高速差分ADC设计考虑

AN-1026ᆌᆩԴऻ

OneTechnologyWaytP.O.Box9106tNorwood,MA02062-9106,U.S.A.tTel:781.329.4700tFax:781.461.3113t

ߛ໏ֶݴADCൻۯഗยऺ੊୯ፕኁǖJohnArdizzoniJonathanPearson

०঻

؜ᇀူ࿔༪ஃႴᄲLjሞُံ௽ඓᅃၵۨᅭăසࡕ๼෇ೝ࢚

ܠຕ၄ߛپႠీADCۼ૧ᆩֶݴ๼෇ઠᅞ዆ࠌఇሯำत߅

ඡLjॽۯༀݔྷ༵ߛ2ԠLjժཚࡗೝ࢚႑ࡽ༵ߛጺ༹Ⴀ

ీă৑ټ࠶ֶݴ๼෇ڦADC੗ᅜথ๴܋ڇ๼෇႑ࡽLjڍሞ

๼෇ֶݴ႑ࡽ้LjADCڦႠీ֍ీڟٳፌॅጒༀăADCൻ

ۯഗ—ཚ׉ยऺᆩᇀ༵ࠃُૌ႑ۉڦࡽୟ—ኴႜܠዖዘᄲ

ࠀీLjԈઔ܈ޗ໫ݣĂ܋ڇ-ֶݴገ࣑Ă؋࣐Ăࠌఇ฿ۙۙ

ኝĂ୳հڪăጲAD8138ླྀ؜ᅜઠLjֶݴADCൻۯഗᅙׯ

ྺຕ਍֑णဣཥዐՂփ੗ณڦ႑ࡽۙ૙ᇮॲă

႑ࡽLjVIPࢅVINᅜࠌཞएጚۉუྺ֖ቷLjഄఁᅭ܈ޗ၎

ڪĂ၎࿋၎ݒăړ๼෇܋ڇ႑ࡽ้Ljᅃ߲๼෇ۉ܋უࠦ

ۨLjଷᅃ๼෇܋ሶᅺഄܸՎࣅăଇዖ൧઄ူLj๼෇႑ࡽ਩

ۨᅭྺVIP–VINă

ֶఇ๼෇ۉუVIN,dmᅜतࠌఇ๼෇ۉუVIN,cmݴ՚ᆯڪ๕1

ڪࢅ๕2ۨᅭă

VIN,dm=VIP–VIN(1)

R

F1

RG1

V

A

+VIP

VON

–

VIP+VIN

VIN,cm=(2)

2

VIN,dmVOCM

VOUT,dm

ܔᇀೝ࢚๼෇႑ࡽLjࠌ޿ఇۨᅭᅃణକ඗Lj܋ڇܔڍ๼෇

–V

IN

V

OP

+

R

G2

V

A

R

F2

཮1.ֶٷݣݴഗ

཮1໯๖ྺᅃዖएԨڦඇֶۉݴუݒઍADCൻۯഗă੗

९Ljഄᇑدཥڦሏ໙ٷݣഗݒઍۉୟ٪ሞଇۅֶᅴăֶݴ

႑ࡽཞᄣᆶၳă

๼ۉ؜უཞᄣᆶֶఇࠌࢅఇଇዖLjݴ՚ᆯڪ๕3ڪࢅ๕4ۨ

ᅭă

VOUT,dm=VOP–VON(3)

ADCൻۯഗܠᅃ߲๼؜ᆅগ(VON)ࢅ๼෇ᆅগ(VOCM)ăॽ႑

ࡽথ෇ټֶݴ๼෇ڦ܋ADC้Ljኄၵᆅগ੗ټઠटڦٷଳ

VOP+VON

VOUT,cm=2(4)

ऄႠă

ֶݴADCൻۯഗׂิڦփ๟܋ڇ๼؜႑ࡽLjܸ๟ሞVOPࢅ

VONኮक़ᅜVOCMྺ֖੊ׂิೝֶ࢚ݴ๼؜႑ࡽă(P՗๖ኟ

टLjN՗๖޶टă)๼෇܋VOCMᆩᇀ੦዆๼ࠌ؜ఇۉუăኻ

ᄲ๼෇ᇑ๼ت؜ᇀ߳ጲ၌܈ኮాLj๼ࠌ؜ఇۉუᅃۨڪᇀ

ᆌᆩᇀVOCM๼෇ۉڦ܋უăݒ޶ઍߛࢅਸ࣍ሺᅮࣷ๑VA+

ࢅVA–ଇ߲ٷݣഗ๼෇ᆅগۉڦتუํाฉ၎ڪă

൩ጀᅪํा๼ࠌ؜ఇۉუVOUT,cmᇑVOCM๼෇ᆅগኮֶLjࢫ

ኁᆩᇀඓۨ๼ࠌ؜ఇۉೝă

ݴဆֶݴADCൻۯഗԲݴဆدཥሏ໙ٷݣഗᄲްሗܠڥă

ྺକ०پࣅຕ๕Ljփݟۨᅭଇ߲ݒઍᅺጱβ1ࢅβ2Ljසڪ๕

5ڪࢅ๕6໯๖ă

R

β(5)

1=+G1

RR

F1G1

R

β2=+

G2

RR

F2G2

(6)

Rev.0

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Fax:781.461.3113©2009AnalogDevices,Inc.Allrightsreserved.

AN-1026ᆌᆩԴऻ

ణ୤

०঻1ሯำ7

Ⴊ۩૦๏2ۉᇸۉუ!9

!ॽ๼෇ᆅগ܋থ዁ADCൻۯഗ3ၿհ฿ኈ10

!๼෇ࠌఇۉუݔྷ(ICMVR)5ټ੻ࢅუӦ୲11

!๼෇ࢅ๼؜᳘ࢇǖ঍ୁई኱ୁ6࿘ۨႠ11

!๼؜Ӧޗ7PCBۉୟӱքਆ!12

Ⴊ۩૦๏

2009౎11ሆ——ӲԨ0ǖ؛๔Ӳ

Rev.0|Page2of16

ᆌᆩԴऻ!AN-1026

ሞܠຕADCൻۯᆌᆩዐLjβ1=β2LjڍᅜVIPĂVINĂVOCMĂβ1

ࢅβ2ྺᅺጱLjVOUT,dmڦᅃӯԿڪ࣍๕੗ᆩᇀକ঴β฿ದ๟ස

ࢆᆖၚႠీڦăڪ๕7໯๖VOUT,dmڪ๕Ԉઔٷݣഗᆶ၌ೕ୲

ᅈડႠLjਸۉ࣍უሺᅮA(s)ă

ॽ๼෇ᆅগ܋থ዁ADCൻۯഗ

ADCൻۯഗཚ׉ᆩሞت૙ߛ໏႑ڦࡽဣཥዐăਐ૗ࡗג႑

ࡽհ׊ᅃၭևڦݴഗॲՂႷཚࡗፆੇ๴੦ۉڦഘد๼၍၎

૶Ljᅜݞኹ໦฿႑ࡽྜኝႠăدړ๼၍ଇ܋਩ᅜഄ༬Ⴀፆ

2V(β-β)+V(1-β)-V(1-β)

[[1]

]

V=OCM12IP1IN2

OUT,dmβ112

+β

2

+

A(s)(β+β)

2

(7)

ੇ܋থ้Lj੗इڥፌॅႠీăൻۯഗᅃӯዃᇀADC޹ৎLj

ᅺُଇኁዐक़փႴᄲ๴੦ፆੇ૶থǗ඗ܸLj६ᇀ዁ADCൻ

ۯഗ๼෇ڦ܋๼෇႑ࡽ૶থড׊LjՂႷ๑ᆩᅃ߲๴੦ፆੇ

૶থLjժӀ๢ۉړፆ৊ႜ܋থă

ړβ1≠β2้Ljֶݴ๼ۉ؜უൽਦᇀVOCMLjኄዖ঳ࡕժփ૙

ၙLjᅺྺ໲ࣷሞֶݴ๼؜ዐׂิ฿ۙࡗࢅଉሯำăۉუݒ

ઍ঳ڦࠓሺᅮټ੻ओྺ׉ຕăᆶ඀ڦ๟Ljሺᅮټ੻ओዐڦ

ሺᅮྺଇ߲ݒઍᅺጱೝ਩ኵڛڦຕă

ADCൻۯഗڦ๼෇ۉፆLj࿮ஃຌᇀֶ࣏ݴ๟܋ڇႠዊLjۼ

ՂႷٷᇀईڪᇀణՔۉ܋ፆLjᅜՍཁेᅃ߲ۉ܋ፆRTᇑݣ

ٷഗ๼෇܋ժ૴Ljᅜइڥ໯Ⴔۉፆăሞُت੊୯ڦ߳๖૩

ዐLj໯ᆶADCൻۯഗ਩֑ᆩೝݒ࢚ઍԲยऺLjස཮2໯

ړβ1=β2≡β้Ljڪ๕7੗०ࣅྺ8ă

๖ă

V

OUT,dm

V

IN,dm

R

[

=F

R

G

]

