AD7608BSTZ Datasheet, PDF (27/32 Pages) Analog Devices – 8-Channel DAS with 18-Bit, Bipolar, Simultaneous Sampling ADC

Data Sheet
Figure 46 to Figure 52 illustrates the effect of oversampling on
the code spread in a dc histogram plot. As the oversample rate
is increased, the spread of codes is reduced. (In Figure 46 to
Figure 52, AVCC = VDRIVE = 5 V and the sampling rate was scaled
with OS ratio.)
1600
1400
NO OVERSAMPLING
1200
1377
1170 1208
1000
800
1001
852
708
600
588
411
400
328
200
188
146
82
3 3 ³⁵
0
66
21 ₅ 0
–9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9
CODE
Figure 46. Histogram of Codes—No OS (18 Codes)
2000
1800
OVERSAMPLING BY 2
1759
1600
1400
1524
1397
1200
1000
800
1065
902
600
538
498
400
208
200
0 ^{0 1 15 54}
165
57
9
–8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6
CODE
Figure 47. Histogram Of Codes—OS × 2 (14 Codes)
2500
OVERSAMPLING BY 4
2224
2000
1913
1500
1551
1000
1072
684
500
427
199
0 ^{4 40}
64 ₁₄
–5 –4 –3 –2 –1 0 1 2 3 4 5
CODE
Figure 48. Histogram of Codes—OS × 4 (11 Codes)
AD7608
3500
3000
OVERSAMPLING BY 8
3027
2500
2000
1500
2176
1756
1000
648
457
500
4
0
–4
78
–3 –2
–1
0
1
CODE
44
2
2
3
4
Figure 49. Histogram of Codes—OS × 8 (9 Codes)
4500
4000
3947
OVERSAMPLING BY 16
3500
3000
2500
2703
2000
1500
1000
1081
500
69
0
–2
–1
385
7
0
1
2
3
CODE
Figure 50. Histogram of Codes—OS × 16 (6 Codes)
6000
OVERSAMPLING BY 32
5403
5000
4000
3000
2000
1000
1301
1460
11
17
0
–2
–1
0
1
2
CODE
Figure 51. Histogram of Codes—OS × 32 (5 Codes)
Rev. A | Page 27 of 32