15-Types of Op Amps

1Purdue University EET 368 Analog Integrated Circuits

Types of Op Amps

Op Amp Selection Criteria

Types


Op Amp Selection CriteriaspeedDCsystem

Types

Types of Op Amps


Op Amp Selection CriteriaspeedDCsystem

TypesgeneralFETCMOSwideband & current feedbackpower amps and buffers

Types of Op Amps


Op amp Selection CriteriaHow must the circuit perform?

Speed

DC

System



Speedcircuit closed loop gain A CLgain accuracy (30%, 10%, 1%)f max (f H, f 10% , f 1% )Vout pk

DC

System



Speedcircuit closed loop gain A CL

gain accuracy (30%, 10%, 1%)f max (f H, f 10% , f 1% )Vout pk

DC

System

GBW



Speedcircuit closed loop gain A CL

gain accuracy (30%, 10%, 1%)f max (f H, f 10% , f 1% )Vout pk

DC

System

GBW

SR



Speed

DCsource impedanceDC output error allowabletemperature range

System



Speed

DC

Systempower available +/-V or just +, I available, battery?Vout & Iout neededVin $availability

10

Purdue University EET 368 Analog Integrated Circuits

General Purpose Op ampspeed 8MHzDC

cost examples

11



Ibias 100snAIos 10snAVios mVdrift 5microV/degC

cost examples

12




cost lowest

13




cost lowest

14


FET Input Op Ampsspeed 10MHzDC

cost examples

15



much improved over general purposeIbias 100s pAIos 100s pAVios 0.1mVdrift 1microV/degC

cost examples

16




cost few $sexamples

17




cost few $sexamples

TLO84National Semiconductor's LF series

LT 1056

18


CMOS Op Amps

speed 1MHz or belowDC

cost

examples

system considerations

19


CMOS Op Amps

speed 1MHz or belowDC

much better than FETIbias & Ios fA (1E-15)Vios mVZin 1E12drift 10microV/degC

cost

examples


20


CMOS Op Amps

speedDC

cost examples

system considerationsallows low supplies +1V +3Vprogrammable IQ 100 uAlow saturation voltage 10mVChopper Stabilized more later

21


CMOS Op Amps

speedDC

cost few $

examples


22


CMOS Op Amps

speedDC

cost

examples


LMCxxxx National SemiconductorCAxxxx RCAICLxxxx Intersil now GELTCxxxx Linear TechnologyTLCxxxx Texas Instruments

23


CMOS Op AmpsBeware!

Iout may be

24


Chopper Stabilized (CMOS) Op Amp

Speed MHzDC

System Considerations Examples

25



SpeedDC

IB & Ios 10pAVios micro Volts

drift 0.01 to 0.5 microV/deg CSystem Considerations Examples

26



SpeedDCSystem Considerations

same as other CMOS op amps

Examples

27



Speed MHzDCSystem Considerations

same as other CMOS op amps

ExamplesLTC 1049, 1051, 1053, ... Linear TechnologyTLC2652P Texas InstrumentsAD 855x &AD857x Analog Devices

28


Chopper Stabilized Op Amp Schematic

nullpin

nullpin

In +

In -

Out

A

B

A' B'

V-

CXA CXB

nullamp

mainamp

29


Wide band Op Amps

SpeedGBW 600MHzfull power bandwidth 9MHzslew rate 600V/microsec

DC

Cost

30


Wide band Op Amps

SpeedGBW 600MHzfull power bandwidth 9MHzslew rate 600V/microsec

DC Ibias mA

Cost

31


Wide band Op Amps

SpeedGBW 10GHzfull power bandwidth 100MHzslew rate 600V/microsec

DC Ibias mA

Cost

$10 - $100

32


Current Feedback Op AmpsSpeed

fH is a constant, not affected by A CL

DC

System Considerations

33



fH is a constant, not affected by A CL

DCIbias 100nA

Vios mV

Zin MOhms

System Considerations

34



fH is a constant, not affected by ACL

DCIbias 100nA

Vios mV

Zin MOhms

System Considerations+5V to +18V

rf BEWARE!

Rf is usually specified

35


High Power Op Ampsaudio

drive a speaker 20-20kHz single +12V not an op amp

buffers

op amps

36



drive a speaker 20-20kHz single +12V

not an op amp

buffers 100s mA

$

must be used inside a feedback loop

op amps

load

precision, inst rument qualityop amp

Rf

Ri

unity gainpower buffer

LT 1010

37



drive a speaker 20-20kHz single +12V

not an op amp

buffers 100s mA

$

must be used inside a feedback loop

op amps

speed & DC similar to general purpose10 A & 100V

internal o r external I limitthermal shutdown$ to $10

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15-Types of Op Amps