[

1+

1

]

1

A(s)(β)

(8)

RG

RIN,dmVOCM

RF

ኄ߲ڪ๕߸ྺᄅຄǗړA(s)→∞้Lj૙ၙԿ࣍ሺᅮ०ࣅྺ

RF/RGăሺᅮټ੻ओཞᄣᄅຄLjሯำሺᅮڪᇀ1/βLjᇑدཥ

ሏ໙ٷݣഗᅃᄣă

RG

RF

཮2.ֶٷݣݴഗ๼෇ፆੇ

ᆯᇀݒ޶ઍ๑ٷݣഗଇ߲๼෇܋ኮक़ۉڦუՎׯଭLjᅺ

೅ದݒઍᅺጱֶݴADCൻۯഗڦ૙ၙԿ࣍ሺᅮසڪ๕9໯

๖ă

VR

A==

OUT,dmF

vVR

IN,dmG

(9)

ُLjଇ߲๼෇܋ྺႵ૴থLjֶݴ๼෇ۉፆRINৈྺ2×RGă

ྺକ೅ದد๼၍ۉፆRLLjॽۉፆRT)ཚڪࡗ๕11ऺ໙؜ڥ*

ዃᇀֶݴ๼෇ฉă཮3໯๖ྺۆ႙ۉፆRF=RG=200ΩLjణ

ՔRL,dm=100Ω൐RT=133Ωă

ፕྺֶݴADCൻۯഗڦዘᄲႠీኸՔኮᅃڦ๼؜ೝ࢚Ԉઔ

ଇ߲ևݴǖ܈ޗೝࢅ࢚၎࿋ೝ࢚ă܈ޗೝ࢚๟࢚ଉଇ߲๼

؜ሞ܈ޗฉڦ೅ದڦ܈ײᅃၜኸՔǗሞ૙ၙٷݣഗዐLjܾ

ኁ৛ඓ೅ದă๼؜၎࿋ೝ࢚ኄၜኸՔኼሞ࢚ଉଇ߲๼ڦ؜

1

R=11

T

-

RR

LIN

(10)

၎࿋ֶ૗180°ڦਐ૗ă๼܈ޗ؜ई๼؜၎࿋ැ٪ሞ฿࢚Lj

঳ࣷࡕሞ๼؜ዐׂิփଆࠌఇݴׯă๼؜ೝ࢚ဃֶ)ڪ๕

200

200

10*ྺֶݴ๼෇႑ࡽׂิڦ๼ࠌ؜ఇۉუᇑཞᅃ๼෇႑ࡽׂ

RL,dm=100RTVOCM

ิڦ๼؜ֶఇۉუኮܔຕԲLjڇ࿋ྺݴԞă

200

200

ΔV

=20log[

OUT,cm

๼؜ೝ࢚ဃֶ

10ΔV

out,dm

]

(10)

RT

=

1

100−

1

−

1

400−

=133−

ాևࠌఇݒઍ࣍ୟ೨๑VOUT,cmڪᇀᆌᆩᇀVOCM๼෇ۉڦუLj

঳ࡕׂิଆڦࡻ๼؜ೝ࢚ă

཮3.೅ದ100Ω၍ୟ

Rev.0|Page3of16

AN-1026ᆌᆩԴऻ

܋থ܋ڇ๼෇ᄲ஑ݑႹܠă཮4ቛ๖କADCൻۯഗሞ܋ڇ

๼෇तֶݴ๼؜ူ߾ڦፕݛ๕ă

૧ᆩڪ๕12੗໙܋ڇ؜๼෇ۉፆ267Ωăߵ਍ڪ๕13੗ኪLj

ᄲ๑267Ωڦ๼෇ۉፆই዁50ΩLjժ૴ۉፆRTᆌྺ61.5Ωă

2V

0V

–2V

3.5V

2.5V

1.5V

RF

500

RG

500

VINVON

–

2.5V

VOCMVOUT,dm

+

VOP

RG

500

RF

5003.5V

1.75V

1.25V

2.5V

0.75V

1.5V

཮4.዁ADCൻۯഗ܋ڇڦ๼෇๖૩

1=

R

=

61.5

(13)

T

1

1

−

50Ω

267Ω

཮6໯๖ۉୟ؜ߴକᇸۉፆۉ܋ࢅፆăړᇸۉፆኵྺ50Ω้Lj

ᇸۉፆڦਸୟۉუྺ2Vp-păړᇸۉፆ܋থᇀ50Ω้Lj๼෇

ۉუইྺ1Vp-pLj޿ኵཞ้ྺڇ࿋ሺᅮൻۯഗڦֶݴ๼ۉ؜

უă

200

50200

VON

–

RT

2.5VVV

2Vp-p

61.5

+

V

200

໚඗๼෇ྺ܋ڇႠዊLjڍධڪᇀăᆯᇀۉፆࢅ

VVRR

IN,dmINFG

၎ڪ൐ೝ࢚Ljࠤྺڇ࿋ሺᅮLj൐ֶݴ๼؜ڪᇀ๼

V−V

OPON

෇LjनăڪᇀǗઠጲݒگઍۉୟ

4Vp-pVV=2.5V

OUT,cmOCM

ڦଇ߲๼෇ۉუࢅڪᇀă

VVV/2

A+A−OP

૧ᆩڪ๕3ڪࢅ๕4Lj੗ڥVOP=VOCM+VIN/2Lj±1Vཞ၎Ӧ

ۯሀ2.5VăVON=VOCM–VIN/2Lj±1Vݒ၎Ӧۯሀ2.5Văᅺ

ُLjVA+ࢅVA−ሞ±0.5VူሀӦۯ1.25VăՂႷᆯVIN༵ۉڦࠃ

ୁڦ঍ୁݴׯྺ(2V–0.5V)/500Ω=3mALjᅺُLjՂႷ೅

ದڦথۉںፆ)ٗVINੂࡗඁ*ྺ667Ωă

ሞ߳࣍ୟݒઍᅺጱ၎೅ದ้Ljඓۨ܋ڇ๼෇ۉፆڦཚᆩࠅ

200

཮6.ټᇸۉፆۉ܋ࢅፆۉ܋ڇڦୟ

ۉ޿ୟߴටڼڦᅃᆇၡ๟ྜኝLjڍৈฉ࿋ۉፆRG৽ཁेକ

ᅃ߲61.5Ωڦ࿄೅ದۉፆLjᇑ50Ωۉፆժ૴ăኄ߀ࣷՎሺᅮ

त܋ڇ๼෇ۉፆLjժ๑ݒઍᅺጱ฿ඁ೅ದăܔᇀၭሺᅮLj

๼෇ۉፆڦՎࣅডၭLj੗ሡ้ࢮ୼փऺLjݒڍઍᅺጱධ඗

ՂႷڟڥ೅ದăፌ०ݛڦڇ݆๟گߴ࿋ۉፆRGሺेۉፆă

཮7໯๖ྺᅃዖٻྼౢڪၳۉୟLjഄዐLjമຎժ૴ፇࢇ؊

ړᇸۉፆă

RTH

27.6

๕ྺڪ๕12LjഄዐLjRIN,seྺ܋ڇ๼෇ۉፆă

VTH

1.1Vp-p

R

IN,se

R

()

=

G

R

1-F

2×(R+R)

GF

(12)

཮7.ٻྼౢڪၳ๼෇ᇸ

ሞ޿༺ۉپୟዐLjၠگ࿋࣍ୟሺेକᅃ߲27.6ΩۉፆRTSLjᅜ

.

