AN-642: 将单端时钟源耦合至第三代TxDAC®和TxDAC+®产品的差分时钟输入端 (Rev. 0)

AN-642
ᆌᆩԴऻ
One Technology Way t P.O. Box 9106 t Norwood, MA 02062-9106, U.S.A. t Tel: 781.329.4700 t Fax: 781.461.3113 t www.analog.com
ॽ‫้܋ڇ‬ዓᇸ᳘ࢇ዁‫ڼ‬ෙ‫پ‬TxDAC®ࢅTxDAC+®
ׂ೗‫้ݴֶڦ‬ዓ๼෇‫܋‬
ፕኁǖDoug Mercer Steve Reine David Carr
०঻
‫ڼ‬ෙ‫پ‬TxDACࢅTxDAC+ဣଚ + ದᆶᅃ߲ଳऄ‫้ݴֶڦ‬
ዓ๼෇ăCLK+ࢅCLK–ଇֶ߲‫้ݴ‬ዓ๼෇‫܋‬੗ᅜ֑ᆩ
‫ܠ‬ዖ‫้ݴֶࢅ܋ڇ‬ዓᇸઠൻ‫ۯ‬ăሞႹ‫܋ڇܠ‬ገֶ‫ݴ‬ᆌ
ᆩዐLjՎუഗ᳘ࢇ๟ᅃዖๆ‫ݴ‬ᆶᆩ‫ݛڦ‬๕ă඗ܸLjሞ
గၵ൧઄ူLj‫ى‬᳘ࢇՎუഗ੗ీժփ‫ݛ‬Սăᅃ߲‫܋ڇ‬
้ዓ႑ࡽ੗ཚࡗ‫ܠ‬ዖ‫ݛ‬๕᳘ࢇ዁้ዓ๼෇‫܋‬ă‫ړ‬ሞ
CLK–๼෇‫܋‬แेᅃ߲๢‫ڦړ‬኱ୁពኵ‫ۉ‬უ้Lj੗ᅜൻ
‫ۯ‬CLK+๼෇‫܋‬Ljස཮Ǎ໯๖ă‫ۉ‬ፆR1ĂR2ᇑ‫ۉ‬ඹC3ᅃ
ഐྺCLK–‫ิׂ܋‬ᅃ߲‫ڪ‬ᇀCLKVDD/2‫ڦ‬኱ୁ‫ۉ‬ೝă้
ዓᇸՂႷྺ‫ڇ‬टႠLjӦ‫ޗ‬থৎࡆ‫ࡆڟ‬ăኄዖದዃ৑࠶
०‫ڇ‬Ljඐ࿮݆༵ࠃട‫ڦړ‬ᇸ‫܋‬থፆੇLj‫ۉܔ‬ᇸሯำई
থ‫ں‬ሯำबࢭ࿮ቲॐኮ૰ă
ᆅ෇CLK–๼෇‫܋‬ă૙ၙ൧઄ူLjᆌ޿૶থሞᇑ้ዓᇸ
၎ཞ‫(ۅࠌࠅڦ‬९཮2)ă
C3
0.1 F
R3
1kΩ
RTERM
50Ω
C3
0.1 F
R2
1kΩ
R4
1kΩ
CLK–
C2
1nF
CLKCOM
཮2.‫ۉ‬ፆ೅ದথ੨
CLK+
ଇ߲1 nF‫ڦ‬๼෇᳘ࢇ‫ۉ‬ඹC1ࢅC2ॽྪஏ‫ߛڦ‬ཚገችೕ୲
ยሞ5 MHzፑᆸă੗ߵ਍ᅜူࠅ๕ฉူۙবߛཚገችೕ୲
R1
1kΩ
50 Ω
SOURCE
CLK+
R1
1kΩ
50 Ω
SOURCE
CLKVDD
RSERIES
CLKVDD
C1
1nF
f3dB =
R2
1kΩ
CLK–
1
2π × C × 50
where C = C1 × C2
C1 + C2
CLKCOM
቏‫ټ‬೅ದ
཮1. ‫܋ڇ‬থ੨
ᅃዖডࡻ‫پ༺ڦ‬Ӹ݆๟֑ᆩᅃዖ०‫ۉټ੻ڦڇ‬ፆ೅ದྪ
ஏ(९཮2)ăස཮Ǎ໯๖Lj‫ۉ‬ፆR1ĂR2ࢅ‫ۉ‬ඹC3ׂิ‫ڪ‬
