AD6644
AD6644AST-40/65
Typ
Parameter
Name
Temp
Test Level1
Unit
Min
Max
DATA READY (DRY6)/DATA, OVR
Data Ready to DATA Delay (Hold Time)3
Encode = 65 MSPS (50% Duty Cycle)
Encode = 40 MSPS (50% Duty Cycle)
Data Ready to DATA Delay (Setup Time)3
@ 65 MSPS (50% Duty Cycle)
@ 40 MSPS (50% Duty Cycle)
APERTURE DELAY
tH_DR
See note7
8.6
13.4
See note7
5.5
10.3
Full
Full
IV
IV
8.0
12.8
9.4
14.2
ns
ns
tS_DR
Full
Full
IV
IV
V
3.2
8.0
6.5
11.3
ns
ns
tA
tJ
25°C
25°C
100
ps
APERTURE UNCERTAINTY (JITTER)
V
0.2
ps rms
1 See the Explanation of Test Levels section.
2 Several timing parameters are a function of tENC and tENCH
.
3 To compensate for a change in duty cycle for tH_DR and tS_DR use the following equations:
NewtH_DR = (tH_DR − % Change(tENCH)) × tENC/2
NewtS_DR = (tS_DR − % Change(tENCH)) × tENC/2
4 ENCODE to data delay (hold time) is the absolute minimum propagation delay through the ADC.
5 ENCODE to data delay (setup time) is calculated relative to 65 MSPS (50% duty cycle). To calculate tS_E for a given encode, use the following equation:
NewtS_E = tENC(NEW) − tENC + tS_E (that is, for 40 MSPS, NewtS_E(TYP) = 25 × 10−9 − 15.38 × 10−9 + 9.8 × 10−9 = 19.4 × 10−9).
6 DRY is an inverted and delayed version of the encode clock. Any change in the duty cycle of the clock correspondingly changes the duty cycle of DRY.
7 Data ready to data delay (tH_DR and tS_DR) is calculated relative to 65 MSPS (50% duty cycle) and is dependent on tENC and duty cycle. To calculate tH_DR and tS_DR for a
given encode, use the following equations:
NewtH_DR = tENC(NEW)/2 − tENCH + tH_DR (that is, for 40 MSPS, NewtH_DR(TYP) = 12.5 × 10−9 − 7.69 × 10−9 + 8.6 × 10−9 = 13.4 × 10−9).
NewtS_DR = tENC(NEW)/2 − tENCH + tS_DR (that is, for 40 MSPS, NewtS_DR(TYP) = 12.5 × 10−9 − 7.69 × 10−9 + 5.5 × 10−9 = 10.3 × 10−9).
AC SPECIFICATIONS
ENCODE
All ac specifications tested by driving ENCODE and
differentially.
ENCODE
AVCC = 5 V, DVCC = 3.3 V; ENCODE and
= maximum conversion rate MSPS; TMIN = −25°C, TMAX = +85°C, unless otherwise noted.
Table 5.
AD6644AST-40
AD6644AST-65
Parameter
SNR
Conditions
Temp
Test Level1
Unit
Min
Typ
Max
Min
Typ
Max
Analog Input
@ −1 dBFS
2.2 MHz
15.5 MHz
30.5 MHz
25°C
25°C
25°C
V
II
II
74.5
74.0
73.5
74.5
74.0
73.5
dB
dB
dB
72
72
SINAD2
Analog Input
@ −1 dBFS
2.2 MHz
15.5 MHz
30.5 MHz
25°C
25°C
25°C
V
II
V
74.5
74.0
73.0
74.5
74.0
73.0
dB
dB
dB
72
83
85
WORST HARMONIC (2ND or 3RD)2
Analog Input
2.2 MHz
15.5 MHz
30.5 MHz
25°C
25°C
25°C
V
II
V
92
90
85
92
90
85
dBc
dBc
dBc
@ −1 dBFS
WORST HARMONIC (4TH or Higher)2
Analog Input
2.2 MHz
15.5 MHz
30.5 MHz
25°C
25°C
25°C
Full
V
II
V
V
93
92
92
93
92
92
dBc
dBc
dBc
dBFS
@ −1 dBFS
TWO-TONE SFDR2, 3, 4
100
100
TWO-TONE IMD REJECTION2, 4
F1, F2 @ −7 dBFS
Full
V
V
90
90
dBc
ANALOG INPUT BANDWIDTH
25°C
250
250
MHz
1 See the Explanation of Test Levels section.
2 AVCC = 5 V to 5.25 V for rated ac performance.
3 Analog input signal power swept from −7 dBFS to −100 dBFS.
4 F1 = 15 MHz, F2 = 15.5 MHz.
Rev. D | Page 5 of 24