Ս೅ದ࣍ୟݒઍᅺጱLjස཮8໯๖ă

ኄ๟ऺ໙ۉ܋ፆڼڦᅃօă඗ܸLjႴᄲጀᅪڦ๟Lj߳ٷݣ

ഗሺᅮڪ๕਩एᇀፆੇ๼෇ᇸྺଭڦ्ยăړ٪ሞᆯ܋ڇ

๼෇ڞዂڦ฿้࢚LjՂႷ၎೅ದڦᆶၳᇸፆੇኻߴࣷฉ࿋

ۉፆRGሺेۉፆăྺԍ׼ೝ࢚LjՂႷگߴ࿋ۉፆRGሺेۉ

ፆLjڍኄᆼࣷᆖၚሺᅮă

VTH

1.1Vp-p

RTH

27.6

RTS

27.6

RG

200

2.5V

RG

200

RF

200

VON

–

VOCMVOUT,dm

+

VOP

໚඗ሞ܋থ܋ڇ႑ࡽ้੗֑ᆩԿ๕঴Ljڍ۞پ݆߸ྺ׉

RF

200

ᆩăሞᅜူ๖૩ዐLj۞پ݆ڦፕᆩ߸े௽၂ă

཮8.ೝ܋܋ڇ࢚टۉୟ

཮5ዐLjྺԍگ׼ሯ܈LjႴᄲᅃ߲ኵྺ1܋ڇڦገֶݴሺ

ᅮLjᅃ߲50Ωڦ๼෇ᆅগᅜतኵথৎ200Ωڦැݒ߅ઍۉፆࢅሺᅮۉፆă

267

200

2.5V

200

200

VON

–

VOCMVOUT,dm

+

VOP

200

཮5.܋ڇ๼෇ፆੇ

Rev.0|Page4of16

ᆌᆩԴऻ!AN-1026

ጀᅪLj1.1Vp-pٻڦྼౢۉუٷᇀ1Vp-pڦኟඓ܋থۉუLj

߲߳ሺᅮۉፆڦኵ਩ሺे27.6ΩLj঳ࡕইگକԿ࣍ሺᅮăሞ

ۉٷፆ(>1kΩ)ࢅၭሺᅮ)1ई2*ڦ൧઄ူLjኄዖݒၠፕᆩ੗၎

ړԿ࣍ሺᅮྺ1ई2้Ljُت໯ຎݛ݆۞پᅃْन੗ăܔᇀ

߸ߛሺᅮLjRTSڦኵথৎRGLjߵ਍ڪ๕18໙ڦ؜RIN,seኵᇑߵ

਍ڪ๕12൱ڦڥኵኮֶॽՎٷăኄૌ൧઄Ⴔᄲ৊ႜܠْ۞

ڸࢻၩLjڍሞၭۉፆईߛሺᅮ൧઄ူLjժփీྜඇڸၩăپă

၄ሞLj࿢்੗ᅜൟ຿ݴںဆ཮8໯๖ۉୟLjഄֶݴ๼ۉ؜

უ੗૧ᆩڪ๕14ऺ໙ă

ኄ߲ඪခփ໙ड़਎ǖፌৎ݀քڦֶٷݣݴഗऺ໙ഗ߾ਏ

ADIsimDiffAmp™तADIDiffAmpCalculator™੗ᅜڅ׶໯ᆶ

(200Ω

=).

V1.1Vp-p=097Vp-p

,dm.6OUT227Ω

DesiredV

R227.6=

OUT,d

F=Ω(.Vp-p)

11

1.0Vp-p

227().

.6Ω11=2069Ω

.Vp-p

཮9ቛ๖ڦ๟ྜኝۉୟLj֑ᆩՔጚ1%ۉፆኵă

ݏዘહۯLjৈႴຕ௱न੗ྜׯᅜฉऺ໙ăᆶ࠲߸ܠ႑တLj

൩֖ੂă

๼෇ࠌఇۉუݔྷ(ICMVR)

ICMVRࡀۨ੗ᆌᆩᇀֶٷݣݴഗ๼෇܋ܸփᆖၚኟ׉ሏႜ

ۉڦუݔྷăኄၵ๼෇؜܋၄ۉڦუ੗׬ྺICMVĂVacm

ईVA±ăڍኄᅃࡀ߭ঢ়׉ԥဃ঴ăፌ׉९ڦઓవ๟ඓֶۨ

ٷݣݴഗ๼෇ڦ܋ํाۉუLjᆮഄ๟၎ܔᇀ๼෇ۉუܸ

ჾăሞᅙኪVIN,cmĂβࢅVOCMෙ߲Վଉڦ൧઄ူLj੗໙ݣ؜

ٷഗ๼෇ۉუ(VA±)Lj߳βփڪ้๑ᆩཚᆩڪ๕19Lj߳β၎ڪ

้๑ᆩ०ڪࣅ๕20ă

2Vp-p

RIN,se

RS

RG

200

50

RT

2.5V

61.9

RTS

28

RG

200

RF

205

VON

–

VOCMVOUT,dm

+

VOP

RF

205

21βV+Vβ(1-β)+Vβ(1-β)

β

(19)

(20)

Vacm៪VA

=

2OCMIP11IN12

±

β+β

12

Vacm៪V±=V+β(V-V

AIN,CMOCMICM

)

ጀᅪLjVA๔ዕ๟๼෇႑ڦࡽ໫ၭӲԨ(ස཮4໯๖)ă๼෇ࠌ

ఇۉუݔྷᅺٷݣഗڦૌ՚ܸᅴăADIߛ໏ֶݴADCൻۯ

཮9.ྜኝ܋܋ڇटۉୟ

֖ቷ཮9LjᅺRFࢅRGଇ߲ۉፆ݀ิՎࣅLjൻۯഗ܋ڇڦ๼

෇ۉፆRIN,seᄺໜኮՎࣅăൻۯഗڦሺᅮۉፆሞฉ࿋࣍ୟዐྺ

200ΩLjူ࿋࣍ୟዐྺ200Ω+28Ω=228Ωăሞփཞڦሺᅮ

ۉፆኵူLjऺ໙RIN,se๯ံႴᄲऺ໙ଇ߲βኵLjݴ՚සڪ๕

16ڪࢅ๕17໯๖ă

ഗᆶଇዖ๼෇पದዃLjݴ՚ྺዐ႐႙ࢅೋᅎ႙ăዐ႐႙

ADCൻۯഗڦ௅߲ۼࡆۉࠃᆶሀ1Vڦᇧଉ(ᅺܸ׬ྺዐ႐

႙)ăೋᅎ႙๼෇पሺेକଇ߲ৗ༹࠶LjᅜሎႹ๼෇܋৑ଉ

੍ৎ–VSࡆӦۯă཮10໯๖ྺᅃዖۆ႙ڦֶٷݣݴഗڦ०

ࣅ๼෇๖ᅪ཮(Q2ࢅQ3)ă

A

Q2Q3

R200Ω

β1=RR.

G

==0494

+405Ω

FG

(16)

–IN+IN

Q1Q4

R+R228Ω

GTS==0527

=.

R+R+R433Ω

FGTS

β

2

(17)

཮10.०ࣅӲֶٷݣݴഗ(ೋᅎ႙ICMVR)

ೋᅎ႙๼෇঳ࠓሎႹֶٷݣݴഗت૙ມटႠ๼෇႑ࡽLjन

๼෇ۉፆRIN,seڦऺ໙ݛ݆සڪ๕18໯๖ă

๑ٷݣഗᆯۉڇᇸൻۯᄺ๟සُLj༬՚๢ࢇ֑ᆩۉںუई

R(β+β)

R=G12=271Ω

(18)

IN，N，

β(β+1)

12

ഄ঳ࡕᇑፌ؛໙ڦ؜ֶ՚փٷLjܔփׂࣷิڦٷᆖ

267ΩR

T

ၚLjᅺྺᇑຌᇀժ૴࠲ဣă

RR

IN,seT

ۉںუᅜူ๼෇ۉڇڦᇸᆌᆩă๼෇܋ሺेڦPNPৗ༹࠶

(Q1ࢅQ4)ॽ๼෇ၠֶܔݴೋᅎᅃ߲ৗ༹࠶Vbeă૩සLjැ

–INᆌᆩۉუྺ–0.3VLjሶAۅྺ0.7VLj๑ֶܔݴ੗ᅜኟ׉ሏ

ႜăැ࿮PNP(ዐ႐႙๼෇प)LjAۅ–0.3Vۉڦუࣷ๑NPNֶ

ܔݴ݀ิݒၠೋዃLjժዐ܏ኟ׉ሏႜă

සࡕႴᄲ߸े৛ඓڦጺሺᅮLj੗๑ᆩ߸ߛ৛ۉڦ܈ፆزࢅ

૴ۙኝۉፆă

Rev.0|Page5of16

AN-1026ᆌᆩԴऻ

՗1.ߛ໏ADCൻۯഗࡀ߭

ۉᇸۉუ(V)

ADCൻۯഗICMVRVOCM

ೋ૗ࠃڦࡆۉ

ټ੻უӦ୲ሯำ

๼؜Ӧޗ

ISUPPLY

ׂ೗႙ࡽ(V/μs)(nV)±5V+5V+3.3V+3V±5V+5V+3.3V+3V(V)(mA)

