EE 230Lecture 10

Operational Amplifiers and Basic Applications

Review from last time

OUTIN

Aβ1AAFB +

=

β1AFB≅

Review from last time

Feedback significantly and simultaneously improves most parameters of interest by a factor of about 1+Aβ

Feedback properties is the major driving factor behind the evolution and use of operational amplifiers

Review from last time

Feedback significantly and simultaneously improves most parameters of interest by a factor of about 1+Aβ

Review from last time

For a VCVS Op Amp

Review from last time

2

1

OUT

( )12OUT VVAV −=

For a VCVS Op Amp

Consider the following circuit

AV

Consider the following circuit

This is exactly the feedback architecture in the case where the input and output variables are voltages

This is a voltage feedback amplifier

AV

Consider the following circuit

Aβ1AAFB +

=

1

2FB R

Rβ1A +=≅ 1

VAA =

AV

21

1

RRRβ+

=

1

2

IN

OUTFB R

RV

VA +≅= 1

Basic Noninverting Amplifier

Redraw this feedback circuit

1

2

IN

OUTFB R

RV

VA +≅= 1