LM149 National Semiconductor, LM149 Datasheet - Page 11

• Manufacturer Part Number: LM149
• Description: Quad 741 Op Amps LM149 Wide Band Decompensated (AV MIN = 5)
• Manufacturer: National Semiconductor

Typical Applications — LM148
(Continued)
A 4th Order 1 kHz Elliptic Filter (4 Poles, 4 Zeros)
DS007786-14
R1C1 = R2C2 = t
R'1C'1 = R'2C'2 = t'
= 1 kHz, f
= 2 kHz, f
= 0.543, f
= 2.14, Q = 0.841, f'
= 0.987, f'
= 4.92, Q' = 4.403, normalized to ripple BW
f
C
S
p
Z
P
Z
Use the BP outputs to tune Q, Q', tune the 2 sections separately
R1 = R2 = 92.6k, R3 = R4 = R5 = 100k, R6 = 10k, R0 = 107.8k, R
= 100k, R
= 155.1k,
L
H
R'1 = R'2 = 50.9k, R'4 = R'5 = 100k, R'6 = 10k, R'0 = 5.78k, R'
= 100k, R'
= 248.12k, R'f = 100k. All capacitors are 0.001 µF.
L
H
Lowpass Response
DS007786-15
11
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