900CT Datasheet, PDF (11/19 Pages) Frequency Devices, Inc. – Tunable Active Filter Instrument

8-Pole
Appendix A
Bessel
Low-Pass
Theoretical Transfer Characteristics
f/fc
Amp Phase Delay1
(Hz) (dB) (deg) (sec)
0.00 0.00
0.00 .506
0.10 -0.029 -18.2 .506
0.20 -0.117 -36.4 .506
0.30 -0.264 -54.7 .506
0.40 -0.470 -72.9 .506
0.50 -0.737 -91.1 .506
0.60 -1.06 -109
.506
0.70 -1.45 -128
.506
0.80 -1.91 -146
.506
0.85 -2.16 -155
.506
0.90 -2.42 -164
.506
Frequency Response
0
-20
-40
-60
-80
-100
0.1
2 3 4 5 6 78_1.0 2 3 4 5 6 7 _10.0
Normalized Frequency(f/fc)
0.95 -2.71 -173
.506
1.00 -3.01 -182
.506
1.10 -3.67 -200
.506
1.20 -4.40 -219
.506
1.30 -5.20 -237
.506
Delay (Normalized)
1.0
1.40 -6.10 -255
.505
1.50 -7.08 -273
.504
1.60 -8.16 -291
.502
1.70 -9.36 -309
.498
1.80 -10.7 -327
.492
0.5
1.90 -12.1 -345
.482
2.00 -13.7 -362
.468
2.25 -18.1 -402
.417
2.50 -23.1 -436
.352
2.75 -28.3 -465
.291
3.00 -33.4 -489
.241
3.25 -38.3 -509
.201
3.50 -43.1 -526
.170
4.00 -51.8 -552
.126
5.00 -66.8 -587
.077
6.00 -79.2 -610
.052
7.00 -89.8 -626
.038
8.00 -99.0 -638
.029
9.00 -107
-647
.023
10.0 -114
-655
.018
0.0
0.1 ^{0.15 2 3 4 5 6 7 8 9}1.0 ^1.5
Normalized Time (1/f sec)
Step Response
1.2
1.0
0.8
0.6
0.4
0.2
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).
Normalized Delay
Actual Delay =
Actual Corner Frequency (fc) in Hz
-0.0
-0.2
0
1
2
3
4
5
Normalized Time (1/f sec)
4
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