ᇀCLKVDD/2‫ڦ‬኱ୁೋዃ‫ۅ‬ă‫ۉ‬ፆR3ĂR4ྺֶ‫ݴ‬๼෇‫܋‬
CLK+ࢅCLK–༵ࠃ኱ୁೋዃăᅃ߲‫܋‬থ‫ۉ‬ፆRTERM (50Ω)
༵ࠃՂᄲ‫ڦ‬ᇸ‫܋‬থLj‫ۉ‬ඹC1ĂC2ሶ༵ࠃ߰኱ă‫܋‬থ‫ۉ‬
ፆፌࡻ኱থੵথᇀ๼෇ᆅগCLK+ࢅCLK–Ljഄፕᆩ๟ሞ
้ዓ႑ࡽና‫ޗ‬ডၭ‫ڦ‬൧઄ူই‫گ‬኱ୁೋዃ‫ۉ‬უ‫ڦ‬੗ీփ
૧ᆖၚăሞ‫گ‬ೕ൧઄ူLjኄዖ঴ਦ‫ݛ‬ӄժփ‫؜‬෥Ljᅺྺ໲
ᄲ൱๑ᆩড‫ڦٷ‬᳘ࢇ‫ۉ‬ඹăᇑ཮Ǎዐ‫ۉ‬ୟփཞ‫ڦ‬๟Lj๼෇
ᇸ੗ᅜ๟ມटႠǗཞ้LjᆯᇀR3ࢅR4ᇑ50Ω RTERMኮԲ
ড‫ٷ‬Lj዁ณ੗ᅜᅞ዆ᅃۨ‫ۉڦ‬ᇸሯำࢅথ‫ں‬ሯำă‫ڍ‬᳘
ࢇ‫ۉ‬ඹC2‫ࠌڦ‬ఇ֨໯֑ᆩ‫૶ڦ‬থ‫ݛ‬๕‫ܸݒ‬੗ీॽሯำ
ሞ੻‫ټ‬ᆌᆩዐLjՎუഗ᳘ࢇๆ‫ݴ‬ᆶᆩă඗ܸLjሞገ࣑ഗ
ᆌᆩዐLj้ዓཚ‫֑׉‬ᆩ‫ڇ‬ᅃ‫ۨࠦڦ‬ೕ୲ăሞߛ้ዓೕ୲Lj
ईኁᅺ้ዓᇸᇑገ࣑ഗ၎ਐডᇺܸ੗ీ่ൽୟ০߅ඡ‫ڦ‬
൧઄ူLjཚ‫֑׉‬ᆩ቏‫ټ‬೅ದྪஏࣷ߸ࡻă቏‫ټ‬LC೅ದ
੗ᅜ֑ᆩᅃዖ‫ߌۉ૴ز‬/ժ૴‫ۉ‬ඹLjई‫ۉ૴ز‬ඹ/ժ૴‫ۉ‬
ߌઠํ၄ă඗ܸLjᆯᇀCLK+ࢅCLK–ଇ้߲ዓ๼෇‫ڦ܋‬
ժႜᄲ൱֑ᆩ঍ୁ᳘ࢇ‫ݛ‬๕Ljᅺُ‫ۉ૴ز‬ඹ/ժ૴‫ߌۉ‬
ૌ೅ದ߸ྺࢇ๢(९཮3)ă
+ AD9740ACPĂAD9742ACPĂAD9744ACPĂAD9748ACPĂ
AD9751ĂAD9753ĂAD9755ĂAD9772ĂAD9773ĂAD9775Ă
AD9777
Rev. 0 | Page 1 of 4
AN-642
֑ᆩኄᄣ‫ټڦ‬ཚྪஏᆶबၜᆫ๞ăᆯᇀֶ‫ݴ‬๼෇‫ڦ܋‬
๼෇ፆੇডߛ൐बࢭྺ‫ك‬ඹႠLjᅺُ੗ᅜํ၄ᅃۨଉ
‫ۉڦ‬უሺᅮăሞኻᆶ‫گ‬ና‫้ޗ‬ዓ႑ࡽ੗ᆩ‫ڦ‬൧઄ူLj
ኄ੗ᅜ༵ߛሯำ௨ᅧ૰ăᇮॲຕଉณǖ‫أ‬କׂิ኱ୁ
ೋዃՂփ੗ณ‫ڦ‬ᇮॲྔLj࣏ᆶଇ߲‫ۉ‬ඹࢅᅃ߲ডՍᅓ
‫ೌڦ‬๕‫ߌۉ‬ă
CLKVDD
C1
R1
1kΩ
R3
1kΩ
C3
0.1 F
R2
1kΩ
R4
1kΩ
LMATCH
1
2π × f0 =
L2 × CIN
໯ᅜǖ
L2 =
1
( 2π × f0 )2 × C IN
ැዐ႐ೕ୲ྺ100 MHz൐CIN = 2.5 pFLjሶL2 = 1.01 μHă
ሞሡ้ࢮ୼CIN‫ڦ‬൧઄ူLj੗ᅜ৊ႜ၎࠲ऺ໙Ljᅜ๑50 Ωᇸ
