Amplifiers - AGH

AmplifiersAmplifiersAmplifiersAn electronic amplifierAn electronic amplifier,, amplifieramplifier,, oror ampamp-- is an electronic device that is an electronic device that increases the power ofincreases the power of aa signalsignal. .

[http://[http://enen..wikipediawikipedia..orgorg//wikiwiki/]/]

AA Wheatstone bridge is an electrical circuit usedWheatstone bridge is an electrical circuit used toto measure an measure an unknown electrical resistanceunknown electrical resistance byby balancing two legs ofbalancing two legs of aa bridge bridge

circuitcircuit..

Rx is the unknown resistanceRx is the unknown resistance to beto be measuredmeasured. R1, R2. R1, R2 andand R3R3 are are resistors of known resistance and the resistanceresistors of known resistance and the resistance R2R2 is adjustableis adjustable.. If the If the ratio of the two resistances ratio of the two resistances R2 / R1R2 / R1 is equalis equal toto the ratio of Rxthe ratio of Rx / R3,/ R3, then then the voltage between the two midpointsthe voltage between the two midpoints; ; CC andand D will be zero. D will be zero.

R1

R2

R3

Rx

VgVcc

A

B

C D

A Wheatstone bridge A Wheatstone bridge A Wheatstone bridge

At theAt the pointpoint of balanceof balance,, the ratio ofthe ratio of::

31

231

2

RR

RRx

R

Rx

R

R

=

=

VccRR

R

RxR

RxVg )

21

2

3(

+−

+=

If all resistor values and the supply voltageIf all resistor values and the supply voltage ((VVcccc) ) are knownare known,, and the and the resistance of the galvanometer is highresistance of the galvanometer is high, , the voltage across the bridgethe voltage across the bridge((VVgg) ) cancan bebe foundfound byby working out the voltage from each potential divider working out the voltage from each potential divider and subtractingand subtracting oneone from the otherfrom the other.. The equationThe equation forfor this isthis is::

A Wheatstone bridge A Wheatstone bridge A Wheatstone bridge

[[wwwwww.analog..analog.comcom]]

Bridge CircuitsBBridgeridge CCircuitsircuits

Resistive elements are some of theResistive elements are some of the mostmost common sensorscommon sensors..

SensorSensor elements' resistances can range fromelements' resistances can range from lessless thanthan 100100ΩΩ totoseveral hundredseveral hundred kkΩΩ,, dependingdepending onon thethe sensorsensor design and the physical design and the physical environmentenvironment to beto be measuredmeasured..

Resistance of popular sensorsResistance of popular sensors::

--Strain GagesStrain Gages (czujniki nap(czujniki naprrężężeniaenia) 120) 120ΩΩ , 350, 350ΩΩ , 3500, 3500ΩΩ

--Pressure SensorsPressure Sensors (czujniki ci(czujniki ciśśnienia) 350nienia) 350ΩΩ -- 35003500ΩΩ

--Relative HumidityRelative Humidity (czujniki(czujniki wigotnowigotnośścici) 100k) 100kΩΩ -- 10M10MΩΩ

--Resistance Temperature DevicesResistance Temperature Devices (czujniki temperatury) 100(czujniki temperatury) 100ΩΩ , , 10001000ΩΩ

--ThermistorsThermistors (termistory) 100(termistory) 100ΩΩ -- 10M10MΩΩ

The basic Wheatstone bridge[[wwwwww.analog..analog.comcom]]


BBridgeridge CCircuitsircuits

InIn many bridge applicationsmany bridge applications,, there maythere may bebe twotwo,, or even four elements or even four elements which varywhich vary..

