AD775
54
48
42
36
–36
–30
S / (N + D) - 分贝
30
24
18
12
6
0
0.1
THD - 分贝
–42
–48
1
f
IN
- 兆赫
10
–54
0.1
1
f
IN
- 兆赫
10
图2. S / (N + D) - 输入频率为20 MSPS时钟
速率(V
IN
= -0.3 dB为单位)
图5. THD与输入频率为20 MSPS时钟速率
(V
IN
= -0.3 dB为单位)
0
–10
–20
–30
–40
dB
0
–10
–20
–30
–40
dB
0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
–50
–60
–70
–80
–90
–100
频率 - 兆赫
–50
–60
–70
–80
–90
–100
0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
频率 - 兆赫
图3.典型FFT在1 MHz输入, 20 MSPS时钟速率
(V
IN
= -0.5 dB为单位)
图6.典型FFT在5 MHz输入, 20 MSPS时钟速率
(V
IN
= -0.5 dB为单位)
+0.4
+0.3
+0.2
+0.1
0
–0.1
–0.2
–0.3
–0.4
-FULLSCALE
INL - LSB
+1
DNL - LSB
0
+满量程
–1
-FULLSCALE
+满量程
图4.典型微分非线性( DNL )
图7.典型的积分非线性( INL )
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