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Delay Equalized Lowpass

Anti-Aliasing Reconstruction
Custom Built LC Filters - 1 KHz to 500 MHz

page LC_F/DELP
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The Allen Avionics DELAY EQUALIZED LOWPASS FILTERS tabulated on this page are the result of many years of experience in the use of specialized computer programs for the design and optimization of Delay Equalized Filters. By using modern digital computers, the composite behavior of the filter and equalizer are optimized to yield the ultimate in both amplitude, delay and phase response.

This type of filter is ideally suited for use as an Anti-Aliasing Filter in analog to digital conversion. When used as a Post-Aliasing Filter in digital processing applications, the passband can be shaped to correct for sin x/x amplitude distortion.

The filters tabulated below represent a widely used group. However, many other combinations of stopband ratio, impedance, delay distortion and size are possible. Two stopband ratios are listed in the table below, 1.375 @ 45dB and 1.575 @ 60dB.

Units normally supplied in metal cans for printed circuit mounting. SMA connectors same size. BNC connectors may require larger cans.

Amplitude, phase and/or delay matching between filters is also available.

CALL FACTORY FOR SPECIAL SIZES AND DELIVERY INFORMATION.

ORDER ANY CUT-OFF FREQUENCY FROM 1KHz TO 20MHz. INTERPOLATION BETWEEN TABULATED DATA ALLOWABLE.

Click here for mechanical specs


Normalized Plot of Amplitude & Delay Response of Delay Equalized Lowpass Filter

A = -.25dB Frequency
B = -3dB Frequency
C = -45dB Frequency or -60dB

Stopband Ratio #1 = 1.375 @ 45dB
Delay (D) =
18.63
Stopband Radio
#2 = 1.575 @ 60dB
Delay (D)
= 17.83

APPROXIMATE PASSBAND DELAY (seconds)=
Delay (D)
2 x
π x Frequency A(Hz)

Delay Equalized Lowpass Anti-Aliasing Reconstruction Filters

± .25dB MAXIMUM RIPPLE—2dB MAXIMUM INSERTION LOSS
MAXIMUM DELAY VARIATION 3% TO - .25dB FREQUENCY

Maximum - 25dB
Cut-Off Frequency
(Last point that delay flatness Is specified)


(Graph location A)

Maximum 3dB Attenuation Frequency

 (Graph location B)

