Chap2

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Chapter 2 – Operational Amplifiers

Introductionhttp://engr.calvin.edu/PRibeiro_WEBPAGE/courses/engr311/Handouts/OpAmp-tutorial-1.ppt

Textbook CD

http://www.clarkson.edu/%7Esvoboda/eta/designLab/InvertingAmplifierDesign.html

http://engr.calvin.edu/PRibeiro_WEBPAGE/courses/engr311/Handouts/OpAmp-tutorial-1.ppt

http://www.clarkson.edu/~svoboda/eta/designLab/InvertingAmplifierDesign.html

http://www.clarkson.edu/~svoboda/eta/designLab/InvertingAmplifierDesign.html








The OP-AMP Terminals

Symbol

Power Supplies



Fairchild uA702 – The first op-amp designed by Bob Widlar









The Ideal OP-AMP

-VS

vid

Inverting

Noninverting

Output

+

_ i(-)

i(+)

v

O = Advid

RO

ARi

Open-loop gain

Exercise 2.2



Analysis of Circuits Containing Ideal OP-AMPS

The Inverting Configuration

The inverting closed-loop configuration.

Closed-Loop Gain

Virtual Short-Circuit

Virtual Ground

Negative and Positive Feedback




The Closed-Loop Gain

Analysis of the inverting configuration

-




Effect of Finite Open-Loop Gain

i1

vI

vo

A

R1

vI

vo

A

R1

vo

vo

Ai1 R2

vo

A

vIvo

A

R1

R

G

vo

vI

R2

R1

1

1R2

R1

A




Exercise 2.1




Input and Output Resistances

R

i

vI

iI

vI

vI

R1

R1

R

o

0




Exercise 2.2



Other Applications of the Inverting Configuration

With General Impedances

R2

+

R1

vo

is

vs

Z1

Z2




The Integrator

+ vo

ic

i-

R

vs

is

C vo t( )1

C R0

t

tvI t( )

d

Vo

VI

1

s C R




PSpice Simulation Tips




The Differentiator

R2

+

R1

vo

is

vs

Z1 = 1/sC

Z2 = R




The Weighted Summer




The Non-Inverting Configuration

vi

v2

v1

vo

AA infinit

vo

vI

vI

R1R2

vo

vI

1

R2

R1




The Voltage Follower



A difference amplifier.


The Difference Amplifier



Applications of superposition to the analysis of the current circuit of Fig.. 2.21.


The Difference Amplifier



Finding the input resistance of the difference amplifier.


The Difference Amplifier – Input Resistances



Representation of the common-mode and differential components of the input signal to a difference amplifier. Note that v1 = vCM - vd /2

and v2 = v

CM + vd /2.


The Difference Amplifier – Common-Mode and Differential

Components of the input signal



(a) A popular circuit for an instrumentation amplifier. (b) Analysis of the circuit in (a) assuming ideal op-amps. (c) To make the gainvariable, R1 is implemented as the series combination of a fixed resister R1 f and a variable resistor R1v. Resistor R1 f ensures that the

maximum available gain is limited.


Instrumentation Amplifier



Open-loop gain of a typical general-purpose internally

compensated op amp.

Effect Of Finite Open-Loop Gain and Bandwidth On Circuit

Performance

fb = 3-db or break frequency

ft = unity gain bandwidth



(a) Unity-gain follower. (b) Input step waveform. (c) Linearly rising output waveform obtained when the amplifier is slew-rate

limited. (d) Exponentially rising output waveform obtained when V is sufficiently small so that the initial slope (wt V ) is smaller then or

equal to SR.



Effect of slew-rate limiting on output sinusoidal waveforms.

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Chap2