Datasheet

OP177 Data Sheet
Rev. H | Page 12 of 16
PRECISION POSITIVE PEAK DETECTOR
In Figure 32, C
H
must be polystyrene, Teflon®, or polyethylene
to minimize dielectric absorption and leakage. The droop rate is
determined by the size of C
H
and the bias current of the AD820.
PRECISION THRESHOLD DETECTOR/AMPLIFIER
In Figure 33, when V
IN
< V
TH
, amplifier output swings negative,
reverse biasing diode D
1
. V
OUT
= V
TH
if R
L
= ∞. When V
IN
≥ V
TH
,
the loop closes.
(
)








+
−
+=
S
F
TH
IN
THOUT
R
R
V
V
VV
1
C
C
is selected to smooth the response of the loop.
–
+
OP177
0.1µF
+15V
R
S
1kΩ
R
1
2kΩ
R
F
100kΩ
0.1µF
–15V
2
3
7
6
4
00289-032
C
C
D
1
1N4148
V
OUT
V
TH
V
IN
Figure 33. Precision Threshold Detector/Amplifier