High-speed ADC techniques - overview and scaling issues

40 Pages·2001·0.44 MB·English

High-speed ADC techniques
- overview and scaling issues -
civonajot SrimidalV
Outline
• snoitacilp pC aDdAeepS-hgiH
• metricsperformance ADC Basic
• weivrevo – serutcetihcrA
• 90sin ADCs
• srotc agfnitimiL
• noisulcnoC
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High-speed ADC applications
• )b01- 6,s/SM05-1 (lennah Cata DNA LsseleriW
• )b8- 6,s/SM0001-002 (lennah Cdae Regarot ScitengaM
• ADSL data channel (3-10MS/s, 12-16b)
• V TdradnatS-itlu MlatigiD dnabesaB ADC
(20MS/s, 8-10b)
• CATV Decoder Modem ADC (10-20MS/s, 8-10b)
• HDTV – various apps (50-75MS/s, 10b)
• V Ttsacdaor Bdradnats-itlu Mro fFI-latigiD rcvr
(100-200Mb/s, 8-12b)
• noitaludo mMAP Mhti wskni ldeeps-hgi hlaireS
(5-10Gs/s, 4-6b)
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Basic ADC performance metrics
• ytniatrecnu emit erutrepA
ytniatr e ecemnriuuttrepA
• kRaNeSP
e meirtutrepA
pRNS ]B d6[7.1+N20.6=
• sti bf o#evitceffE
Digital
out
]Bd[67.1+BONE20.6=RDNS MSB
• egnar cimanyD Gain
111
BSL error
=RD P / P
110
full scale sin nis @0dB SNR
• egnaR cimanyD eerF suoirupS
101
100
• :srorr ecitatS
011 Analog
LNI
DNL ytiraenil-no nlaitnereffi d- in
010
INL ytiraenil-non largetni -
001
DNL+LSB
tesffO
rorr eniaG
V /8 V /2
V
SF SF
SF
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Architectures
• Flash
– noitalopretnI
– gnigarevA
• Folding
– noitalopretn Idn agnidloF
• Two-step
– gnignarbuS
– hsalF
• Pipeline
– noitarbila cegats-reP
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C D A h s a l F
: s t i b 8 o t p u t s e B
0
+
: e l p m a x E
d e e p S
0
C D A h s a l F t i b 3
+
y t i c i l p m i S
0
2 s r e i f i l p m a - e r p
3
0
2 s r o t a r a p m o c
3
y t i x e l p m o c l a i t n e n o p x E -
e c n a t i c a p a c t u p n i g i B -
1
e d o c o m r e h t n i s e l b b u B -
1
- P o w e r
1
l a n g i s n i e c n e r e f f i D -
1
r o t a r a p m o c h c a e o t y a l e d
rotarapmoc
reifilpma-erp
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Interpolation in Flash ADC
V
r12
V V
r1 r2
• Redupocrf#ee d- amps
– ecnaticapa ctupn irellams
– hsal fllu fnah trewo pssel
• Improved DNL due to
distributiooenfr rors
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Averaging in Flash ADC
)Vm05-51 ~( tesffo rotarapmoc fo tceffe ecuder spma-erP
)Vm01-Vm3~( stesffo ecudortni tuB
krowten rotsiser htiw stesffo reifilpma-erp eht tuo egarevA – noituloS
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Effect of Averaging
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Averaging effect on offset, INL, DNL
• gnigarev aretf adetalerro cylhgi hslangi sgnirobhgie n
s
• D (= V - V dn a5/) = individual
s
n -2 n +3 average
5
•
• segat sgnigarev af o #hti wsevorpm iLN D
• segat sgnigarev af otoor-erauq shti wevorpm itesff o,LN I
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