(MHz)

AD813235012008–4.7዁+30.3዁30.3዁1.30.3዁1±3.61዁3.7N/A0.3዁1±112

AD8137764508.25–4዁+41to41዁2.31዁2±41዁41዁2.31዁2ࡆڟࡆ3.2

AD813832011505–4.7዁+3.40.3዁3.2N/AN/A±3.81዁3.8N/AN/A±1.420

AD81394108002.25–4዁+41዁4N/AN/A±3.81዁3.8N/AN/Aࡆڟࡆ25

ADA4927-1/

ADA4927-2

ADA4932-1/

ADA4932-2

ADA4937-1/

ADA4937-2

ADA4938-1/

ADA4938-2

ADA4939-1/

ADA4939-2

230050001.4–3.5዁+3.51.3዁3.7N/AN/A±3.51.5዁3.5N/AN/A±1.220

100028003.6–4.8዁+3.20.2዁3.2N/AN/A±3.81.2዁3.2N/AN/A±19

190060002.2N/A0.3዁30.3዁1.2N/AN/A1.2዁3.81.2዁2.1N/A±0.940

100047002.6–4.7዁+3.40.3዁3.4N/AN/A±3.71.3዁3.7N/AN/A±1.237

140068002.3N/A1.1዁3.90.9዁2.4N/AN/A1.3዁3.51.3዁1.9N/A±0.837

՗1ྺADIADCൻۯഗܠڦዖࡀ֖߭ຕ༵ࠃକ੺໏֖੊LjԈ

ઔనၵൻۯഗ֑ᆩକೋᅎ႙ICMVRದዃLjనၵ࿄֑ᆩă

๼෇ࢅ๼؜᳘ࢇǖ঍ୁई኱ୁ

Ⴔᄲ঍ୁ᳘࣏ࢇ๟኱ୁ᳘ࢇ੗ీܔֶݴADCൻۯഗڦ჋ስ

ഐጣዘᄲڦᆖၚă๼෇᳘ࢅࢇ๼؜᳘ࢇଇዖ൧઄ᆶփཞڦ

঍ୁ᳘܋ڇࢇገֶݴᆌᆩᇑֶݴ๼෇ᆌᆩ၎ຼLjڍሞٷݣ

ഗ๼෇ᆅগتᆶࠌఇ࿖հLjྺ๼෇႑ڦࡽ໫ၭݴଉă֑ᆩ

ዐ႐႙๼෇ࠌఇݔྷڦADCൻۯഗॽ๼෇ࠌఇۉუዃᇀՔ

ۨݔྷዐ႐޹ৎLjྺܠຕᆌᆩዐڦ࿖հ༵ࠃକ؊ፁڦᇧ

ଉă

੊୯ă

঍ୁ᳘ࢇ๼෇पස཮11໯๖ă

ړ๼෇᳘ࢇ੗჋้Ljኵڥጀᅪڦ๟Ljټ঍ୁ᳘ࢇ๼෇ڦ

ADCൻۯഗگࡼࠀڦᇀټ኱ୁ᳘ࢇ๼෇ڦૌຼൻۯഗLjᅺ

ྺଇ߲ݒઍ࣍ୟዐۼփ٪ሞ኱ୁࠌఇۉୁă

CIN

C

IN

R

G

V

OCM

RG

RF

RF

঍ୁ᳘ࢇLjړADCᄲ൱๼෇ࠌఇۉუᇑൻۯഗ๼ڦ܋؜੗

ᆩۉუ၎ֶٷ࢔้Lj੗ܔADCൻۯഗڦ๼܋؜৊ႜ঍ୁ᳘

ࢇăړVOCMยྺۉᇸۉუᅃӷ޹ৎ้Ljൻۯഗڦ๼؜Ӧޗ

ፌٷǗሞൻۯᄲ൱टگ๼෇ࠌఇۉუۉگڦუADC้Ljኄ

཮11.঍ୁ᳘ࢇADCൻۯഗ

ܔᇀټ঍ୁ᳘ࢇ๼෇ڦ܋ֶݴገֶݴᆌᆩLj؜၄ሞٷݣഗ

๼෇ᆅগڦت኱ୁࠌఇۉუڪᇀ኱ୁ๼ࠌ؜ఇۉუLjᅺྺ

ټࣷઠᅃ߲࿚༶ăᅃዖ०ڦڇ঴ਦӸ݆๟ॽൻۯഗ๼܋؜

ᇑADC๼෇܋ኮक़ڦ૶থ঍ୁ᳘ࢇഐઠ(ස཮12໯๖)Ljᅜ

ၩأADCൻۯഗ๼ڦ܋؜኱ୁࠌఇۉუLjժሎႹၠADC঍

ୁ᳘ࢇᅃ֨ጀ෇ࢇ๢ࠌڦఇۉೝă૩සLjൻۯഗ੗ీ֑ᆩ

๼෇ۉඹፆ܏କ኱ୁݒઍۉୁăཞ้Lj኱ୁူݒڦઍᅺጱ

၎ࢻ೅ದ൐ྜඇᇑڇ࿋ኵ၎ڪăVOCMत኱ୁ๼෇ࠌఇۉუ

ཚ׉ยዃሞۉᇸۉუᅃӷ޹ৎă֑ᆩዐ႐႙๼෇ࠌఇݔྷ

ڦADCൻۯഗሞኄૌᆌᆩዐ߾ፕଆࡻLjഄ๼෇ࠌఇۉუথ

ৎՔۨݔྷڦዐ႐ă

5VۉڇڦᇸLjഄዐVOCM=2.5VLjADC੗ీ֑ᆩ1.8Vڇڦ

ۉᇸLjᆌᆩᇀADCCMVڦᄲ൱๼෇ࠌఇۉუྺ0.9Vă

RF

COUT

RG

ROUT

VOCMADC

CMV

ROUT

R

COUT

R

TO

ADC

཮12.ټ঍ୁ᳘ࢇ๼ڦ؜኱ୁ᳘ࢇ๼෇

Rev.0|Page6of16

ᆌᆩԴऻ!AN-1026

֑ᆩೋᅎ႙๼෇ࠌఇݔྷڦൻۯഗᅃӯሞ֑ᆩۉڇᇸڦ኱

–20

VOUT=2Vp-p

ୁ᳘ࢇဣཥዐ੗݀؜ࣩፌٷᆫ๞ăഄᇱᅺሞᇀLj๼ࠌ؜ఇ

–30

ۉუཚݒࡗઍ࣍ୟݴუLjഄ੗Վݴׯ੗ీথৎᇀথۉںუ

–40

(ࡆۉ޶)ăሞ܋ڇ๼෇൧઄ူLj๴๼෇၎࠲࿖հᆖၚLj๼

෇ࠌఇۉუฯ዁߸থৎࡆۉ޶ă

–50

–60

HD2@10MHz

HD3@10MHz

HD2@30MHz

HD3@30MHz

–70

֑ᆩ܋ڇईֶݴ๼෇ࢅ঍ୁ᳘ࢇई኱ୁ᳘ڦࢇມۉᇸဣ

–80

ཥLjᅺᇧଉሺेLjሞଇૌ๼෇पዐۼ੗इڥᆫᅴڦႠీă

՗2ጺ঳କ߳ዖ๼෇᳘ࢇतۉᇸፇࢇཉॲူፌ׉९ڦADC

–90

–100

ൻۯഗ๼෇पૌ႙ă඗ܸLjُૌ჋ስփᅃۨ๟ፌॅ჋ስLj

–110

௅߲ဣཥۼᆌ৊ႜਏ༹ݴဆă

՗2.᳘ࢇत๼෇प჋ၜ

๼෇᳘ࢇ๼෇႑ࡽۉᇸ๼෇ૌ႙

ඪᅪඪᅪມۉᇸඪᅃ

–120

1.41.61.82.02.22.42.62.83.03.23.4

VOCM(V)

཮13.ADA4932ሞփཞೕ୲ူڦၿհ฿ኈᇑVOCM(ۉᇸۉუǖ5V)