B = 1.1 x A
Attenuation Frequency Graph Location C Impedance Range (Ohms) Approximate Passband Delay Micro-Seconds Standard Size (Inches) "Space-Saving" Size (Inches)
45dB
Ratio #1
C = 1.375 x A
60dB
Ratio #2
C = 1.575 x A
Ratio
#1
Ratio
#2
1 .0 KHz 1.10 KHz 1 .38 KHz 1.58 KHz 500-2.5K 2965 2837 6 x 2 x 1-1/4 -
2.5 KHz 2.75 KHz 3.44 KHz 3.94 KHz 500-2.5K 1186 1135  6 x 2 x 1-1/4 -
5.0 KHz 5.50 KHz 6.88 KHz 7.88 KHz 500-2.5K 593 567 6 x 2 x 1-1/4 -
10.0 KHz 11 .00 KHz 13.75 KHz 15.75 KHz 500-2.5K 297 284 6 x 2 x 1-1/4 5 x 2 x 1-1/4
25.0 KHz 27.50 KHz 34.37 KHz 39.38 KHz 100-1.0K 119 114 5 x 2 x 1-1/4 4 x 2 x 1-1/4
50.0 KHz 55.00 KHz 68.75 KHz 78.80 KHz 50-600 59 57  5 x 2 x 1-1/4 4 x 2 x 1-1/4
100.0 KHz 110.00 KHz 137.50 KHz 157.50 KHz 50-200 30 28 5 x 2 x 1-1/4 4 x 2 x 1-1/4
250.0 KHz 275.00 KHz 343.75 KHz 393.75 KHz 50-100 12 11 4 x 2 x 1-1/4 4 x 2 x 3/4
500.0 KHz 550.00 KHz 687.50 KHz 787.50 KHz 50-100 5.94 5.67 4 x 2 x 1-1/4 4 x 2 x 3/4
1.0 MHz 1.10 MHz 1.38MHz 1.58MHz 50-75 2.97 2.84 4 x 2 x 1-1/4 4 x 2 x 3/4
2.5 MHz 2.75 MHz 3.44 MHz 3.94 MHz 50-75 1.19 1.14 4 x 2 x 1-1/4 3 x 1-5/8 x 1-1/8
5.0 MHz 5.50 MHz 6.88 MHz 7.88 MHz 50-75 0.590 0.567 4 x 1-1/2 x 1-1/4 3 x 1-5/8 x 1-1/8
7.5 MHz 8.25 MHz 10.31 MHz 1 1 .82 MHz 50-75 0.395 0.378 4 x 1-1/2 x 1-1/4 3 x 1-5/8 x 1-1/8
10.0 MHz 11.00 MHz 13.75 MHz 15.75 MHz 50-75 0.296 0.284 4 x 1-1/2 x 1-1/4 3 x 1-5/8 x 1-1/8
12.5 MHz 13.75 MHz 17.18 MHz 19.69 MHz 50-75 0.237 0.226 4 x 1-1/2 x 1-1/4 3 x 1-5/8 x 1-1/8
15.0 MHz 16.50 MHz 20.63 MHz 23.63 MHz 50-75 0.197 0.188 4 x 1-1/2 x 1-1/4 3 x 1-1/4 x 3/4
17.5 MHz 19.25 MHz 24.06 MHz 27.57 MHz 50-75 0.169 0.162 4 x 1-1/2 x 1-1/4 3 x 1-1/4 x 3/4
20.0 MHz 22.00 MHz 27.50 MHz 31.50 MHz 50 0.148 0.141 4 x 1-1/2 x 1-1/4 3 x 1-1/4 x 3/4
25.0 MHz 27.50MHz 34.38MHz 39.38MHz 50 0.118 0.113 4 X 1.5 X 1.25 3 x 1-1/4 x 3/4
30.0 MHz 33.00 41.25MHz 47.25MHz 50 0.099 0.095 4 x 1.5 x 1.25 3 x 1-1/4 x 3/4
35.0 MHz 38.5 48.12MHz 55.12MHz 50 0.840 0.081 4 x 1.5 x 1.25 3 x 1-1/4 x 3/4
40.0 MHz 44.0 55.00MHz 63.00MHz 50 0.740 0.071 4 x 1.5 x 1.25 3 x 1-1/4 x 3/4
45.0 MHz 49.50 61.88MHz 70.87MHz 50 0.066 0.063 4 x 1.5 x 1.25 3 x 1-1/4 x 3/4
50.0 MHz 55.00 68.75MHz 78.75MHz 50 0.059 0.056 4 x 1.5 x 1.25 3 x 1-1/4 x 3/4
60.0 MHz 66.00 82.50MHz 94.50MHz 50 0.049 0.047 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
70.0 MHz 77.00 96.25MHz 110.3MHz 50 0.042 0.040 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
80.0 MHz 88.00. 110.0MHz 126.0MHz 50 0.037 0.035 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
90.0 MHz 99.00 123.8MHz 141.8MHz 50 0.033 0.031 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
100.0 MHz 110.00 137.MHz 157.5MHz 50 0.029 0.028 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
* 150.0 MHz 165.00 206.3MHz 236.2MHz 50 0.019 0.019 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
* 200.0 MHz 220.00 275.0MHz 315.0MHz 50 0.014 0.014 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
* 250.0 MHz 275.00 343.8MHz 393.8MHz 50 0.011 0.011 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
* 300.0 MHz 330.00 412.5MHz 472.5MHz 50 0.009 0.009 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
* 400.0 MHz 440.00 550.0MHz 630.0MHz 50 0.007 0.007 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
* 500.0 MHz 550.00 687.5MHz 787.5MHz 50 0.005 0.005 4 x 1.5 x 1.25 3 x 1-1/4 x 1/2
*At frequencies above 100MHz, the maximum attenuation at location A becomes .5dB and the delay variation up to location A becomes ± 5%.

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