LT1366/LT1367
LT1368/LT1369
Typical applicaTions
10k
the 2 op amp loop to create a negative summing junction
1
at A1’s positive input . The circuit has low sensitivities for
+
V
center frequency and Q, which are set with the following
equations:
2
3
–
1
1/2 LT1366
V
OUT
2
V
IN
+
ω
0
= 1/(R1 • C1 • R2 • C2)
SIGNAL AMP
where:
R1 = 1/(ω • Q • C1) and R2 = Q/(ω • C2).
0
0
1M
5
TheDCbiasappliedtoA2andA4,halfsupply,isnotneeded
when split supplies are available. The circuit swings rail-
to-rail in the passband making it an excellent anti-aliasing
filter for ADCs. The amplitude response is flat to 1kHz then
rolls off at 80dB/decade.
+
7
CANCELLATION AMP
1/2 LT1366
6
–
22pF
1366 F10
1
James Hahn, “State Variable Filter Trims Predecessor’s Component Count,” Electronics, April
21, 1982.
1M
Figure 10. Input Bias Current Cancellation
180
144
108
0
–20
–40
–60
–80
GAIN
V
CC
PHASE
72
36
0
R
P
+
10k
–36
–72
–108
1/2 LT1366
–
R
L
–144
–180
10k
100
1k
1366 F11
FREQUENCY (Hz)
1366 F09
Figure 9. Frequency Response of 4th Order Butterworth Filter
Figure 11. Rail-to-Rail Potentiometer Buffer
1366fb
ꢀꢅ
Linear [ Linear ]