঍ୁ܋ڇۉڇᇸዐ႐႙

኱ୁ!܋ڇۉڇᇸೋᅎ႙

঍ୁֶݴۉڇᇸዐ႐႙

኱ୁֶݴۉڇᇸዐ႐႙

཮13ቛ๖ڦ๟ADA4932ሞփཞೕ୲ူڦၿհ฿ኈᇑVOCMLj

ഄۆ႙๼؜Ӧޗྺ1.2V/ࡆă๼෇ӦޗྺVOCMᇑ႑ࡽVPEAKኮ

ࢅ(1V)ăጀᅪLjۉუࡗג2.8V้Lj฿ኈࣷथਗሺे(3.8VPEAK

ईԲ5Vگࡆۉࠃ1.2)ă܋گ้Lj฿ኈሞ2.2V(–1VPEAK)้Lj

๼؜Ӧޗ

ධ඗گ࢔ăټ੻ࢅუӦ୲ڦ༪ஃዐ༵ࣷڟૌຼ՗၄ă

ྺକํ၄ADCۯༀݔྷڦፌࣅٷLj๼෇႑ࡽႴᄲڟٳADC

ڦ஢܈ޗ๼෇ݔྷă඗ܸLjൻۯADCᆌ৉ัྺฉăසࡕ

ADCൻܠࡗۯLj੗ీ໦࣋๼෇܋ǗසࡕൻۯփፁLjᆼࣷ໦

฿ݴՐ୲ăܔADC৊ႜ஢܈ޗ๼෇ݔྷൻۯժփ՗๖ٷݣ

ഗ๼܋؜ՂႷඇݔྷӦۯăֶݴ๼ڦ؜ዘٷᆫ๞ኮᅃሞ

ᇀLj߳๼܋؜ৈႴӦدۯཥ܋ڇ๼ڦ܋؜ᅃӷăൻۯഗ๼

܋؜੗ᅜᇺ૗ࡆۉࠃLj঳ࡕ੗३ณ฿ኈăڍ๟Lj܋ڇൻۯ

ሯำ

ADCڦඍ။ԈઔଉࣅሯำĂۉሯำईໜऐሯำᅜतၿհ฿

ኈăፕྺܠຕᆌᆩዐڦዘᄲᅺ໎Ljሯำཚ׉๟੻ټဣཥዐ

ፌዘᄲڦႠీኸՔă

໯ᆶADCᇑิਓઠۼ٪ሞଉࣅሯำLjਏ༹๫࿋ຕܸۨ(n)Ǘ

ཚࡗሺे࿋ຕ(n)Lj੗३ณଉࣅሯำăन๑๟૙ၙڦገ࣑ഗ

ᄺׂࣷิଉࣅሯำLjᅺُLjට்ӝଉࣅሯำړፕ࢚ଉໜऐ

ഗժݥසُăൻۯഗڦ๼ۉ؜უሁথৎࡆۉࠃLjٷݣഗڦ

ሯำࢅၿհ฿ኈڦᅃዖएጚăADCൻۯഗׂิڦ๼؜ሯำ

၍Ⴀ܈ሁֶLj฿ኈሁ௽၂ă

ᆌ၎ړᇀईگᇀADCڦໜऐሯำࢅ฿ኈăথူઠLj࿢்๯

ܔᇀᄲ൱ޚࡹ๼ۉ؜უڦᆌᆩLj൩֖९՗1ዐࡆڟࡆټ๼

ံ੊ִADCሯำत฿ኈڦ༬ۅLj඗ࢫ༑༪සࢆएᇀႠీઠ

ڦ܋؜ADCൻۯഗLjഄᇧଉٗຕڟޚࡹຕӥޚࡹփڪLjਏ

࢚ଉADCൻۯഗڦሯำă

༹ൽਦᇀ޶ሜă

ଉࣅሯำׂิڦᇱᅺሞᇀLjADCॽݴՐ୲࿮၌ڦఇె႑ࡽ

ଉׯࣅຕଉᆶ၌ڦ૗ොຕ਍ăᅃ߲n࿋ADCᆛᆶ2n߲ܾ৊

዆पă߳पኮֶپ՗ጣ੗ᅜ঴ဆڦፌၭֶLj׬ྺଉࣅपڦ

ፌگᆶၳ࿋(LSB)Lj०׬qăᅺُLjᅃ߲ଉࣅपྺገ࣑ഗݔ

ྷڦ1/2năසࡕ੗Վۉუᆯྜெڦn࿋ADCገ࣑Lj඗ࢫՎ࣑

࣮ఇె႑ࡽLjምٗADCڦ๼෇႑ࡽዐ३أLjഄᇆֶሶ՗၄

ྺሯำăഄ਩ߵݛኵྺ

਩ߵݛଉࣅሯำ

=

q

12

=

2n

1

12

(21)

Rev.0|Page7of16

AN-1026ᆌᆩԴऻ

ߵ਍ڪ޿๕Lj੗ᅜླྀ؜ڞn࿋ADCሞഄలઊຯټ੻ူڦ႑

ࡽ-ଉࣅሯำԲܔຕ(dB)ࠅ๕(ڪ๕22)Ǘኄ๟n࿋ገ࣑ഗ੗

[1

SINAD(dB)log

=2010THD+N

]

(24)

इڦڥፌॅ႑ሯԲă

!႑ࡽ-ଉࣅሯำԲ(dB)=6.02n+1.76dB(22)

ADCዐڦໜऐሯำᆯඤሯำĂො૭ሯำࢅ෻ຮሯำׯࠓLj

ᅃӯԲଉࣅሯำٷăၿհ฿ኈ๟ADCዐݥڦ၍Ⴀڞ܈ዂ

ڦLjࣷሞ๼؜ዐׂิሞၿհฉᇑ๼෇႑ࡽ၎ڦ࠲փଆ႑

ࡽăጺၿհ฿ኈࢅሯำ(THD+N)๟ADCڦᅃၜዘᄲႠీኸ

ՔLjᆩᇀॽۉሯำࢅၿհ฿ኈᇑথৎADC஢ଉײ๼෇ݔྷ

ڦఇె๼෇৊ႜԲডăۉሯำሞ༬ۨټ੻ݔྷాओݴLj޿

ැᅜ႑ࡽ-ଉࣅሯำԲ(ڪ๕22)پ༺SINADLjሶ੗ۨᅭገ࣑

ഗሞ႑ࡽ-ଉࣅሯำԲڪᇀഄSINAD(ڪ๕25)ڦ൧઄ူڦᆶ

ၳ࿋ຕ(ENOB)ă

SINAD(dB)=6.02(ENOB)+1.76dB(25)

ENOBᄺ੗ᅜSINADྺᅺጱLjසڪ๕26໯๖ă

SINAD(dB)-1.76dB

ENOB

=.

602

(26)

ټ੻ݔྷԈઔႴᄲ੊୯ฉْၿհڦೕ୲ăሞڪ๕23ዐLjጺ

ၿհ฿ኈTHDԈઔമ࿵߲ၿհ฿ኈݴׯLjᇑሯำᅃഐൽ਩

ߵݛኵă

ENOB੗ᆩܔADCൻۯഗڦሯำႠీᇑADCڦሯำႠీ৊

ႜܔԲLjᅜඓۨഄ๟ޏ๢ࢇൻ޿ۯADCă཮14໯๖ྺᅃዖ

ֶݴADCሯำఇ႙ă

THD+ሯำ=

[ν2(rms)]+[ν(rms)]+[ν(rms)]+[ν(rms)]+[ν(rms)]+ν

222222

3456n

[ν(rms)]

2

1

VnRG1

RG1

inIN+

RF1

+

VnRF1

(23)

inIN–

VnIN

Vno,dm

๼෇႑ࡽྺv1Ljമ࿵߲ၿհ฿ኈኮओྺv2዁v6LjADCۉሯ

ำྺvnă

THD+ሯำڛڦຕLjन႑ሯ฿ኈԲ(SINAD)ཚ׉՗๖ྺݴԞ

(ڪ๕24)ă

VOCM

RG2RF2

VnRG2

VnRF2

཮14.ֶݴADCൻۯഗڦሯำఇ႙

VnCM

ᅃӯ൧઄ူ൐β1=β2≡β้Ljӗ߲ᇸܔጺ๼؜ሯำ௢ڦ܈߳

ጲࠋ၅ݴ՚ස27ዐ၎ᆌڪ๕໯๖ă

2vv

vvnIN=nIN=nIN，β

noᅺ

,dm1

β+ββ

12

=

β=

2

β

2v(β-β)

vv=nCM1=0，β

ᅺ

2

no,dmnCM1

β+β

12

=

β=

2

β

2i(1-β)R

vinIN+==(i)(R)，β

nIN+1G1

noᅺ

,dmβ11

β+nIN+F

12

=

β=

2

β

2i(1-β)R

v=

iG

nIN=nIN-iR，

12()()β

noᅺ

,dmβnIN-F21

-+β

12

=

β

2

=β

(24kTR)(1-β)R

vnRG1R，

v=1β

G

11=4()

kTRF

noᅺ

,dmβ+β

G11

12G1

=

β=

2

β

(24kTR)(1-β)R

vnRG2R，β

v=kTRF2

G

22=4()

noᅺ

,dmβ+βG21

12G2

=

β=

2

β

(2β4kTR)

vnRF1=14kTR，

v=β

F1

noᅺ

,dmβ+β

F11

12

=

β=

2

β

(2β4kTR)

vnRF2=14kTR，

v=β

F2

noᅺ

,dmβ+β

F21

12

=

β=

2

β

(27)