Four commonly used bridges suitableFour commonly used bridges suitable for sensorfor sensor applicationsapplications. . [[wwwwww.analog..analog.comcom]]


AmplifiersAmplifiersAmplifiers

-

+K

Vout

R VccR

RR

Bridge AmplifierBridge Amplifier

The Differential Amplifier circuit isThe Differential Amplifier circuit is aa very useful opvery useful op--amp circuit andamp circuit and bybyadding more resistors in parallel with the input resistorsadding more resistors in parallel with the input resistors R1R1 andand R3,R3, the the resultant circuit canresultant circuit can bebe mademade toto eithereither ""AddAdd"" oror ""SubtractSubtract"" the voltages the voltages appliedapplied toto their respective inputstheir respective inputs. One. One of theof the mostmost common ways of common ways of doing this isdoing this is toto connectconnect a "a "Resistive BridgeResistive Bridge"" commonly calledcommonly called aaWheatstone BridgeWheatstone Bridge toto the input of the amplifierthe input of the amplifier..

[http://[http://wwwwww..electronicselectronics--tutorialstutorials..wsws]]

-

+K

Vcct

VccR1

R2P

Thermistor

Adjust

V-V+

Rf

R3

RelayD

Temperature Activated SwitchTemperature Activated Switch

The circuit actsThe circuit acts as aas a temperaturetemperature--activated switch which turns the output activated switch which turns the output relay eitherrelay either "ON""ON" oror "OFF" as"OFF" as the temperature level detectedthe temperature level detected byby the the thermistor exceeds or falls belowthermistor exceeds or falls below aa prepre--setset value atvalue at V+V+ determineddetermined bybythe position ofthe position of P. P.


Instrumentation AmplifierInstrumentation Amplifier

Instrumentation AmplifiersInstrumentation Amplifiers ((inin--ampsamps)) are very high gain differential are very high gain differential amplifiers which haveamplifiers which have aa high input impedance andhigh input impedance and a singlea single ended outputended output..Instrumentation amplifiers are mainly usedInstrumentation amplifiers are mainly used toto amplify very small amplify very small differential signals from strain gaugesdifferential signals from strain gauges,, thermocouples or current sensing thermocouples or current sensing devices indevices in motormotor control systemscontrol systems..

The instrumentation amplifier also hasThe instrumentation amplifier also has aa very good common mode very good common mode rejection ratiorejection ratio, CMRR (zero, CMRR (zero output whenoutput when V1 = V2)V1 = V2) well in excess ofwell in excess of100dB100dB atat DC.DC.



-+

-

+

-

+R1

R2

R2

RA

RA

RB

RBK1

K2

K3

V1

V2

Vout

Va

Vb

High Input Impedance Instrumentation AmplifierHigh Input Impedance Instrumentation Amplifier



)](1

221)[12(

RA

RB

R

RVVVout +−=

Instrumentation Amplifier EquationInstrumentation Amplifier Equation


PrecisionPrecision Instrumentation AmplifierInstrumentation Amplifier AD524AD524

FEATURES

-Low noise: 0.3 µV p-p at 0.1 Hz to 10 Hz

-Low nonlinearity: 0.003% (G = 1)

-High CMRR: 120 dB (G = 1000) Low offset voltage: 50 µV

-Low offset voltage drift: 0.5 µV/°C

-Gain bandwidth product: 25 MHz

-Pin programmable gains of 1, 10, 100, 1000

-Input protection, power-on/power-off

-No external components required

-Internally compensated [[wwwwww.analog..analog.comcom]]


Functional blockFunctional block diagramdiagram



Metallization Photograph Contact factoryMetallization Photograph Contact factory forfor latest dimensionslatest dimensions;;Dimensions shown in inches andDimensions shown in inches and (mm)(mm)



Indirect Ground ReturnsIndirect Ground Returns forfor Bias CurrentsBias Currents——ThermocoupleThermocouple



Typical Bridge ApplicationTypical Bridge Application



SingleSingle Supply BridgeSupply Bridge Transducer AmplifierTransducer Amplifier AD22055AD22055

FEATURES:

-Gain of 400. Alterable from 40 to 1000

-Supply Voltage: +3 V to +36 V

-Peak Input Voltage (40 ms): 60 V

-Reversed Supply Protection: –34 V

-Operating Temperature Range: –40°C to +125°C

APPLICATIONS:

