LS404 STMicroelectronics, LS404 Datasheet - Page 7

• Manufacturer Part Number: LS404
• Description: Low-noise bipolar op-amps
• Manufacturer: STMicroelectronics

Fixed R = R1 = R2, we have (see figure 13)
Figure 13 : Filter Configuration
Three parameters are needed to characterize the
frequency and phase response of a 2nd order ac-
tive filter: the gain (Gv), the damping factio ( ) or
the Q factor (Q = 2 )
(fc).
Table 1
EXAMPLE
Figure 14 : 5th Order Low-pass Filter (Butterworth) with Unity Gain configuration
C 1 =
Bessel
Butterworth
Chebyschev
--- -
R
1
------ -
c
Filter Response
Vin
1
), and the cuttoff frequency
R1
R2
------ -
------ -
------ -
2
2
2
3
2
2
C1
The higher order response are obtained with a se-
ries of 2nd order sections. A simple RC section is
introduced when an odd filter is required.
The choice of ’ ' (or Q factor) determines the filter
response (see table 1).
------ -
------ -
------ -
C 2 =
Q
3
2
2
C2
1
1
1
--- -
R
1
Frequency at which Phase Shift is -90°C
Frequency at which Gv = -3dB
Frequency at which the amplitude response
passes through specified max. ripple band and
enters the stop bank.
---------- -
1
c
Cuttoff Frequency fc
Vout
LS404
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