Rev.0|Page8of16

ᆌᆩԴऻAN-1026

ጺ๼؜ሯำۉუ௢܈vno,dmཚࡗऺ໙ኄၵڦݴׯ਩؜ڥߵݛă

ۉᇸۉუ

ॽኄၵڪ๕๼෇ۉጱ՗߭๟ऺ໙ጺ๼؜ሯำۉუ௢ڦ܈ፌ

ॅݛ๕ăADIDiffAmpCalculator੗੺໏໙؜ሯำĂሺᅮत

ֶݴADCൻۯഗڦഄ໱ᆶᆩ႑တLj੗ٗူ

੊୯ۉᇸۉუۉࢅୁ๟໫ၭADCൻۯഗ჋ስݔྷڦ०Սݛ

๕ă՗1०ᄲጺ঳କADCൻۯഗሞ߳ዖۉᇸۉუူڦႠ

ీLj੗ࠃ֖੊ăۉᇸۉუࣷᆖၚټ੻Ă႑ࡽӦޗत

ሜă

ICMVRă჋ስֶٷݣݴഗ้LjႴᄲ࢚ଉ߳ၜ֖ຕࢅችዔ๚

၄ሞLj੗ᅜॽADCൻۯഗڦሯำႠీᇑADCڦENOB৊ႜ

ԲডăԲසLjሺᅮྺ2ڦAD9445ADCֶݴൻۯഗLj֑ᆩ5V

ۉᇸࢅ2V஢ଉײ๼෇Ǘ޿ൻۯഗت૙኱থ᳘ࢇ੻ټ႑ࡽLj

቞ᆩ50MHz(−3dB)ټڦ੻Ljᅜڇट୳հഗ৊ႜ၌዆ăߵ਍

࠲ᇀ߳ዖཉॲူENOBࡀ߭ڦຕ਍՗Ljሞలઊຯ༬ټ੻ྺ

50MHzڦ൧઄ူLjENOB=12࿋ă

ADA4939๟ᅃዖߛႠీڦ੻ټֶݴADCൻۯഗLjኧ׼኱থ

᳘ࢇă৽ሯำܸჾLj໲๟ൻۯAD9445ڦฉࡻ჋ስăຕ਍՗

ླྀ४RF=402Ω൐RG=200ΩLjֶݴሺᅮሀྺ2ăኄዖದዃڦ

ጺ๼ۉ؜უሯำ௢܈ྺ9.7nV√Hză

๯ံLjऺ໙ဣཥڦሯำټ੻BNLjኸڦ๟๼؜ሯำࡼࠀᇑํ

ၜLjኄ๟׉ݥዘᄲڦă

ଷᅃၜዘᄲࡀ֖߭ຕ๟ۉᇸᅞ዆(PSR)ăۉᇸᆅগሞፕྺݣ

ٷഗ๼෇ݛ܋௬໯ഐڦፕᆩྫྫԥࢮ๫ăۉᇸ၍٪ሞڦඪ

ࢆሯำईኁ᳘ۉڟࢇᇸ၍ዐڦሯำۼ੗ీ೦࣋๼؜႑ࡽă

૩සLjሞADA4937-1ฉेฉ50mVp-pĂ50MHzሯำۉڦᇸă

ഄ50MHzۉᇸᅞ዆ྺ−70dBăኄ৽ᅪ࿆ጣLjሞٷݣഗ๼؜

܋Ljۉᇸ၍ฉڦሯำॽই዁16μVፑᆸăሞټ1V஢ଉײ๼෇

ڦ16࿋ဣཥዐLj1LSBྺ15.3μVǗᅺُLjઠጲۉᇸ၍ڦሯำ

ࣷޮ߃1߲LSBă

ྺକ߀฀ኄዖ൧઄Lj੗ሺेز૴SMTཎᄟ༹ىዩL1ࢅL2Lj

ᅜतݴୁಖୟۉඹC1ࢅC2(९཮15)ă

ा୳հഗ၎ڪڦڪၳਈႚگཚ୳հഗټڦ੻Ljํा୳հഗ

V+

ඓۨᅙኪ׉ຕ๼෇ሯำࠀ୲ೕ೷௢ڦ܈ဣཥټ੻ăܔᇀڇ

टۅ୳հഗLjBNڪᇀπ/2ױᅜ3dBټ੻໯ױڥओLjසڪ๕28

L1

໯๖ă

π

(2)=

B=50MHz78.5MHz(28)

N

থူઠLjऺ໙ሯำ௢܈ሞဣཥټ੻਩ߵݛူڦओݴLjᅜ൱

U1

AD8138AR

8

2

3

VOCM

C1

10nF

5–OUT

؜๼؜਩ߵݛሯำ(ڪ๕29)ă

14+OUT

6

vno,dm(rms)=(9.7nV/√Hz)(√78.5MHz)

=86μVrms(29)

L2

C2

10nF

ߵ਍्ยLjሯำ܈ޗᆌߛװຯݴքǗᅺᆅLj૧ᆩރރኵሯ

V–

ำ)ٷሀሞ99.7%ڦ้क़ዐLjሯำۉუࣷሞኄၵ၌ኵኮक़Ӧ

ۯ*׉ڦ९±3σ၌ኵLjރރኵ๼؜ሯำऺ໙ݛ݆සူ໯๖ǖ

vno,dm(p-p)≈6(86μVrms)=516μVp-p(30)

၄ሞLj࿢்ઠԲডᅃူൻۯഗڦރރኵ๼؜ሯำᇑ

AD9445LSBڦ1LSBLjԲডڦएإ๟ENOBྺ12࿋Lj൐஢ଉ

ײ๼෇ݔྷྺ2VLjසڪ๕31໯๖ă

཮15.ۉᇸಖୟ

50MHzူLjཎᄟ༹ىዩڦፆੇྺ60ΩLj10nF(0.01μF)ۉඹ

ڦፆੇྺ0.32Ωăኄଇ߲ᇮॲڦׯࠓປ३ഗ੗༵ࠃ45.5dBڦ

ປ३)९ڪ๕32*ă

0.32

=20log()=−45.5dB(32)

أ݆ഗປ३

0.32+60

!ڇLSB=2V/212=488μV(31)

ሞ12࿋ENOBူLjൻۯഗׂิރރڦኵ๼؜ሯำૌຼᇀ

ADCڦLSBǗᅺُLjٗሯำঙ܈ઠੂLj޿ൻۯഗ๟Ԩᆌᆩ

ڦፌॅ჋ስăፌዕਦ֧ՂႷएᇀܔൻۯഗतADCፇࠓڦࢇ

ॺࢅ֪๬ă

أ݆ഗປ३ᇑ–70dBۉڦᇸᅞ዆ᅃഐ੗ׂิሀ115dBڦᅞ዆

Ⴀీă঳ࡕ๑ሯำই዁ሀ90nVp-pLjᇺᇺگᇀ1LSBă

Rev.0|Page9of16

AN-1026ᆌᆩԴऻ

ၿհ฿ኈ

ೕᇘฉڦگၿհ฿ኈܔ቏ࢅټ੻ټဣཥ׉ݥۼዘᄲăൻۯ

ഗዐݥڦ၍Ⴀࣷ܈ሞٷݣഗ๼܋؜ׂิڇೕၿհ฿ኈतܠ

ೕ঍ۙ฿ኈׂ࿿ă

ݴဆሯำᅃ૩ዐᆩݛڦڟ݆੗ᅜᆩઠݴဆၿհ฿ኈLjԲড

ADA4939ڦၿհ฿ኈᇑAD944512࿋ENOBሞ2V஢ଉײ๼؜

ူڦ1߲LSBăሯำݴဆዐLjᅃ߲ENOBLSBྺ488μVă

ADA4939֖ຕ՗ዐڦ฿ኈຕ਍๟ሺᅮྺ2้Ljሞփཞೕ୲

ူԲড2ْࢅ3ْၿհڦ؜ڥ঳ࡕă՗3໯๖ྺሞሺᅮྺ2൐

ֶݴ๼؜Ӧޗྺ2Vp-p้ڦၿհ฿ኈຕ਍ă

՗3.ADA4939ڦْܾतෙْၿհ฿ኈ

֖ຕၿհ฿ኈ(dBc)