Interface for Pressure Transducers, Position, Temperature Transducers

Indicator, Strain Gages and Other Low Level Signal Sources



Functional block diagram[[wwwwww.analog..analog.comcom]]

Typical Application Circuit for a Pressure Sensor Interface


LT1101LT1101 PrecisionPrecision,, MicropowerMicropower, Single, Single Supply Instrumentation Supply Instrumentation AmplifierAmplifier ((Fixed GainFixed Gain = 10= 10 oror 100)100)

FEATURES:FEATURES:

--Supply CurrentSupply Current: 105: 105µµA MaxA Max

--OffsetOffset VoltageVoltage: 160: 160µµV MaxV Max

--CMRR, G = 100: 100dB MinCMRR, G = 100: 100dB Min

--Gain Bandwidth ProductGain Bandwidth Product: : 250kHz Min250kHz Min

--SingleSingle or Dual Supply Operationor Dual Supply Operation

APPLICATIONSAPPLICATIONS::

a.a.Differential Signal Amplification in Differential Signal Amplification in Presence of Common Mode VoltagePresence of Common Mode Voltage

b.b.Micropower Bridge Transducer Micropower Bridge Transducer AmplifierAmplifier

–– ThermocouplesThermocouples

–– Strain GaugesStrain Gauges

–– ThermistorsThermistors

c.c.Differential VoltageDifferential Voltage--toto--Current Current ConverterConverter

d.4mA to 20mAd.4mA to 20mA Bridge TransmitterBridge Transmitter[[wwwwww..linearlinear..comcom]]


Block Block diagramdiagram

[[wwwwww..linearlinear..comcom]]


MicropowerMicropower,, Battery Operated Remote TemperatureBattery Operated Remote Temperature SensorSensorTrim output to 250mV AT 25°C, Temperature range = 2.5°C TO 150°C, Accuracy = ±0.5°C [[wwwwww..linearlinear..comcom]]


Voltage Controlled Current Voltage Controlled Current SourceSource



Differential Voltage Amplification fromDifferential Voltage Amplification from aa Resistance BridgeResistance Bridge




INA333INA333 MicroMicro--PowerPower (50mA), Zer(50mA), Zerøø--DriftDrift,, RailRail--toto--Rail Out Rail Out Instrumentation AmplifierInstrumentation Amplifier

FEATURESFEATURES::

--LowLow offsetoffset voltagevoltage: 25mV (max),: 25mV (max),

--HighHigh CMRR: 100dB (min), G CMRR: 100dB (min), G ≥≥ 1010,,

Supply rangeSupply range: +1.8V to +5.5V: +1.8V to +5.5V,,

Input voltageInput voltage: (V: (V––) +0.1V to (V+) ) +0.1V to (V+) ––0.1V0.1V,,

Output rangeOutput range: (V: (V––) +0.05V to (V+) ) +0.05V to (V+) ––0.05V0.05V,,

Operating temperatureOperating temperature: : ––4040°°C to C to +125+125°°CC..

APPLICATIONS:APPLICATIONS:

--Bridge amplifiersBridge amplifiers,,

--Pressure sensorsPressure sensors,,

--Medical InstrumentationMedical Instrumentation,,

--Thermocouple amplifiersThermocouple amplifiers,,

--Data Data acquisitionnacquisitionn..

[[wwwwww..titi..comcom]]

Block diagram[[wwwwww..titi..comcom]]


BasicBasic ConnectionsConnections



SingleSingle--Supply Bridge AmplifierSupply Bridge Amplifier



OscillatorsOscillatorsOscillatorsAn electronic oscillator is an electronic circuit that producesAn electronic oscillator is an electronic circuit that produces aa repetitiverepetitive,,

oscillating electronic signaloscillating electronic signal,, oftenoften a sinea sine wave orwave or aa square wavesquare wave..

