Datasheet

TLV2401, TLV2402, TLV2404
FAMILY OF 880-nA/Ch RAIL-TO-RAIL INPUT/OUTPUT
OPERATIONAL AMPLIFIERS WITH REVERSE BATTERY PROTECTION
SLOS244B – FEBRUARY 2000 – REVISED NOVEMBER 2000
14
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
general configurations
When receiving low-level signals, limiting the bandwidth of the incoming signals into the system is often
required. The simplest way to accomplish this is to place an RC filter at the noninverting terminal of the amplifier
(see Figure 38).
V
I
V
O
C1
+
–
R
G
R
F
R1
f
–3dB
1
2 R1C1
V
O
V
I
1
R
F
R
G
1
1 sR1C1
Figure 38. Single-Pole Low-Pass Filter
If even more attenuation is needed, a multiple pole filter is required. The Sallen-Key filter can be used for this
task. For best results, the amplifier should have a bandwidth that is 8 to 10 times the filter frequency bandwidth.
Failure to do this can result in phase shift of the amplifier.
V
I
C2
R2R1
C1
R
F
R
G
R1 = R2 = R
C1 = C2 = C
Q = Peaking Factor
(Butterworth Q = 0.707)
(
=
1
Q
2 –
)
R
G
R
F
_
+
f
–3dB
1
2 RC
Figure 39. 2-Pole Low-Pass Sallen-Key Filter