LT1568
15
1568f
Table 5. Resistor Values in Ohms, 4th Order Lowpass
Chebyshev, ±0.25dB Passband Ripple, Gain = 1
f
CUTOFF
(MHz) R11, R21 R31 R12, R22 R32
1 1.87k 2.05k 2.21k 634Ω
2 931Ω 1.05k 1.10k 324Ω
3 604Ω 681Ω 698Ω 205Ω
4 453Ω 511Ω 499Ω 154Ω
5 357Ω 402Ω 383Ω 121Ω
6 287Ω 332Ω 309Ω 100Ω
7 243Ω 287Ω 255Ω 86.6Ω
8 205Ω 249Ω 215Ω 76.8Ω
9 178Ω 221Ω 182Ω 66.5Ω
10 154Ω 196Ω 158Ω 61.9Ω
Amplitude Response 4th Order Lowpass Chebyshev,
±0.25dB Passband Ripple, f
CUTOFF
= 1MHz
FREQUENCY (MHz)
0.1
–60
GAIN (dB)
–48
–36
–24
–12
11020
1568 TA13
–72
–84
–96
–108
0
12
4th ORDER LOWPASS FILTER DESIG S
U
Transient Response 4th Order Lowpass Chebyshev,
±0.25dB Passband Ripple, f
CUTOFF
= 1MHz
INPUT
500mV/DIV
OUTPUT
200mV/DIV
1µs/DIV
1568 TA16
Table 6. Resistor Values in Ohms, 4th Order Lowpass Bessel,
Gain = 1
f
CUTOFF
(MHz) R11, R21 R31 R12, R22 R32
1 715Ω 1.15k 1.91k 324Ω
2 357Ω 562Ω 432Ω 365Ω
3 237Ω 374Ω 280Ω 243Ω
4 174Ω 280Ω 205Ω 187Ω
5 137Ω 221Ω 162Ω 147Ω
6 115Ω 187Ω 130Ω 124Ω
Amplitude Response
4th Order Lowpass Bessel, f
CUTOFF
= 1MHz
FREQUENCY (MHz)
0.1
–60
GAIN (dB)
–48
–36
–24
–12
11020
1568 TA17
–72
–84
–96
–108
0
12
Transient Response
4th Order Lowpass Bessel, f
CUTOFF
= 1MHz
INPUT
500mV/DIV
OUTPUT
200mV/DIV
1µs/DIV
1568 TA18
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
