This preview shows pages 1–9. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: 1 The Operational Amplifier t In this lecture, you will learn: s The characteristics of an ideal operational amplifier s The application of the operational amplifier to five circuit configurations: The comparator The inverting amplifier The noninverting amplifier The summing amplifier The difference amplifier 2 The Operational Amplfier t The term is rooted in the days of the analog computer s A unit used to perform addition, subtraction, multiplication, division, differentiation or integration t Today, the term op amp usually refers to a highly integrated circuit capable of performing these same operations by adding external components 3 The 741 Op Amp t One of the first solidstate integrated opamps (1966) t Still widely used today Inverting input Noninverting input Output V + V 2 3 7 4 6 15 Offset null + + Inverting input 2 Noninverting input 3 V 4 Offset null 1 7 V + 6 Output 5 Offset Null 8 NC 4 The 741 OpAmp You get all of this for around 20 cents. Inverting input Noninverting input Output V + V 2 3 7 4 6 15 Offset null + 5 Output Input Characteristics OutputInput Characteristics2015105 5 10 15 200.200.150.100.05 0.00 0.05 0.10 0.15 0.20 Input Voltage vd in mV O u t p u t V o l t a g e v o in V PositiveSaturationRegionP ositiveSaturationRegion PositiveSaturationRegion PositiveSaturationRegion NegativeSaturationRegionN egativeSaturationRegion NegativeSaturationRegion NegativeSaturationRegion LinearRegionL inearRegion LinearRegion LinearRegion + + v 1 + v 2 v d + + v o 6 The Ideal Operational Amplifier t We will make some assumptions about the o p amp characteristics that simplify circuit analysis. t For many circuits, these simplifications are justified. t The ideal operational amplifier can be characterized as follows: s Infinite open loop gain, A s Infinite input resistance, R i s Zero output resistance, R o v o R i Av d R o + v d + 7 Real World (Nonideal) Op Amp t All real op amps have: s A finite input resistance R i s A finite (but very large) gain called the openloop gain (A) s A nonzero output resistance R o s Current drive limitations s Power dissipation limitations s Input offsets that must be dealt with in some circuits v o R i Av d R o + v d + 8 Real vs. Ideal Specs. t The ideal op amp: s Infinite open loop gain, A s Infinite input resistance, R i s Zero output resistance, R o 0 t Real opamp specs (LM741): s A = 200,000 (typical) s R i = 6 M (typical) s R o 300 (typical for R L 2k ) v o R i Av d R o + v d + o v i Av d + v d + 9...
View
Full
Document
This note was uploaded on 02/13/2010 for the course EE 302 taught by Professor Mccann during the Spring '06 term at University of Texas at Austin.
 Spring '06
 MCCANN

Click to edit the document details