Operational Amplifier

Vd

+

Vo

Rin~inf Rout~0

Input 1

Input 2

Output

+Vcc

-Vcc

Operational Amplifier (Op-Amp)

Very high differential gain

High input impedance

Low output impedance

Provide voltage changes (amplitude and polarity)

Used in oscillator, filter and instrumentation

Accumulate a very high gain by multiple stages

ddo VGV

510say large,y ver

normally gain aldifferenti : dG

Basic Opamp Configuration

Voltage Comparator

digitize input

Voltage Follower

buffer

Non-Inverting Amp • Inverting Amp

More Opamp Configurations

Summing Amp

Differential Amp

Integrating Amp

Differentiating Amp

Converting Configuration

Current-to-Voltage

Voltage-to-Current


Ideal Op Amp

Non-inverting Amplifier

Unity-Gain Buffer

Inverting Amplifier

Differential Amplifier

Current-to-Voltage Converter

Non-ideal Op Amp

Ideal Op Amp

1) 0 vv A v v

The open-loop gain, Av, is very large, approaching

infinity. 2) 0i i

The current into the inputs are zero.

+

-

i

ov

v

vi

DDV

SSV

0SS DDV v V

Ideal Op Amp with Negative Feedback

+

-ov

v

v

Network

Golden Rules of Op Amps:

1. The output attempts to do whatever is

necessary to make the voltage difference

between the inputs zero.

2. The inputs draw no current.