[http://[http://enen..wikipediawikipedia..orgorg//wikiwiki/]/]

BasicBasic Oscillator Feedback CircuitOscillator Feedback Circuit

+

Vin Vout

Attenuator B

Amplifier

VoutB Vout

Vin+B VoutA

OscillatorsOscillatorsOscillators

AA-- open loop voltage gainopen loop voltage gain

BB-- feedback fractionfeedback fraction

AB

A

Vin

Vout

ABVoutAVin

VoutBVoutVinA

−=

−==+

1

)1(

)(

OscillatorOscillators are circuits that generates are circuits that generate aa continuous voltage output continuous voltage output waveform atwaveform at aa required frequency with the values of the inductorsrequired frequency with the values of the inductors,,capacitors or resistors formingcapacitors or resistors forming aa frequency selectivefrequency selective LCLC resonantresonant tanktankcircuit and feedback networkcircuit and feedback network.. This feedback network is an attenuation This feedback network is an attenuation network which hasnetwork which has aa gain ofgain of lessless thanthan one ( one ( BB <1 )<1 ) and starts oscillations and starts oscillations whenwhen AABB >1>1 which returnswhich returns to unity ( Ato unity ( ABB =1 )=1 ) once oscillations once oscillations commencecommence..


TTypes of Oscillatorsypes of Oscillators

Sinusoidal OscillatorsSinusoidal Oscillators-- generatesgenerates aa purely sinusoidal waveform purely sinusoidal waveform which is of constant amplitude and frequencywhich is of constant amplitude and frequency..

NonNon--Sinusoidal OscillatorsSinusoidal Oscillators-- generate complex nongenerate complex non--sinusoidal sinusoidal waveformswaveforms as "as "SquareSquare--wavewave", "", "TriangularTriangular--wavewave"" oror ""SawtoothedSawtoothed--wavewave""


TheThe RC RC OscillatorOscillator

AA singlesingle stage amplifierstage amplifier willwill produceproduce 180180OO of phase shift between its of phase shift between its output and input signals when connected inoutput and input signals when connected in aa classclass--AA type configurationtype configuration..

InIn anan RCRC Oscillator circuit the input is shiftedOscillator circuit the input is shifted 180180OO through the amplifier through the amplifier stage andstage and 180o180o again throughagain through aa second inverting stage giving ussecond inverting stage giving us " " 180180OO

+ + 180180OO = = 360360OO" " of phase shiftof phase shift..

In a RC In a RC OscillatorOscillator, we, we make use of the fact thatmake use of the fact that aa phase shift occurs phase shift occurs between the inputbetween the input to a RCto a RC network and the output from thenetwork and the output from the samesamenetworknetwork byby usingusing RCRC elements in the feedback branchelements in the feedback branch..

RC OscillatorsRC RC OscillatorsOscillators

RCRC PhasePhase--ShiftShift NetworkNetwork

C

R

input output

60o

C

R

C

R

C

Ro0

o0 o180


90O

60O

output

180O

outputinput

Single stage

Three stage

PPhase shift between the inputhase shift between the input RC RC network and the outputnetwork and the output..

fCX C π2

1=

22 )( CXRZ +=

R

X C1tan −=φ


An amplifier circuit will produce a phaseAn amplifier circuit will produce a phase--shift of shift of 180180OO between its input between its input and output. If a threeand output. If a three--stage RC phasestage RC phase--shift network is connected shift network is connected between this input and output of the amplifier, the total phase between this input and output of the amplifier, the total phase shift shift necessary for regenerative feedback will become 3 x necessary for regenerative feedback will become 3 x 6600OO + + 180180OO = = 360360OO ..

