±
200
±
160
±
120
±
80
±
40
0
0
50000
100000
150000
200000
250000
A
m
p
lit
u
d
e
(
d
B
)
Input Frequency (Hz)
C068
-90.35
-90.3
-90.25
-90.2
-90.15
-90.1
-90.05
-90
-89.95
-89.9
-89.85
70
72
74
76
-40
-7
26
59
92
125
S
N
R
,
S
IN
A
D
(
d
B
)
Free-Air Temperature (
o
C)
C069
SNR
THD
SINAD
T
H
D
(
d
B
)
0
1000
2000
3000
4000
5000
2044 2045 2046 2047 2048 2049 2050 2051 2052
N
u
m
b
e
r
o
f
H
it
s
Output Codes
C066
±
4.0
±
3.0
±
2.0
±
1.0
0.0
1.0
2.0
3.0
4.0
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
-40
-7
26
59
92
125
O
ff
s
e
t
E
rr
o
r
(m
V
)
G
a
in
E
rr
o
r
(%F
S
R
)
Free-Air Temperature (
o
C)
C067
Gain Error
Offset Error
SBAS492 – JULY 2015
The AUX channel in the ADS8664 and ADS8668 offers a true 12-bit performance with no missing codes. Some
typical performance characteristics of the AUX channel are shown in
to
AUX channel
Mean = 2048, sigma = 0
Figure 82. Offset and Gain vs Temperature
Figure 81. DC Histogram for Mid-Scale Input
(AUX Channel)
(AUX Channel)
f
IN
= 1 kHz
f
IN
= 1 kHz, SNR = 74.06 dB, SINAD = 74.03 dB,
THD = –95.40 dB, SFDR = 97.04 dB, number of points = 64k
Figure 84. SNR, SINAD, and THD vs Temperature
Figure 83. Typical FFT Plot
(AUX Channel)
(AUX Channel)
32
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