AD7661
Rev. 0 | Page 13 of 28
370
81
0
10005
16406
0
20000
40000
60000
80000
100000
120000
140000
7FFD 7FFE 7FFF 8000 8001 8002 8003 8004 8005 8006
COUNTS
CODE IN HEX
03033-0-011
000
117518
116740
Figure 11. Histogram of 261,120 Conversions of a
DC Input at the Code Transition
–180
–160
–140
–120
–100
–80
–60
–40
–20
0
AMPLITUDE (dB of Full Scale)
f
S
= 100kSPS
f
IN
= 45kHz
SNR = 89.2dB
THD = –102dB
SFDR = 103.1dB
S/[N+D] = 88.9dB
050
FREQUENCY (kHz)
03033-0-012
10 20 30 40
Figure 12. FFT Plot
81
82
83
84
85
86
87
88
89
90
91
1 10 100 1000
FREQUENCY (kHz)
SNR, S/[N+D] (dB)
13.0
13.5
14.0
14.5
15.0
15.5
ENOB (Bits)
SNR
S/[N+D
]
ENOB
03033-0-013
Figure 13. SNR, S/(N+D), and ENOB vs. Frequency
0
59
5181
3745
8
56132
61586
0
20000
40000
60000
80000
100000
120000
140000
7FFD 7FFE 7FFF 8000 8001 8002 8003 80047FFC
COUNTS
CODE IN HEX
03033-0-014
160000
180000
0
134409
Figure 14. Histogram of 261,120 Conversions of a
DC Input at the Code Center
–120
–115
–110
–105
–100
–95
–90
–85
–80
–75
–70
1 10 100 1000
20
30
40
50
60
70
80
90
100
110
120
SFDR
THD
THIRD
HARMONIC
FREQUENCY (kHz)
THD, HARMONICS (dB)
SFDR (dB)
03033-0-015
SECOND
HARMONIC
Figure 15. THD, Harmonics, and SFDR vs. Frequency
87
88
89
90
91
92
–60 –50 –40 –30 –20 –10 0
INPUT LEVEL (dB)
SNR, S/[N+D] REFERRED TO FULL SCALE (dB)
SNR
S/[N+D]
03033-0-016
Figure 16. SNR and S/(N+D) vs. Input Level (Referred to Full Scale)
