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

Exercise 2.1

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

vIvo

A

R1

vIvoA

R1

vovo

Ai1 R2

vo

A

vIvoA

R1

R2

GvovI

R2

R1

11

R2R1

A

Analysis of Circuits Containing Ideal OP-AMPS

Example 2.1

Analysis of Circuits Containing Ideal OP-AMPS

Input and Output Resistances

RivIiI

vIvI

R1

R1

Ro 0

Analysis of Circuits Containing Ideal OP-AMPS

Example 2.2

Analysis of Circuits Containing Ideal OP-AMPS

Exercises

Other Applications of the Inverting Configuration

With General Impedances

Other Applications of the Inverting Configuration

Example 2.3

A difference amplifier.

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

Finding the input resistance of the difference amplifier.

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.

(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.

Open-loop gain of a typical general-purpose internally compensated op amp.

(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.