C

R

C

R

C

Ro0

o180o120o60 AB=1180o


Basic RCBasic RC Oscillator CircuitOscillator Circuit

C

R

C

R

C

Ro0

o180o120o60

output

Vcc

R1 Rl

Re


If all the resistorsIf all the resistors, R, R and the capacitorsand the capacitors, C, C in the phase shift network are in the phase shift network are equal in valueequal in value,, then the frequency of oscillations producedthen the frequency of oscillations produced byby thethe RCRCoscillator is givenoscillator is given as:as:

WhereWhere::

ƒƒrr-- Output Frequency inOutput Frequency in HertzHertz

RR-- Resistance in OhmsResistance in Ohms

CC-- Capacitance in FaradsCapacitance in Farads

NN-- number ofnumber of RC RC stagesstages (N = 3)(N = 3)

NRCfr

22

1

π−


OpOp--ampamp RCRC Oscillator CircuitOscillator Circuit

C

R

C

R

C

Ro0

o180o120o60

output

A-

+

Rf


ExampleExample

Hzfr

kR

FnFC

75,6491010000062

1

100

1011

9

9

=⋅⋅⋅⋅

=

Ω=⋅==

−

−

π


The Wien Bridge OscillatorThe Wien Bridge Oscillator

The Wien Bridge Oscillator is so called because the circuit is bThe Wien Bridge Oscillator is so called because the circuit is basedased on aon afrequencyfrequency--selectiveselective formform of the Whetstone bridge circuitof the Whetstone bridge circuit..

RCRC PhasePhase ShiftShift NetworkNetwork

C1R1

R2 C2 VoutVin

R1=R2, C1=C2


Output Gain and PhaseOutput Gain and Phase ShiftShift

fr

Vout

φ f

f

90

-90

o

o

Phase Shift

fr

Resonance

1/3 Vin


Resonant FrequencyResonant Frequency

WhereWhere::

ƒƒr is the Resonant Frequency inr is the Resonant Frequency in HertzHertz

RR is the Resistance in Ohmsis the Resistance in Ohms

CC is the Capacitance in Faradsis the Capacitance in Farads

RCfR π2

1=


Wien Bridge OscillatorWien Bridge Oscillator

OneOne part of the feedback part of the feedback signal is connectedsignal is connected toto the the inverting inputinverting input terminal terminal ((negative feedbacknegative feedback) via) via the the resistor dividerresistor divider..

The other part is fed backThe other part is fed back totothe nonthe non--inverting inputinverting inputterminal (terminal (positive feedbackpositive feedback) ) viavia thethe RCRC Wien Bridge Wien Bridge networknetwork

V output

A+

-

RC

C

R

R1R2

1/3Vout


Only aOnly at the selected resonant frequencyt the selected resonant frequency, (, ( ƒƒrr )) the voltages appliedthe voltages applied toto the the inverting and noninverting and non--inverting inputsinverting inputs will bewill be equal andequal and ""inin--phasephase„„..

The positive feedbackThe positive feedback willwill cancel out the negative feedback signal cancel out the negative feedback signal causing the circuitcausing the circuit toto oscillateoscillate..

TThe voltage gain of the amplifier circuithe voltage gain of the amplifier circuit MUST beMUST be equalequal toto threethree ""GainGain = = 3" for3" for oscillationsoscillations to startto start..


The Quartz Crystal OscillatorsThe Quartz Crystal Oscillators

OneOne of theof the mostmost important features of any oscillator is its frequency important features of any oscillator is its frequency stabilitystability..

Frequency stability of the output signal canFrequency stability of the output signal can bebe improvedimproved byby the proper selection the proper selection of the components usedof the components used forfor the resonant feedback circuitthe resonant feedback circuit..

ToTo obtainobtain aa very high level of oscillator stabilityvery high level of oscillator stability aa Quartz Crystal is generally Quartz Crystal is generally usedused asas the frequency determining devicethe frequency determining device toto produce another types of oscillator produce another types of oscillator circuit known generallycircuit known generally as aas a Quartz Crystal OscillatorQuartz Crystal Oscillator

Quartz OscillatorsQuartzQuartz OscillatorsOscillators

Colpitts Crystal OscillatorColpitts Crystal Oscillator

These types of Crystal Oscillators are designed around the commoThese types of Crystal Oscillators are designed around the common n emitter amplifier stage ofemitter amplifier stage of aa Colpitts OscillatorColpitts Oscillator..

