Chapter 2 – Operational Amplifiers

Introduction

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

Textbook CD

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

The OP-AMP Terminals

Symbol

Power Supplies

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

The OP-AMP Terminals

The OP-AMP Terminals

The Ideal OP-AMP

-V-VSS

vvidid

InvertingInverting

NoninvertingNoninverting

OutputOutput

++

__ii(-)(-)

ii(+)(+)

vvOO = A = Addvvidid

RROO

AARRii

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

Analysis of Circuits Containing Ideal OP-AMPS

The Closed-Loop Gain

Analysis of the inverting configuration

-

Analysis of Circuits Containing Ideal OP-AMPS

Effect of Finite Open-Loop Gain

i1

vI

vo

A

R1

vI

vo

A

R1

vo

vo

Ai1 R2

vo

A

vI

vo

A

R1

R2

Gvo

vI

R2

R1

1

1R2

R1

A

Analysis of Circuits Containing Ideal OP-AMPS

Exercise 2.1

Analysis of Circuits Containing Ideal OP-AMPS

Input and Output Resistances

Ri

vI

iI

vI

vI

R1

R1

Ro 0

Analysis of Circuits Containing Ideal OP-AMPS

Exercise 2.2

Other Applications of the Inverting Configuration

With General Impedances

R2

+

R1

vo

is

v s

Z1

Z2

Other Applications of the Inverting Configuration

The Integrator

+ vo

ic

i -

R

vs

is

C vo t( )1

C R0

t

tvI t( )

d

Vo

VI

1s C R

Other Applications of the Inverting Configuration

PSpice Simulation Tips

Other Applications of the Inverting Configuration

The Differentiator

R2

+

R1

vo

is

v s

Z1 = 1/sC

Z2 = R

Other Applications of the Inverting Configuration

The Weighted Summer

Other Applications of the Inverting Configuration

The Non-Inverting Configuration

vi

v2 v1vo

AA infinite

vo vI

vI

R1R2

vo

vI1

R2

R1

Other Applications of the Inverting Configuration

The Voltage Follower

A difference amplifier.

Other Applications of the Inverting Configuration

The Difference Amplifier

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

Other Applications of the Inverting Configuration

The Difference Amplifier

Finding the input resistance of the difference amplifier.

Other Applications of the Inverting Configuration

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 = vCM + vd/2.

Other Applications of the Inverting Configuration

The Difference Amplifier – Common-Mode and DifferentialComponents 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 gain variable, R1 is implemented as the series combination of a fixed resister R1f and a variable resistor R1v. Resistor R1f ensures that the

maximum available gain is limited.

Other Applications of the Inverting Configuration

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 frequencyft = 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 (wtV) is smaller then

or equal to SR.

Effect of slew-rate limiting on output sinusoidal waveforms.