Datasheet

AD6645
Rev. D | Page 12 of 24
FREQUENCY (MHz)
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
5
3
2
6
4
AMPLITUDE (dBFS)
ENCODE = 80.0MSPS
AIN = 30.5MHz @ –29.5dBFS
NO DITHER
50 10152025303540
02647-028
Figure 22. 1 M Sample FFT Without Dither
ANALOG INPUT LEVEL (dBFS)
0
10
20
30
40
50
60
70
80
90
100
110
WORST-CASE SPURIOUS (dBc)
90 80 70 60 50 40 30 20 10 0
SFDR = 90dB
REFERENCE LINE
ENCODE = 80.0MSPS
AIN = 30.5MHz
NO DITHER
02647-029
Figure 23. SFDR Without Dither
FREQUENCY (MHz)
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
AMPLITUDE (dBFS)
2
6
5
4
3
ENCODE = 76.8MSPS
AIN = 69.1MHz @ –1dBFS
SNR = 73.5dB
SFDR = 89.0dBc
50 10152025303540
02647-030
Figure 24. Single Tone @ 69.1 MHz, Encode = 76.8 MSPS
FREQUENCY (MHz)
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
5
3
2
6
4
AMPLITUDE (dBFS)
50 10152025303540
ENCODE = 80.0MSPS
AIN = 30.5MHz @ –29.5dBFS
WITH DITHER @ –19.2 dBm
02647-031
Figure 25. 1 M Sample FFT with Dither
ANALOG INPUT LEVEL (dBFS)
0
10
20
30
40
50
60
70
80
90
100
110
WORST-CASE SPURIOUS (dBc)
–90 –80 –70 –60 –50 –40 –30 –20 –10 0
SFDR = 90dB
REFERENCE LINE
SFDR = 100dB
REFERENCE LINE
ENCODE = 80.0MSPS
AIN = 30.5MHz
WITH DITHER @ –19.2dBm
02647-032
Figure 26. SFDR with Dither
FREQUENCY (MHz)
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
AMPLITUDE (dBFS)
2 6 543
ENCODE = 76.8MSPS
AIN = W-CDMA @ 69.1MHz
0 5 10 15 20 25 30 35 40
02647-033
Figure 27. W-CDMA Tone @ 69.1 MHz, Encode = 76.8 MSPS