noise notes set17.ppt - UCSB · 2010-03-02 · V LO V LO V kTR kTR S j S j S j A gen signal gen signal IF 4 4 ( ) ~ 2 ,, v,mixer d t fi d t SNR ddti We have included only the noise

ECE594I notes, M. Rodwell, copyrighted

ECE594I N t t 17ECE594I Notes set 17:Noise in Mixers and Frequency Translationand Frequency Translation

Mark RodwellUniversity of California, Santa Barbara y

[email protected] 805-893-3244, 805-893-3262 fax


References and Citations:

DevicesState-Solid in Noise :Zielder Van PhysicsThermal : Kroemerand Kittel

:Citations / Sources

ng.EngineeriionsCommunicatofsPrinciple:Jacobs&Wozencraftory)(introduct s PrincipleSignal RandomVariables, Randomty, Probabili: PeeblesZ. Peyton

ive)comprehens(hard, Variables Randomandity Probabil:Papoulis

1982circaStanfordHellmanMartin:noteslectureyProbabilit1982circa Stanford, Cover, Thomas :notes lecture theory nInformatio

Designc ElectroniNoise Low :erMotchenbakng.EngineeriionsCommunicatofs Principle:Jacobs & Wozencraft

t dffS t d

circuits. in Noise :Notes nsApplicatio tor LinearSemiconduc National1982circa Stanford,Hellman, Martin:notes lecturey Probabilit

design)receiver (optical Personik & Smith noise), (device by Fukui Papers Kroemer and Kittel Peebles,Jacobs, & Wozencraft Ziel,der Van

study.for references Suggested

Theory nInformatio of Elements:Williams andCover )(!Notes App. Semi. National


Frequency Translation in Radio Receivers

mixers. ofeffect noise thedeterminefirst must wereceivers, radio odynesuperheter ofy sensitivit compute want to weIf

:Mixers

bandwidthreceiver theinto sfrequencie several from noise Translate 2)owntheir of noise Contribute 1)


Why Superheterodyne Receivers

(IF)frequencyteintermediaantohighafromconvertedisSignal1918. Armstrong :odyneSuperheter

frequency.(LO)oscillatorlocaladjustingbytunedRadioselection. channel provide IF at the filters tuned-fixedNarrow

(IF).frequency teintermediaantohigha fromconverted is Signal

filter. banwidth widegenerally response, image rejectsfilter RFfrequency.(LO) oscillatorlocaladjustingby tunedRadio


Resistive diode mixers

s.but tediourwardstraightfoismixersr transisto toExtension mixers. diode todiscussionour Confine

s.bu ed ouw ds g ose ss s ooe s o

kTqIIgIgrj /)( where)(/1

.density spectralpower noise available has kTRs

.2/density spectralpower noiseavailable has )( kTIg


Noise in Mixers, Noise from Mixing

elementscircuit anddevicemixer ofonscontributi noise find willWeresponses. imagemixer from noise find also willWe

.eliminated be can responses image from noise cases, particular In


Diode Mixers

econductancnonlinear :bias Forward

)1()( / ktqVs eIVI

ecapacitancnonlinear :bias Reverse

)( 2210 VQVQQVQ ...)( 210 VQVQQVQ


Canonical Diode Mixers

current. DCsome withbiased is Diode

coupling.port -2 IF- RF thein ntranslatiofrequency a causes This time.of functiona as impedance diode themodulates LOThe


