AD6652BC/PCB Analog Devices Inc, AD6652BC/PCB Datasheet - Page 37

• Manufacturer Part Number: AD6652BC/PCB
• Description: BOARD EVAL W/AD6652 & SOFTWARE
• Manufacturer: Analog Devices Inc

Specifications of AD6652BC/PCB

• Module/board Type: Evaluation Board
• For Use With/related Products: AD6652
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

FIFTH-ORDER CIC FILTER
The fourth signal processing stage, CIC5, implements a sharp
fixed-coefficient, decimating filter than rCIC2. The input rate to
this filter is f
following equation. N
input mode; otherwise, N
increase M
The decimation ratio, M
(all integer values). The frequency response of the filter is given
by the following equations. Use these equations to calculate the
gain and pass-band droop of CIC5. Both parameters can be
compensated for in the RCF stage.
The scale factor, S
between 0 and 20. It serves to control the attenuation of the data
into the CIC5 stage in 6 dB increments. For the best dynamic
range, set S
overflow condition. This can be safely accomplished using the
following equation, where OL
scale possible at the input to this filter stage. This value is output
from the rCIC2 stage, then pipelined into the CIC5.
The output rate of this stage is given by the following equation:
CIC5 REJECTION
Table 15 lists the amount of bandwidth in percentage of the
input rate that can be protected with various decimation rates
and alias rejection specifications. The maximum input rate into
the CIC5 is 65 MHz when the rCIC2 decimates by 1. As in the
previous rCIC2 table (Table 14), these are the single-sideband
bandwidth characteristics of the CIC5.
OL
H
H
S
f
f
CIC
SAMP
SAMP
(
(
z
CIC
f
5
)
)
=
=
rCIC2
CIC5
5
=
2
5
SAMP2
ceil
=
2
2
≤
=
S
S
to the least attenua
(
CIC
or reduce N
CIC
2
M
N
1
f
f
(
M
1
. The maximum input rate is given by the
S
CLK
log
5
SAMP
CIC
CIC5
CH
CIC
+
5
CIC
5
+
5
5
2
5
+
, is a programmable unsigned integer
×
CH
5
5
(
5
2
×
M
)
⎛
⎜ ⎜
⎝
equals two for diversity channel real
CIC5
×
1
⎛
⎜
⎜
⎜
⎜
⎜
⎝
CIC
CH
−
sin
OL
1
CH
, can be programmed from 2 to 32
equals one. To satisfy this equat
5
z
sin
−
5
.
−
⎛
⎜
⎜
⎝
rCIC2
rCIC
z
M
π
×
⎛
⎜
⎜
⎝
−
CIC
1
π
M
OL
2
tion without creating an
is the largest fraction of full
5
f
f
CIC
⎞
⎟ ⎟
⎠
SAMP
SAMP
rCIC
5
f
5
2
×
)
2
2
)
⎞
⎟
⎟
⎠
−
f
5
⎞
⎟
⎟
⎠
⎞
⎟
⎟
⎟
⎟
⎟
⎠
5
ion,
Rev. 0 | Page 37 of 76
er
The CIC5 stage can protect a much wider band to any given
rejection than rCIC2.
Given the desired filter characteristics, Table 15 can help in t
calculation o
Table 15. SSB CIC5 Alias Rejection Table (f
M
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
CIC5
–110
–130
–150
+10
–10
–30
–50
–70
–90
Figure 48. Double Side-Band Graph Showing CIC5 Filter Response
−50 dB
10.277
7.924
6.213
5.068
4.267
3.68
3.233
2.881
2.598
2.365
2.17
2.005
1.863
1.74
1.632
1.536
1.451
1.
1.307
1.245
1.188
1.137
1.09
1.046
1.006
0.969
0.934
0.902
0.872
0.844
0.818
375
–2
f an upper bound on decimation, M
−60 dB
8.078
6.367
5.022
4.107
3.463
2.989
2.627
2.342
2.113
1.924
1.765
1.631
1.516
1.416
1.328
1.25
1.181
1.119
1.064
1.013
0.967
0.925
0.887
0.852
0.819
0.789
0.761
0.734
0.71
0.687
0.666
and Alias Rejection of −100 dB
MULTIPLES OF CIC5 OUTPUT RATE
–1
−70 dB
6.393
5.11
4.057
3.326
2.808
2.425
2.133
1.902
1.716
1.563
1.435
1.326
1.232
1.151
1.079
1.016
0.96
0.91
0.865
0.824
0.786
0.752
0.721
0.692
0.666
0.641
0.618
0.597
0.577
0.559
0.541
0
−80 dB
5.066
4.107
3.271
2.687
2.27
1.962
1.726
1.54
1.39
1.266
1.162
1.074
0.998
0.932
0.874
0.823
0.778
0.737
0.701
0.667
0.637
0.61
0.584
0.561
0. 4
0.52
0.501
0.484
0.468
0.453
0.439
5
1
−90 dB
4.008
3.297
2.636
2.17
1.836
1.588
1.397
1.247
1.125
1.025
0.941
0.87
0.809
0.755
0.708
0.667
0.63
0.597
0.568
0.541
0.516
0.494
0.474
0.455
0.437
0.421
0.406
0.392
0.379
0.367
0.355
SAMP2
CIC5
= 1)
.
AD6652
2
−100 dB
3.183
2.642
2.121
1.748
1.48
1.281
1.128
1.007
0.909
0.828
0.76
0.703
0.653
0.61
0.572
0.539
0.509
0.
0.459
0.437
0.417
0.399
0.383
0.367
0.35
0.34
0.328
0.317
0.306
0.297
0.287
483
3
he