TLC072A Datasheet, PDF (20/51 Pages) Texas Instruments – FAMILY OF WIDE BAND WIDTH HIGH OUTPUT DRIVE SINGLE SUPPLY OPERATIONAL AMPLIFIERS

TLC070, TLC071, TLC072, TLC073, TLC074, TLC075, TLC07xA
FAMILY OF WIDEĆBANDWIDTH HIGHĆOUTPUTĆDRIVE SINGLE SUPPLY
OPERATIONAL AMPLIFIERS
SLOS219D − JUNE 1999 − REVISED FEBRUARY 2004
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 50).
RG
RF
VI
R1
−
+
VO
C1
f–3dB
+
1
2pR1C1
ǒ Ǔǒ Ǔ ^VO
VI
+
1
)
RF
RG
1
1 ) sR1C1
Figure 50. 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.
C1
VI
R1
+
R2
_
C2
RF
RG
R1 = R2 = R
C1 = C2 = C
Q = Peaking Factor
(Butterworth Q = 0.707)
f–3dB
+
1
2pRC
( ) ^{RG =}
RF
1
2− _Q
Figure 51. 2-Pole Low-Pass Sallen-Key Filter
20
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