Schottky diode structure and parasitics

)(21

contactNNdiodediode RRRC

f


Diode C-V characteristics


Note: Simplification to all Subsequent Analysis

noise. on ntranslatiofrequency ofeffect isinterest mainOur

secondary. is noise vicecircuit/demixer ininterest Our

2/fi t d, as ofpower noise available theeapproximat willWe

kTkTRs

cleareranalysissystemsthemakeandmathsimplifywillThis

.2/ of instead kT

clearer.analysissystemsthemake andmathsimplify willThis


Idealized Mixer Operation

)()()(:tionmultiplica voltageIdealizedV

tVtVtV LORFIF

0V

1 )cos()(:Suppose tVtV LOLO

01 /)cos()()( Then VtVtVtV LOinIF



/)()()(thatgivenGeneralIn VtVtVtV

,)(*)(211)(

/)()()(that given General, In

0

0

jVjVV

jV

VtVtVtV

LORFIF

LORFIF

,)()(211

2

0

0

djjVjVV

V

LORF

spectra.input theof nconvolutio theis spectrumoutput thei.e.0



)()()(),cos()( Since

1

1

VjV

tVtV

LOLOLO

LOLO

Hence

)()()( 1j LOLOLO

,)()(211)(

0

djjVjVV

jV LORFIF

))(())((2

)(0

1LOinLOinIF jVjV

VVjV

0

conversion-down and conversion-upfrequency familiar theNote


Idealized Mixer Operation: Generator Noise Only

:Simplify

noiseless LOlater) noisemixer add will(we noiseless itselfMixer

p y

. impedanceOutput . impedancegenerator , impedanceinput Mixer

ZZZ

out

genin

.power noise availablegenerator Signal kT

noise. onntranslatiofrequency ofeffect theon econcentratpresently We



))(())(()(

)()()(

1

,,

Lin

noisegensignalgengen

jVjVVZZjV

jVjVjV

))(())((

))(())((2

)(

mixerv,

0

1

LOgenLOgen

LOgenLOgenoutL

L

genin

inIF

jVjVA

jVjVVZZZZ

jV

:densities spectral voltageWork with

mixerv, LOgenLOgen

))((~))((~4~ where~~~

,,,

LOVLOV

genVVVV

jSjS

kTRSSSSnoisegennoisegensignalgengen

))((~))((~))(())((

)(~

,,

,,2mixerv,

LOVLOV

LOVLOV

VjSjS

jSjSAjS

noisegennoisegen

signalgensignalgen

IF



LOVLOV jSjS

AS signalgensignalgen))((~))((~

)(~ 2

LOVLOVV

jSjSAjS

noisegennoisegen

signalgensignalgen

IF ))((~))((~ )(,,

,,

mixerv,

LOVLOV

kTRkTR

jSjSA signalgensignalgen

44

))((~))((~ ,,2

mixerv,

gengen kTRkTR 4 4

siondownconver fromnoise & Signal

onupconversi fromnoise&Signal



))((~))((~

gengen

LOVLOVV kTRkTR

jSjSAjS signalgensignalgen

IF 4 4

))(())(( )(~ ,,2

mixerv,

d d tiSNRtfi dtd itself,generator theof noise the*only* included have We

bandsfrequency2becausearisesndegradatioThis

n.degradatioSNRsystema find yet weand

output. the tocouplebandsfrequency 2becausearises ndegradatio This



))((~))((~

gengen

LOVLOVV kTRkTR

jSjSAjS signalgensignalgen

IF 4 4

))(())(( )(~ ,,2

mixerv,

ib dB thoutput. theinput to thefrom map bandsfrequency Two

dB. 3 degraded is SNR thensignal, carries band oneonly Ifnoise.carry bands Both

noise.cuit device/cir of absence thein figure noisemixer dB 3



bandfrequency unwanted an and a wanted both shiftsmixer Theoutput.mixer at the input to RFat the IFf

noise.receiver degrades also response image Thisce.interferenintroducecanresponseimage"" unwanted This


Eliminating Noise from Image Response

response noise image and signal image both suppressesmixer reject -Image

frequency imageat power noise available zero provides Trap

frequency signalat noise ~but frequency imageat noise ~ :Filtering

kTFGkT

Documents

noise notes set17.ppt - UCSB · 2010-03-02 · V LO V LO V kTR kTR S j S j S j A gen signal gen signal IF 4 4 ( ) ~ 2 ,, v,mixer d t fi d t SNR ddti We have included *only* the noise

noise notes set17.ppt - UCSB · 2010-03-02 · V LO V LO V kTR kTR S j S j S j A gen signal gen signal IF 4 4 ( ) ~ 2 ,, v,mixer d t fi d t SNR ddti We have included only the noise