(RS)ᇑ1 kΩ኱ୁೋዃ‫ۉ‬ፆ(RIN)၎೅ದLjཞ้ऺ໙CMATCHࢅL1
‫ڦ‬ኵă
CLK+
50 Ω
SOURCE
ၿናೕ୲ᆯᅜူࠅ๕ۨᅭǖ
CIN
ැ
CLK–
R S × R IN =
L1
CMATCH
C2
ሞᅜူೕ୲ူLj๼෇‫؜ॽ܋‬၄‫ۉ‬ፆǖ
CLKCOM
f0 =
཮3. LC೅ದথ੨
൱঴CMATCHLj঳ࡕ‫ڟڥ‬ǖ
቏‫ټ‬LC೅ದ๖૩(100MHz)
৑࠶ᆶႹ‫ײॲ෉ܠ‬Ⴞ੗ᆩઠൟ຿ऺ໙೅ದᇮॲኵLj‫ڍ‬ൣ
‫ؤ‬କ঴໯ภत‫ڦ‬ਏ༹ऺ໙ᄺ๟ๆ‫ݴ‬ᆶᆩ‫ڦ‬ă੊୯‫ڟ‬ডߛ
ೕ୲ူ٪ሞ‫ڦ‬PCӱքਆसิၳᆌLjԨ๖૩֑ᆩ‫ڦ‬ೕ୲
ኵྺ100 MHzăሞᄲ൱ডߛೕ୲‫ڦ‬PCӱยऺዐLjRFքਆ
‫ݠ‬ኈ෉ॲ‫׉ݥ‬ᆶᆩă
‫ۆ‬႙൧઄ူLj้ዓ๼෇Ⴔᄲ೅ದ዁50 Ωăྺକ०ࣅ೅ದ
ࡗ‫ײ‬Lj੗ሡ้փऺ໙CLK+ࢅCLK–ଇ߲๼෇‫ڦ܋‬๼෇‫ۉ‬
ඹCINLj‫݆ݛ‬๟ཁेᅃ߲Ⴕెժ૴‫(ߌۉ‬L2Lj९཮4)Lj޿
‫ॽߌۉ‬Ӏ໯Ⴔೕ୲ᇑCINၿናăฎࢫඓۨ೅ದ‫ߌۉ‬LMATCH
้ॽ੊୯޿‫(ߌۉ‬९཮3)ăኄᄣፔ੗ᅜሞ50 Ωᇸᇑ1 k Ω኱
ୁೋዃ‫ۉ‬ፆኮक़०‫ۉڦڇ‬ፆ‫ۉڟ‬ፆ೅ದࡗ‫ڦײ‬ए‫إ‬ฉ৊ႜ
ዷᄲऺ໙ă
AC GROUND
L1
C2
L2
RIN
1kΩ
AC GROUND
཮4. ๼෇೅ದ๖૩
CMATCH =
1
2π × f0
R S × R IN
ැf0 = 100 MHzLjRS= 50 ΩLjRIN = 1 kΩLjሶCMATCH = 7.12 pF
থူઠ൱঴L1Lj঳ࡕ‫ڟڥ‬ǖ
L1 =
R S × R IN
2π × f0
ැf0 = 100 MHzLjRS = 50 ΩLjRIN = 1 kΩLjሶL1 = 356 nHă
ᆯᇀL1ࢅL2၎ժ૴LjᅺُጹࢇܾኁLj੗‫ڥ‬LMATCH‫ڦ‬ፌዕ
ኵǖ
LMATCH =
L1 × L2
L1 + L2
ැL1 = 356 nH൐L2 = 1.01 μHLjሶLMATCH = 263 nHă
RIN
1kΩ
C1
50 Ω
SOURCE
1
2π L1 × CMATCH
CLK+
CIN
CLK–
C1ࢅC2ᆶ‫ܠ‬ዖ჋ስă๯ံLj੗ᅜॽC2ยྺᅃ߲‫ٷ‬ኵLjස
1000 pFLjᅜ๑ഄ՗၄ྺᅃ߲RF‫܌‬ୟă඗ࢫᆌॽC1ยྺ‫ڪ‬
ᇀCMATCHऺ໙ኵă‫ܾڼ‬Lj੗ॽC1ࢅC2‫ݴ‬՚ยྺCMATCH‫ڦ‬
