AD7720 Analog Devices, AD7720 Datasheet - Page 9

• Manufacturer Part Number: AD7720
• Description: CMOS Sigma-Delta Modulator with 90 dB Dynamic Range
• Manufacturer: Analog Devices

Specifications of AD7720

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: 25MSPS
• Interface: Ser
• Analog Input Type: Diff-Bip,Diff-Uni
• Ain Range: (Vref) p-p,2.5V p-p,Uni (Vref),Uni 2.5V
• Adc Architecture: Sigma-Delta Modulator
• Pkg Type: SOP

REV. 0
–100
–110
–120
–130
–100
–120
–140
–154
–100
–120
–140
–154
–10
–20
–30
–40
–50
–60
–70
–80
–90
–20
–40
–60
–80
–20
–40
–60
–80
0E+0
0
0E+0
0
0
0
Figure 15. Modulator Output (0 Hz to MCLK/2)
10E+3 20E+3 30E+3 40E+3 50E+3 60E+3
10E+3 20E+3 30E+3 40E+3 50E+3 60E+3
Figure 16. 16K Point FFT
Figure 17. 16K Point FFT
FREQUENCY – MHz
CLKIN = 12.5MHz
SNR = 90.1dB
S/(N+D) = 89.2dB
SFDR = –99.5dB
THD = –96.6dB
2ND = –100.9dB
3RD = –106.0dB
4TH = –99.5dB
XTAL = 12.288MHz
SNR = 89.0dB
S/(N+D) = 87.8dB
SFDR = –94.3dB
THD = –93.8dB
2ND = –94.3dB
3RD = –108.5dB
4TH = –105.7dB
70E+3 80E+3
70E+3
Figure 14. Integral Nonlinearity Error
80E+3
–0.2
–0.4
–0.6
–0.8
–1.0
1.0
0.8
0.6
0.4
0.2
0
0
90E+3
90E+3
6.25
98E+3
96E+3
20000
–9–
CODE
40000
–100
–110
–120
–130
–100
–120
–140
–154
–100
–120
–140
–154
–10
–20
–30
–40
–50
–60
–70
–80
–90
–20
–40
–60
–80
–20
–40
–60
–80
0E+0
0
0
0E+0
0
0
Figure 18. Modulator Output (0 to 393.295 kHz)
10E+3 20E+3 30E+3 40E+3 50E+3 60E+3
10E+3 20E+3 30E+3 40E+3 50E+3 60E+3
AIN = 90kHz
CLKIN = 12.5 MHz
SNR = 89.6dB
S/(N+D) = 89.6dB
SFDR = –108.0dB
AIN = 90kHz
XTAL = 12.288MHz
SNR = 88.1dB
S/(N+D) = 88.1dB
SFDR = –103.7dB
65535
Figure 19. 16K Point FFT
Figure 20. 16K Point FFT
FREQUENCY – kHz
70E+3 80E+3
70E+3
AD7720
80E+3
90E+3
90E+3
393.295 kHz
98E+3
96E+3