900CT Datasheet, PDF (12/19 Pages) Frequency Devices, Inc. – Tunable Active Filter Instrument

Low-Pass
Appendix A
8-Pole
Butterworth
Theoretical Transfer Characteristics
f/fc
Amp Phase Delay1
(Hz) (dB) (deg) (sec)
0.00 0.00
0.00 .816
0.10 0.00 -29.4 .819
0.20 0.00 -59.0 .828
0.30 0.00 -89.1 .843
0.40
0.00
-120
.867
0.50
0.00
-152
.903
0.60 -0.001 -185
.956
0.70 -0.014 -221
1.04
0.80 -0.121 -261
1.19
0.85 -0.311 -283
1.29
0.90 -0.738 -307
1.40
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 -1.58 -333
1.48
1.00 -3.01 -360
1.46
1.10 -7.48 -408
1.17
1.20 -12.9 -445
.873
1.30 -18.2 -472
.672
Delay (Normalized)
2.0
1.40 -23.4 -494
.540
1.50 -28.2 -511
.448
1.60 -32.7 -526
.380
1.70 -36.9 -539
.328
1.80 -40.8 -550
.287
1.0
1.90 -44.6 -560
.253
2.00 -48.2 -568
.226
2.25 -56.3 -586
.174
2.50 -63.7 -600
.139
2.75 -70.3 -611
.113
3.00 -76.3 -621
.094
3.25 -81.9 -629
.080
3.50 -87.1 -635
.069
4.00 -96.3 -646
.052
5.00 -112
-661
.033
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
6.00 -125
-671
.023
1.2
7.00 -135
-678
.017
8.00 -144
-683
.013
1.0
9.00 -153
-687
.010
10.0 -160
-691
.008
0.8
0.6
0.4
0.2
1.Normalized Group Delay:
-0.0
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
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