ଇԠLjᅜ๑ጺ‫ۉ૴ز‬ඹ‫ڪ‬ᇀCMATCHă‫ڼ‬ෙLjཚࡗ๑C1ࢅ
C2୼ྲ٪ሞֶᅴ(न჋ስC2ԲC1‫گ‬10%ፑᆸ)‫ڍ‬๑ഄ‫૴ز‬
ኵ၎‫ڪ‬Ljሶ੗๑CLK+ࢅCLK–‫܋‬႑ࡽ‫ڦ‬ና‫ޗ‬၎‫ڪ‬Ljܸٗ
༵ߛֶ‫ݴ‬๼෇ൻ‫ڦۯ‬ೝ࢚ႠăኻᄲC1ࢅC2‫ࢇڦ‬ժ‫૴ز‬ኵ
(न(C1×C2)/(C1+C2))‫ڪ‬ᇀCMATCHLjሶ੗֑ᆩฉຎෙዖ჋
ၜዐ‫ڦ‬ඪᅪᅃዖă
Rev. 0 | Page 2 of 4
AN-642
ሞ໯ᆶ൧઄ူLjCMATCH(C1, C2)ࢅLMATCH‫ڦ‬ኵՂႷٗՔጚ
ኵዐ৊ႜ჋ስăፌথৎ‫ڦ‬ՔጚኵྺC1 = 16 pFLjC2 = 15 pFLj
LMATCH = 270 nH(ස՗1໯๖)ăُ้LjႴᄲҾጎฉኄၵኵ
‫ܔ‬ᆌ‫ڦ‬ഗॲLjժ֪ଉሞೕ୲ྺ100 MHz้‫ڦ‬Ⴀీăᆯᇀ
٪ሞPCӱࢅքਆसิၳᆌLj໯ᅜ੗ీႴᄲ‫ܔ‬ᅜฉ๖૩
໙‫ڦ؜‬ᇮॲኵ৊ႜۙኝă
՗Iଚ‫؜‬କ཮Ǐ໯๖‫ۉࢅߌۉ‬ඹሞ჋ۨRFೕ୲ူ‫ॺڦ‬ᅱ
ኵăසമ໯ຎLj‫ܔ‬PCӱքਆ৊ႜႪ߀ॽ๑ྪஏႠీᇑ
ࡀ߭٪ሞֶᅴă
ೕ୲
(MHz)
LMATCH
(nH)
C1
(pF)
C2
(pF)
ଷྔLjሞ֑ᆩ‫܋ڇ‬ᇸൻ‫ڦۯ‬൧઄ူLjཚࡗ๑ኄၵ‫ۉ‬ඹ٪
ሞฎႹֶᅴLj੗ᅜ๑CLK+ࢅCLK–‫ڦ܋‬ና‫ޗ‬၎‫ڪ‬Ǘन๟
ຫLjྪஏࣩ݀ጣೝ࢚lj‫ݥ‬ೝ࢚Վ࣑ഗ‫ڦ‬ፕᆩă཮5၂๖
‫ڦ‬๟ዐ႐ೕ୲ྺ100 MHz้‫ڦ‬ၚᆌǗ൩ጀᅪ‫گ‬ೕူ٪ሞ
‫ڦ‬टߛປ३ăߛೕປ३๟้ዓ๼෇ᆅগ‫ڦ‬๼෇‫ۉ‬ඹ໯ዂă
ഄዐLjCLK+ࢅCLK–ଇ‫ݴֶڦ܋‬ና‫ޗ‬ၚᆌࢇժሞᅃഐLj
ཞ้࣏ᆶ၎‫߲߳ڦںࠌࠅܔ‬๼෇‫܋ڇڦ܋‬ၚᆌă६ᇀ೅
ದྪஏ‫ڦ‬ၿናႠዊLjCLK+ࢅCLK–ଇ߲๼෇‫܋‬٪ሞ90°
ፑᆸ‫ڦ‬၎ᅎăኄዖ൧઄ස཮6໯๖ăሞۙኝገ࣑ഗຕ਍
ยዃࢅԍ‫้׼‬क़้LjՂႷ੊୯ኄዖ၎࿋ֶă
61.44
470
24
22
65.00
470
24
18
76.80
390
18
16
78.00
390
18
15
78.64
390
16
16
92.16
330
13
12
100.00
270
16
15
122.88
220
11
10
130.00
180
12
11
153.60
150
10
9
156.00
150
10
8
157.29
120
12
12
184.32
120
8
7
245.76
82
6
5
260.00
56
9
8
