Datasheet

AD7911/AD7921
Rev. A | Page 13 of 28
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 10 and Figure 11 show typical FFT plots for the AD7921
and AD7911, respectively, at a 250 kSPS sample rate and
100 kHz input frequency.
Figure 12 shows the SINAD ratio performance versus the input
frequency for various supply voltages while sampling at
250 kSPS with a SCLK frequency of 5 MHz for the AD7921.
Figure 13 shows the SNR ratio performance versus the input
frequency for various supply voltages while sampling at
250 kSPS with an SCLK frequency of 5 MHz for the AD7921.
Figure 14 and Figure 15 show INL and DNL performance for
the AD7921.
Figure 16 shows a graph of the total harmonic distortion versus
the analog input frequency for different source impedances
when using a supply voltage of 3.6 V and a sampling rate of
250 kSPS. See the Analog Input section.
Figure 17 shows a graph of the total harmonic distortion versus
the analog input frequency for various supply voltages while
sampling at 250 kSPS with an SCLK frequency of 5 MHz.
Figure 18 shows the shutdown current versus the voltage supply
for different operating temperatures.
5
–115
–95
–75
–55
–35
–15
0 20 40 60 80 100 120
04350-0-009
FREQUENCY (kHz)
SNR (dB)
8192 POINT FFT
V
DD
= 2.7V
F
SAMP
= 250kSPS
F
IN
= 100kHz
SNR = 73.13dB
SINAD = 72.73dB
THD = –83.30dB
SFDR = –86.15dB
Figure 10. AD7921 Dynamic Performance at 250 kSPS
8192 POINT FFT
V
DD
= 2.7V
F
SAMP
= 250kSPS
F
IN
= 100kHz
SNR = 73.13dB
SINAD = 72.73dB
THD = –83.30dB
SFDR = –86.15dB
5
–115
–95
–75
–55
–35
–15
0 20 40 60 80 100 120
04350-0-010
FREQUENCY (kHz)
SNR (dB)
8192 POINT FFT
V
DD
= 2.7V
F
SAMP
= 250kSPS
F
IN
= 100kHz
SNR = 61.75dB
SINAD = 61.74dB
THD = –86.24dB
SFDR = –84.46dB
Figure 11. AD7911 Dynamic Performance at 250 kSPS
–70.5
–74.0
–73.5
–73.0
–72.5
–72.0
–71.5
–71.0
10 100 1k
04350-0-011
FREQUENCY (kHz)
SINAD (dB)
V
DD
= 3.6V
V
DD
= 5.25V
V
DD
= 4.75V
V
DD
= 2.35V
V
DD
= 2.7V
Figure 12. AD7921 SINAD vs. Input Frequency at 250 kSPS
–72.0
–73.6
–73.4
–73.2
–73.0
–72.8
–72.4
–72.2
–72.6
10 100 1k
04350-0-012
FREQUENCY (kHz)
SNR (dB)
V
DD
= 2.35V
V
DD
= 3.6V
V
DD
= 5.25V
V
DD
= 4.75V
V
DD
= 2.7V
Figure 13. AD7921 SNR vs. Input Frequency at 250 kSPS