HD2@10MHz−102

HD2@70MHz−83

HD2@100MHz−77

HD3@10MHz−101

HD3@70MHz−97

HD3@100MHz−91

ຕ਍၂๖Ljၿհ฿ኈໜೕ୲ܸሺेLj൐ሞణՔټ੻(50

MHz)ူLjHD2՗၄ԲHD3ֶăၿհ฿ኈׂ࿿ڦೕ୲ߛᇀ

ణՔೕ୲LjᅺُLj੗ཚࡗ၌዆ဣཥೕټઠইگഄ܈ޗăස

ࡕဣཥሞ50MHzူ֑ᆩ“ጇ഻๕”୳հഗLjሶኻႴ੊୯ߛᇀ

25MHzڦೕ୲Ljᅺྺ޿୳հഗၩأକೕ୲߸ڦߛඇևၿհă

඗ܸLjဣཥڦፌټߛ੻ยྺ50MHzLjᅺྺ໯ᆩ୳հഗ੗ీ

࿮݆؊ݴᅞ዆ၿհLj฿ኈׂ࿿੗ీᅜሗො႑ࡽ৊෇႑ټࡽ

੻ă཮16ቛ๖କړ๼؜ྺ2Vp-p้LjADA4939ሞփཞۉᇸۉ

უူڦၿհ฿ኈᇑೕ୲࠲ڦဣă

၎ܔᇀ2Vp-pڦ๼෇႑ࡽLj50MHzူڦHD2ሀྺ−88dBcă

ྺକԲডၿհ฿ኈᇑ1ENOBLSBLjՂႷॽۉ޿ೝገۉׯ࣑

უLjසڪ๕33໯๖ă

-88

HD2=(2Vp-p)(1020)≈80μVp-p(33)

฿ኈׂ࿿ৈྺ80μVp-pLj၎ړᇀ1ENOBLSBڦ16%ăᅺُLj

ٗ฿ኈঙ܈ઠੂLjADA4939๟AD9445ADCൻۯഗڦଆࡻ჋

ስă

ᆯᇀADCൻۯഗຌᇀݒ޶ઍٷݣഗLjഄ๼؜฿ኈൽਦᇀݣ

ٷഗۉୟዐ࣍ڦୟሺᅮଉăݒ޶ઍٷݣഗڦాևਸ࣍฿ኈ

ူই1/(1+LG)LjഄዐLjLG՗๖੗ᆩ࣍ୟሺᅮă

ٷݣഗڦ๼෇(ဃֶۉუ)ױᅜᅃডٷኟၠۉუሺᅮA(s)Lj

඗ࢫཚݒࡗઍᅺጱβLjݒઍڟ๼෇܋Ljሞُۙኝ๼؜ᅜ३

ณဃֶăᅺُLjኄૌٷݣഗ࣍ڦୟሺᅮྺA(s)×βǗໜጣ࣍

ୟሺᅮ(A(s)ĂβLjईኁଇኁग़ܸᆶኮ)ڦ३ณLjၿհ฿ኈࣷ

ሺेăओݴഗኮૌۉڦუݒઍٷݣഗยऺᆩᇀሞ኱ୁतگ

ೕူׂิٷA(s)Lj඗ࢫሞኸۨߛೕוتጣڇ࿋1װ1/fࡐইă

ໜጣA(s)ࡐڦইLj࣍ୟሺᅮࣷ३ၭLj฿ኈࣷሺेă੗९Lj

ၿհ฿ኈྺA(s)ڛڦຕă

ۉୁݒઍٷݣഗ੗ॽဃֶۉୁᆩፕݒઍ႑ࡽăဃֶۉୁ

ױᅜᅃডٷኟၠੵፆT(s)Ljॽۉୁገׯ࣑๼ۉ؜უLj඗ࢫ

ཚݒࡗઍᅺጱ1/RFLjॽ๼ۉ؜უገݒׯ࣑ઍۉୁLjᅜ३

ณ๼෇ဃֶۉୁăᅺُLj૙ၙۉୁݒઍٷݣഗ࣍ڦୟሺᅮ

ྺT(s)×(1/RF)=T(s)/RFăᇑA(s)ૌຼLjT(s)ਏᆶডڦٷ኱ୁ

ኵLjࣷໜጣೕ୲ሺेࡐইLj঳ࡕ३ณ࣍ୟሺᅮĂሺेၿհ

฿ኈă

–60

–65

–70

–75

VOUT,dm=2Vp-p

HD2,VS(SPLITSUPPLY)=±2.5V

HD3,VS(SPLITSUPPLY)=±2.5V

HD2,VS(SPLITSUPPLY)=±1.65V

HD3,VS(SPLITSUPPLY)=±1.65V

࣍ୟሺᅮཞ้ᇑݒઍᅺጱ1/RFᆶ኱থ࠲ဣă૙ၙۉୁݒઍ

ٷݣഗ࣍ڦୟሺᅮժփൽਦᇀԿۉ࣍უሺᅮLjᅺُLjၿհ

฿ኈႠీփࣷໜጣԿ࣍ሺᅮڦሺेܸူইăሞ၄ํۉୁݒ

ઍٷݣഗዐLj࣍ୟሺᅮሞᅃۨ܈ײฉൽਦᇀԿ࣍ሺᅮLjڍ

–80

–85

ᅈડ܈ײᇺگᇀۉუݒઍٷݣഗăኄᄣLjܔᇀᄲ൱ߛԿ࣍

ሺᅮگࢅ฿ኈڦᆌᆩઠຫLjۉୁݒઍٷݣഗ(සADA4927)

HD2–88dBc@50MHzᆫᇀۉუݒઍٷݣഗă

–90

–95

–100

–105

–110

110100

FREQUENCY(MHz)

཮16.ၿհ฿ኈᇑೕ୲࠲ڦဣ

Rev.0|Page10of16

ᆌᆩԴऻAN-1026

཮17ቛ๖କሞԿ࣍ሺᅮሺे้LjADA4927฿ኈႠీڦ൧

უӦ୲(ᅃዖٷ႑ࡽ֖ຕ)ኸሞփ؜၄ࡗଉ฿ኈڦ൧઄ူLj

઄ăٷݣഗ๼܋؜੗ᅜܔ๼෇܋৊ႜ߶ጷڦፌٷՎࣅ୲ă੊୯

–40

VOUT,dm=2Vp-p

უӦ୲ူڦኟ၀հ๼؜ă

–50

–60

–70

V=Vsin2π(34)

OP

ଭ঍ሁူLjڪ๕34ڞڦຕ)Վࣅ୲*नፌٷՎࣅ୲ྺ

–80

–90

dv

dt

maxπfv

=2(35)

p

ഄዐǖ

–100

–110

G=1

–120

–130

G=10

G=20

1101001k

FREQUENCY(MHz)

཮17.฿ኈᇑೕ୲ࢅሺᅮ࠲ڦဣ

dv/dtmaxྺუӦ୲ă

VPྺރኵۉუă

fྺඇࠀ୲ټ੻(FPBW)ă൱঴FPBWǖ

FPBW=

უӦ୲

2πVp

(36)

ټ੻ࢅუӦ୲

ټ੻ࢅუӦ୲ሞADCൻۯഗᆌᆩዐ၂ڥᆮഄዘᄲăᅃӯ

੗९Ljሞ჋ስADCൻۯഗ้LjՂႷ੊୯ሺᅮĂټ੻ࢅუӦ

୲(FPBW)Ljᅜඓۨٷݣഗీޏ஢ፁᆌᆩႴᄲă

ںLjၭ႑ټࡽ੻ྺഗॲټڦ੻LjܸუӦ୲ሶኼሞ࢚ଉٷݣ࿘ۨႠ

ഗ๼܋؜ሞٷ႑ࡽӦޗူڦፌٷՎࣅ୲ă

ֶݴADCൻۯഗ࿘ۨႠ੊୯ᇑሏ໙ٷݣഗ၎ཞă࠲॰֖ຕ

ᇑENOBૌຼLjᆶၳ੗ᆩټ੻(EUBW)௮ຎڦ๟ټ੻ăႹܠ

ADCൻۯഗࢅሏ໙ٷݣഗۼำ׬ਏᆶ࢔੻ټڦ੻Ljڍժݥ

ඇևټ੻ۼీಋฉᆩׇă૩සLj−3dBټ੻๟ټڦࡀ׉੻࢚

ଉݛ๕Ljڍժփ՗๖ඇև−3dBټ੻ۼ๟੗ᆩڦă−3dBټ੻

ࢅ܈ޗڦ၎࿋ဃֶ੗ᅜԲํाڦপኹೕ୲༵മๆԠ؜၄ă

๟၎࿋ᇧଉă༬ۨٷݣഗದዃڦ၎࿋ᇧଉ੗ߵ਍ຕ਍๮֩

ڟڥLj඗ܸLjሞ၄ํဣཥዐLjPCBۉୟӱքਆ٪ሞڦसิ

ၳᆌ੗ీޗٷইگ၎࿋ᇧଉă

ۉ޶უݒઍٷݣഗڦ࿘ۨႠൽਦᇀഄ࣍ୟሺᅮ(नA(s)×β)