Quartz OscillatorsQuartzQuartz OscillatorsOscillators

output

Vcc

R1RL

ReR2Ce

C1 C2

Xt

The Other The Other Electrical WaveformsElectrical Waveforms

Square Wave WaveformsSquare Wave Waveforms

Square-wave Waveforms are used extensively in electronic and micro electronic circuits for clock and timing control signals as they are symmetrical waveforms of equal and square duration representing each half of a cycle and nearly all digital logic circuits use square wave waveforms on their input and output gates.

A

t

Positive HalfNegative Half

Period- T

Electrical WaveformsElectrical WaveformsElectrical Waveforms

Rectangular WaveformsRectangular Waveforms

Rectangular Waveforms are similar to the square wave waveform above,the difference being that the two pulse widths of the waveform are of an unequal time period. Rectangular waveforms are therefore classed as "Non-symmetrical" waveforms.

A

t

Positive HalfNegative Half

Period- T


Triangular WaveformsTriangular Waveforms

Triangular Waveforms are generally bi-directional non-sinusoidal waveforms that oscillate between a positive and a negative peak value.

A

tPeriod- T


Sawtooth WaveformsSawtooth Waveforms

Sawtooth Waveforms are another type of periodic waveform. As its name suggests, the shape of the waveform resembles the teeth of a sawblade.

A

t

Period- T


Function Generator

A Function Generator or sometimes called a Waveform Generator is adevice or circuit that produces a variety of different waveforms at adesired frequency. It can generate Sine waves, Square waves,Triangular and Sawtooth waveforms as well as other types of output waveforms


Functional Functional DiagramDiagram [http://[http://wwwwww..intersilintersil..comcom/]/]

ICL8038ICL8038-- Precision WaveformPrecision Waveform Generator/Generator/VoltageVoltage

Controlled OscillatorControlled Oscillator

IC Electrical WaveformsIC IC Electrical WaveformsElectrical Waveforms

Detailed SchematicDetailed Schematic[http://[http://wwwwww..intersilintersil..comcom/]/]


ParametersParameters::

--Low Frequency Drif with TemperatureLow Frequency Drif with Temperature

--Low DistirtionLow Distirtion-- 1% (Sine 1% (Sine Wave OutputWave Output))

--High LinearityHigh Linearity-- 0,1%0,1%

--Wide Frequency RangeWide Frequency Range-- 0,001Hz0,001Hz--300kHz300kHz

--High Level OutputsHigh Level Outputs-- TTL to 28VTTL to 28V

--EasyEasy to to useuse

[http://[http://wwwwww..intersilintersil..comcom/]/]


WaveformWaveform Generator ICGenerator IC

[[http://http://wwwwww..electronicselectronics--tutorialstutorials..wsws]]


AD5932 AD5932 Programmable Frequency Scan Waveform Generator

ParametersParameters::

--Programmable Frequency ScanProgrammable Frequency Scan

--No No external components necessaryexternal components necessary

--Output frequency upOutput frequency up to 25to 25 MHz MHz

--Power supplyPower supply: 2.3 V to 5.5 V: 2.3 V to 5.5 V

--Automotive temperature rangeAutomotive temperature range: : −−4040°°C to +125C to +125°°CC

[[http://http://wwwwww.analog..analog.comcom//]]


Functional Block Diagram



80C51/80L51 to AD593280C51/80L51 to AD5932 InterfaceInterface



-+

Vin

Voltage Controlled Current Source

C

Comparator

Vref

Vout

Reset

VoltageVoltage--CControlled ontrolled OOscillator scillator (VCO)(VCO)

VCO- Block diagram

[http://sequence15.[http://sequence15.blogspotblogspot..comcom/2008/02//2008/02/howhow--vcovco--worksworks..htmlhtml]]

Voltage-to-Frequency ConvertersVoltageVoltage--toto--Frequency ConverterFrequency Converterss

IfIf aa constant current is appliedconstant current is applied toto the capacitorthe capacitor,, the voltage across the capacitorthe voltage across the capacitorwillwill rise atrise at aa constant rateconstant rate..

