AD6622AS Analog Devices Inc, AD6622AS Datasheet - Page 14

• Manufacturer Part Number: AD6622AS
• Manufacturer: Analog Devices Inc

Specifications of AD6622AS

• Lead Free Status / RoHS Status: Not Compliant

AD6622
Table II lists maximum bandwidth that will be rejected to various
levels for CIC5 interpolation factors from 1 to 32. Figure 15
corresponds to the listing in the –110 dB column and the L
= 5 row. It is worth noting that the rejection of the CIC5 improves
as the interpolation factor increases.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
CIC2
The CIC2 is a second-order interpolating cascaded integrator
comb whose impulse response is completely defined by its inter-
polation factor, L
programmed for each channel at location 0x08. While this con-
trol register is 8 bits wide, L
shown by the table below according to the interpolation factor
of the CIC5. Exceeding the recommended guidelines may result in
overflow for input sequences at or near full scale. While relatively
small values of L
factors with minimal power consumption, L
mized to achieve the best overall image rejection.
–110 dB
Full
0.101
0.126
0.136
0.141
0.143
0.144
0.145
0.146
0.146
0.147
0.147
0.147
0.147
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
0.148
Table II. CIC5 Alias Protection
CIC5
CIC2
–100 dB
Full
0.127
0.159
0.170
0.175
0.178
0.179
0.180
0.181
0.182
0.182
0.182
0.183
0.183
0.183
0.183
0.183
0.183
0.183
0.184
0.184
0.184
0.184
0.184
0.184
0.184
0.184
0.184
0.184
0.184
0.184
0.184
. The value L
allow for the larger overall interpolation
CIC2
–90 dB
Full
0.160
0.198
0.211
0.217
0.220
0.222
0.224
0.224
0.225
0.226
0.226
0.226
0.226
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.227
0.228
should be confined to the ranges
CIC2
–1 can be independently
–80 dB
Full
0.203
0.246
0.262
0.269
0.272
0.275
0.276
0.277
0.278
0.278
0.279
0.279
0.279
0.280
0.280
0.280
0.280
0.280
0.280
0.280
0.280
0.280
0.280
0.281
0.281
0.281
0.281
0.281
0.281
0.281
0.281
CIC5
should be maxi-
–70 dB
Full
0.256
0.307
0.325
0.333
0.337
0.340
0.341
0.342
0.343
0.344
0.344
0.345
0.345
0.345
0.345
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
0.346
CIC5
The transfer function of the CIC2 is given by the following
equations with respect to the CIC2 output sample rate, f
This polynomial fraction can be completely reduced as follows,
demonstrating a finite impulse response with perfect phase lin-
earity for all values of L
The frequency response of the CIC2 can be expressed as follows.
The maximum gain is L
factor normalizes for the increased rate, which is appropriate
when the samples are destined for a DAC with a zero order hold
output.
As an example, we will consider an input from the CIC5 whose
bandwidth is 0.0033 of the CIC5 rate, centered at baseband.
Interpolation by a factor of five reveals five images, as shown
below.
CIC z
CIC z
CIC f
2
2
2
( )
( )
( )
=
=
=
Table III. Maximum L
L
1–19
20
21
22
23
24
25
26
27
28
29
30
31
32




 

CIC5
L
1
L
k
CIC
CIC
∑
1
1
–
=
2 1
–
0
–
2
z
z






–
z
CIC2
L
sin
−
–
CIC2
CIC
1
k

  =

sin
2
.



2



2
π
at baseband. The initial 1/L



L
π
L
CIC
k
∑
CIC
f
f
=
OUT
OUT
2 1
2
1
f
–
Max L
256
209
172
143
119
101
85
73
63
54
47
41
36
32
×







z
CIC2
f
−



1






−
2
Limits
CIC2
e
j
2
π
L
CIC
k
2




2
CIC2
OUT
(14)
(15)
(16)
.