307.20
47
7
6
312.00
47
6
6
314.57
47
6
6
368.64
39
5
4
491.52
22
5
4
520.00
18
6
5
614.40
15
4
4
624.00
15
4
3
629.15
15
4
3
737.28
12
2
2
15
10
DIFFERENTIAL
RESPONSE
VIN
5
0
MAGNITUDE (dB)
–5
–10
–15
–20
CLK+
SINGLE-ENDED
–25
–30
–35
CLK–
SINGLE-ENDED
–40
–45
–50
–55
10M
100M
FREQUENCY (Hz)
1G
཮5. 100 MHz೅ದྪஏ‫ڦ‬ና‫ޗ‬ၚᆌ
175
150
125
100
DIFFERENTIAL
RESPONSE
CLK+
SINGLE-ENDED
MAGNITUDE (dB)
75
՗I. ኍ‫཮ܔ‬4ዐC1ĂC2ࢅLMATCH ‫ॺڦ‬ᅱኵ
50
25
0
–25
–50
–75
CLK–
SINGLE-ENDED
–100
–125
–150
–175
–200
10M
100M
FREQUENCY (Hz)
཮6. 100 MHz೅ದྪஏ‫ڦ‬၎࿋ၚᆌ
1G
޹୤1
ᆩSpiceઠ‫ܔ‬ኄዖথ੨ྪஏ৊ႜॺఇࢅ‫ݠ‬ኈLjኄ๟Ԩ࿔໯
๖๮߾ऺ໙‫ݛ‬๕‫ڦ‬ᆶᆩ༺‫پ‬Ӹ݆ăኄዖఇ๕ူ੗ᅜ੊୯
߸‫ܠ‬सิၳᆌLjԲසԈጎࢅPCӱग၍‫ڪ‬ᇮॲׂิ‫ڦ‬स
ิၳᆌăᅜူଚ‫ڦ؜‬๟ኍ‫้ܔ‬ዓ๼෇঳ࠓ‫ڦ‬Spiceपጱ‫ۉ‬
ୟఇ႙ă֖ቷ཮7ࢅ཮8ዐ‫ڦ‬ᇱ૙཮ᅜतଚ՗‫ۥ‬ևLj‫ߌۉ‬
L1ࢅ‫ۉ‬ඹC1ĂC2ඓۨକྪஏ‫ڦ‬ዐ႐ೕ୲ăഄዐ໯ଚኵ
਩एᇀ100 MHz‫ڦ‬ೕ୲ă‫ۉ‬ፆR1ྺൻ‫ۯ‬ᇸ(V3)ፆੇLj‫ۉ‬
ፆR2ࢅR3ሶྺ঍ୁ᳘ࢇ๼෇༵ࠃ኱ୁೋዃ‫ۉ‬უ(ᆯ‫ۉ‬უ
ᇸV4ยۨ)ă
Rev. 0 | Page 3 of 4
AN-642
C6
16P
CLK_VDD
CLK_P
V3
0 AC 2
L1
270N
R2
1K
CLK_COM
R3
1K
XIPT
CLK_N
C7
5P
V4
1.65
V1
3.3
V2
0
཮7. ๼෇ྪஏ‫ڦ‬SPICEఇ႙
CLK_VDD
CLK_P
L1
2.1N
C1
0.75P
R2
0.0517
D1
D2
D3
R1
193
CLK_COM
CLK_N
C2
9F
C3
18F
L2
2.1N
R3
0.0517
