Datasheet

®
OPA211111
FIGURE 11. 10Hz Fourth-Order Butterworth Low-Pass Filter.
Out
6.3MΩ
1.6MΩ
7.8MΩ
7
0.01µF
NPO
1/2 OPA2111
6
5
0.01µF
NPO
NOTE: Lower value resistors will have lower
thermal noise but capacitors must
be scaled larger.
A
V
= 2.6
f
O
= 10Hz
–24dB/Octave
6.3MΩ
1.6MΩ
944kΩ
1
0.01µF
NPO
1/2 OPA2111
2
3
0.01µF
NPO
1.6MΩ
1.6MΩ
In
FIGURE 9. FET Input Instrumentation Amplifier.
I
B
= ±4pA max
Gain = 100
CMRR ≈ 106dB
R
IN
≈ 10
13
Ω
Differential Voltage Gain = 1 + 2R
F
/R
G
6
5
7
+In
R
G

101Ω
3
2
1
–In
R
F

5kΩ
R
F

5kΩ
2
3
Output
25kΩ
25kΩ
25kΩ
25kΩ
Burr-Brown
INA105
Differential
Amplifier
1
6
5
1/2 OPA2111BM
1/2 OPA2111BM
FIGURE 10. Low-Droop Positive Peak Detector.
6
5
7
Droop ≈ 0.5mV/s
≈10pF
Output
NOTE: (1) Reverse polarity for 
negative peak detection.
0.01µF
Polystyrene
(1)
(1)
2
3
1
(1)
Input
10kΩ
IN914
IN914
1MΩ
2N4117A
1/2 
OPA2111AM
1/2 
OPA2111AM