This preview shows pages 1–7. 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 Document
Unformatted text preview: Chapter 11 Operational Amplifiers Microelectronic Circuit Design Richard C. Jaeger Travis N. Blalock Chap 111 Chapter Goals Understand behavior and characteristics of ideal differential and op amps. Demonstrate circuit analysis techniques for ideal op amps. Characterize inverting, noninverting, summing and instrumentation amplifiers, voltage follower and integrator. Learns factors involved in circuit design using op amps. Provide and introduction to active filters Explore applications of op amps in nonlinear circuits, such as precision rectifiers. Provide examples of multivibrator circuits employing positive feedback. Demonstrate use of ac analysis capability of SPICE. Chap 112 Differential Amplifier Model: Basic Represented by: A = opencircuit voltage gain v id = ( v +v ) = differential input signal voltage R id = amplifier input resistance R o = amplifier output resistance Signal developed at amplifier output is in phase with the voltage applied at + input (noninverting) terminal and 180 out of phase with that applied at  input (inverting) terminal. Chap 113 Differential Amplifier Model: With Source and Load R L = load resistance R S = Thevenin equivalent resistance of signal source v s = Thevenin equivalent voltage of signal source L R o R L R A + = id v * o v Op amp circuits are mostly dccoupled amplifiers. Signals v o and v s may have a dc component representing a dc shift of the input away from Qpoint. Opamp amplifies both dc and ac components. L R o R L R S R id R id R v A + + = = s v o v S R id R id R + = s v id v and Chap 114 Differential Amplifier Model: With Source and Load (Example) Problem : Calculate voltage gain Given Data : A =100, R id =100k , R o = 100 , R S =10k , R L =1000 Analysis : Ideal amplifiers output depends only on input voltage difference and not on source and load resistances.This can be achieved by using fully mismatched resistance condition ( R id >> R S or infinite R id and R o << R L or zero R o ). or A = openloop gain (maximum voltage gain available from the device) dB 3 . 38 6 . 82 100 100 1000 k 100 k 10 k 100 100 s v o v = = + + = + + = = L R o R L R S R id R id R v A id v o v A = A v A = = id v o v Chap 115 Ideal Operational Amplifier Ideal op amp is a special case of ideal differential amplifier with infinite gain, infinite R id and zero R o . and If A is infinite, v id is zero for any finite output voltage. Infinite input resistance R id forces input currents i + and i to be zero. Ideal op amp has following assumptions: Infinite commonmode rejection, power supply rejection, openloop bandwidth, output voltage range, output current capability and slew rate Zero output resistance, inputbias currents and offset current, inputoffset voltage....
View
Full
Document
This note was uploaded on 03/29/2009 for the course ECE 51 taught by Professor Martinbrooke during the Fall '08 term at Duke.
 Fall '08
 MartinBrooke
 Amplifier, Operational Amplifier

Click to edit the document details