Low-Pass
4-Pole
Bessel
Appendix A
Theoretical Transfer Characteristics
1
Frequency Response
0
-20
-40
-60
-80
-100
f/fc
Amp
(dB)
Phase
(deg)
Delay
(sec)
(Hz)
0.00
0.10
0.20
0.30
0.40
0.50
0.00
0.00
-12.1
-24.2
-36.3
-48.4
-60.6
.336
.336
.336
.336
.336
.336
-0.028
-0.111
-0.251
-0.448
-0.705
0.60
0.70
0.80
0.85
0.90
-1.02
-1.41
-1.86
-2.11
-2.40
-72.7
-84.8
-96.8
-103
-109
.336
.336
.335
.334
.333
2
2
3 4 5 6 7
0.1
3 4 5 6 78 1.0
10.0
Normalized Frequency(f/fc)
0.95
1.00
1.10
1.20
1.30
-2.69
-3.01
-3.71
-4.51
-5.39
-115
-121
-133
-144
-156
.332
.330
.325
.318
.308
Delay (Normalized)
1.0
0.5
0.0
-166
-177
-187
-195
-204
1.40
1.50
1.60
1.70
1.80
-6.37
-7.42
-8.54
-9.71
-10.9
.295
.280
.263
.246
.228
1.90
2.00
2.25
2.50
2.75
-12.2
-13.4
-16.5
-19.5
-22.4
-212
-219
-235
-248
-259
.211
.194
.158
.129
.107
2
3
4
0.1
5 6 7 8 91.0
0.15
1.5
-267
-275
-281
-291
-305
3.00
3.25
3.50
4.00
5.00
-25.1
-27.6
-30.0
-34.4
-41.9
.089
.076
.065
.049
.031
Normalized Time (1/f sec)
Step Response
1.2
1.0
0.8
0.6
0.4
0.2
-0.0
-0.2
6.00
7.00
8.00
9.00
10.0
-48.1
-53.4
-58.0
-62.0
-65.7
-315
-321
-326
-330
-333
.021
.016
.012
.009
.008
1.Normalized Group Delay:
The above delay data is normalized to a corner frequency
of 1.0Hz.The actual delay is the normalized delay divided
by the actual corner frequency (fc).
0
1
2
3
4
5
Normalized Time (1/f sec)
Normalized Delay
Actual Delay =
Actual Corner Frequency (fc) in Hz
2
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