Datasheet

AD7985
Rev. A | Page 10 of 28
0
–180
–160
–140
–120
–100
–80
–60
–40
–20
0 12501000750500250
AMPLITUDE (dB)
FREQUENCY (kHz)
f
S
= 2.5MSPS
f
IN
= 20kHz
SNR = 89.87dB
THD = –102.76dB
SINAD = 89.66dB
07947-111
Figure 11. FFT Plot (External Reference)
100
95
90
85
80
16
15
14
13
12
2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00
SNR, SINAD (dB)
ENOB (Bits)
REFERENCE VOLTAGE (V)
SNR
SINAD
ENOB
07947-112
Figure 12. SNR, SINAD, and ENOB vs. Reference Voltage
95
90
85
80
75
70
65
1 100010010
SINAD (dB)
FREQUENCY (kHz)
07947-113
Figure 13. SINAD vs. Frequency
0
–180
–160
–140
–120
–100
–80
–60
–40
–20
0 12501000750500250
AMPLITUDE (dB)
FREQUENCY (kHz)
f
S
= 2.5MSPS
f
IN
= 20kHz
SNR = 88.45dB
THD = –103.42dB
SINAD = 88.32dB
07947-114
Figure 14. FFT Plot (Internal Reference)
–90
–95
–100
–105
–110
100
95
90
85
80
2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00
THD (dB)
SFDR (dB)
REFERENCE VOLTAGE (V)
SFDR
THD
07947-115
Figure 15. THD and SFDR vs. Reference Voltage
–85
–90
–95
–100
–105
–110
1 100010010
THD (dB)
FREQUENCY (kHz)
07947-116
Figure 16. THD vs. Frequency