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EEL 3304C Fall 2007: Introduction to Electronic Circuits

• Instructor: Prof. Rizwan Bashirullah• Preview

– Goals– Logistics

• Requirements/expectations

– Introduction• Reading

– Chapter 1 (Intro) – Chapter 2 (Operational Amplifiers)

Textbook

Title: Microelectronic CircuitsAuthor: A.S. Sedra & K.C. SmithPublication date and edition: 5th ed, Oxford University Press, 2004ISBN number: 0-19-514251-9

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Goals• Concise

– To understand and apply Fundamentals of electronic circuits and systems

• Both theoretical and experimental (practical—lab)

• Background– EEL 3111C Circuits 1

• Linear• Passive

– Electronic Devices & Circuits• Nonlinear• Active

Logistics

• Class www sites:– http://www.icr.ece.ufl.edu/teaching/EEL3304-F07/3304home.htm

• Syllabus, course calendar, announcements, homeworks, solutions

– http://lss.at.ufl.edu• Grades, secure content• Available to all registered students

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Course Focus

1. Input signals, amplifier models (Chapter 1)2. Nearly ideal electronic circuit—Operational amplifier

and its Basic Uses (Chapter 2)3. Electron device #1—Diode and its Basic Circuit

Applications (Chapter 3)4. Electron device #2—MOS Transistor and its Basic

Circuit Applications (Chapter 4)5. Electron device #3—Bipolar Junction Transistor and its

Basic Circuit Applications (Chapter 5)6. Single-stage integrated circuit amplifiers (Chapter 6)7. Differential and multi-stage amplifiers (Chapter 7)

What’s next? EEL 4306C, EEL 4310, etc.

Review: Thevenin Equivalent• Replace a complex network with a voltage

source and series resistance• Measure the open circuit voltage at the

network terminals • This voltage becomes the Thevenin

equivalent voltage • "Zero" all independent supplies

– short circuit voltage supplies – open circuit current supplies

• Measure the resulting resistance between the terminals Thevenin equivalent resistance – Might be able to do this by inspection

series/parallel resistors – apply a test voltage and compute test

current

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Simple Example of Thevenin Equivalent

• Circuit with a 1V supply in series with 5k and 10k resistor -10k across network terminals

• Open circuit voltage is 1V * 10k / 15k = 0.66V

• Zero supplies - short circuit voltage supply - 10k in parallel with 5k = 3.33k

• Equivalent is a 0.66V supply with a 3.33k resistor in series

Review: Norton’s Theorem• Replace a complex network with a

current source and parallel resistor• Measure the short-circuit current across

terminals • This current is the Norton equivalent

current • "Zero" all independent supplies

– short circuit voltage supplies – open circuit current supplies

• Measure the resulting resistance between the terminals Norton equivalent resistance – Might be able to do this by inspection

series/parallel resistors – apply a test voltage and compute test current

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Simple Example of Norton Equivalent

• Circuit with a 1V supply in series with 5k and 10k resistor - 10k across network terminals

• Short circuit current is 1V / 5k = 200uA

• Zero supplies - short circuit voltage supply - 10k in parallel with 5k = 3.33k

• Equivalent is a 200uA supply with a 3.33k resistor in parallel

• Continuous-time signal (Analog)• Sampling→ Discrete time• Finite number of digits → Digital

Figure 1.7 Sampling the continuous-time analog signal in (a) results in the discrete-time signal in (b).

sensorNonelectricalElectricalSignal (t)

Signals

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Fundamental Building Block for Analog (and also Digital Systems)

• Amplifier• Circuit Symbol

Figure 1.10 (a) Circuit symbol for amplifier. (b) An amplifier with a common terminal (ground) between the input and output ports.

Applications• What are some applications of amplifiers?

http://electronics.howstuffworks.com/radio8.htm

Amplitude Modulation

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Figure 1.13 An amplifier transfer characteristic that is linear except for output saturation.

What does it mean to amplify a signal?

Linear and non-linear regions of operation

Amplifier Gain and DC Bias

)()( tVVtV iII +=Total

InstanteousValue

DCQuiescent AC

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Amplifier Gain• Voltage Gain: Av =

(dB) 20log |Av| dB• Current Gain : Ai =

(dB) 20log |Ai| dB• Power Gain: Ap =Av AI

(dB) 10log |Ap|dB

I

o

VV

I

o

ii

[ ])()(21)( dBAdBAdBA IVP +=

Note: multiplication of two numbers is equivalent to adding their logarithms

A few words about dB• When is the Gain in dB a negative number?

– Inverting amplifier (180 degrees phase difference between input and output)

– Or when the amplifier is attenuating• dB is unitless:20log (V/V) or 20log (I/I) or

10log(W/W)• Find the log of 0.1, 1, 10 , 100, • If the gain is -6dB, what is the gain in V/V• If gain is -3dB, what is the gain in V/V

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Amplifier Models• Voltage Amplifier• Current Amplifier• Transconductance Amplifier• Tranresistance Amplifier

1. Voltage Amplifier

• Avo = open circuit voltage gain

• Ri= input resistor• Ro= output resistor

⎟⎠⎞

⎜⎝⎛=

=VV

VV

oii

o

0

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With Signal and Load

si

isi RR

RVV

+=

oL

Livo RR

RVAV

o +=

s

o

VV

≡oL

L

si

iv RR

RRR

RA

o ++=

• Voltage Buffer Amp– Ri high, Ro low– Unity Gain Avo = 1

• Find overall Gain

2. Current Amplifier Model

• Ais = Short Circuit Current Gain

⎟⎠⎞

⎜⎝⎛=

=AA

ii

oVi

o

0

• Current Buffer Amp– Ri low, Ro high– Unity gain, Ais = 1

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3. Transconductance Amp Model

• Gm = Short Circuit Transconductance

⎟⎠⎞

⎜⎝⎛=

=VA

Vi

oVi

o

0

4. Transresistance Amp Model

• Rm = Open Circuit Transresistance

⎟⎠⎞

⎜⎝⎛=

=AV

iV

oVi

o

0

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Summary• Goals• Logistics• Electronic Circuits• Signal sources• Amplifier models