AA fairly basic circuit can take the control voltage and outputfairly basic circuit can take the control voltage and output aa constant current constant current which is proportionalwhich is proportional toto the voltagethe voltage..

While capacitor is chargingWhile capacitor is charging, a, a voltage comparator constantly compares the voltage comparator constantly compares the voltage across the capacitorvoltage across the capacitor to ato a reference voltagereference voltage..

When the voltage across theWhen the voltage across the capcap exceeds the reference voltageexceeds the reference voltage,, the comparator the comparator momentarily triggers the transistor which shorts out themomentarily triggers the transistor which shorts out the cap,cap, discharging it backdischarging it backtoto the starting voltagethe starting voltage..

-+

Vin

Voltage Controlled Current Source

C

Comparator

Vref

Vout

Reset

VCOVCOVCO

VCOVCOVCO

LM566CLM566C Voltage Controlled OscillatorVoltage Controlled Oscillator

ConnectionConnection DiagramDiagram

[[wwwwww..nationalnational..comcom]]

VCOVCOVCO

Typical ApplicationTypical Application

11 kHz andkHz and 1010 kHzkHz TTL TTL CompatibleCompatible Voltage Controlled OscillatorVoltage Controlled Oscillator[[wwwwww..nationalnational..comcom]]

VCOVCOVCO

kRk

where

CR

VVf

O

OOO

202

)5(4,2

<<

−=+

V5V5-- voltage between pin voltage between pin 5 i 5 i pin pin 11

FeaturesFeatures

--Wide supply voltage rangeWide supply voltage range: 10V to : 10V to 24V24V

--Very linear modulation characteristicsVery linear modulation characteristics

--High temperature stabilityHigh temperature stability

--Frequency programmableFrequency programmable byby means of means of currentcurrent,, voltagevoltage,, resistor or capacitorresistor or capacitor

ApplicationsApplications

--FM FM modulationmodulation

--Signal generationSignal generation

--Function generationFunction generation

--Frequency shift keyingFrequency shift keying

--Tone generationTone generation

[[wwwwww..nationalnational..comcom]]


LM231A/LM231/LM331A/LM331LM231A/LM231/LM331A/LM331 Precision VoltagePrecision Voltage--toto--Frequency ConvertersFrequency Converters

The LM231/LM331 family of voltage-to-frequency converters are ideally suited for use in simple low-cost circuits for analog-to-digital conversion,precision frequency-to-voltage conversion.

Parameters:

-Operates on Single 5V Supply

-Pulse Output Compatible with All Logic Forms pulse

-Low Power Consumption: 15 mW Typical at 5V

-Wide Range of Full Scale Frequency: 1 Hz to 100 kHz

-Low Cost


[[wwwwww..titi..comcom]]Functional Block Diagram


Simplified BlockSimplified Block DiagramDiagram of Standof Stand--AloneAlone VoltageVoltage--toto--Frequency Frequency Converter andConverter and External ComponentsExternal Components



The voltage comparator compares a positive input voltage, V1, at pin 7 to the voltage, Vx, at pin 6. If V1 is greater, the comparator will trigger the 1-shot timer. The output of the timer will turn ON both the frequencyoutput transistor and the switched current source for a period t=1.1 RtCt.During this period, the current i will flow out of the switched current source and provide a fixed amount of charge, Q = i × t, into the capacitor, CL. This will normally charge Vx up to a higher level than V1.At the end of the timing period, the current will turn OFF, and the timerwill reset itself.



Simple StandSimple Stand--AloneAlone VV--toto--F F ConverterConverter withwith ±±0.03%0.03% Typical LinearityTypical Linearity (f = (f = 1010 HzHz to 11to 11 kHzkHz)) [[wwwwww..titi..comcom]]


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