C4
0.75P
D4
D6
R4
193
D5
C5
9F
཮8. XlPTఇ੷‫ڦ‬SPICEጱ‫ۉ‬ୟ
ଚ՗1
้ዓ๼෇೅ದྪஏఇ႙
+
V1 CLK_VDD 0 3.3
V2 CLK_COM 0 0
V3 SRC_P 0 0 AC 2
V4 CML 0 1.65
R1 SRC_P CAP_P 50
R2 CLK_P CML 1K
R3 CLK_N CML 1K
C1 CAP_P CLK_P 16p
C2 CLK_N 0 15p
L1 CLK_P CLK_N 270n
XXIPT CLK_P CLK_N CLK_COM CLK_VDD CLK_INPUT
.SUBCKT CLK_INPUT CLK_P CLK_N CLK_COM CLK_VDD
C1 CLK_VDD C1_B 0.75p
C2 CLK_VDD C2_B 9f
C3 C2_B C3_B 18f
C4 CLK_VDD C4_B 0.75p
C5 CLK_VDD C3_B 9f
D1 C1_B CLK_VDD DP1 1
D2 CLK_COM C1_B DN2 1
D3 C2_B CLK_VDD DP3 1
D4 CLK_COM C4_B DN2 1
D5 C3_B CLK_VDD DP3 1
D6 C4_B CLK_VDD DP1 1
L1 L1_A CLK_P 2.1n
L2 L2_A CLK_N 2.1n
R1 C2_B C1_B 193
R2 C1_B L1_A 0.0517
R3 C4_B L2_A 0.0517
R4 C3_B C4_B 193
.ENDS CLK_INPUT
E03631–0–4/03(0)
R1
50
.model DP1 D (bv=5.5 cjo=1.17088p eg=1.106 fc=500m
ibv=608.2p is=1.299342f m=632.669m)
.model DP3 D (bv=5.5 cjo=325.2446f eg=1.106 fc=500m
ibv=608.2p is=3.609284e-16 m=632.669m)
.model DN2 D (bv=8.0 ibv=1.54587E-06 cjo=1.411p
m=0.3675268 is=1.759f eg=1.140)
.AC DEC 400 10E6 1E9
.PROBE
.OP
.END
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