ڦଉࡽޙࢅăֶݴADCൻۯഗᆛᆶଇ߲ݒઍᅺጱLjᅺܸԲ

ඓۨ੗ᆩټ੻ڦᅃ߲ࡻӸ݆๟ֱለຕ਍๮֩ዐڦ฿ኈ཮ă

ۆ႙ڦሏ໙ٷݣഗۉୟᄲްሗᅃၵă࣍ୟሺᅮ؜၄ሞڪ๕

཮18၂๖Ljྺକ๑ْܾࢅෙْၿհྼ׼ሞٷᇀ−80dBcڦ຤

ೝLjሶփీሞߛᇀ60MHzڦೕ୲ူ๑ᆩADCൻۯഗăᆯᇀ

7ڪࢅ๕8ݴڦజዐăڪ๕37௮ຎڦ๟࿄೅ದݒઍᅺጱူڦ

࣍ୟሺᅮ(β1≠β2)ă

ᆌᆩ߳փ၎ཞLjᆌߵ਍ဣཥᄲ൱ઠ჋ስټ੻؊ፁĂ฿ኈႠ

ీଆڦࡻൻۯഗă

࣍ୟሺᅮ

=

A(s)(β1+β)

2

2

(37)

–50

–60

–70

–80

–90

–100

HD2,G=1,RF=200

HD3,G=1,RF=200

HD2,G=2,RF=402

HD3,G=2,RF=402

ݒړઍᅺጱփ೅ದ้Ljᆶၳݒઍᅺጱྺଇ߲ݒઍᅺጱڦ

ೝ਩ኵăړܾኁ၎೅ದ൐ۨᅭྺβ้Lj࣍ୟሺᅮ੗०ࣅྺ

A(s)×βă

ྺକ๑ݒઍٷݣഗԍ׼࿘ۨLjഄ࣍ୟሺᅮփڪڥᇀ−1ई

ഄڪၳኵLjन၎ᅎ−180°้܈ޗྺ+1ăܔᇀۉუݒઍٷݣ

ഗܸჾLjሞഄਸ࣍ሺᅮೕ୲ፖՔ཮ฉLj࣍ୟሺᅮڪᇀ1

(न0dB)ۅڦኟࡻ๟A(s)ڦଉڪᇀݒઍᅺጱڛຕۅڦăܔᇀ

एԨٷݣڦഗᆌᆩLjݒઍك٦ྺۉፆ๕Ljփࣷሞݒઍ࣍ୟ

–110

–120

110100

FREQUENCY(MHz)

཮18.ADA4937ۉୁݒઍADCൻۯഗڦ฿ኈ൸၍

ዐׂิ၎ᅎăݒړઍᅺጱ၎೅ದ้Lj܀૬ᇀݒઍᅺጱڛຕ1+

RF/RGڦೕ୲ཚ׬׉ྺሯำሺᅮăසࡕॽᅜݴԞྺڇ࿋ڦ

փՎሯำሺᅮࣃሞᇑਸ࣍ሺᅮA(s)၎ཞڦፖՔ཮ฉLjሶଇ

ཉ൸၍၎঍ڦتೕ୲ྺ࣍ୟሺᅮྺ1ई0dBኮتăA(s)ሞ޿

ೕ୲ူڦ၎࿋ᇑ−180°ኮֶԥۨᅭྺ၎࿋ᇧଉLjྺକሏႜ

࿘ۨLjഄኵՂႷٷᇀईڪᇀ45°ă

Rev.0|Page11of16

AN-1026ᆌᆩԴऻ

཮19ቛ๖କADA4932ሞRF/RG=1(ሯำሺᅮ=2)้ڇڦ࿋࣍

ୟሺᅮࢅۅ၎࿋ᇧଉă

8090

40

20

GAIN

PHASE

RF

1+=2

RG

LOOP

GAIN=0dB

0

–45

6045

(6dB)

࣍ୟሺᅮྺ0dBLj300Ωݒઍۉፆ຤ೝ၍ᇑੵፆଉ൸၍၎঍

ᇀُăሞُೕ୲ူLjT(s)ڦ၎࿋ሀྺ−135°Lj঳ڟڥࡕ+45°

ڦ၎࿋ᇧଉă၎࿋ᇧଉࢅ࿘ۨႠᇑRFཞၠืইăۉୁݒઍ

ٷݣഗᆌ๔ዕ֑ᆩ၎࿋ᇧଉ؊ᇧۉكڦፆ๕ݒઍă

PCBۉୟӱքਆ

ሞยऺ࿘ۨڦADCൻۯഗ้LjኄዖາၙՂႷሞPCBۉୟӱ

6

0

–90

ฉํ၄ăۉୟӱዐڦसิᇮॲڞࣷዂևݴ၎࿋ᇧଉ໦฿Lj

ᅺُՂႷॽُૌᇮॲ३዁ፌณăႴᄲ༬՚ጀᅪڦ๟޶ሜۉ

–20

PHASE

MARGIN70°

–135

ඹĂݒઍ࣍ୟࢅߌۉ൱ࢅবۉۅඹăُ߲߳ૌसิۉੇۼ

ࣷሺेݒઍ࣍ୟዐڦውࢫ၎ᅎLjᆯُڞዂ၎࿋ᇧଉ३ณă–40–180

–60–225

සࡕPCBۉୟӱքਆփړLjยऺԨวन੗໦฿20°ईᅜฉڦ

၎࿋ᇧଉă

–80–270

1k10k100k1M10M100M1G10G

FREQUENCY(Hz)

཮19.ADA4932ਸ࣍ሺᅮଉࢅ၎࿋ᇑೕ୲࠲ڦဣ

ጮဦ੊ִ཮19੗ᅜ݀၄Ljړሯำሺᅮྺ1(߳࣍ୟݒઍ100%)

้LjADA4932ڦ၎࿋ᇧଉሀྺ50°ă໚඗๑ADCൻۯഗሏ

ႜᇀଭሺᅮူ๟փൎํाڦLj࠵ڍִ՗௽LjADA4932੗ሞ

ၭຕֶݴሺᅮ(૩සLjRF/RG=0.25Ljሯำሺᅮ=1.25)ူ࿘ۨ

ሏႜăڍժݥ໯ᆶֶݴADCൻۯഗদ๟සُăሞ໯ᆶADC

ሞۉუݒઍٷݣഗڦ൧઄ူLjፌࡻ֑ᆩၭڦRFLjᅜ३ณᅺ

RFᇑ൱ࢅবۉۅඹႚڦׯटڞۅዂڦ၎ᅎăසࡕႴᄲ֑ᆩ

ٷRFLj੗ሞ߳ݒઍۉፆฉ૧ᆩၭۉඹCFઠցۉ޿׋ඹLjၭ

ۉඹڦኵᆌ๑RFCFڪᇀRGᇑ൱ࢅবۉۅඹኮओă

PCBۉୟӱքਆํाฉ๟ยऺୁڦײፌࢫօየኮᅃăփ႞

ڦ๟Lj৑ߛ࠶໏ۉୟڦႠీ܈ߛᅈડᇀքਆLjኄཞ้ᄺ๟

ยऺײࡗዐፌᅟԥࢮ๫ڦօየኮᅃăยऺփڦړքਆ੗ీ

๑Ⴀీٶٷች੩Ljฯ዁๑ഄ฿ඁၳᆩă໚඗ُتփ੗ీࡥ

ൻۯഗڦຕ਍๮֩ዐLj੗ᅜੂڟፌၭ࿘ۨሺᅮă

ۉୁݒઍADCൻۯഗڦ၎࿋ᇧଉᄺ੗ߵ਍ਸ࣍ၚᆌઠඓ

ۨăۉୁݒઍٷݣഗ֑ᆩڦփ๟ኟၠሺᅮA(s)Ljܸ๟ኟၠ

ੵፆT(s)Ljᅜဃֶۉୁ